WO2016008151A1

WO2016008151A1 - Stretch blow molding cylinder and related method

Info

Publication number: WO2016008151A1
Application number: PCT/CN2014/082485
Authority: WO
Inventors: Xiaolin DENG; Jiqiang CHEN
Original assignee: Norgren, Inc.
Priority date: 2014-07-18
Filing date: 2014-07-18
Publication date: 2016-01-21

Abstract

A stretch cylinder (300) is provided that includes a barrel (101) and an actuatable stretch rod (102) that extends and retracts from the barrel (101). The stretch cylinder (300) further comprises a front end cover (308) and a rear end cover (310) that are attached to opposing ends of the barrel (101). An internal fluid conduit (306) with the barrel (101) fluidly connects the front end cover (308) to the rear end cover (310). At least one valve has a body defined by the front end cover (308).

Description

STRETCH BLOW MOLDING CYLINDER AND RELATED METHOD

FIELD OF THE INVENTION

The embodiments described below relate to power cylinders, and more particularly, to an improved stretch blow molding cylinder having internally integrated valves and fluid lines and related method.

BACKGROUND

Blow molding is a process for molding a preform part into a desired end product. The preform is in the general shape of a tube with an opening at one end for the introduction of pressurized gas, typically air; however, other gases may be used. One specific type of blow molding is stretch blow molding (SBM). In typical SBM applications, a valve block provides both low and high-pressure gas to expand the preform into a mold cavity. The mold cavity comprises the outer shape of the desired product. SBM can be used in a wide variety of applications; however, one of the most widely used applications is in the production of Polyethylene terephthalate (PET) products, such as drinking bottles. Typically, the SBM process uses a low-pressure fluid supply along with a stretch rod that is inserted into the preform to stretch the preform in a longitudinal direction and radially outward, and then uses a high-pressure fluid supply to expand the preform into the mold cavity. The low-pressure fluid supply, along with the stretch rod, is typically employedfor a pre-blowing phase of the molding cycle. The high-pressure fluid supply that expands the preform into the mold cavity is typically referred to as the blowing phase of the molding cycle. The low-pressure and high- pressure fluid supplies can be controlled using blow-mold valves. The resulting product is generally hollow with an exterior shape conforming to the shape of the mold cavity. The gas in the preform is then exhausted through one or more exhaust valves. This process is repeated during each blow molding cycle.

FIG. 1 shows an example of a prior art stretch cylinder 100. The stretch cylinderlOO can include a barrel 101, a stretch rod 102, a stretch rod control valve 103, and a blow-mold valve 104. In this prior art example, the stretch rod control valve 103 and the blow-mold valve 104 are shown as being coupled to the barrel 101, but in other examples, the valves 103, 104 are commonly separated from the barrel 101. The barrel 101 is typically adapted to form a substantially fluid-tight seal with a mold cavity 105. The barrel lOlmay also be adapted to form a substantially fluid-tight seal with the preform 1 1 1, which is positioned partially in the mold cavity 105 and in fluid communication with the blow-mold valve 104. A portion of the preform 1 1 1 is illustrated outside of the mold cavity 105, and coupled to the barrel 101. In other examples, the barrel 101 is coupled to the mold cavity 105 and the entire preform 1 1 1 is positioned within the mold cavity 105. It should be appreciated that the mold cavity 105 may be provided as a separate component provided by an end user, for example, and may not form part of the stretch cylinder 100. Therefore, the stretch cylinder 100 may be adapted to couple numerous different types of mold cavities 105 and performs 1 1 1.

With continued reference to the prior art assembly of FIG. 1, the stretch rod control valve 103 may, in some examples,comprise a proportional valve, and the blow- mold valve 104may also comprises a proportional valve. Proportional valves are generally known in the art and can operate to open a port of the valve at virtually any point between a fully open and fully closed position. Therefore, rather than simple on/off operation as in traditional valves, proportional valves are capable of maintaining an actuation state between fully on and fully off. Because of the simple on/off operation of traditional valves, many prior art blow molding systems utilize two or more pressurized fluid sources and associated on/off blow-mold valves.

Proportional stretch cylinders can operate with a single blow-mold valve 104 and a single pressurized gas source to pressurize the preform 1 1 1 and mold cavity 105. This is because a valve port in a proportional valve may be partially opened, for example. This is advantageous in situations where the valve is provided with a high input pressure and the desired output pressure is a pressure less than the input pressure. In such situations, the proportional valve can be partially opened, thereby restricting the fluid flow through the proportional valve. An example of a proportional valve is provided in PCT Publication WO/2009/018843, which is assigned to the present applicant, and provides a proportional spool valve, its contents being incorporated by reference herein, in its entirety.

A stretch cylinder 100 will typically undergo thousands or even millions of cycles in the course of the device's useful lifetime. Such a large scale of cycles renders the response time and speed of a cylinder's action important. Even differences in speed measured in secondssignificantly add up over time.

Therefore, there is a need for a stretch cylinder with an improved response time and improved speed. The embodiments described below overcome these and other problems and an advance in the art is achieved. The embodiments described below provide a stretch cylinderwith an airline integrated into the barrel. The embodiments described below also provide a cylinder having a control valve, quick exhaust valve, and check valve integrated into the cylinder end covers. The result is a stretch cylinder that exhibits an improved response time and improved speed while simplifying construction and lowering construction cost. Maintenance and related maintenance costs are also reduced.

SUMMARY OF THE INVENTION

A stretch cylinder with a barrel, a stretch rod actuatable from the barrel, a front end cover, and a rear end cover attached to opposing ends of the barrelis provided according to an embodiment. According to an embodiment, the stretch cylinder comprises: an internal fluid conduit within the barrel, wherein the internal fluid conduit fluidly connects the front end cover to the rear end cover; and at least one valve having a body defined by the front end cover.

A method of manufacturing a stretch cylinder is provided according to an embodiment. The method comprises the steps of: providing a barrel and an actuatable stretch rod that extends and retracts from the barrel; providing an internal fluid conduit with the barrel; attaching a front end cover and a rear end cover to opposing ends of the barrel, wherein the front end cover comprises at least one valve having a body defined by the front end cover; and fluidly connecting the front end cover to the rear end cover via the conduit.

A method of using a stretch cylinder is provided according to an embodiment. The method comprises the steps of: supplying a fluid supply to a front end cover, wherein the front end cover is attached to a barrel having an internal fluid conduit and an actuatable stretch rod that extends and retracts from the barrel; actuating a valve having a body defined by the front end cover to allow a fluid from the fluid supply to enter the barrel, wherein the front end cover is in fluid communication with a rear end cover via the internal fluid conduit; and exhausting the fluid from the fluid supply from a port defined by at least one of the front end cover and the rear end cover.

ASPECTS

According to an aspect astretch cylinder with a barrel, a stretch rod actuatable from the barrel, a front end cover, and a rear end cover attached to opposing ends of the barrel, comprises:

an internal fluid conduit within the barrel, wherein the internal fluid conduit fluidly connects the front end cover to the rear end cover; and at least one valve having a body defined by the front end cover.

Preferably, the stretch cylinder comprises at least one second valve having a body defined by the rear end cover.

Preferably, the internal fluid conduit comprises a conduit integrally formed with the barrel.

Preferably, the internal fluid conduit comprises a conduit formed by an extrusion of the barrel.

Preferably, the at least one valve comprises a stretch rod control valve.

Preferably, the stretch rod control valve comprises a 5/2 valve.

Preferably, the stretch rod control valve comprises a proportional valve.

Preferably, the stretch rod control valve comprises a first pilot valve input and second pilot valve input, wherein the second pilot valve input comprises a valve member having a greater cross-sectional area than a valve member with the first pilot valve input such that an equal fluid pressure applied to first and second pilot valve inputs, actuates the stretch rod control valve.

Preferably, a solenoid valve provides a pilot fluid to the second pilot valve input.

Preferably, the at least one valve comprises a quick exhaust valve.

Preferably, the at least one valve comprises a check valve.

Preferably, the at least one second valve comprises a quick exhaust valve.

Preferably, the at least one second valve comprises a check valve.

Preferably, the barrel and the stretch rod are at least one of pneumatic and hydraulic. Preferably, the at least one valve having a body defined by the front end cover comprises both a stretch rod control valve and a quick exhaust valve.

Preferably, the at least one valve having a body defined by the front end cover comprises both a stretch rod control valve and a check valve.

Preferably, the at least one valve having a body defined by the front end cover comprises a stretch rod control valve, a quick exhaust valve, and a check valve.

According to an aspect, a method of manufacturing a stretch cylinder comprises the steps of:

providing a barrel and an actuatable stretch rod that extends and retracts from the barrel;

providing an internal fluid conduit with the barrel;

attaching a front end cover and a rear end cover to opposing ends of the barrel, wherein the front end cover comprises at least one valve having a body defined by the front end cover; and

fluidly connecting the front end cover to the rear end cover via the conduit.

Preferably, the rear end cover comprises at least one valve having a body defined by the rear end cover, and wherein the at least one valve having a body defined by the rear end cover is in fluid communication through the internal fluid conduit with the at least one valve having a body defined by the front end cover.

Preferably, the step of providing an internal fluid conduit with the barrel comprises forming the conduit by an extrusion of the barrel.

Preferably, the at least one valve having a body defined by the front end cover comprises a control valve.

Preferably, the control valve comprises a 5/2 valve.

Preferably, the control valve comprises a proportional valve.

Preferably, the control valve comprises a first pilot valve input and a second pilot valve input, wherein the second pilot valve input comprises a valve member having a greater cross-sectional area than a valve member with the first pilot valve input such that an equal fluid pressure applied to the first and second pilot valve inputs actuates the control valve. Preferably, the method of manufacturing a stretch cylinder further comprises the step of providing a solenoid valve that provides a pilot fluid to at least one of the first and second pilot valve inputs.

According to an aspect, a method of using a stretch cylinder comprises the steps of:

supplying a fluid supply to a front end cover, wherein the front end cover is attached to a barrel having an internal fluid conduit and an actuatable stretch rod that extends and retracts from the barrel;

actuating a valve having a body defined by the front end cover to allow a fluid from the fluid supply to enter the barrel, wherein the front end cover is in fluid communication with a rear end cover via the internal fluid conduit; and

exhausting the fluid from the fluid supply from a port defined by at least one of the front end cover and the rear end cover.

Preferably, the internal fluid conduit with the barrel is formed by an extrusion of the barrel.

Preferably, the valve having a body defined by the front end cover comprises a control valve.

Preferably, the control valve comprises a 5/2 valve.

Preferably, the control valve comprises a proportional valve.

Preferably, the control valve comprises a first pilot valve input and a second pilot valve input, wherein the second pilot valve input comprises a valve member having a greater cross-sectional area than a valve member with the first pilot valve input such that an equal fluid pressure applied to the first and second pilot valve inputs actuates the control valve.

Preferably, the method of using a stretch cylinder further comprises the step of providing a solenoid valve that provides a pilot fluid to at least one of the first and second pilot valve inputs. Preferably, at least one second valve has a body defined by the rear end cover. Preferably, the internal fluid conduit is in fluid communication with a check valve.

Preferably, the step of exhausting the fluid from the fluid supply from a port defined by at least one of the front end cover and the rear end cover comprises a quick exhaust valve.

BRIEF DESCRIPTION OF THE DRAWINGS

The same reference number represents the same element on all drawings. The drawings are not necessarily to scale.

FIG. 1 illustrates a prior art stretch cylinder;

FIG. 2 illustrates a cross section of the prior art stretch cylinderof FIG. 1 ;

FIG. 3 illustrates a view of an embodiment of a stretch cylinder;

FIG. illustrates aview of a barrel according to an embodiment;

FIG. 5 is a schematic diagram of an embodiment of a stretch cylinder according to an embodiment;

FIG.6illustrates a view of a front end cover of a stretch cylinder according to an embodiment;

FIG. 7 illustrates a view of thefront end cover of a stretch cylinderof FIG. 6;

FIG. 8 illustrates an alternate view of arear end cover of astretch cylinderaccording to an embodiment;

FIG. 9 illustrates a view of an alternate rear end cover of a stretch cylinder according to an alternate embodiment; and

FIG. 10 illustrates a view of an alternate front end cover of a stretch cylinder according to an alternate embodiment.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1-10 and the following description depict specific examples to teach those skilled in the art how to make and use the best mode of embodiments of a stretch cylinder andrelated methods. For the purpose of teaching inventive principles, some conventional aspects have been simplified or omitted. Those skilled in the art will appreciate variations from these examples that fall within the scope of the invention. Those skilled in the art will appreciate that the features described below can be combined in various ways to form multiple variations of the invention. As a result, the invention is not limited to the specific examples described below, but only by the claims and their equivalents.

FIGS, land 2illustrate a prior art stretch cylinder 100. The stretch rod control valve 103 is adapted to control movement of the stretch rod 102 using pressurized fluid provided from a pressurized fluid source 1 13 via a fluid supply conduit 106. The pressurized fluid may comprise a liquid or a gas. For example, the stretch rod control valve 103 may be suitable for use as a pneumatic or a hydraulic valve. While the pressurized fluid provided to the stretch rod control valve 103 may be at any suitable pressure, typically the pressurized fluid source 1 13 is at a pressure between approximately 10 and 16 bar (145 and 232 psi). However, because the stretch rod control valve 103 comprises a proportional valve in some embodiments, the pressure of the fluid delivered to the barrel 101 may be at a pressure less than the pressurized fluid source 1 13. In other examples, the stretch rod control valve 103 comprises a traditional valve, in which case, the pressure supplied to the barrel 101 comprises approximately the same pressure supplied to the stretch rod control valve 103.

The blow-mold valve 104 is adapted to control a pressurized gas supply to/from the mold cavity 105. While the pressurized gas is typically air, other gases may be desired depending on the particular application. In the prior art example shown in FIG. 2, the pressurized gas is received by the blow-mold valve 104 from a high-pressure gas supply 1 14 via a pressurized fluid supply conduit 107. The pressurized gas supplied to the blow-mold valve 104 may be at a pressure around 40 bar (580 psi), for example, without limitation. Other pressures are certainly contemplated by the present invention.

Based on the blow-mold valve's position, the pressurized gas can be provided to the mold cavity 105 through an opening 108 defined between the preform 1 1 1 and the stretch rod 102. The conduits or other fluid communication paths between the valves 103, 104 and the barrel 101 are not shown in FIG. 2 in order to minimize the complexity of the drawing. As can be appreciated, because the blow-mold valve 104 in this example comprises a proportional valve, the fluid communication path formed in the valve 104 for providing the pressurized gas to the mold cavity 105 may be restricted, resulting in a decreased pressure being provided to the mold cavity 105. In an example utilizing electrically controlled valves, the stretch rod control valve 103 and the blow-mold valve 104 may be in electrical communication with one another. In the example shown, the two valves 103, 104 are in electrical communication via cable 109 (FIG. 1); however, the two valves 103, 104 could communicate via a wireless communication interface. Additionally, the two valves 103, 104 may be pneumatic or hydraulic, without the need for electricity or electrical connections.

Further shown in FIG. 1 is a cable 1 10, which provides an electrical communication interface between the stretch rod control valve 103 and a position sensor 230a-b (See FIG. 2) provided in the barrel 101. The position sensor 230a-b may provide a signal to the stretch rod control valve 103 indicating a position of the stretch rod 102 relative to the barrel 101, for example. Additionally shown in FIG. 1 is a cable 1 12. The cable 1 12 can provide an electrical communication interface between the blow-mold valve 104 and a valve controller, such as an external processing system (not shown).

In this prior art example, the cable 1 12 may also provide power to the valves 103, 104 if the valves are electrically actuated, such as for solenoid-controlled valves. The processing system may comprise a microprocessor, a CPU, or some other processing device. The processing system may be distributed among multiple devices. The processing system may include an internal and/or an external storage system. The processing system may include various valve set-points and stretch rod position set- points to accommodate various blow-molding applications. The processing system may include a user interface such as a monitor, keyboard, and mouse, etc., as is well known in the art. The processing system may allow a user or operator to control the valves 103, 104. Alternatively, each of the valves 103, 104 may include a programmable logic controller (PLC) (not shown) and the cable 1 12 can be provided to supply power to the valves 103, 104. The PLC may be provided to control the valve's solenoid and/or provide feedback to the valve's controller. In some embodiments, the use of a PLC may reduce the response time of the valves 103, 104 thereby providing increased accuracy. The PLC may provide an output signal to a user or operator via the cable 1 12.

FIG. 2 shows a cross-sectional view of a prior art stretch cylinder 100. The valves 103, 104 are shown schematically. Further, it should be appreciated that the electrical cablesl09, 1 10, 1 12 are not shown in FIG. 2 in order to simplify the complexity of the drawing. The stretch rod control valve 103 is in fluid communication with a first port 221 and a second port 222 formed in the barrel 101. A piston 202 separates the barrel 101 into a first chamber 231 and a second chamber 232. According to an embodiment of the invention, the piston 202 is coupled to the stretch rod 102. The piston 202 and stretch rod 102 may be movable within the barrel 101. The piston 202 may include a sealing member 203, which can provide a substantially fluid-tight seal between the piston 202 and the barrel 101. Further, the barrel 101 can include additional sealing members 250, 251, 252, which form substantially fluid-tight seals with the stretch rod 102. The sealing members 203 and 250-252 can prevent pressurized fluid from passing between chambers 231, 232 or from the second chamber 232 to the mold cavity 105. The first port 221 may be in fluid communication with the first chamber 231 and the second port 222 is in fluid communication with the second chamber 232. When pressurized fluid is provided to the first port 221, the first chamber 231 is pressurized thereby actuating the piston 202 and thus the stretch rod 102 in a first direction. Conversely, when pressurized fluid is provided to the second port 222, the second chamber 232 is pressurized, which actuates the piston 202 and thus the stretch rod 102 in a second direction, substantially opposite the first direction.

Also provided in FIG. 2, is the position sensor 230, which comprises a first sensor portion 230a coupled to the barrel 101 and a second sensor portion 230b coupled to the piston 202. Although not shown in FIG. 2, the first sensor portion 230a may be in communication with the stretch rod control valve 103 via the cable 1 10. The first portion of the position sensor 230a may also comprise one or more magnetic sensors while the second portion 230b comprises a magnet. One example of a position sensor that may be used with the present invention is disclosed in United States Patent 7,263,781, which is assigned to the applicants of the present invention. However, it should be appreciated that other position sensors— or no position sensor— may certainly be utilized with the present invention without departing from the scope of the invention.

The stretch rod control valve 103 may comprises a proportional valve. However, the stretch rod control valve 103 does not have to comprise a proportional valve and other types of valves may be used. In the example provided in FIG. 2, the stretch rod control valve 103 comprises a 5/3 proportional valve. The stretch rod control valve 103 may comprise a 5/3 proportional spool valve, for example. The stretch rod control valve 103 may comprise a solenoid-actuated proportional spool valve. A spring 265' or other biasing member may be provided to de-actuate the stretch rod control valve 103 or bring this valve 103 to a default position. A second solenoid (not shown) may be provided. According to the prior art example, in a de-actuated position, the stretch rod control valve 103 is closed. In a related example, in the de-actuated position, pressurized fluid is not provided to or exhausted from the first or second chambers 231, 232.

A solenoid 265 is used to open the stretch rod control valve 103 towards one or more actuated positions. Further, in embodiments where the stretch rod control valve 103 comprises a proportional valve, the solenoid 265 may be used to actuate the valve 103 to positions between a de-actuated position and a fully actuated position based on the set point signal provided to the solenoid 265. As mentioned briefly above, the set point signal may be provided by the processing system according to the desired operating parameters.

When the solenoid 265 actuates the stretch rod control valve 103 to a first actuated position, pressurized fluid is provided from a first port 103 a to a second port 103b. In the example shown, the first port 103a is adapted to receive a pressurized fluid. For example, the first port 103a is shown in fluid communication with the pressurized fluid source 1 13 while the second port 103b is in fluid communication with the first port 221 formed in the barrel 101 via fluid pathway 241. The first port 103a is selectively in fluid communication with the second port 103b when the stretch rod control valve 103 is opened towards the first actuated position. Further, pressurized fluid can be exhausted from the third port 103c to the fourth port 103d. Therefore, as the stretch rod control valve 103 is actuated towards the first actuated position, pressurized fluid is supplied from the pressurized fluid source 1 13 to the first chamber 231 and exhausted from the second chamber 232. It should be appreciated that when the stretch rod control valve is partially opened and between the de-actuated position and the first actuated position, the fluid communication path between the first port 103a and the second port 103b is only partially opened. Thus, less than the full pressure is provided to the first port 103a of the stretch rod control valve 103 from the pressurized fluid source 1 13 is delivered to the second port 130b of the stretch rod control valve 103. Additionally, prior to fully reaching the first actuated position, the fluid communication path between the third port 103c and the fourth port 103d is not fully opened and therefore, the fluid exhausted from the second chamber 232 is limited. Advantageously, if only a small movement of the stretch rod 102 is desired, the stretch rod control valve 103 can be actuated to a position between the de-actuated position and the first actuated position and only partially opened. Of course, partial positioning of the valve is only applicable to examples having a proportional valve arrangement.

When the stretch rod control valve 103 is actuated and opened towards a second actuated position, the first port 103a is brought into fluid communication with the third port 103c and the second port 103b is brought into fluid communication with the fifth port 103e, which comprises an exhaust. Therefore, when the stretch rod control valve is opened towards the second actuated position, the stretch rod control valve 103 provides pressurized fluid to the second chamber 232 and exhausts the first chamber 231 to move the piston 202 and thus, the stretch rod 102 in a second longitudinal direction.

Also shown schematically in FIG. 2 is the blow-mold valve 104. As briefly discussed above, the blow-mold valve 104 may comprise a proportional valve. According to the example shown, the blow-mold valve 104 comprises a solenoid- actuated proportional valve with a solenoid 266; however, in other embodiments, the blow-mold valve 104 could be fluid actuated. In the embodiment shown, a spring 266' or other biasing member is provided to bias the blow-mold valve 104 to a de-actuated or default position. However, in other embodiments, a second solenoid (not shown) could be provided. The blow-mold valve 104 may comprise a proportional spool valve, for example. According to the embodiment shown, the blow-mold valve 104 comprises a 3/3-way proportional spool valve. In examples where the blow-mold valve 104 comprises a 3/3-way valve, a separate exhaust valve is not required and the blow-mold valve 104 can pressurize the mold cavity 105 as well as exhaust the mold cavity 105. However, in other examples, a separate exhaust valve may be provided to exhaust the mold cavity 105 at the end of a molding cycle. Further, it should be understood that the blow-mold valve 104 is not limited to a 3/3 valve, but rather other valves may be utilized such as a 3/2, a 2/2, etc. According to an embodiment of the invention, when the blow-mold valve 104 is in a de-actuated position, the valve is closed and pressurized gas is not provided to the mold cavity 105 or exhausted from the mold cavity 105. In other embodiments, such as for example, when the blow-mold valve 105 comprises a 3/2-way valve, a second port 104b may be open to exhaust when the blow-mold valve 104 is in a de-actuated position.

When the blow-mold valve 104 is actuated towards a first actuated position using the solenoid 266, for example, a first port 104a is in fluid communication with the second port 104b, thereby providing pressurized gas to a third port 223 formed in the barrel 101. The third port 223 formed in the barrel 101 may be in fluid communication with a preform 1 1 1 or mold cavity 105 when the barrel 101 is coupled to the preform 1 1 1 or mold cavity 105. Therefore, when the blow-mold valve 104 is in a first actuated position, the pressurized gas provided to the first port 104a from the pressurized gas source 1 14is provided to the mold cavity 105. It should be appreciated that prior to the blow-mold valve 104 fully reaching the first actuated position, the pressure of the gas provided to the second port 104b, and thus the mold cavity 105, is less than the pressure supplied to the first port 104a. This is because the fluid communication path between the first port 104a and the second port 104b is only partially opened, thereby restricting flow through the blow-mold valve 104 and creating a pressure drop. The amount of the pressure drop may depend on the precise position of the blow-mold valve 104 in combination with the pressure of the pressurized gas source 1 14. The position of the blow-mold valve 104 can be determined based on the set point signal received by the solenoid 266, for example. The set point signal may be received from a controller (not shown) or a PLC (not shown) associated with the blow-mold valve 104, as discussed above. When the blow-mold valve 104 is opened towards a second actuated position, the third port 223 and thus, the mold cavity 105 is exhausted through the second port 104b and the third port 104c. It should be appreciated that when the blow-mold valve 104 is between the de-actuated position and the second position, the fluid communication path between the second port 104b and the third port 104c may not be fully open. Therefore, the rate at which the mold cavity 105 can exhaust will be less than when the blow-mold valve 104 has fully reached the second actuated position. This prior art blow mold system is described as background for the present embodiments. Features with the same or similar function are designated in the specification and figures with common numbering for consistency and clarity.

FIG. 3 illustrates a stretch cylinder 300 according to an embodiment. Unlike prior art devices, the embodiment provides a stretch rod control valve 103, a quick exhaust valve 302, a check valve 304, and fluid conduit 306 (see FIG. 4) that are integrated into the barrel 101 and/or end covers 308, 310.

In an embodiment, the fluid conduit 306 is integrated into the barrel 101. FIG. 4 illustrates an extrusion formed as a barrel 101 wherein the fluid conduit 306 is integrally formed with the material from which the barrel 101 is made. In an embodiment, the barrel is made from a metal that comprises aluminum, for example, without limitation. The fluid conduit 306 is formed as part of the extrusion process, but may alternatively be drilled, milled, cast formed, or formed through any manner known in the art. A seal 312, such as an O-ring for example, without limitation, is disposed between each end of the fluid conduit 306 and each end cover 308, 310 so that a fluid-tight seal is made between the fluid conduit 306 and the valves integrated into the end covers 308, 310. The barrel 101 may be round, square, polygonal, and/or comprise sharp or rounded edges, have concavities and/or convex regions, and/or combinations thereof.

Turning back to FIG. 3, a front end cover 308 is attached to a front end of the barrel 101, and a rear end cover 310 is attached to a second end of the barrel 101. In an embodiment, the front end cover 308 comprises a stretch rod control valve 103 and quick exhaust valve 302, while the rear end cover 310 comprises the check valve 304. In another embodiment, the control vale 103 and check valve 304 are located in the rear end cover 310, while the exhaust valve 302 is in the front end cover 308. In yet another embodiment, the stretch rod control valve 103, check valve 304, and quick release valve 302 are located in either the front or rear end cover 308, 310. In another embodiment, a solenoid valve is located in at least one of the end covers 308, 310.

FIG. 5 illustrates an embodiment of a valve diagram according to an embodiment. For clarity, a number of features are not shown, but will be apparent to those skilled in the art. In one embodiment, a fluid supply 502 is attached to a first port 103adefined by the front end cover 308 or the rear end cover 310 (depending on where the stretch rod control valve 103 is located). The first port 103a is a fluid path with the stretch rod control valve 103. In an embodiment, the stretch rod control valve 103 is a proportional valve, but thestretch rod control valve 103 does not have to comprise a proportional valve and other types of valves may be used. In an embodiment, the stretch rod control valve 103 comprises a 5/2 valve. The stretch rod control valve 103 may comprise a spool valve. The stretch rod control valve 103 may comprise a 5/2 proportional valve, for example. The stretch rod control valve 103 may comprise a solenoid-actuated proportional valve. A spring 265' (see FIG. 2 for example) or other biasing member may be provided to de-actuate the valve 103 or bring the valve 103 to a default position. A second solenoid 504 valve may be provided, and incorporated within an end cover 308, 310. A second solenoid 504 valve may be provided, and connected to the stretch rod control valve 103 remotely. The second solenoid valve 504 is used to open the stretch rod control valve 103 towards one or more actuated positions. In an embodiment, when the second solenoid valve 504 is in a de-actuated position (see as illustrated in FIG. 5), the stretch rod control valve 103allows fluid to pass from the first port 103a to a second port 103b— also incorporated within an end cover 308, 310. In this de-actuated position,pressurized fluid is provided to the second chamber 232, which causes the stretch rod 102 to retract and be maintained in a retracted state.

Pilot lines 506, 508 are in fluid communication with the fluid supply 502. The first pilot line 506 is in communication with a first pilot valve input 510 with the stretch rod control valve 103. When the solenoid valve 504 is actuated, fluid from the fluid supply line 514 passes through a first port 504a of the solenoid valve 504 to a second port 504b of the solenoid valve 504. This allows fluid to travel through the second pilot line 508 to a second pilot valve input 512. In an embodiment, the second pilot valve input 512 is proximate a valve member (not shown) having a greater cross-sectional area than a valve member (not shown) proximate thefirst pilot valve input 510, so an equal pressure applied to both pilot valves 510, 512 will cause the stretch rod control valve 103 to actuate.

When the stretch rod control valve 103 is actuated, fluid from the fluid supply 502 enters the first port 103a, and travels to a third port 103c (defined by an end cover 308, 310)that connects to the fluid conduit 306, thus fluidly connecting the fluid source 502 with the check valve 304 and the first chamber 231. This causes the stretch rod 102 to actuate and extend from the barrel 101. Fluid pressure with the second chamber 232 is exhausted via the front end cover 308 through the quick exhaust valve 302. The quick exhaust valve 302, which, in general, is well known in the art, allows the second chamber 232 to fill with fluid, but when a rapid loss in pressure associated with the second port 103b is experienced, the imbalance in pressure between the first port 302a and 302b causes the quick release valve 302 to open an exhaust port 302c, which allows rapid exhausting of the fluid pressure within the second chamber 232. A silencer 516 in fluid communication with the exhaust port 302c may be installed to reduce the sound associated with such rapid system purging.

With the stretch rod 102being in an extended position, when the solenoid valve

504 is de-actuated, fluid from the fluid supply 502 is cut off from the second pilot line 508 and the first pilot valve input 510 bias overcomes the bias imposed by the second pilot valve input 512. Fluid in the second pilot line 508 is exhausted through the second port 504b and through the solenoid valve 504 to exit through a third port 504c and optionally out through a silencer 516. At the same time, the first port 103a of the stretch rod control valve 103 is placed in fluid communication with the second port 103b. This allows fluid from the fluid supply 502 to reach the second chamber 232. Additionally, the third port 103c is placed in fluid communication with a fourth port 103d. This allows fluid from the first chamber 231 to escape the barrel 101. The check valve 304 is oriented such that fluid flow from the first chamber 231 to the stretch rod control valve 103 is restricted so to provide fluid cushioning, and fluid passing through the fluid conduit 306 that exits via the fourth port 103d passes through a needle valve 518, which may be adjustable. The exhausting of the first chamber 231 through the needle valve 518 serves as means for metered cylinder speed control.

FIGS. 6-8 illustrate the front 308 (FIGS. 6 and 7) and rear 310 (FIG. 8) end covers. In an embodiment the end covers 308, 310 are constructed at least partially from a metal, such as aluminum, steel, or stainless steel, for example, without limitation. Turning to FIGS. 6 and 7, the front end cover 308 is constructed so that a first face 602 is configured to engage the barrel 101, and comprises a plurality of orifices. For example, the third port 103c is positioned to fluidly engage the fluid conduit 306 of the barrel 101. In the embodiment illustrated, a seat is formed with the third port 103c to accept a seal 312, such as an O-ring for example. The first face 602 also comprises the quick exhaust port 302c and first port 103a. A bore 604 that allows the stretch rod 102 to pass therethrough is disposed on the first face 602. FIG. 8 illustrates an embodiment of the rear end cover 310, and also illustrates a bore 702 that accommodates the stretch rod 102. An orifice 704 that accommodates the check valve 304 is disposed in the rear end cover 310. Similarly, a passage 706 fluidly connects the rear end cover 310 to the fluid conduit 306 of the barrel 101. Additionally, in an embodiment, an orifice 710 is provided that provides fluid flow for an adjustable cushion with the stretch cylinder 300. Of course, these are just exemplary orientations, and it will be clear to one skilled in the art that alternate positions or placement on alternate faces of an end cover 308, 310 are possible, and contemplated by the present disclosure. As an example, FIGS. 9 and 10 illustrate alternate embodiments of the end covers 308a, 310a wherein the front end cover 308a comprises only an exhaust valve 302, while the rear end cover 310a comprises the check valve 304 and stretch rod control valve 103. In an embodiment, either the front end cover 308 or rear end cover 310 comprises the stretch rod control valve 103, quick exhaust valve 302, and check valve 304.

The detailed descriptions of the above embodiments are not exhaustive descriptions of all embodiments contemplated by the inventors to be within the scope of the invention. Indeed, persons skilled in the art will recognize that certain elements of the above-described embodiments may variously be combined or eliminated to create further embodiments, and such further embodiments fall within the scope and teachings of the invention. It will also be apparent to those of ordinary skill in the art that the above-described embodiments may be combined in whole or in part to create additional embodiments within the scope and teachings of the invention.

Thus, although specific embodiments of, and examples for, the invention are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize. The teachings provided herein can be applied to other devices and method, and not just to the embodiments described above and shown in the accompanying figures. Accordingly, the scope of the invention should be determined from the following claims.

Claims

What is claimed is:

1. A stretch cylinder (300)with a barrel (101), astretch rod (102)actuatablefrom the barrel (101), a front end cover (308), and a rear end cover (310) attached to opposing ends of the barrel (101), comprising:

an internal fluid conduit (306) within the barrel (101), wherein the internal fluid conduit (306) fluidly connects the front end cover (308) to the rear end cover (310); and

at least one valve having a body defined by the front end cover (308).

2. The stretch cylinder (300) of Claim 1, further comprising at least one second valve having a body defined by the rear end cover (310).

3. The stretch cylinder (300) of Claim 1, wherein the internal fluid conduit (306) comprises a conduit integrally formed with the barrel (101).

4. The stretch cylinder (300) of Claim 1, wherein the internal fluid conduit (306) comprises a conduit formed by an extrusion of the barrel (101).

5. The stretch cylinder (300) of Claim 1, wherein the at least one valve comprises a stretch rod control valve (103).

6. The stretch cylinder (300) of Claim 5, wherein the stretch rod control valve (103) comprises a 5/2 valve.

7. The stretch cylinder (300) of Claim 5, wherein the stretch rod control valve (103)comprises a proportional valve.

8. The stretch cylinder (300) of Claim 5, wherein the stretch rod control valve (103) comprises a first pilot valve input (510) and second pilot valve input (512), wherein the second pilot valve input (512) comprises a valve member having a greater cross- sectional area than a valve member with the first pilot valve input (510) such that an equal fluid pressure applied to first and second pilot valve inputs (510, 512) actuates the stretch rod control valve (103).

9. The stretch cylinder (300) of Claim 8, wherein a solenoid valve (504)provides a pilot fluid to the second pilot valve input (512).

10. The stretch cylinder (300) of Claim 1, wherein the at least one valve comprises a quick exhaust valve(302).

1 1. The stretch cylinder (300) of Claim 1, wherein the at least one valve comprises a check valve(304).

12. The stretch cylinder (300) of Claim 2, wherein the at least one second valve comprises a quick exhaust valve(302).

13. The stretch cylinder (300) of Claim 2, wherein the at least one second valve comprises a check valve(304).

14. The stretch cylinder (300) of Claim 1, wherein the barrel (101) and the stretch rod (102)are at least one of pneumatic and hydraulic.

15. The stretch cylinder (300) of Claim 1, wherein the at least one valve having a body defined by the front end cover (308) comprises both a stretch rod control valve (103) and a quick exhaust valve (302).

16. The stretch cylinder (300) of Claim 1, wherein the at least one valve having a body defined by the front end cover (308) comprises both a stretch rod control valve (103) and a check valve (304).

17. The stretch cylinder (300) of Claim 1, wherein the at least one valve having a body defined by the front end cover (308) comprises a stretch rod control valve (103), a quick exhaust valve (302), and a check valve (304).

18. A method of manufacturing a stretch cylindercomprising the steps of:

providing an internal fluid conduit with the barrel;

attaching a front end cover and a rear end cover to opposing ends of the barrel, wherein the front end cover comprises at least one valve having a body defined by thefront end cover; and

fluidly connecting the front end cover to the rear end covervia the conduit.

19. The method of manufacturing a stretch cylinderof claim 18, whereinthe rear end cover comprises at least one valve having a body defined by the rear end cover, and wherein the at least one valve having a body defined by the rear end cover is in fluid communication through the internal fluid conduit with the at least one valve having a body defined by the front end cover.

20. The method of manufacturing a stretch cylinder of claim 18, wherein the step of providing an internal fluid conduit with the barrel comprises forming the conduit by an extrusion of the barrel.

21. The method of manufacturing a stretch cylinder of claim 18, wherein the at least one valve having a body defined by the front end cover comprises a control valve.

22. The method of manufacturing a stretch cylinder of claim 21, wherein the control valve comprises a 5/2 valve.

23. The method of manufacturing a stretch cylinder of claim 21, wherein the control valve comprises a proportional valve.

24. The method of manufacturing a stretch cylinder of claim 21, wherein the control valve comprises a first pilot valve input and a second pilot valve input, wherein the second pilot valve input comprises a valve member having a greater cross-sectional area than a valve member with the first pilot valve input such that an equal fluid pressure applied to the first and second pilot valve inputsactuates the control valve.

25. The method of manufacturing a stretch cylinder of claim 24, further comprising the step of providing a solenoid valve that provides a pilot fluid to at least one of the first and second pilot valve inputs.

26. A method of using a stretch cylinder comprising the steps of:

supplying a fluid supply to a front end cover, wherein the front end cover is attached to a barrelhaving an internal fluid conduit and anactuatable stretch rod that extends and retracts from the barrel;

27. The method of using a stretch cylinder of claim 26, wherein the rear end cover comprises at least one valve having a body defined by the rear end cover, and wherein the at least one valve having a body defined by the rear end cover is in fluid communication through the internal fluid conduit with the at least one valve having a body defined by the front end cover.

28. The method of using a stretch cylinder of claim 26, wherein the internal fluid conduit with the barrelis formed by an extrusion of the barrel.

29. The method of using a stretch cylinder of claim 26, wherein the valve having a body defined by the front end cover comprises a control valve.

30. The method of using a stretch cylinder of claim 29, wherein the control valve comprises a 5/2 valve.

31. The method of using a stretch cylinder of claim 29, wherein the control valve comprises a proportional valve.

32. The method of using a stretch cylinder of claim 29, wherein the control valve comprises a first pilot valve input and a second pilot valve input, wherein the second pilot valve input comprises a valve member having a greater cross-sectional area than a valve member with the first pilot valve input such that an equal fluid pressure applied to the first and second pilot valve inputs actuates the control valve.

33. The method of using a stretch cylinder of claim 32, further comprising the step of providing a solenoid valve that provides a pilot fluid to at least one of the first and second pilot valve inputs.

34. The method of using a stretch cylinder of claim 26, wherein at least one second valve has a body defined by the rear end cover.

35. The method of using a stretch cylinder of claim 26, wherein the internal fluid conduit is in fluid communication with a check valve.

36. The method of using a stretch cylinder of claim 26, wherein the step of exhausting the fluid from the fluid supply from a port defined by at least one of the front end cover and the rear end cover comprises a quick exhaust valve.