WO2005118253A1

WO2005118253A1 - Ejector or slide system

Info

Publication number: WO2005118253A1
Application number: PCT/EP2005/002012
Authority: WO
Inventors: Jörg Dantlgraber
Original assignee: Bosch Rexroth Ag
Priority date: 2004-06-04
Filing date: 2005-02-25
Publication date: 2005-12-15
Also published as: DE102004027280A1

Abstract

The invention relates to an ejector or slide system (1), especially for an injection molding machine or a like machine used in plastics processing. Said system comprises at least one ejector or slide which can be displaced from a withdrawn position to an ejection position by means of a drive. The ejector or an actuation element (10) of the ejector/slide is actuated hydraulically by subjecting the ejector/the actuation element to pressure from a high-pressure reservoir (HD) via a directional control valve (24).

Description

description

Ejector or slide arrangement

The invention relates to an ejector or slide arrangement for an injection molding machine according to the preamble of claim 1.

Usually, ejector or slide assemblies in injection molding machines are operated either purely mechanically, hydraulically or electronically with the aid of electrical drives and cooperate with tool-side ejectors to eject molded parts after injection molding and opening the tool, or operate slides to demold the undercut molded part can. In DE 101 21 024 AI of the applicant, an ejector arrangement is shown with FIGS. 27 to 30, in which the actuation of an ejector guided in a movable tool clamping plate takes place electromechanically. An ejector is connected to an axially displaceable spindle which is in engagement with a spindle nut which in turn is driven by an electric drive. By actuating the spindle nut, the ejector can be moved from its retracted position to its ejector position. Such a construction can also be used in slide arrangements or the like.

The disadvantage of this solution is that the electric drive with the drive motor Spindle nut and the spindle is very complex and therefore expensive and furthermore requires considerable storage space.

In contrast, the invention has for its object to provide an ejector or slide arrangement, in particular for an injection molding machine, which is compact with minimal outlay on equipment. This object is achieved by an ejector or slide arrangement with the features of claim 1.

According to the invention, the ejector or slide is actuated hydraulically by applying pressure from a high-pressure accumulator to it or to an actuating element connected to it.

Such a hydraulic solution can be implemented very inexpensively and in a space-saving manner. Another advantage over the mechanical or electromechanical constructions mentioned at the outset is that the hydraulic actuation is practically noiseless and extremely reliable.

In a particularly preferred exemplary embodiment, the high-pressure accumulator is charged via a pump, which charges the high-pressure accumulator as a function of a stroke of the injection molding machine.

In such a variant, it is preferred if this pump is designed as a plunger pump, which is actuated, for example, by the stroke of a movable platen of an injection molding machine and whose pumping chamber has a low-pressure accumulator via a suction valve and a pump valve via a High pressure accumulator is connected. This means that the hydraulic drive of the ejector / slide is designed as a closed circuit, pressure medium being sucked in from a low-pressure accumulator and fed to a high-pressure accumulator under pressure.

Such a hydraulic circuit does not require an external, electrically driven pump and can be integrated into the injection molding machine without the hydraulic function being recognizable from the outside.

The hydraulic connection of the high-pressure accumulator and the low-pressure accumulator to a pressure chamber accommodating the ejector / slide or its actuating element is preferably carried out via a proportionally adjustable directional valve which connects the low-pressure accumulator to the pressure chamber in a basic position and controls the connection to the high-pressure accumulator in its control positions.

To limit the maximum storage pressure, either a pressure relief valve can be provided, which opens a connection from the high pressure branch to the low pressure branch when a maximum pressure is reached, or a plunger or plunger cylinder of the plunger pump can be supported in the axial direction by a preloaded spring. This spring deflects when the intended maximum pressure is reached, so that a further pressure build-up is not possible.

The actuating element, the ejector and / or slide can be designed as a piston in a single-acting or double-acting cylinder, the piston being integrally connected to the slide / ejector or being indirectly operatively connected to it. Other advantageous developments of the invention are the subject of further dependent claims.

Preferred exemplary embodiments of the invention are explained in more detail below with the aid of schematic drawings. Show it:

Figure 1 is a functional diagram of an ejector arrangement of an injection molding machine and

FIG. 2 shows a variant of the ejector arrangement from FIG. 1.

FIG. 1 shows a functional diagram of the ejector arrangement 1 of an injection molding machine. This has a frame 2 on which a fixed

Tool platen 4 and a movable

Tool platen 6 are stored. The latter is guided displaceably via spars of the frame 2, which are not shown, and can be displaced via a locking unit, also not shown, which acts either mechanically (toggle lever), hydraulically (hydraulic cylinder), electromechanically or as a hybrid drive (electromechanically / hydraulically). This locking unit is supported on a support plate 8 of the frame 2.

In the exemplary embodiment shown, ejectors or slides of the tool are actuated via one or more actuating elements 10, which are mounted on the movable platen 6. In the exemplary embodiment shown, these actuating elements 10 have a single-acting cylinder 12, in which an ejector or piston with a piston collar 14 and a piston rod 16 is guided in an axially displaceable manner. In the annular space penetrated by the piston rod 16 a spring 18 is arranged, via which the ejector is biased into a basic position. In this basic position, the piston rod 16 is retracted into the platen 6 - the tool-side ejector or slide is not actuated.

The piston collar 14 and the cylinder 12 enclose a pressure chamber 20 which is connected via a pressure line 22 to an outlet port B of a proportionally adjustable directional valve 24. This is biased by a spring into a basic position in which the working connection B is connected to a working connection A. A low-pressure line 26 is connected to this, which opens into a suction line 28. This connects a low-pressure accumulator ND to a suction valve 29, which enables a pressure medium flow from the low-pressure accumulator ND to a line 31 connecting the outlet of the suction valve 29 to a connection of the plunger pump 30. This is connected via a branching line section to the input of a filling valve 40, the output of which is connected via a filling line 38 to a high-pressure accumulator HD. The filling valve 40 opens in the direction of the high-pressure accumulator HD.

The plunger pump 30 has a fixed plunger 32 which is supported on the support plate 8 and a plunger cylinder 34 which is mounted on the movable platen 6 and into which the plunger 32 is immersed. The plunger cylinder 34 and the plunger 32 delimit a pump chamber 36 which has a maximum volume in the closed position of the tool 38 indicated by the broken line. An input or pressure port P of the proportionally adjustable directional valve 24 is connected to the filling line 38 via a line 42. In the embodiment shown in FIG. 1, a pressure limiting line 44 branches off from the filling line 38 and leads to a section of the suction line 28 between the suction valve 29 and the low-pressure accumulator ND. A pressure limiting valve 46 is arranged in the pressure limiting line 44 and is acted upon in its closed position by the force of a spring and in its open position by the pressure in the filling line 38, which is tapped via a control line 48. The spring of the pressure relief valve 46 is set such that the high-pressure accumulator HD can be charged to a pressure sufficient for the function of the ejector.

When opening the tool 39 and thus when moving the movable platen 6 to the left in FIG. 1 via the electromechanical clamping unit (not shown), the plunger 32 plunges deeper into the pump chamber 36 so that pressure medium from this pump chamber 36 via the opening filling valve 40 in the high-pressure accumulator HD is promoted - the accumulator is charged. When the tool 39 is opened, the directional control valve 24 is controlled via a control unit of the injection molding machine in such a way that the ejector extends according to a predetermined path or force curve and in the process actuates the tool-side ejector to eject the molded part from the opened tool. The ejector is retracted into the platen 6 by switching the directional valve 24 into its basic position, in which the pressure chamber 20 is connected to the low-pressure accumulator ND via the pressure line 22, the directional valve 24 and the low-pressure line 26. The ejector is moved back into its illustrated basic position by the force of the spring 18, in which it does not, for example, on one shown stop is present. In the case of a double-acting cylinder 12, this return movement takes place hydraulically. During the opening movement of the movable tool clamping plate 6, the pump chamber 36 is reduced, so that the pressure in the pump chamber 36 increases with increasing opening travel and the high-pressure accumulator HD is charged via the filling valve 40 and the filling line 38. When the maximum pressure in the high-pressure accumulator HD is exceeded, the pressure-limiting valve 46 opens the connection between the filling line 38 and the suction line 29, so that the pressure peak is reduced to the low-pressure accumulator ND.

To close the tool 38, the clamping unit (not shown) is activated in the opposite direction, so that the tool clamping plate 6 moves to the right. Correspondingly, the pump chamber 36 is enlarged and pressure medium is drawn into the pump chamber 36 from the low-pressure accumulator ND via the suction line 28 and the suction valve 29. When the tool 39 is closed, an injection unit 50 which is displaceably mounted on the frame 2 of the injection molding machine with a screw 52, a screw drive 54 and a filling funnel 56 is brought into contact with a nozzle (not shown) in the fixed mold platen 4 and the homogenized melt is brought into the cavity of the closed tool 39 injected. After a holding pressure phase, the tool 39 is opened in the manner described above and the ejectors are actuated to eject the molded part - the cycle starts again. The very compact closed hydraulic circuit with only two comparatively small valves 24, 46 and the two memories HD, ND can be integrated very compactly into the injection molding machine. The proportionally controlled directional valve 24 makes it possible to control the stroke of the ejector or a slide in the predetermined manner, so that even complex tasks can be solved.

FIG. 2 shows an exemplary embodiment in which the hydraulic circuit of the ejector arrangement is further simplified.

The exemplary embodiment shown in FIG. 2 largely corresponds to the previously described exemplary embodiment and also has two memories HD, ND, which are connected to a connection of a plunger pump 30. As in the exemplary embodiment described above, the piston rod 16 of the ejector is extended by connecting the high-pressure accumulator HD via the proportionally adjustable directional valve 24 to the pressure chamber 20 of the cylinder 12. To relieve the pressure on the ejector, this pressure chamber 20 is connected to the suction line 28.

The only difference between the exemplary embodiments shown in FIGS. 1 and 2 is that the maximum pressure of the high-pressure accumulator HD in the

Embodiment according to Figure 2 not by a

Pressure relief valve 46 is limited but by a resilient support of the plunger 32 on the support plate 8. In the illustrated embodiment, the plunger 32 passes through the support plate and dips with a radially widened end section 58 into a spring chamber 60, in which a prestressed

Support spring 62 is supported, which engages the end portion 58 of the plunger 32. The pretensioning of the support spring 62 is selected such that when the maximum pressure in the pump chamber 36 of the plunger pump 30 is exceeded, the plunger 32 can deflect to the left against the force of the support spring 62 during the ascending movement of the movable tool clamping plate 6, so that this maximum pressure is not exceeded and thus the high pressure accumulator HD is protected against overload. Otherwise the function corresponds to

Ejector arrangement of that of the above

Embodiment, so that further explanations are unnecessary. As mentioned at the beginning, instead of the single-acting cylinder 12, a double-acting cylinder can also be used, in which the extension and retraction takes place by connecting the pressure chambers to the high-pressure accumulator HD or the low-pressure accumulator ND.

What is disclosed is an ejector or slide arrangement, in particular for an injection molding machine or another machine for processing plastics, with at least one ejector or slide, which can be moved from a retracted position into an ejector position via a drive. According to the invention, the ejector or an actuating element of the ejector / slide is actuated hydraulically by connecting it to pressure from a high-pressure accumulator via a directional valve. LIST OF REFERENCE NUMBERS

1 ejector arrangement

2 frames

4 fixed platen

6 movable platen

8 support plate

10 actuating element

12 cylinders

14 piston collar

16 piston rod

18 spring

20 pressure room

22 pressure line

24 way valve

26 low pressure line

28 suction line

29 suction valve

30 plunger pump

31 line

32 plungers

34 plunger cylinders

36 pump room

38 filling line

39 tools

40 filling valve

42 line

44 pressure relief line

46 Pressure relief valve

48 control line

50 injection unit

52 snail

54 worm drive

56 hopper

58 end section Spring chamber support spring

Claims

claims

1. ejector or slide arrangement, in particular for an injection molding machine, with at least one ejector or slide, which can be moved from a retracted position into an extended position by a drive, characterized in that the ejector / slide or an actuating element (10) of the ejector / Slider is slidably guided in a pressure chamber (20) which can be connected to a high-pressure accumulator (HD) via a directional valve (24) for extending.

2. Arrangement according to claim 1, with a pump (30) which charges the high-pressure accumulator (HD) as a function of a stroke of a drive unit.

3. Arrangement according to claim 2, wherein the pump is a plunger pump (30) which is actuated by a stroke of a movable platen (6) of an injection molding machine and the pump chamber (36) via a suction valve (29) with a low pressure accumulator (ND) and is connected to the high-pressure accumulator (HD) via a filling valve (40).

4. Arrangement according to claim 3, wherein the directional valve (24) is proportionally adjustable and in a basic position connects the pressure chamber (20) with the pump chamber (36) and controls the connection of the pressure chamber (20) to the high-pressure accumulator (HD) in its control positions.

5. Arrangement according to claim 3 or 4, wherein a plunger (32) or a plunger (34) Plunger pump (30) is supported in the axial direction via a prestressed support spring (62).

6. Arrangement according to claim 3 or 4, wherein a pressure relief valve (44) is provided between the high pressure branch and the low pressure branch.

7. Arrangement according to one of the preceding claims, wherein the ejector / slide or the actuating element as a piston (14, 16) is arranged in a single- or double-acting cylinder (12).