WO1998006519A1

WO1998006519A1 - Expansion machine with a return device

Info

Publication number: WO1998006519A1
Application number: PCT/EP1997/004366
Authority: WO
Inventors: Friedrich Imgram
Original assignee: Wirsbo Rohrproduktion Und Vertriebs-Gmbh
Priority date: 1996-08-13
Filing date: 1997-08-12
Publication date: 1998-02-19
Also published as: DE29613985U1; AU4298497A

Abstract

An expansion machine with a housing (1) allowing for the axial movement of hydraulic or mechanical control members for an expansion cone (4) is disclosed. An expansion chuck (5) is made of a number of spreader members (9) defining a partially tapered opening (6), which the expansion cone (4) runs into. The axial forward motion of the expansion cone makes the spreader members go radially apart and slide against a pretension at a housing end. The control members are connected to the expansion cone. The return members, composed preferably of spring washers, bear, when loosened, against a control member stop (25) and an expansion cone front side (7); when stressed, the spring washers are squeezed between the limit stop and the inner shoulder (28) of the housing.

Description

Spreading tool with return device

The invention relates to a spreading tool containing

a generally cylindrical expanding mandrel with an at least partially conical inner bore, which is composed of a plurality of cylindrical sector-shaped expanding members,

Holding parts on the outer circumference of the cylindrical sector-shaped expansion members and prestressing means acting on the holding parts,

a housing with a guide in which the holding parts are guided in a radially displaceable manner,

an expanding cone which engages in the at least partially conical inner bore of the expanding mandrel, and

Actuator for the expanding cone

Such a spreading tool is described in the unpublished, older German patent application 195 04 868.3 and is used for the reversible widening of the ends of plastic tubes which are to be connected firmly and sealingly to a connecting part such as a pipe end or a pipe connector.

With the expansion tool described above, pressure-actuated actuators contain a double-acting piston-cylinder unit. As a result, the technical setup of the spreading tool is relatively complex. The object of the invention is to provide a spreading tool of the aforementioned type which fulfills the same purpose with less effort.

According to the invention, this object is achieved in that return means are provided between the actuating means and the expansion cone, which are preferably designed as return springs, in particular as disc springs.

In this way, the spreading tool is designed to be less expensive in terms of technology and price, without impairing its functionality.

Such a spreading tool serves for the reversible widening of the ends of plastic tubes, which can be firmly and sealingly connected to another tube or a tube connector during jerk deformation, cf. generally DE-OS 38 16 442, DE-OS 42 20 784, DE-Gb 84 04 512 and EP-A-0 618 142.

Advantageously, the expansion tool according to the invention is designed such that the expansion members have a recess between their free end and their holding part, which extends along the circumference of the expansion members. It is thereby achieved that the respective pipe end in the area of the recesses is widened uniformly with good approximation and the gaps running along the circumference, which form when the expanding mandrel is spread between the expansion members, have little or no influence on the expansion in the region of the recess. The lower widening of the pipe end applied to the expanding mandrel in the region of the recess prevents the application of the Pipe end on the respective connecting part not or only slightly. Rather, this less widened area of the pipe end comes evenly into contact with the outer surface of the respective connecting part, as a result of which the desired firm and sealing connection is ultimately ensured.

In an advantageous further development, the recess can also accommodate a ring made of an elastic material, a material that is self-deformable at room temperature, or a material that is comparable in terms of the deformation to that of the pipe end to be expanded. This not only facilitates the application of the widened pipe end to the respective connecting part, but also provides a restoring force for the expansion members after the expansion cone has been withdrawn.

It is particularly advantageous if the expanding tool is used with connecting parts, the connecting parts of which have at least one sealing edge, and if the at least one recess is aligned with the at least one sealing edge. The recess on the expansion members can be arranged symmetrically to the sealing edge on the connecting part. With such a configuration of the expanding mandrel, the area of the pipe end, which is widened less uniformly but substantially in the circumferential direction, undergoes an expansion and self-jerk deformation at the transition over the sealing edge of the connecting part. This ensures that at least this area of the pipe end comes into firm and sealing contact with the connecting part on both sides of the sealing edge and thus a firm and sealing connection is formed overall. An exemplary embodiment of the expanding tool according to the invention is shown in the figures and is explained and described in detail below with reference to the reference numerals. Show it

1 shows a longitudinal section through the embodiment of the expanding tool according to the invention;

2 shows a cross section through the expanding tool according to FIG. 1 along the line II-II;

FIG. 3 shows a view of a connecting part for use with the expanding tool according to FIG. 1; and

4 shows a cross section through a modified design of the expanding mandrel in the expanding tool according to FIG.

FIG. 1 shows a long section of an exemplary embodiment of an expanding tool with a housing 1, which has actuating means actuated by pressure medium in the form of a single-acting piston-cylinder unit with a cylinder 2 and a piston 3 at one end, the piston 3 with an expanding means in the form of an expanding cone 4 cooperates. Instead of the pressure medium-actuated piston 3, other, for example mechanical, actuating means can also be provided. The pressure medium can be supplied to the housing 1 axially or radially. The housing 1 can be provided with holding means which allow it to be held during operation, and it is designed in such a way that it can also be used for overhead work. In the opposite end of the housing 1, a generally cylindrical expanding mandrel 5 is attached. This expanding mandrel 5 contains a conical inner bore 6 which, in the exemplary embodiment shown, extends from an inner end face 7 over the entire length of the expanding mandrel 5. The inner bore 6 can also be designed so that it extends only over part of the length of the expanding mandrel 5 and merges into a cylinder bore that opens into the free end of the expanding mandrel 5. At the free end, the expanding mandrel 5 is provided with a chamfer 8, which can run at an angle of 5 ° to 20 ° to the peripheral surface of the expanding mandrel 5 and is preferably provided with rounded edges. The chamfer 8 prevents damage to the inner wall of the pipe end into which the expanding mandrel 5 is inserted for expansion.

The expanding mandrel 5 is divided several times in the longitudinal direction and consists of a number of cylindrical sector-shaped expansion members 9; in the illustrated embodiment, cf. Figure 2, the expanding mandrel 5 is divided into eight expansion members 9. In the idle state or the unactuated state of the spreading tool, the spreading members 9 lie against one another in the circumferential direction and thus form a generally cylindrical outer surface.

At the inner end of the expanding mandrel 5 or at the inner ends of the expanding members 9, a thickening 10 is formed, from which holding parts extend, by means of which the expanding mandrel 5 is exchangeably held in the housing 1. In particular, each holding part consists of an arm 11 projecting radially from the periphery of the thickening 10, on the periphery of which a receptacle 12 is provided for a prestressing means, which for example forms an annular spring 13. The ring spring 13 loaded acts a radially inward bias on the expansion members 9, whereby these are held in mutual contact in the unactuated state of the expanding mandrel 5 and the generally cylindrical shape of the expanding mandrel 5 is formed. The radially projecting arms 11 are mounted in the associated end face of the housing 1 so as to be radially displaceable in a guide composed of a holding plate 14 and a bearing plate 15. The guide can contain a sliding element 16 between the radial arms 11 and the holding plate 14 and / or the bearing plate 15; the surfaces of the holding plate 14 and the bearing plate 15 can instead be provided with incisions 17 in the adjustment region of the radial arms 11, as a result of which the surface adhesion between the parts in contact is reduced and their adjustability is improved. The holding plate 14 is detachably fastened by screws to the end face of the housing 1, so that the expansion members 9 or the expanding mandrel 5 are arranged interchangeably in the end face of the housing 1 by means of the radial arms 11 and the holding plate 14.

Between the thickening 10 and the chamfer 8 of the expanding mandrel 5 there is a recess 18 on each expanding member 9, which forms a circumferential groove when the expanding mandrel 5 is not actuated. The edges of the cutouts 18 are preferably beveled in order to avoid damage to pipe ends when the expanding mandrel 5 is inserted.

The spreading tool described above includes return means with which the expansion cone can be brought 4 after spreading from the inner bore 6 of the expanding mandrel 5 ^¬ back. For this purpose, the piston 3 is provided with an extension 19 on the end facing the expansion cone 4, forming a shoulder 25, on which Return means are located, which in the illustrated embodiment are formed by disc springs 26, for which the shoulder 25 forms an abutment. The free end of the extension 19 is screwed into a threaded bore 27 so that the piston 3 and the expansion cone 4 are connected to one another in the interior of the housing 1. In this embodiment, the disc springs 26 are located between the shoulder 25 on the piston 3 and the inner end face 7 of the expansion cone 4. The displacement path of the expansion cone 4 and the expansion of the expansion mandrel 5 are achieved by the disc springs 26 bearing against an inner shoulder 28 of the housing 1 and the compression of the plate springs 26 limited. If desired, this displacement path can be reduced by a spacer sleeve which is placed on the extension 19 between the plate springs 26 and the inner end face 7 of the expansion cone 4.

In the exemplary embodiment shown, the mechanically highly stressed parts, such as the expanding cone 4 and the expanding members 9 of the expanding mandrel 5, are made from high-quality tool steel. In this way, on the one hand, the occurrence of friction and seizure points between the parts acting on one another and, on the other hand, deformation of the tension members 9 is avoided with high expansion forces.

In the upper half of Figure 1, the spreading tool is shown in the idle state. In this state, the pressure-actuated piston 3 and also the expansion cone 4 connected to it via the extension 19 are withdrawn, the plate springs 26 are relaxed. The expanding cone 4 is located in the conical inner bore 6 of the expanding mandrel 5 in a position in which no axially directed force on the Expanding mandrel 5 is exercised. The expansion members 9 are in mutual contact, and the expansion mandrel 5 forms the generally cylindrical body shown in FIG.

When the single-acting piston-cylinder unit 2, 3 is pressurized, the piston 3 and also the expansion cone 4 connected to it via the extension 19 are displaced within the inner bore 6 against the expansion mandrel 5. This displacement takes place up to the point at which the plate springs 26 come to rest on the inner shoulder 28 of the housing 1 and the plate springs 26 between the shoulder 25 on the piston 3 of the pressure-actuated piston-cylinder unit 2, 3 and the inner shoulder 28 of the housing 1 be excited. The lower half of FIG. 1 shows the piston 3 and the expansion cone 4 in the end position of their displacement path, in which the maximum expansion of the expansion mandrel 5 is achieved and a pipe end into which the expansion mandrel 5 is inserted until it contacts the thickening 10 is expanded .

After expansion, the piston-cylinder unit is relieved of the pressure medium pressure applied. As a result, the prestressed disk springs 26 can act on the shoulder 25 of the piston 3 in such a way that the piston 3 and the expansion cone 4 connected to its extension 19 are withdrawn from the inner bore 6 of the expanding mandrel 5 until the disk springs 26 are released. This displacement path is sufficient to loosen the expansion members 9 from the inner wall of the widened tube end to such an extent that the tube end can be easily removed from the expanding mandrel. 5 can be removed. Thereafter, the piston 3 together with the expansion cone 4 can be easily moved back into the rest position shown in the upper half of FIG. 1. When the pipe end is widened, the expansion members 9 act on the inner wall of the pipe end, which is applied to the expanding mandrel up to the stop on the thickening 10. The inner wall of the pipe end only comes into contact in the peripheral area of the expansion members 9, but not in the area of the gaps that develop between the adjacent expansion members 9 during the expansion process. This creates axially extending, inwardly projecting ribs on the inner wall of the pipe end. In addition, the inner wall of the pipe end does not abut the expansion members 9 in the region of the cutouts 18. In this way, an inwardly projecting region or web of a height that is determined by the depth of the recess 18 also arises on this inner wall.

The importance of the recess 18 and the web thus formed on the inner wall of the widened tube end can be seen in view of the connecting part with which the widened tube end connects by self-jerking if the tube end consists, for example, of medium-density, high-density or cross-linked polyolefin. Such a connecting part can be designed, for example, like the pipe connector according to G 94 04 512 and is shown in longitudinal section in FIG. 3. This pipe connector 20 forms a straight piece of pipe, which has connecting parts 21 at opposite ends. For connection to a widened pipe end, each connecting part 21 contains a holding element 22, which gradually falls to the free end of the pipe connector 20 and defines a sealing edge 24, which drops steeply to the other side. The recesses 18 of the expansion members 9 are aligned with the axial position of the sealing edge 24 on the connecting part 21, to which the reversibly widened pipe end is applied. The recesses 18 are preferably arranged symmetrically to the sealing edge 24, so that the webs remaining on the circumference of the inner wall of the pipe end after its widening are likewise formed symmetrically to the sealing edge 24 in the axial direction. When the widened pipe end is applied, these webs are subjected to a temporary, likewise reversible deformation and then lie over the entire circumference of the connecting part 21 on both sides of the sealing edge 24. As a result, a firm and sealing connection between the pipe end and the connecting part 21 is achieved at least in this area.

The connecting part 21 may optionally have more than one sealing edge; in this case, recesses 18 are provided on the expansion members 5 at corresponding locations.

The longitudinal section of FIG. 4 shows a modified embodiment of the expanding mandrel 5, the expanding members of which contain one, possibly also more than one, recess 18. A ring 29 is inserted into the recess.

The ring 29 advantageously only partially fills the recess 18. It consists of an elastic or self-deformable material at ambient temperature, possibly made of the same material as the pipe end to be expanded. As a result of the presence of the ring 27, a practically uniformly deformed area is formed in the area of the widened tube end, which, however, protrudes less far inwards than the web, which in the absence of the Rings 29 is formed. This makes it easier to push the widened pipe end onto the connecting part 21 without impairing the advantageous effects which are achieved by the presence of the web, that is to say the region which projects essentially from the inner circumference of the widened pipe end. Irrespective of this, the ring 29 forms part of the prestressing means which hold the expansion members 9 together, because the ring 29 generates a restoring force acting on the expansion members 9 in addition to the ring spring 13 after the retraction of the expansion cone 4.

Claims

claims

1. Containing spreading tool

a generally cylindrical expanding mandrel (5) with an at least partially conical inner bore (6), which is composed of a plurality of cylindrical sector-shaped expanding members (9),

Holding parts on the outer circumference of the cylindrical sector-shaped expansion members (9) and biasing means (13) acting on the holding parts,

a housing (1) with a guide (14, 15, 16) in which the holding parts are guided so as to be radially displaceable,

an expanding cone (4) which engages in the at least partially conical inner bore (6) of the expanding mandrel (5), and

Actuating means for the expansion cone (4),

characterized by return means between the actuating means and the expansion cone (4).

2. Spreading tool according to claim 1, characterized in that the actuating means is a single-acting piston-cylinder unit (2,3) with a piston (3) which is connected to the expansion cone (4) and in the rest position of the piston (3) and the expansion cone (4) are retracted and in its extended position Spreader mandrel (5) is spread by the expansion cone (4), and that the return means contain return springs (26) which relax in the retracted position of the piston (3) and in its extended position, bearing against an inner shoulder (28) of the Housing (1) are excited.

3. Spreading tool according to claim 2, characterized in that the return springs (26) are designed as disc springs.

4. Spreading tool according to one of claims 1 to 3, characterized in that the return means are attached to the circumference of an extension (19) of the piston (3) projecting against the expansion cone (4).

5. Spreading tool according to claim 4, characterized in that the return means on the circumference of the extension (19) between an abutment and an end face (7) of the expansion cone (4) are arranged.

6. Spreading tool according to Claim 5, characterized in that a spacer sleeve is arranged between the end face (7) of the expansion cone (4) and the return means.

7. Spreading tool according to claim 5 or 6, characterized in that the abutment is formed by a shoulder (25) which is formed between the piston (3) and the extension (19).

8. Spreading tool according to one of the preceding claims, characterized in that the expansion members (9) have between their free end and their holding part at least one recess (18) which extends along the circumference of the expansion members (9).

9. Spreading tool according to claim 8, characterized in that the recess (18) is limited by chamfered edges.

10. Spreading tool according to claim 8 or 9, characterized in that a ring (29) is received in the recess (18).

11. Spreading tool according to claim 10, characterized in that the ring (29) essentially fills the recess (18).

12. Spreading tool according to claim 10 or 11, characterized in that the ring (29) is selected from an elastic, a material which is self-deformable at room temperature or from a material whose recovery behavior is comparable to that of the material of a pipe end to be expanded.

13. Spreading tool according to claim 12, characterized in that the ring material is a reinforced material.

14. Spreading tool according to one of the preceding claims, characterized in that the holding part forms a radial arm (11) which starts from an end region facing away from the free end of the expansion member (9).

15. Spreading tool according to claim 14, characterized in that the housing (1) on a face facing away from the piston-cylinder unit (2, 3) contains a guide (14, 15, 16) in which the radial arms (11) are radially displaceable are led.

16. Spreading tool according to claim 15, characterized in that the expansion members (9) are arranged interchangeably on the end face of the housing (1).

17. Spreading tool according to claim 16, characterized in that a guide part (14) of the guide is detachably attached to the end face of the housing (1) and the expansion members (9) by means of the radial arms (11) and the detachably fastened guide part (14) are interchangeably held on the front of the housing (1).

18. Spreading tool according to one of the preceding claims, characterized in that the expansion members (9) have a chamfer (8) at their free end.

19. Spreading tool according to claim 18, characterized in that the chamfer (19) is limited by rounded edges.

20. Spreading tool according to one of the preceding claims, characterized in that the end region facing away from the free end of the expansion member (9) has a thickening (10) from which the holding part extends and which has a contact edge for an expansion to be expanded onto the expanding mandrel (5). push-on pipe end forms.

21. Spreading tool according to claim 20, characterized in that the at least one recess (18) between the thickening (10) and the chamfer (8) is formed.

22. Spreading tool according to claim 21 for use with a connecting part having a connecting part (21) with at least one sealing edge (24), characterized in that the at least one recess (18) on the expansion members (9) to the at least one sealing edge ( 24) of the connecting part (21) is aligned.

23. Spreading tool according to claim 22, characterized in that the at least one recess (18) is arranged symmetrically to the at least one sealing edge (24).