WO1996025255A1

WO1996025255A1 - Expanding tool for-cold-forming

Info

Publication number: WO1996025255A1
Application number: PCT/EP1996/000501
Authority: WO
Inventors: Friedrich Imgram
Original assignee: Wirsbo Rohrproduktion Und Vertriebs-Gmbh
Priority date: 1995-02-15
Filing date: 1996-02-07
Publication date: 1996-08-22
Also published as: NO973754D0; PL321799A1; FI973328A; NO973754L; AU4788196A; SK110397A3; JPH11500358A; EP0809553A1; CA2211897A1; HUP9801997A2; FI973328A0; DE19504968A1

Abstract

The expanding tool has a cylindrical expanding mandrel (5) consisting of a plurality of cylinder-sector expanding components (10) which are interchangeably secured and guided on a face of a housing (1). The expanding mandrel (5) has a partially conical inner drilling (6) with which engages an expanding cone (4) operating together with actuating means (2) which advance the expanding cone (4) into the inner drilling (6) of the expanding mandrel (5) to expand the end (19) of a pipe fitted on said mandrel (5). In addition, the expanding mandrel (5) is bevelled (9) at its free end. Between the bevel (9) and a thickening (11) from which the holding component proceeds there is at least one recess (18) running around the entire periphery of the expanding mandrel (5).

Description

Spreading tool for cold forming

Technical field

The present invention relates to a spreading tool consisting of a generally cylindrical expanding mandrel which is provided with an at least partially conical inner bore and is divided in the axial direction into a plurality of essentially cylindrical sector-shaped expanding members, a holding part projecting from the outer circumference of each expanding member. pretensioning means acting on the holding parts, which pretension the expanding members in mutual contact with the generally cylindrical expanding mandrel, a housing in which the holding parts are guided in a radially displaceable manner, conical expanding means for engaging in the at least partially conical inner bore of the expanding mandrel, and actuating means for axially displacing the expanding means in the inner bore of the expanding mandrel while spreading the same against the force of the biasing means.

Underlying state of the art

Such a spreading tool is known from German Offenlegungsschrift 42 20 794 and is used to widen the tubes of the reversibly deformable plastic tubes so that the tube ends can be firmly and sealingly connected to other tubes or a tube connector .

A similar spreading tool is known, for example, from published European patent application 0 619 152 and contains a cap which is connected to the spreading members by specially designed connecting and guiding means. Furthermore, a connecting part is known from DE-OS 38 17 442 and from DE-G 94 04 513, which has at least one connecting part for connecting a reversibly widened pipe end. The connecting part is provided with at least one holding element for the firm and sealing connection to the pipe end, which determines an inclined outer surface towards its free end and a steeply falling surface towards the opposite side. The sloping outer surface makes it easier to push on the widened pipe end, while the steeply sloping surface together with the sloping outer surface determines a sealing edge which is important for the formation of the firm and sealing connection.

The expansion tool mentioned at the beginning contains an expansion mandrel which forms a closed peripheral surface only when the expansion means are not actuated. In the actuated, ie spread, state, the expansion members are pushed outwards and thus apart by the expansion means, so that there are gaps in the circumferential direction of the expansion mandrel between the expanded expansion members which extend along the expansion mandrel. In the area of these gaps, the widening of the pipe end applied to the expanding mandrel is only imperfect, so that the inner wall of the widened pipe end does not form a closed cylinder surface, but rather contains areas of less widening distributed in the circumferential direction. This can have the consequence that the widened pipe end does not come to rest evenly over the circumference of the connecting part, as a result of which the strength and tightness of the connection produced in this way can be impaired. Disclosure of the invention

The object of the invention is accordingly to provide a spreading tool of the type mentioned at the outset which ensures firm and sealing contact of the widened tube end on the respective connecting part.

According to the invention, this object is achieved in that the expansion members have a recess between their free end and their holding part, which extends along the circumference of the expansion members.

The design of the expansion members according to the invention has the result that there is no non-uniform widening of the pipe end in the area of the cutouts, but rather that the pipe end is widened uniformly with good approximation. In this area, the widening of the pipe end is somewhat less, but this less widening hampers the application of the pipe end to the respective connecting part little or not at all. When the widened pipe end is pushed onto the respective connecting part, this area comes to bear much more evenly against the outer surface of the respective connecting part, as a result of which the desired firm and sealing connection is ensured in the end.

In an advantageous development of the invention, a ring made of a self-reshapable material is received in the recess and can essentially completely or partially fill the recess. The ring material can be selected from an elastic material that is self-deformable at room temperature or from a material whose reshaping behavior is comparable to the material of the pipe end to be expanded; it can also be formed from a reinforced material. In the presence of such a ring, a uniformly deformed area is also formed on the inner wall of the widened pipe end, but this projects less inward than the area which is formed in the absence of the ring. In comparison, this makes it easier to push the pipe end onto the connecting part. The advantage of the uniformly deformed area is maintained, and the additional advantage is gained that the ring contributes to better cohesion of the expansion members and also provides a higher 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 the above-mentioned holding elements with a sealing edge and the cutouts on the expanding members are aligned with this sealing edge. In particular, the axial arrangement of the recess on the expansion members can be such that the sealing edge on the holding element is arranged symmetrically with respect to the recesses. If necessary, more than one recess can be provided on the expanding mandrel and more than one sealing edge on the connecting part.

With such a configuration of the expanding mandrel, the less, but uniformly widened area of the tube end, which extends closed over the inner wall in the circumferential direction, experiences a temporary expansion and self-reshaping when passing over the sealing edge of the respective connecting part. This ensures that at least this area of the pipe end on both sides of the sealing edge comes into firm and sealing contact with the connecting part and thus a firm and sealing connection is formed overall. Exemplary embodiments of the expanding tool according to the invention are shown in the figures and are explained and described in detail below using the reference numerals. Show it

Brief description of the drawings

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

FIG. 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 which can be used in connection with the spreading tool according to FIG. 1 or 4;

FIG. 4 shows a longitudinal section through a modified design of the spreading tool according to FIG. 1; and

FIG. 5 shows a longitudinal section through a further embodiment of the spreading tool according to the invention.

Preferred embodiment of the invention

FIG. 1 shows in longitudinal section a first exemplary embodiment of a spreading tool with a housing 1 which contains actuating means 2 for the spreading tool at one end. In the illustrated embodiment, the actuating means 2 contains a pressure-actuated piston 3, which is connected to an expanding means in the form of an expanding cone 4, for example by a screw connection. Instead of the pressure medium-actuated piston 3, other, for example mechanical, actuation means can also be provided his. 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 such that it can also be used for overhead work.

A generally cylindrical expanding mandrel 5 is attached in the opposite end of the housing 1. This expanding mandrel 5 contains an inner bore 6 made of a conical bore part 7, with which the expanding cone 4 is engaged or can be brought into engagement, and a cylindrical bore part 8 in its free end. At this free end the expanding mandrel 5 is provided with a chamfer 9 which can run at an angle in the range from 5 ° to 20 ° to the peripheral surface of the expanding mandrel 5. The edges that limit the chamfer 9 are rounded. The chamfer 9 and its rounded edges prevent damage to the inner wall of a pipe end 19 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 10; in the illustrated embodiment, cf. FIG. 2, the expanding mandrel 5 is divided into eight parts and thus consists of eight expanding members 10. When the expanding mandrel 1 is in the idle state or is not actuated, the expanding members 10 lie against one another in the circumferential direction and thus form a generally cylindrical peripheral surface.

At the inner end of the expanding mandrel 5 or at the inner ends of the expanding members 10, a thickening 11 is formed, from which holding parts extend, by means of which the expanding mandrel 5 is held in the associated end of the housing 1 so that it can be replaced. In particular, each holding part consists of an arm projecting radially from the circumference of the thickening 11 12, on the circumference of which a receptacle 13 for a preloading means, for example an annular spring 14, is provided. The annular spring 14 exerts a radially inward bias on the expansion members 10, whereby the expansion members 10 are held in mutual contact in the unactuated state of the expanding mandrel 5 and the generally cylindrical peripheral surface of the expanding mandrel 5 is formed. The radially projecting arms 12 are mounted in the associated end face of the housing 1 so as to be radially displaceable in a guide comprising a holding plate 15 and a bearing plate 16 with a sliding element 17. The holding plate 15 is detachably fastened to the end face of the housing 1 by means of screws, so that the expansion members 10 or the expanding mandrel 5 are interchangeably arranged in the end face of the housing 1 by means of the radial arms 12 and the holding plate 15.

Between the thickening 11 and the chamfer 9 of the expanding mandrel 5 there is a recess 18 on each expanding member 10, which in the closed or unactuated state of the expanding mandrel 5 is designed in the manner of a circumferential groove. The edges of the cutouts 18 are preferably beveled in order to avoid damage to the pipe end 19 during insertion.

In this and the exemplary embodiments described below, the mechanically highly stressed parts, such as the expanding cone and the expanding members of the expanding mandrel, are made from a higher quality tool steel. As a result, the occurrence of friction and seizure points between the parts acting on one another and, on the other hand, deformation of the expansion members at high expansion forces are avoided.

In the upper half of Figure 1, the spreading tool is shown in the idle state. In this state, the spreading cone 5 only in the conical bore part 7 of the inner bore 6 of the expanding mandrel 5, without an axially directed force acting on the expanding cone 4. The expansion members 10 are then in mutual contact, and the expansion mandrel 5 forms a generally cylindrical body, as shown in FIG.

When the piston 3 is pressurized, it and the expanding cone 4 are displaced within the housing 1 against the expanding mandrel 5. The expansion cone 4 is thereby pressed into the conical bore part 7, whereby the expansion members 10 are pushed apart against the force of the ring spring 14 in the radial direction. The lower half of FIG. 1 shows the expansion cone 4 in the end position of its displacement path, in which the maximum expansion of the expansion mandrel 5 is achieved. With this expansion, gaps extending in the longitudinal direction arise between the expansion members 10.

To widen the expanding mandrel 5, when the expanding tool is at rest, it is inserted into a pipe end 19 made of a material which is preferably self-deformable at ambient temperature, for example of medium-density, high-density or cross-linked polyolefin. The end face of the pipe end 19 comes to rest against the thickening 11, as a result of which the axial length of the pipe end 19 to be expanded is limited. When the expansion cone 4 is actuated, the expansion members 10 are pushed outwards against the force of the ring spring 14, as a result of which the tube end 19 is widened by a corresponding amount. The inner surface of the pipe end 19 lies against the outer surface of the expanding mandrel 5, but not in the area of the above-mentioned axial gaps between the spreading members 10 which are pushed apart Ribs. In addition, the The inner wall of the pipe end 19 does not adhere to the circumference of the expanding mandrel 5 when it is widened, even in the area of the cutouts 18. Accordingly, on the inner wall of the widened pipe end 19, an inwardly projecting region or web of a height is formed which is determined by the depth of the recess 18.

The importance of the recess 18 and the web formed thereby on the inner wall of the widened tube end 19 can be seen in view of the connecting part with which the widened tube end 19 connects by self-reshaping. Such a connecting part can be designed, for example, as in the pipe connector according to G 94 04 513 and is shown in longitudinal section in FIG. 4. The pipe connector 20 forms a straight piece of pipe which has connecting parts 21 at opposite ends. Each connecting part 21 contains a holding element 22 for connection to a widened pipe end such as the pipe end 19. Each holding element 22 contains an outer surface 23 which gradually slopes down to the free end of the pipe connector 21 and a sealing edge 24 which drops steeply to the other side.

The recesses 18 of the expansion members 10 are aligned with the axial position of the sealing edge 24 on the connecting part 21, to which the reversibly widened pipe end 19 is applied. The sealing edge 24 is preferably arranged symmetrically to the cutouts 18, so that the webs remaining on the circumference of the inner wall after the widening of the pipe end 19 likewise run symmetrically to the sealing edge 24 in the axial direction. When the widened pipe end 19 is applied, these webs are subject to a short-term, likewise reversible deformation and then lie on the connecting part 21 on both sides of the sealing edge 24 over their entire circumference, as a result of which at least in this area a firm and sealing connection between the pipe end 19 and the connecting part 21 is achieved.

The connecting part 21 may optionally have more than one sealing edge 24; in this case, more than one recess 18 is provided on the expanding mandrel 5 at corresponding points.

Figure 4 is a representation corresponding to Figure 1 and shows a modified version of the spreading tool. The same parts are provided with the same reference numerals. One recognizes therein the housing 1 with the actuating means 2 in the form of a pressure-actuated piston 3, which cooperates with an expansion cone 4.

An expanding mandrel 25 contains a consistently conical inner bore 26 which extends over the entire axial length of the expanding mandrel 25. Otherwise, the expansion mandrel 25 is also composed of eight expansion members, which are held together under prestress by an annular spring 14. The annular spring 14 is held in a receptacle 13 in radial arms 12, which start from a thickening 11 at the inner end of the expanding mandrel 25 and can be moved radially between a holding plate 15 and a bearing plate 16 with a sliding element 17 on the end face of the housing 1 are attached.

The expanding mandrel 25 has a chamfer 9 with rounded edges and between the chamfer 9 and the thickening 11 there is at least one recess 18 on the expansion members 10. The function of the recesses 18 and the mode of operation of this expanding tool correspond to that described above in connection with Figures 1 to 3 has been described. The longitudinal sectional view of FIG. 5 shows, from a further exemplary embodiment, only one expanding mandrel 27, the expanding members of which have one, possibly also more than one, recess 18. The expanding mandrel 27 contains a ring 28 inserted into the recesses 18. Otherwise, the expanding tool is designed in accordance with FIGS. 1 and 2 or FIG.

The ring 28 completely or partially fills the recesses 18. It consists of an elastic material or a material that can be self-deformed at ambient temperature, possibly made of the same material as that of the pipe end to be expanded. As a result, when the tube end is widened in the area of the ring 28, a practically uniformly deformed area is formed which extends over the inner wall of the tube and has the same effect as the corresponding area which is formed in the absence of the ring 28 . However, this area protrudes less far inwards, which makes it easier to push the widened pipe end onto the respective connecting part 20 without the effects achieved by the presence of the uniformly deformed area being impaired. In addition, the ring 28 forms part of the pretensioning means, since the presence of the ring 28 causes the expansion members of the expansion mandrel 27 to be held together and to be subjected to an additional restoring force after the expansion cone 4 has withdrawn.

Claims

claims

1. Spreading tool consisting of a generally cylindrical expanding mandrel (5, 25, 27) which is provided with an at least partially conical inner bore (6, 26) and divided in the axial direction into a plurality of essentially cylindrical sector-shaped expanding members (10) is, a holding part protruding from the outer circumference of each expansion member (10), pretensioning means which engage the holding parts and which preload the expansion members (10) in mutual contact with the generally cylindrical expansion mandrel (5, 25, 27), a housing (1), in which the holding elements are guided in a radially displaceable manner, conical expansion means (4) for engaging in the at least partially conical inner bore (6, 26) of the expansion mandrel (5, 25, 27), and actuating means (2) for axially displacing the Expanding means (4) in the inner bore (6,26) of the expanding mandrel (5,25,27) while spreading the same against the force of the prestressing means,

characterized in that the expansion members (10) have between their free end and their holding part at least one recess (18) which extends along the circumference of the expansion members (10).

2. Spreading tool according to claim 1, characterized in that the recess (18) is limited by chamfered edges.

3. Spreading tool according to claim 1 or 2, characterized gekenn¬ characterized in that a ring (28) made of a self-deformable material is received in the recess (18).

4. Spreading tool according to claim 3, characterized in that the ring (28) substantially fills the recess (18).

5. Spreading tool according to claim 3 or 4, characterized gekenn¬ characterized in that the ring material is selected from an elastic, a self-deformable material at room temperature or from a material whose reshaping behavior is comparable to the material of the pipe end to be expanded.

6. Spreading tool according to claim 5, characterized in that the ring material is a reinforced material.

7. Spreading tool according to one of the preceding claims, characterized in that the holding part forms a radia¬ len arm (12) which starts from an end region opposite the free end of the expansion member (10).

8. Spreading tool according to claim 7, characterized in that the housing (1) on one end side contains a guide (15, 16, 17) in which the holding parts are guided in a radially displaceable manner.

9. Spreading tool according to claim 8, characterized in that the expansion members (10) are arranged interchangeably on the front side of the housing (1).

10. Spreading tool according to claim 9, characterized in that a guide part (15) of the guide is releasably attached to the end face of the housing (1) and the expansion members (10) by means of the holding parts and the detachably fastened guide part (15) the front of the housing (1) are held.

11. Spreading tool according to one of claims 1 to 10, da¬ characterized in that the expansion members (10) have a chamfer (9) at their free end.

12. Spreading tool according to claim 11, characterized gekennzeich¬ net that the chamfer (9) is limited by rounded edges.

13. Spreading tool according to one of claims 1 to 12, characterized in that the the free end of the

Spreading member (10) opposite end region has a thickening (11) from which the holding part extends and which forms a contact edge for a pipe end (19) which can be pushed onto the expanding mandrel (5, 25, 27).

14. Spreading tool according to claim 13, characterized gekennzeich¬ net that the at least one recess (18) between the thickening (11) and the chamfer (9) is formed.

15. Spreading tool according to claim 14 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 spreading members (10) is aligned with the at least one sealing edge (24) of the connecting part (21).

16. Spreading tool according to claim 15, characterized in that the at least one sealing edge (24) is symmetrical to the at least one recess (18) angeord¬ net.

17. Spreading tool according to one of claims 1 to 16, characterized in that the inner bore (6) of the Expanding mandrel (5) is composed of a conical bore part (7) and a cylindrical bore part (8).

18. Spreading tool according to one of the preceding claims, characterized in that the inner bore (26) of the expanding mandrel (25) is conical over its entire axial length.