EP2919927B1 - Expansion head for expansion tools and expansion tool comprising the same - Google Patents

Description

The present invention relates to an expansion head for expansion tools for hollow workpieces, in particular for the ends of pipes made of plastics and coated with plastics metals.

Such expansion heads are for example from the FR 2 828 125 A1 . EP 0 044 795 A2 and the DE 42 02 348 C1 known. The expansion heads comprise individual segments, the so-called. Spreizbacken whose base parts are housed together in a head housing. The expansion jaws are movable in the radial direction outwards and separated from one another via parting lines. Such expansion heads are attached to Aufweitwerkzeugen and in particular connected via a screw with these. The expansion tools are basically of a pressing device with a mandrel which is axially displaceable in or on the housing of the pressing device and at its one axial end portion has a conical surface, wherein the opening angle of the corresponding cone is usually about 9 °, and an expansion head, the preferably via a receiving device for the expansion head on the pressing device can be fixed, constructed. At an opening angle of the cone of the expanding mandrel of 9 ° is called a so-called. Standard recording. By a drive device which can be driven manually or by machine, the mandrel is moved in the axial direction in the direction of the expansion head. On the inside, the expansion jaws of the expansion head define a central conical seat into which engages the conical surface of the mandrel displaceable in the axial direction by the pressing device. Upon actuation of the pressing device, the mandrel is pressed into the expansion head, wherein there is a contact between the conical surface of the mandrel and the receptacle formed by the expanding jaws. Upon further axial movement of the mandrel in the direction of the expansion head, the expansion jaws are pressed radially outward and there is a radial stroke of the expansion jaws, so that the expanding jaws the ends of a hollow workpiece, in particular a plastic pipe or a metal-plastic composite pipe in the the expansion head is inserted, widen. The expansion jaws go over from the closed state to the expansion state. Upon a radial backward movement of the mandrel from the expansion head, the segments become by return means (for example, an annular spring or an elastic O-ring) moved back to its original position. In order to achieve the most uniform possible expansion of the hollow workpiece during the expansion process, it may be necessary to rotate the position of the expansion head in the pipe end by loosening the expansion jaws by a predetermined angle (in expansion heads with six expansion jaws, the rotation should be at an angle of preferably about 30 °) and perform a second expansion process. A regular expansion of a pipe end is therefore necessary to after insertion of a connecting piece by pressing with a guided over the pipe end sliding or compression sleeve (axial sliding a sliding sleeve on the pipe end with inserted therein connector in a sliding sleeve connection or radial compression of a compression sleeve via a pipe end with inserted therein connector) to achieve a tight connection.

The disadvantage of the in the EP 0 044 795 A2 and the DE 42 02 348 C1 seen expansion heads seen that with a given expansion mandrel of the expansion tool used (standard recording) with a correspondingly possible Axialweg only the ends of tubes with a small diameter (maximum about 26 mm outer diameter) can be expanded.

Thus, the object of the present invention is to provide an expansion head for hollow tool widening tools which overcomes the disadvantages of the prior art. In particular, the expansion head according to the invention should be suitable for expanding larger-sized tubes (in particular with an outer diameter of at least 40 mm), wherein the expansion head according to the invention with the usual Aufweitwerkzeugen (which have a standard recording) should be compatible. These and other objects are achieved by an expansion head for hollow tool widening tools, in particular for the ends of pipes made of plastics and of plastics coated metals, with the features of claim 1 or by means of a hollow workpiece widening tool according to claim 9. Preferred embodiments of the expansion head according to the invention are described in the claims dependent therefrom.

In accordance with the present invention, it has been recognized that by incorporating a tapered adapter element into the head housing of the expansion head, an increased radial stroke of the expansion jaws can be achieved. This effect is inventively characterized achieved that the adapter element has on its inner side a further conical surface whose opening angle is smaller than the opening angle of the conical surface formed by the conical segment surfaces on the inside of the expansion jaws. In this way, you get a one-piece expansion head that can be used with standard Aufweitwerkzeugen with a standard recording, which can be easily mounted on the expansion tool and through which the ends larger sized tubes can be expanded. Furthermore, the invention provides that the expansion head further comprises at least one restoring element, which is accommodated in the head housing and is located on one side with the adapter element in engagement, wherein the restoring element exerts a force acting in the axial direction on the adapter element at least in the expansion state. The provision of an internal return element causes an independent return operation of the adapter element after completion of the expansion process. The use of a plate spring has proved to be particularly advantageous as a restoring element because it can be easily integrated into the head housing.

Accordingly, the present invention resides in an expansion head for hollow tool widening tools, particularly for the ends of plastic and plastic coated metal pipes, which includes a head housing having a radially inwardly directed guide flange; a set of sector-shaped spreader jaws individually guided by an inner flange sector overlapping with the guide flange and a radial groove radially movably on the guide flange, the set of spreader jaws being movable between a closed state and an expansion state, and the spreader jaws their inside are limited by conical segment surfaces, which complement each other in the closed state of the expansion head to a conical surface; and an accommodated in the head housing, conical and axially movable adapter element, wherein the cone angle of the adapter element corresponds to the opening angle β of the conical segment surfaces and the adapter element is bounded on its inner side by a further conical surface, wherein the opening angle α of the conical surface on the inside of the adapter element smaller than the opening angle β through the conical segment surfaces on the inside of the expansion jaws formed conical surface comprises, and the expansion head further comprises at least one return element which is received in the head housing and is located on one side with the adapter element is engaged, wherein the return element at least in the expansion state exerts a force in the axial direction of the adapter element. Moreover, the present invention resides in a hollow expansion tool Workpieces, in particular for the ends of pipes of plastics and plastics-coated metals, comprising an expansion head according to the invention.

With regard to the expansion head according to the invention, it may be advantageous if the opening angle of the conical surface on the inside of the adapter element by 1 ° to 20 °, in particular 2 ° to 10 ° and preferably 4 ° to 6 ° smaller than the opening angle of the through Cone segment surfaces on the inside of the expansion jaws formed conical surface. With a smaller difference, a sufficiently greater axial stroke is not achieved, while larger differences in the opening angle lead to an insufficiently stable expansion process (so-called self-locking of the expansion jaws by tilting).

It may also be helpful if the adapter element is fixed in the head housing by an attachment means in the axial direction. By fixing the adapter element and thus the sector-shaped expansion jaws in the head housing or the cap over a fastening means manufacturing tolerances and thus the game of sector-shaped expansion jaws can be optimized and / or adjusted. In this case, the use of a pressed-in in the cap attachment plates, a threaded disc, a shim or a locking ring has proven to be particularly useful as the fastener. Especially when using a threaded disc inserted into an internal thread of the cap, the bias of the spreader jaws in the cap can be set very precisely and thereby optimized.

In addition, it may prove to be advantageous if the expansion head further comprises at least one return means by which the expansion jaws from the expansion state in the closed state are traceable. Such a return means prevents tilting or hooking of the individual expansion jaws during the return process. The return means is preferably designed as an annular sleeve or annular spring, more preferably, the return means is arranged in an annular groove formed on the outside of the expansion jaws.

It may also be helpful if the expansion jaws have a taper on their side facing away from the head housing. As a result, a smooth transition between the flared and unexpanded portions of the hollow workpiece after the flaring operation can be achieved.

It may also be useful if at least one of the expansion jaws has on its outer side a sliding shoe, which cooperates with a corresponding sliding groove in the head housing. As a result, the expansion jaws are guided during the expansion process safely in the expansion head according to the invention, whereby the risk of tilting of the expansion jaws is reduced. In this context, it is particularly preferred if all expansion jaws each have on their outer side a sliding shoe, which cooperates with a respective sliding groove in the head housing. This ensures a particularly secure guidance of the expanding jaws in the expansion head according to the invention during the expansion process.

In the following, the present invention will be explained in detail with reference to the embodiment shown in the figures.

Brief description of the drawings

FIG. 1

shows a plan view of an expansion head according to an embodiment of the present invention in the closed state.

FIG. 2

shows a sectional view of the in Fig. 1 shown expansion head along the line AA with a view in the direction of arrow.

FIG. 3

shows a plan view of the in Fig. 1 shown expansion head in the open state.

FIG. 4

shows a sectional view of the in Fig. 3 shown expansion head along the line AA with a view in the direction of arrow.

FIG. 5

shows a sectional view of the expanding jaws of in Fig. 4 shown expansion head along the line AA with a view in the direction of arrow.

Detailed description of preferred embodiments

In the figures, an expansion head according to an embodiment of the present invention is in the closed state ( Fig. 1 and 2 ) and in the open state ( Fig. 3 to 5 ).

The expansion head 1 according to the invention comprises a head housing 2, a set of sector-shaped expanding jaws 3 and an adapter element 4.

The head housing 2 is constructed from a cap 5 with a radially inwardly directed guide flange 6 and an extension portion 7, wherein the cap 5 and the extension portion 7 are connected to each other via a spring wire steel 8.

Together, the set of sector-shaped expansion jaws 3 in the closed state of the expansion head 1 results in a closed mold having a substantially cylindrical shape in the expansion area of the expansion head 1. The term "expansion area" here refers to the area of the expansion jaws 3 which protrudes beyond the head housing 2. During the expansion process, the hollow workpiece to be widened is located in this widening region, on the outside of the spreading jaws 3. In addition, each of the expanding jaws 4 is bounded on its inner side by conical segment surfaces 9, which complement each other in the closed state of the expansion head 1 to a conical surface ( Fig. 2 ). The opening angle of the conical segment surfaces 9 in the embodiment shown is 13 °. In other embodiments, other opening angles are conceivable. In the embodiment shown, the set of spreader jaws 3 comprises six identical spreader jaws 3. Thus, each spreader jaw 3 forms a cone segment of 60 °.

Each of the sector-shaped expansion jaws 3 is individually guided by an inner flange sector 10, which overlaps with the guide flange 6, and a radial groove 11 in the head housing 2 radially movable on the guide flange 3. The Innenflanschsektoren 10 have on their outsides Nutsektoren included in the entire circumference of the expansion head 1 to a circumferential annular groove on the outside of Innenflanschsektoren 10, in which an annular return means 12 for the return of the expanding jaws 4 from the open to the closed state of the expansion head 1 is. The return means 12 is preferably chosen so that its restoring force is sufficient for the return of the expanding jaws 4 from the open to the closed state. In the illustrated embodiment, the return means 12 is an O-ring 12. Alternatively, a ring spring can be used advantageously as well.

The adapter element 4 has a two-part construction and is tapered on its outer side. The cone is formed from a cone element 13, whose cone angle coincides with the opening angle of the cone segment surfaces 9, in the embodiment shown is therefore also 13 °. The cone element 13 has a contoured inner cavity into which a push-in element 14 is inserted. The outer contour of the insertion element 14 is complementary to the contour of the cavity of the cone element 13. On its inside, the insertion element 14 in turn has a further conical surface 15. The opening angle of the conical surface 15 in the embodiment shown is 9 °. In other embodiments, other opening angles are conceivable. However, this opening angle of the conical surface 15 is consistent with the cone angle of the mandrel of the expansion tool. Alternatively, the adapter element 4 may also be formed in one piece or in several parts. However, the embodiments of the outer cone and the inner conical surface also apply to a one-piece or multi-part design of the adapter element. 4

At the open side of the head housing 2 facing side of the cone element 13 is formed on this as a plate spring 16 formed return element 16 in the head housing 2. The plate spring 16 exerts a force in the axial direction on the adapter element 4 in the expansion state. Thereby, and by the action of the return means 12, the expansion head 1 according to the invention returns to the closed state after completion of the expansion process.

In the region of the open side of the head housing 2, a fastening means 17 is arranged, which is formed in the embodiment shown as pressed into the extension portion 7 mounting plate. In alternative embodiments, a circlip, a washer with a circlip, a threaded washer inserted into a thread 18 on the inside of the head housing 2, or a shim may be used as the fastener. Of course, the fastening means 17 has a central recess through which the mandrel of the expansion tool can be guided. The fastening means 17 fixes the adapter element 4 and thereby also the set of expanding jaws 3 in the axial direction in the head housing 2.

On its inner side, the head housing 2, the thread 18 through which the expansion head 1 of the invention can be screwed on a widening tool via complementary external thread. The expansion tool is in principle a Tool with manual or electric drive, by which an expanding mandrel is driven in the axial direction. The expanding mandrel has the shape of a cone with a certain cone angle, which corresponds to the opening angle of the opening angle of the conical surface 15 of the cone element 13. In practice, a cone angle of the expanding mandrel of 9 ° has prevailed. Due to the movement of the expanding mandrel in the axial direction, the conical surface of the expanding mandrel cooperates with the conical surface 15 of the adapter element 4 during the expansion process. By driving the expanding mandrel into the expansion head 1, the conical surface of the expanding mandrel slides against the conical surface 15 of the adapter element 4. The axial movement of the adapter element 4 causes its outer conical surface to be pushed against the conical surface formed by the conical-segment surfaces 12 on the inside of the expansion cheeks 3. This in turn causes a movement of the expanding jaws 3 radially outward. Is on the outer surfaces of the set of expansion jaws 3 of the expansion head 1, a hollow workpiece, such as an end of a plastic pipe or a metal-plastic composite pipe out, the outer surfaces of the expansion head 1 are initially on the inside of the pipe. With increasing penetration depth of the expanding mandrel, the outer surfaces of the expanding jaws 3 are moved radially outward, whereby the pipe end, which is guided over the expanding jaws 3, is widened. After completion of the expansion process, the expansion head 1 according to the invention is in the state of expansion in the FIGS. 3 to 5 is shown.

The expanding jaws 3 are made by disassembling (sawing) a rotationally symmetrical body with the axis B along the column 19. In the embodiment shown in the figures, the body has been divided into six equal segments which form the spreading jaws 3 ( Fig. 1 ).

Fig. 5 shows a sectional view of the expanding jaws of in Fig. 4 shown expansion head along the line AA with a view in the direction of arrow. It can be seen that the expansion jaws 3 each have on their outer side a sliding shoe 20 which cooperates with a corresponding sliding groove 21 in the head housing 2. As a result, the expanding jaws 3 are guided safely in the expansion head 1 according to the invention during the expansion process. As a result, the risk of tilting of the spreading jaws 3 is reduced.

In preferred embodiments of the present invention, the spreader jaws 3 on its side facing away from the head housing 2, a taper 22. By such a taper 22, a smooth transition between the expanded and unexpanded part of the hollow workpiece after the expansion process can be achieved.

Claims (9)

1. Expansion head (1) for expansion tools for hollow workpieces, in particular for the ends of tubes made from plastics and from metals covered with plastics, comprising:

   - a head housing (2) with a radially inwardly directed guide flange (6);

   - a set of expanding jaws (3) which are of sector-shape design and are in each case individually guided in a radially movable manner on the guide flange (6) by an inner flange sector (10), which overlaps with the guide flange (6), and by a radial groove (11), wherein the set of expanding jaws (3) is movable between a closed state and an expansion state, and the expanding jaws (3) are bounded on the inner side thereof by conical segment surfaces (9) which, in the closed state of the expansion head (1), complement one another to form a conical surface; and

   - a conical adapter element (4) which is accommodated in the head housing (2) and is movable in the axial direction, wherein the cone angle of the adapter element (4) corresponds to the opening angle (β) of the conical segment surfaces (9), and the inner side of the adapter element (4) is bounded by a further conical surface (15),

   characterized in that
   the opening angle (α) of the conical surface (15) on the inner side of the adapter element (4) is smaller than the opening angle (β) of the conical surface formed by the conical segment surfaces (9) on the inner side of the expanding jaws (3), and the expansion head (1) furthermore comprises at least one resetting element (16) which is accommodated in the head housing (2) and is in engagement on one side with the adapter element (4), wherein, at least in the expansion state, the resetting element (16) subjects the adapter element (4) to a force action in the axial direction.
2. Expansion head (1) according to Claim 1, characterized in that the opening angle (α) of the conical surface (15) on the inner side of the adapter element (4) is smaller by 1° to 20° in particular 2° to 10° and preferably 4° to 6° than the opening angle (β) of the conical surface formed by the conical segment surfaces (9) on the inner side of the expanding jaws (3).
3. Expansion head (1) according to Claim 1 or Claim 2, characterized in that the expansion head (1) furthermore comprises a fastening means (17), by means of which the adapter element (4) is fixed in the axial direction in the head housing (2).
4. Expansion head (1) according to Claim 1, characterized in that the resetting element (16) is designed as a disc spring.
5. Expansion head (1) according to one of Claims 1 to 4, characterized in that the expansion head (1) furthermore comprises at least one resetting means (12) by means of which the expanding jaws (3) can be returned from the expansion state into the closed state.
6. Expansion head (1) according to Claim 5, characterized in that the at least one resetting means (12) is designed as an annular resetting means which is arranged in complementary groove sectors on the inner flange sectors (10) and subjects the expanding jaws (3) to an action of force in the radial direction.
7. Expansion head (1) according to one of Claims 1 to 6, characterized in that the expanding jaws (3) have a taper (22) on the side thereof facing away from the head housing (2).
8. Expansion head (1) according to one of Claims 1 to 7, characterized in that at least one of the expanding jaws (3), preferably all of the expanding jaws (3), each has/have, on the outer side thereof, a sliding block (20) which cooperates in each case with a corresponding sliding groove (21) in the head housing (2).
9. Expansion tool for hollow workpieces, in particular for the ends of tubes made from plastics and from metals covered with plastics, said expansion tool comprising an expansion head (1) according to one of Claims 1 to 8.

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