CN104797358B - The expansion head of expansion tool and the expansion tool containing this expansion head - Google Patents

Abstract

The invention relates to an expanding head (1) for an expanding tool for hollow workpieces, in particular tube ends made of plastic and metal coated with plastic, wherein the expanding head (1 ) comprising: an expansion head housing (2) with a radially inwardly directed guide flange (6); a set of fan-shaped expandable expansion pliers (3), which are individually overlapped with the guide flange (6) The inner flange section (10) and the radial groove (11) are guided to be movable in the radial direction on the guide flange (6), wherein the set of expansion forceps (3) can be moved between the closed state and the expanded state and the inner side of the expansion forceps (3) is limited by the conical section surfaces (9) which complement each other in the closed state of the expansion head (1) to form a conical surface; Conical and axially displaceable adapter (4) in the head housing (2), wherein the cone angle of the adapter (4) corresponds to the opening angle (β) of the cone section surface (9) And the inner side of the adapter (4) is limited by another conical surface (15), wherein the opening angle (α) of the conical surface (15) on the inner side of the adapter (4) is smaller than that on the inner side of the expansion forceps (3) The opening angle (β) formed by the cone segment surface (9). The invention also relates to an expanding tool for hollow workpieces, in particular for tube ends made of plastic and metal covered with plastic, comprising an expanding head ( 1 ) of the type described.

Description

Spreading head of spreading tool and spreading tool containing the spreading head

technical field

The invention relates to an expanding head of an expanding tool for hollow workpieces, in particular for the ends of tubes made of plastic and of metal coated with plastic.

Background technique

Expansion heads of this type are known, for example, from EP 0 044 795 A2 and DE 42 02 348 C1. The spreading head consists of individual segments, so-called spreading jaws, the base parts of which are accommodated together in the spreading head housing. The expansion jaws are movable radially outward and are separated from each other by a separating gap. Such an expansion head is attached to the expansion tool and is connected to the expansion tool, in particular via a screw connection. The expansion tool is basically constructed from a pressing device with a mandrel and an expanding head, the mandrel is held axially offset in or on the housing of the pressing device and at one axial end of the mandrel With conical surfaces in the area, wherein the opening angle of the corresponding cone is generally about 9°, the expansion head can preferably be fastened to the pressing device by means of a receiving device for the expansion head. When the opening angle of the cone of the expansion mandrel is 9°, it is called the so-called standard accommodation. Via a drive that can be driven manually or mechanically, the mandrel is moved axially in the direction of the expansion head. The expansion jaws of the expansion head define a conical central receptacle on the inside, into which the conical surface of the mandrel, which can be moved axially by the pressing device, engages. When the pressing device is actuated, the mandrel is pressed into the expansion head, wherein contact is produced between the conical surface of the mandrel and the receptacle formed by the expansion jaws. During a further axial movement of the mandrel in the direction of the expanding head, the expanding jaws press radially outwards and cause a radial lift of the expanding jaws, so that the expanding jaws engage the ends of hollow workpieces, in particular plastic tubes or metal-plastic - The end of the composite tube is expanded and the expansion head enters the tube. Here, the dilating jaws pass from the closed state to the expanded state. During the radially rearward movement of the mandrel from the expansion head, the segments are returned to their original position by means of a restoring device, such as an annular tension spring or an elastic O-ring. In order to be able to expand the hollow workpiece as evenly as possible during the expansion process, it may be required to rotate the position of the expansion head in the end of the pipe by a predetermined angle after the expansion clamps are released (when the expansion head has six expansion clamps, it should Rotation is preferably at an angle of approximately 30°) and a second dilation procedure is performed. Therefore a regular expansion of the pipe end is necessary in order to establish a tight connection by pressing after the introduction of the connector with a sliding sleeve or compression sleeve passing through the pipe end (in the case of a sliding sleeve connection the sliding sleeve is moved axially past the pipe end connected with the connecting piece entering it, or the pressure sleeve is radially pressed into the end of the pipe and connected with the connecting piece entering it).

A disadvantage of the expansion heads described in EP 0 044 795 A1 and DE 42 02 348 C1 is that, given the expansion mandrel (standard accommodation) of the expansion head used, it is only possible to expand Tubes of small diameter (up to an outer diameter of about 26 mm).

Contents of the invention

It is therefore the object of the present invention to provide an expanding head for an expanding tool for hollow workpieces which overcomes the disadvantages of the prior art. In particular the dilating head according to the invention should be suitable for dilating tubes of larger dimensions (in particular with an outer diameter of at least 40 mm), wherein the dilating head according to the invention should be compatible with conventional dilating tools which have standard accommodation. This object and others are achieved by an expanding head for an expanding tool for hollow workpieces, in particular by an expanding head for the end of a tube made of plastic and consisting of plastic-coated metal The expansion head has the features of claim 1 , or the objects are achieved by an expansion tool for hollow workpieces according to claim 10 . Preferred embodiments of the expansion head according to the invention are described in the dependent claims.

According to the invention, it was found that an increased radial lift of the spreading pliers can be achieved by integrating the conical adapter part into the spreading head housing of the spreading head. According to the invention, this effect is achieved in that the adapter part has a further conical surface on its inner side, the opening angle of which is smaller than the opening angle of the conical surface formed by the conical section surfaces on the inside of the expanding jaws. In this way a one-piece spreading head is obtained which can be used together with conventional spreading tools with standard accommodation and which can be easily mounted on the spreading tool and by means of which also larger dimensions can be expanded end of the tube.

Accordingly, the present invention relates to a spreading head for a spreading tool for hollow workpieces, in particular to a spreading head for the end of a tube made of plastic and consisting of plastic-coated metal, The expansion head comprises: an expansion head housing with a guide flange directed radially inward; Guided radially displaceably on the guide flange, wherein the set of expansion jaws is movable between a closed position and an expanded position and the expansion jaws are delimited on their inner sides by a cone-shaped section surface, which is located at the expansion head Conical surfaces complement each other in the closed state; a conical and axially movable adapter accommodated in the expansion head housing, wherein the cone angle of the adapter is equal to the opening angle β of the cone segment surface and The adapter is bounded on its inner side by a further conical surface, wherein the opening angle α of the conical surface on the inner side of the adapter is smaller than the opening angle β of the conical surface formed by the conical section surfaces on the inner side of the expanding jaws . The invention also relates to an expanding tool for hollow workpieces, in particular for tube ends made of plastic and metal-coated plastic, which includes an expanding head according to the invention.

It can be advantageous for the expansion head according to the invention that the opening angle of the conical surface on the inside of the adapter part is 1° to 20° smaller than the opening angle of the conical surface formed by the cone section surface on the inside of the expansion jaws, In particular, it is smaller by 2° to 10° and preferably smaller by 4° to 6°. In the case of smaller angular differences, a sufficiently greater axial lift cannot be achieved, whereas in the case of larger angular differences, an unsteady expansion process results (so-called spreading jaws self-braking due to tilting).

It can be advantageous if the adapter is fixed axially in the expansion head housing by means of a fastening device. Manufacturing tolerances and the play of the fan-shaped spreader tongs can be optimized and/or adjusted by means of the adapter piece and the fastening of the fan-shaped spreader tongs in the spreader head housing or locking cap via the fastening element. The use of fastening disks, threaded disks, adjusting washers or snap rings which are pressed into the locking boot as fastening means has proven to be particularly useful here. The use of a threaded disc which engages in the internal thread of the locking boot allows particularly precise adjustment and thus optimization of the pretensioning of the expanding pliers in the locking boot.

It may be advantageous for the expansion head to additionally comprise at least one restoring element, which is accommodated in the housing of the expansion head and engages on one side with the adapter, wherein the restoring element is fitted axially at least in the expanded state. exert force on the part. The provision of the internal restoring element results in an automatic restoring process of the adapter after the expansion process has ended. The use of a disk spring as the restoring element has proven to be particularly advantageous here, since it can be integrated very well in the expansion head housing.

Furthermore, it has proven to be advantageous if the expansion head additionally comprises at least one restoring device, by means of which the expansion forceps can be returned from the expanded position to the closed position. This resetting device prevents the tilting or jamming of each expansion forceps during the resetting process. In this case, the restoring device is preferably formed as an annular sleeve or as an annular spring. It is particularly preferred to arrange the reset device in an annular groove formed on the outside of the spreading jaws.

It can be advantageous if the expansion pliers have a point on their side facing away from the expansion head housing. A uniform transition between the expanded and the non-expanded hollow workpiece part can thus be achieved after the expansion process.

It can be advantageous if at least one expanding pliers has a slide on its outer side, which interacts with a corresponding link in the expanding head housing. As a result, the spreading jaws are reliably moved in the spreading head according to the invention during the spreading process, so that the risk of tipping of the spreading jaws is reduced. In the context of the invention it is particularly preferred that all the spreading pliers each have slides on their outer sides, which each interact with a corresponding link in the spreading head housing. This ensures a particularly reliable movement of the expansion jaws in the expansion head according to the invention during the expansion process.

Description of drawings

Next, the present invention will be specifically described with reference to the embodiments shown in the drawings.

Fig. 1 shows a top view of an expansion head in a closed state according to an embodiment of the present invention.

Fig. 2 shows a cross-sectional view of the expansion head shown in Fig. 1 along the line A-A looking in the direction of the arrow.

Fig. 3 shows a top view of the expansion head shown in Fig. 1 in an open state.

Fig. 4 shows a cross-sectional view of the expansion head shown in Fig. 3 along the line A-A looking in the direction of the arrow.

FIG. 5 shows a cross-sectional view of the expansion pliers of the expansion head shown in FIG. 4 along the line A-A looking in the direction of the arrow.

detailed description

The figures show a dilating head in a closed state ( FIGS. 1 and 2 ) and in an open state ( FIGS. 3 to 5 ) according to an embodiment of the invention.

The expansion head 1 according to the present invention includes an expansion head housing 2 , a set of fan-shaped expansion pliers 3 and adapters 4 .

The expansion head housing 2 here consists of a locking cap 5 with a radially inwardly directed guide flange 6 and an extension 7 , wherein the locking cap 5 and the extension 7 are connected to each other by a spring wire 8 .

In the closed state of the expansion head 1 , the group of sector-shaped expansion pliers 3 together form an essentially cylindrical closed shape in the expansion region of the expansion head 1 . The region in which the expanding jaws 3 protrude from the expanding head housing 2 is called the “expanding region”. During the expansion process, the hollow workpiece to be expanded is located in this expansion region, wherein the workpiece rests against the outside of the expansion jaws 3 . Furthermore, each expansion pliers 4 is delimited on its inner side by a conical section surface 9 which complementarily forms a conical surface in the closed state of the expansion head 1 ( FIG. 2 ). In the embodiment shown, the opening angle of the cone section surface 9 is 13°. In other embodiments, other opening angles can also be provided. In the embodiment shown, the set of expanding forceps 3 comprises six identical expanding forceps 3 . Each expansion jaw 3 thus forms a 60° cone section.

Each sector-shaped spreading pliers 3 is individually movable on the guide flange 3 via an inner flange section 10 overlapping the guide flange 6 and a radial groove 11 in the expanding head housing 2 . The inner flange section 10 has on its outer side a groove section which is formed as a circumferential annular groove on the outer side of the inner flange section 10 over the entire circumference of the expansion head 1 for An annular resetting device 12 for resetting the expansion pliers 4 from the open state to the closed state of the expansion head 1 is accommodated in the annular groove. Here, the reset device 12 is preferably selected so that its reset force is sufficient to reset the expansion forceps 4 from the open state to the closed state. In the illustrated embodiment, the reset device 12 is an O-ring 12 . Alternatively, spring coils can also advantageously be used.

The adapter part 4 has a two-part design and is tapered on its outer side. The cone is formed by a cone element 13 whose cone angle is adapted to the opening angle of the cone section surface 9 , ie likewise 13° in the illustrated embodiment. The cone element 13 has a structured inner cavity, into which the insert 14 is inserted. The outer contour of the insert 14 is complementary to the hollow contour of the cone element 13 . The insert 14 also has a further conical surface 15 on its inner side. The opening angle of the conical surface 15 is 9° in the embodiment shown. In other embodiments, other opening angles can also be provided. However, this angle of the conical surface 15 needs to match the cone angle of the mandrel of the expansion tool. Alternatively, the adapter part 14 can also be formed in one or more parts. However, the design of the outer conical and inner conical surfaces is also suitable for a one-piece or multi-part design of the adapter part 4 .

On the side of the cone element 13 facing the open side of the expansion head housing 2 , a restoring element 16 formed as a disk spring 16 on the cone element 13 is accommodated in the expansion head housing 2 . In the expanded state, the disk spring 16 exerts a force on the adapter part 4 in the axial direction. As a result and through the action of the reset device 12 , the expansion head 1 according to the invention returns to the closed state after the expansion process has ended.

In the region of the open side of the expansion head housing 2 there is a fastening device 17 which, in the embodiment shown, is formed as a fastening disk pressed into the extension section 7 . In an alternative embodiment, the fixing means take the form of a retaining ring, a disc with a retaining ring, a threaded disc introduced into the thread 18 on the inside of the expansion head housing 2, or an adjusting washer. The fixing device 17 necessarily has a central opening through which the mandrel of the expansion tool can pass. The fixing device 17 fixes the adapter 4 and the set of expansion pliers 3 axially in the expansion head housing 2 .

The expansion head housing 2 has a thread 18 on its inner side, by means of which the expansion head 1 according to the invention can be screwed onto the expansion tool via a complementary external thread. The expansion tool is usually a tool with a manual or electric drive, by means of which the expansion mandrel is axially driven. Here, the unfolding mandrel has the shape of a cone with a specific cone angle which is equal to the opening angle of the conical face 15 of the conical element 13 . In practice, the cone angle of the expanding mandrel is implemented at 9°. By moving the expansion mandrel in the axial direction, the conical surface of the expansion mandrel interacts with the conical surface 15 of the adapter part 4 during the expansion process. By driving the expansion mandrel into the expansion head 1 , the conical surface of the expansion mandrel is displaced towards the conical surface 15 of the adapter part 4 . The resulting axial displacement of the adapter part 4 displaces its outer conical surface towards the conical surface formed by the conical section surface 12 on the inner side of the spreading pliers 3 . This in turn causes the expansion jaws 3 to move radially outwards. If the end of a hollow workpiece, such as a plastic pipe or a metal-plastic composite pipe, passes through the outer surface of the set of expanding jaws 3 of the expanding head 1, the outer surface of the expanding head 1 first abuts against the inside of the tube. As the penetration depth of the expansion mandrel increases, the outer surface of the expansion jaws 3 moves radially outwards, whereby the end of the tube passing through the expansion jaws 3 is expanded. After the end of the expansion process, the expansion head 1 according to the invention is in the expanded state shown in FIGS. 3 to 5 .

The expansion pliers 3 are formed by the disassembly (sawing) of the rotationally symmetrical main body with the axis B along the slit 19 . In the embodiment shown in the figures, this body is broken down into six identical sections, which form the dilating forceps 3 ( FIG. 1 ).

Fig. 5 shows a cross-sectional view of the expansion pliers of the expansion head shown in Fig. 4 viewed along the line A-A in the direction of the arrow. It can be seen here that the expanding pliers 3 each have a slide 20 on their outer sides, which interact with a corresponding link 21 in the expanding head housing 2 . The expansion forceps 3 are thus reliably guided in the expansion head 1 according to the invention during the expansion process. The risk of tipping of the expansion jaws 3 is thus reduced.

In a preferred embodiment of the invention, the expansion pliers 3 have a tip 22 in their region facing away from the expansion head housing 2 . A uniform transition between the expanded part and the non-expanded part of the hollow workpiece after the expansion process can be achieved by means of such a tip 22 .

Claims (15)

1. An expansion head (1) for an expansion tool for hollow workpieces, which can be used with conventional expansion tools with standard accommodation, said expansion head comprising: - an expansion head housing (2) with a radially inwardly directed guide flange (6); - a set of sector-shaped expansion pliers (3), which are individually guided in the guide by an inner flange section (10) overlapping with the guide flange (6) and radial grooves (11) Guided radially displaceably on a flange (6), wherein the set of expansion pliers (3) can move between a closed state and an expanded state and said expansion pliers (3) are formed on their inner sides by a cone section face ( 9) define that said conical body section surface (9) is complementarily formed as a conical surface in the closed state of said expansion head (1); and - a conical and axially displaceable adapter (4) accommodated in the expansion head housing (2), wherein the cone angle of the adapter (4) is equal to the cone section The opening angle (β) of the surface (9) and the adapter (4) is defined on its inside by another conical surface (15), wherein the taper on the inside of the adapter (4) The opening angle (α) of the surface (15) is smaller than the opening angle (β) of the conical surface formed on the inner side of the spreading jaws (3) by the conical section surface (9). 2. The expansion head (1) according to claim 1, characterized in that the expansion head is used for expansion tools for tubes made of plastic and of metal coated with plastic Ends. 3. The expansion head (1) according to claim 1 or 2, characterized in that the opening angle (α) of the conical surface (15) on the inner side of the adapter (4) is larger than the expansion angle (α) The opening angle (β) of the conical surface formed by the conical section surface (9) on the inner side of the pliers (3) is 1° to 20° smaller. 4. The expansion head (1) according to claim 3, characterized in that, the opening angle (α) of the tapered surface (15) on the inner side of the adapter (4) is smaller than that of the expansion forceps ( 3) The opening angle (β) of the conical surface formed by the conical section surface (9) on the inner side is 2° to 10° smaller. 5. The expansion head (1) according to claim 3, characterized in that, the opening angle (α) of the tapered surface (15) on the inner side of the adapter (4) is smaller than that of the expansion forceps ( 3) The opening angle (β) of the conical surface formed by the conical section surface (9) on the inner side is 4° to 6° smaller. 6. The expansion head (1) according to claim 1 or 2, characterized in that, the expansion head (1) additionally includes a fixing device (17), and the adapter (4) passes through the fixing device along the Axially fixed in the expansion head housing (2). 7. The expansion head (1) according to claim 1 or 2, characterized in that, the expansion head (1) additionally comprises at least one restoring element (16), the at least one restoring element (16) is housed in the in the expansion head housing (2) and engages on one side with the adapter (4), wherein the at least one return element (16) is at least in the expanded state axially in the adapter Apply force to piece (4). 8. The expansion head (1 ) according to claim 7, characterized in that the at least one restoring element (16) is designed as a disk spring. 9. The expansion head (1) according to claim 1 or 2, characterized in that, the expansion head (1) additionally comprises at least one reset device (12), by which at least one reset device (12), the The dilating forceps (3) can be guided back from the expanded state to the closed state. 10. The expansion head (1) according to claim 9, characterized in that the at least one reset device (12) is formed as an annular reset device, and the annular reset device is arranged on the inner flange section The complementary groove sections of (10) exert a force action on the expansion pliers (3) in the radial direction. 11. The expansion head (1) according to claim 1 or 2, characterized in that the expansion pliers (3) have a tip (22) on the side facing away from the expansion head housing (2) . 12. The expansion head (1) according to claim 1 or 2, characterized in that at least one of the expansion clamps (3) has a slide block (20) on its outer side respectively, and the slide block (20) is connected with each other Corresponding sliding slots (21) in the expansion head housing (2) work together. 13. The expansion head (1) according to claim 12, characterized in that, all of the expansion forceps (3) have sliders (20) on their outer sides respectively, and the sliders (20) are respectively connected to the Corresponding slots (21) in the expansion head housing (2) work together. 14. An expansion tool for hollow workpieces, said expansion tool comprising an expansion head (1 ) according to any one of claims 1-13. 15. Dilation tool according to claim 14, characterized in that it is used for the end of a tube made of plastic and of metal coated with plastic.