EP1660257B1 - Method and device for producing at least partially profiled tubes - Google Patents

Abstract

A method and device are disclosed for producing tubes that are at least partially profiled on their interior and preferably on their exterior from a hollow cylindrical blank (3), using a mechanical cold forming method, wherein the end of the blank (3) that is not to be machined (3′) is fed to a clamping device (10). The blank (3) is then secured in the clamping device (10) and a mandrel (2) is subsequently inserted into the end of region (3) of the blank (3) that is to be machined. A lance (8) is guided in the mandrel so that it can be coaxially displaced in a longitudinal direction and the free end of the lance (8′) can be introduced into the clamping device (10). The tip (8′) of the lance (8) is then brought into a positive fit with the clamping device (10) in the axial direction of the blank (3) and the mandrel (2), together with the clamping device (10) and the blank (3) is guided axially through a fixed machining point (6). Radial exterior machining of the surface of the blank (3) along the section that is to be machined (3′) takes place at the machining point (6), to create the interior and exterior profiling of the blank (3). During the process, the mandrel (2) is preferably rotated about its axis in an intermittent manner.

Description

The present invention relates to a method according to the preamble of claim 1 and a device according to the preamble of claim 9.

Profiled tubes resp. Pipe sections are made, for example, in the automotive industry for use as sliding pieces for propshafts or sliding steering columns. In this case, two mutually longitudinally displaceable tubes are generally used, which are positively connected with respect to rotation about their longitudinal axes. Thus, changes in the distance between the end points of these tubes can be compensated and still be transmitted an exact rotation. These requirements are, as already mentioned, required both in the powertrain or the steering in motor vehicles. These tubes should on the one hand be built as light as possible, have an exact profiling with the least possible play and high strength.

For the production by cold forming in particular such thin-walled, inside and outside profiled resp. With a tooth-like profile provided pipe sections of metal, a likewise profiled mandrel is conventionally used, such as in the US 5,001,916 shown. This mandrel is introduced into a tube blank and acted from the outside mechanically on the surface of the blank, for example in the form of impact rollers. This is usually done automatically in a suitably designed production machine. In this case, the mandrel must have a greater length than the area to be machined of the blank, since the mandrel must remain used for the profiling within the entire length of the blank and then must be withdrawn into the production machine to remove the finished workpiece and the production machine with to feed a new blank.

Thus, this conventional method and the corresponding production machines are only suitable for the production of a limited length tubes. If correspondingly longer pipes have to be produced, these production machines come to their limits due to their dimensions, especially since any extension of the mandrel is also out of the question due to the then to be taken into account larger production costs.

The object of the present invention was to find a method and a device which is also suitable for the production of relatively long, at least partially profiled pipe sections by means of mechanical forming machines.

This object is achieved according to the invention by the features of the method according to claim 1. Preferred embodiments of the inventive method further result from the features of further claims 2 to 8.

Characterized in that the blank is supplied to the end of the non-machinable region of the clamping device, the length of the mandrel can be selected according to the length of the region to be machined of the blank. In particular, thus the range of motion of the mandrel can be practically limited to the length of the area to be machined. This leads advantageously to smaller machine dimensions, especially in the field of drives and guides. The drive of the processing station and the rotary drive of the mandrel can thus be arranged very compact on the same machine frame.

Furthermore, the loading of the clamping device with the blank outside the machining area can thus take place on the side opposite the mandrel. Likewise, the processed pipe can then be unloaded there again after processing. Thus, both the charging and the discharging process can advantageously be carried out by means of a single device.

Through the use of a secondary headstock, which is positively connected by a lance with the primary headstock, a very powerful and reliable clamping of the blank for the subsequent processing can be achieved.

By means of the method according to the invention, it is possible, in particular advantageously, to provide relatively long, thin-walled blanks at least regionally with a profiling formed on the inside and outside. As a rule, an axially running tooth geometry is produced, whereby these tubes are used as torsion resistant telescopic tubes are suitable. However, such pipes are not used exclusively in vehicle technology, for example in propeller shafts or steering columns.

The method is particularly suitable for the application of the impact rolling process as a mechanical forming process, i. the successive hammering resp. beating blanks radially from the outside by means of profiled or flat rolling rolls. This allows both internal gears as well as simultaneously produce internal and external gears in a known manner.

The first clamping of the blank preferably takes place via a spring-loaded pretensioning device, which is realized in the clamping device. That that the blank is introduced from the loading device in the biasing means and is held there for delivery via the mandrel.

By a positive and / or non-positive connection between the primary headstock and clamping device a reliable and accurate transmission of the rotational movement of the mandrel is achieved on the blank, which finally guarantees a high machining accuracy.

Preferably, the blank is pushed by an axial movement of the clamping device over the mandrel and then together through the processing station. The drives are both the longitudinal movement through the processing station as well as the possible intermittent rotational movement for the generation of a Accurate gearing advantageously implemented in the primary headstock.

The object is further achieved according to the invention by a device having the features of claim 9. Preferred embodiments of the device according to the invention are further evident from the features of the further claims 10 to 14.

The inventive arrangement of primary headstock, processing station and secondary headstock a space-saving and compact design of the device is achieved. The machine frame with the integrated thereon primary headstock and the processing station thus has in comparison to conventional devices no larger or even smaller dimensions, although so longer to be machined areas of the blanks resp. longer blanks can be processed. The protruding from this machine frame areas for holding and guiding the secondary headstock are also very compact and compact and can also load the resp. Have unloading the blanks, resp. keep enough space for the access of such devices.

By the preferred embodiment of the clamping device with a hollow cylindrical shell and disposed therein Klemmresp. Clamping elements, which act partly spring-loaded, a very compact element is created. The rotation of the clamping device resp. of the blank held therein is advantageously carried out in the Clamping device to be inserted lance resp. their free end.

• Fig. 1 schematisch den Aufbau einer herkömmlichen Vorrichtung zur Herstellung von innen und aussen profilierten Rohren;
• Fig. 2 schematisch die Aufsicht auf den Primärspindelbereich und den Bearbeitungsbereich einer erfindungsgemässen Vorrichtung;
• Fig. 3 die Aufsicht auf den Sekundärspindelbereich der erfindungsgemässen Vorrichtung nach Figur 2;
• Fig. 4 den Längsschnitt durch die Klemmvorrichtung des Sekundärspindelbereiches der Vorrichtung nach Figur 3 in der Beschickungsposition;
• Fig. 5 den Längsschnitt nach Figur 4 mit eingesetztem Rohling;
• Fig. 6 den Längsschnitt nach Figur 4 mit eingeführter Spitze der Lanze;
• Fig. 7 den Längsschnitt nach Figur 4 im Betriebszustand mit geklemmter Lanze und gespanntem Rohling.

An embodiment of the present invention will be explained below with reference to drawings. Show it

• Fig. 1 shows schematically the structure of a conventional device for the production of internally and externally profiled tubes;
• 2 is a schematic plan view of the primary spindle area and the processing area of a device according to the invention;
• 3 shows the plan view of the secondary spindle region of the device according to the invention according to FIG. 2;
• 4 shows the longitudinal section through the clamping device of the secondary spindle region of the device according to FIG. 3 in the loading position;
• 5 shows the longitudinal section of Figure 4 with inserted blank.
• 6 shows the longitudinal section of Figure 4 with inserted tip of the lance.
• Fig. 7 shows the longitudinal section of Figure 4 in the operating state with clamped lance and clamped blank.

In Figure 1 is a schematic view of the structure of a conventional device for the production of inside and outside profiled tubes shown. The device has on the right side a headstock 1 with intermittent rotation drive. Arranging to the left of the headstock 1, a mandrel 2 is arranged, which has a corresponding to the applied to the blank 3 profiling surface.

The blank 3 has two diameter regions, a first region 3 'with a smaller diameter and a second region 3 "with a larger diameter The profiling should be formed on the region 3" of the blank 3 in the illustrated example. Typically, this is a tooth profile running parallel to the blank axis a. Such internally profiled workpieces are used, for example, for two-part telescopic tubes for forming telescopic connections in vehicle construction.

On the left side, a counter-holder 4 is formed, which has a longitudinally displaceable quill 5. In the region of the rest position of the tip 5 'of the sleeve 5, the mechanical machining means 6 acting radially from the outside onto the blank 3 are shown schematically in the form of two circles. By way of example, the machining means are known rotating impact rollers which are brought into engagement with the surface of the blank 3 in a circular movement path and thereby form the profiling in accordance with the shape of the mandrel 2 on the blank 3.

For this purpose, the front of the mandrel 2 is known to be inserted into the opening of the blank 3 from right to left and the mandrel 2 further brought together with the blank 3 against the quill 5 into abutment. Thereafter, the formation of the profiling under intermittent rotational movement and longitudinal displacement of the mandrel 2 relative to the processing means. 6

After the formation of the profiling of the mandrel 2 is moved back to its rest position on the right side back and stripped now finished blank 3 from the mandrel 2 with separate means and led away.

It is clear from this illustration that, depending on the total length of the blank 3, the mandrel 2 must be designed to be correspondingly long and thus also the distance between the headstock 1 and the anvil 4. Furthermore, the mandrel 2 has to be fully retracted into the blank 3 But also completely out of the blank 3 can be extended so that it can be supplied at all and then led away again.

To now also longer tubes resp. To be able to process blanks 3, a device according to FIG. 2 and FIG. 3 is proposed according to the invention.

A primary headstock 1 is also arranged here longitudinally displaceable in the machine frame 7 of the processing device. From the primary headstock 1, the mandrel 2 is further driven to rotate intermittently about its longitudinal axis. Further, on the machine frame 7, the processing means 6 are arranged to act radially with respect to the primary headstock axis. For example, here too, the processing means 6 are designed in the form of impact rollers. So that all drive means resp.

Drive axes arranged both for the movement of the primary headstock 1 and thus the mandrel 2 as well as the processing means 6 on the machine frame 7.

Next, a lance 8 is now coaxial with the mandrel 2, which is guided axially displaceably through the mandrel 2. The left end of the lance 8 is held in a drive, which allows an axial movement of the lance 8 relative to the primary headstock 1. For the sake of clarity, this drive is not shown in FIG. The drive may be, for example, a hydraulic cylinder, which allows the lance 8 to be acted upon by a high static tensile force in the direction of the primary headstock 1.

The free end of the lance 8 is in the region of the tip 8 'with a toothing resp. Grooved, as will be described in more detail below.

Compared with the tip 8 'of the lance 8 in extension of the primary headstock axis, a secondary headstock 4 is arranged to be longitudinally displaceable on a support 9 of the machine frame 7, as can be seen in FIG.

This secondary headstock 4 has a clamping device 10 in the form of a collet for holding the blank 3. The front of the area 3 "of the blank 3 to be machined is directed towards the primary headstock 1, while the end of the area 3 'which is not to be processed is held in the clamping device 10.

In this rest or feed position, the secondary headstock 4 is so far to the left of the area of the processing means 6, that the entire length of the Blank 3 is left outside the range of the processing means 6. Thus, the blank 3 before processing by means of suitable supply means (not shown here) easily and automatically perform the clamping device 10 and after processing of the blank 3, if necessary, remove again without interfering with the machining means 6 in the area of the machine frame 7.

By this arrangement, in particular the mandrel 2 can be formed only in the length of the area to be machined 3 '' of the blank 3 and thus also short the length of the guides of the primary spindle 4 for the longitudinal movement thereof. Furthermore, the length of the machine frame in the area of the primary headstock 1 and the machining means 6 can therefore be relatively short even for relatively long blanks 3 corresponding to the length of the area 3 "to be machined and need not be, as in conventional arrangements, at least over the full length respectively. extend to twice the length of the blank 3.

The clamping device 10 is freely rotatably arranged in the longitudinally displaceable headstock 4, as can be seen from the figure 3 in longitudinal section. The clamping device 10 advantageously has a cylindrical shell 11, within the right end of a collet 12 is arranged. In the cylindrical gap formed between the collet 12 and the clamping ring 13 arranged around it, the end of the blank 3 can be inserted, as shown in Figure 4.

The collet 12 is actuated by means of a sleeve 11 in the longitudinally displaceable cone 14. The cone 14 is resiliently supported against a likewise slidably disposed in the jacket 11 clamping piston 15 which is rotatably mounted and held on the actuating rod 16.

Figure 5 shows the inserted and held between the collet 12 and the clamping ring 13 blank 3. The clamping piston 15 has been moved against the collet 12 out in the shell 11 and thus pushes the cone 14 via the spring 17 to the inside of the collet 12 and thus fixes the blank 3 in the corresponding position.

In order now to achieve a rotationally fixed connection between the clamping device 10 and the mandrel 2, a rotational driver 18, which is arranged longitudinally displaceably in the casing 11, is furthermore arranged, as can be seen from FIG. This Rotationsmitnehmer 18 has not been shown in Figures 4 and 5 for the sake of clarity.

By inserting the tip 8 'of the lance 8 now a positive connection between the lance 8 and the Rotationsmitnehmer 18 is achieved. For this purpose, the lance 8 in the region of its tip 8 'has a longitudinal toothing 19, which engage in corresponding slots of the rotary driver 18. By the leading edges of the longitudinal teeth 19 are wedge-shaped, the Rotationsmitnehmer 18 is positioned respectively. the clamping device 10 automatically in the correct Verdrehlage.

Finally, FIG. 7 shows the clamping device 10 and the lance 8, which are completely connected with each other shown. The rear portion 20 of the Drehmitnehmers 18 is conically shaped as a collet and its inner side has radial circumferential grooves, in which the radially encircling ribs of the tip of the lance 8 can engage positively. By pressing the clamping piston 15 to the right this comes now form and locks with the Rotationsmitnehmer 18 in contact and thus forms the axial connection for the clamping operation. The lance 8 can now be pulled by its drive to the right to the primary headstock 1 and put under tension, which is now firmly clamped on the Rotationsmitnehmer 18 and the collet 12 of the blank 3 for machining and rotationally pressed against the stop on the mandrel 2.

This embodiment of the clamping device 10 thus allows, according to the invention, the blank 3 to grip and fix it on its area 3 'which is not to be machined. The movement for fixing is effected by a longitudinal drive arranged on the secondary headstock 4, for example an electric or hydraulic drive, which moves the tensioning piston 15 in the casing 11 of the clamping device 10 in the direction of the blank 3.

The clamping device 10 connected to the primary headstock 1 by the lance 8 is now moved axially together with the blank 8 through the processing area of the processing means 6, whereby an intermittent rotation of the blank 3 is effected due to the drive of the mandrel 2.

The profiling of the blank 3 is now carried out preferably by means of the impact rollers of the processing means 6 in a known manner. In this case, depending on the choice of the shape of the impact rollers, either profiled or flat rollers, inside and outside or possibly only inside a profiling of the blank 3 done.

After the finished formation of the profiling of the blank 3, usually a spline, the finished blank 3 can be fixed after radial advancement of the processing means 6 in this position and held by the feed device. Thus, the mandrel 2 with the primary headstock 1 can now be removed from the blank 3 to the right. Thereafter, the processing means 6 can be moved back into its rest position and then the blank 3, by retracting the clamping device 10 with the secondary headstock 4 in the starting position, are retracted in the region of the feeder. After releasing the clamping connection in the clamping device 4, the blank 3 can now be unloaded from the loading area and a new blank 3, as described above, the clamping device 4 are supplied.

Another advantage of this device resp. This method can be seen in the fact that the mandrel 2 can be easily changed due to the relatively short length. Preferably, this can be done via a quick-change device to quickly convert to another gear configuration can. This is practically a compared to the conventional method simpler and faster change of the mandrel 2 allows. Another advantage is that the loading and subsequent removal of the finished blank 3, the same device can be used.

For example, blanks having an outer diameter of between 20 mm and 200 mm and a length of up to 6,000 mm can be machined with the method and apparatus according to the invention, whose area to be machined has a length of up to 1,000 mm. Such thin-walled tubes can have a wall thickness between 1.0 mm and 8.0 mm and are then joined together to form a high-precision telescopic tube. The blanks consist of steel or other metals. Of course, with the method and the device even shorter tubes can be processed with shorter areas to be machined.

Claims (13)

1. Method for producing tubes that are at least partially profiled, at least on the inside, from a hollow cylindrical blank (3) by mechanical cold-forming methods, characterised in that

   - the blank (3) is fed to a clamping mechanism (10) by the end (3') not to be machined,

   - the blank (3) is held clamped in the clamping mechanism (10),

   - a mandrel (2) arranged on a primary headstock (1) is then introduced into the end of the region (3") of the blank (3) to be machined,

   - and the free end of a lance (8) is guided coaxially through the mandrel (2) and the blank (3) and into the clamping mechanism (10),

   - thereafter, the lance (8) is brought into a positive connection with the clamping mechanism (10), at least with regard to traction and rotation,

   - thereafter, the mandrel (2), together with the clamping mechanism (10) and the blank (3), is guided axially through a stationary machining station (6), in such a way that the machining station (6) acts radially on the surface of the blank (3) from the outside along the portion (3") to be machined, in order to produce at least the inner profiling of the blank (3).
2. Method according to claim 1, characterised in that the mandrel (2) is driven axially and in intermittent rotation, preferably by means of a drive arranged on the primary headstock (1).
3. Method according to any one of claims 1 to 2, characterised in that the impact rolling method is used as the mechanical cold-forming method, i.e. a successive radial beating or hammering action of profiled or non-profiled rollers is used on the blank (3), and an inner and outer or only an inner profiling of the blank (3) is achieved thereby.
4. Method according to any one of claims 1 to 3, characterised in that following the machining of the blank (3), the machining means (6) are fed at least partially with a positive fit onto the blank, thereafter the mandrel (2) is withdrawn from the blank (3), then the machining means (6) are retracted again from the positive feed and the blank (3) with the clamping mechanism (10) is moved out of the machining region into the original loading region and then the machined blank (3) is fed to a transfer mechanism or is fetched by it, whereupon the clamping mechanism (10) is released.
5. Method according to any one of claims 1 to 4, characterised in that the blank (3) is held in the clamping mechanism (10) by means of a biassing mechanism, the biassing being produced at least partially by means of spring force.
6. Method according to any one of claims 1 to 5, characterised in that the connection between the primary headstock (1) and clamping mechanism (10) in relation to the axial displacement is achieved by means of a positive and/or force-transmitting connection and is achieved in relation to the rotation by means of a positive and/or force-transmitting connection, preferably by means of a driver member (18) arranged in the clamping mechanism.
7. Method according to any one of claims 1 to 6, characterised in that the drive for applying the traction on the lance (8) for clamping the blank (3) in the clamping mechanism (10) and against the mandrel (2) takes place at the primary headstock (1), preferably by means of hydraulic force.
8. Method according to any one of claims 1 to 7, characterised in that any replacement of the mandrel (2) between various machining processes is carried out by means of a quick change mechanism.
9. Device for carrying out the method according to any one of claims 1 to 8 with a primary headstock (1) and a mandrel (2) that can be displaced axially therewith, a secondary headstock (4) and a stationary machining station, acting radially with respect to the head axis, with cold-forming tools (6), wherein the secondary headstock (4) is arranged axially opposite the primary headstock (1), with a clamping mechanism (10) arranged so as to be displaceable coaxially to the primary head axis relative to the machining station, and wherein the machining station is arranged stationarily between the primary headstock (1) and the secondary headstock (4), characterised in that a lance (8) is arranged axially moveably, axially symmetrically inside the mandrel (2), which lance has an axial toothing in the head region (8') and radially peripheral grooves at the end face.
10. Device according to claim 9, characterised in that only the primary headstock (1) is equipped with a preferably intermittently moved rotation drive.
11. Device according to either of claims 9 or 10, characterised in that the clamping mechanism (10) has a hollow cylindrical jacket (11), a collet chuck (12) arranged therein and a cone (13), which can be brought to bear axially against the collet chuck (12) from the inside.
12. Device according to any one of claims 9 to 11, characterised in that the clamping mechanism (10) has a clamping piston (15) connected to an actuating rod (16).
13. Device according to any one of claims 9 to 12, characterised in that the clamping mechanism (10) has a rotation driver member (18) axially displaceably mounted in the interior of the clamping mechanism (10), the one end of which driver member is configured as a clamping piston with a conical outer face and profiled inner face, preferably with peripheral grooves.

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