EP2127775B1 - Method for manufacturing workpieces and spinning machine therefor - Google Patents

Abstract

The method involves slidingly placing a portion of a preform (8) onto a mandrel (4), and aligning the mandrel such that a surface (3b) placed within the preform defines a negative profile of an inner surface to be formed in the preform. A relative movement is caused between the preform and a pressure roller (7) in a direction parallel to a longitudinal axis, such that material of the preform is displaced by the pressure roller in such a way that the mandrel is moved longitudinally along the longitudinal axis by the displaced material. An independent claim is also included for a flow-forming machine for producing workpieces, comprising a mandrel.

Description

The invention relates to a method for the production of workpieces according to the preamble of claim 1.

A method according to the preamble of claim 1 is made DE 10 2005 057 945 A1 known. In particular processes rotationally symmetric preforms are processed by spin forming, for example, to produce support rollers, automotive parts or gas cylinders. With regard to the stress of such products, it is desirable to stiffen areas already during the forming process. When using appropriate products, especially the middle areas are more stressed, so that a material reinforcement in this area is preferred. Particularly preferred here are moldings with concave or conical inner surfaces, which were not produced with the previously known flow-forming process.

The object of the invention is therefore to provide a method of the type mentioned, with which can be produced from a preform workpieces with concave or conical inner surface.

This object is achieved by a method having the features of claim 1 or by a flow-forming machine with the features of claim 10. Advantageous embodiments can be found in the dependent claims.

According to the invention, according to a first embodiment, the preform, preferably a cylindrical tube, is clamped onto the mandrels of a main spindle box and a tailstock.

Main spindle box and tailstock each have a tool housing, which are each arranged concentrically around the respective mandrel and provide for external centering of the preform. Mandrels and tool housing are each movable parallel to the machine axis or to the longitudinal axis of the preform. The mandrels each have outer surfaces which taper in one direction so as to form a negative mold of the concave or conical inner surface to be formed in the preform. According to the invention, pressure is now exerted on the outer surface of the preform by one or preferably a plurality of pressure rollers. During machining, the facing sides of the two mandrels are held in contact with each other. The mandrels and tool housing are moved so that initially a material flow of the material of the preform takes place in a space between the tailstock mandrel and associated tool housing. Subsequently, a movement of the tool housing of the main spindle box and the associated mandrel is such that the material flow takes place substantially in the direction of the main spindle box in the region of the outer surface of the associated mandrel and so the workpiece is finished with concave or conical inner surface.

Figur 1 -

zeigt eine Längsschnittansicht durch eine Drückwalzmaschine die zur Ausführung des erfindungsgemäßen Verfahrens ausgelegt ist, beim Einspannen der Vorform und vor dem Zusammenfahren der Dorne,

Figur 2 -

zeigt die Maschine aus Figur 1 mit eingespannter Vorform, vor dem Zusammenfahren der Dorne,

Figur 3 -

zeigt die Maschine aus Figur 1 vor Beginn der erfindungsgemäßen Bearbeitung der Vorform,

Figur 4 -

zeigt die Umformsituation nach Umformung eines Teils der Vorform,

Figur 5 -

zeigt die Umforsituation gegen Ende der Umformung der Vorform,

Figur 6 -

zeigt die Maschine nach Entnehmen des fertigen Werkstücks,

Figur 7 -

zeigt eine weitere erfindungsgemäße Ausführungsform mit einer Längsschnittansicht durch eine Drückwalzmaschine, die zur Ausführung des erfindungsgemäßen Verfahrens ausgelegt ist, beim Einspannen der Vorform und vor dem Zusammenfahren der Dorne,

Figur 8 -

zeigt die Maschine aus Figur 7 mit eingespannter Vorform vor dem Zusammenfahren der Dorne,

Figur 9 -

zeigt die Maschine aus Figur 7 vor Beginn der erfindungsgemäßen Bearbeitung der Vorform,

Figur 10 -

zeigt die Umformsituation nach Umformung eines Teils der Vorform,

Figur 11 -

zeigt die Umformsituation gegen Ende der Umformung der Vorform,

Figur 12 -

zeigt die Maschine nach Entnehmen des fertigen Werkstücks,

Figur 13 -

zeigt eine dritte- Ausführungsform der erfindungsgemäßen Drückwalzmaschine in Längsschnittansicht, welche zur Herstellung von Flaschen mit einem Spreizdorn ausgebildet ist, vor dem Einspannen der Vorform,

Figur 14 -

zeigt die Maschine aus Figur 13 mit eingespannter Vorform,

Figur 15 -

zeigt die Maschine aus Figur 13 in einer Umformsituation nach Umformung eines Teils der Vorform,

Figur 16 -

zeigt die Umformsituation gegen Ende der Umformung der Vorform,

Figur 17 -

zeigt die Maschine beim Entnehmen des fertigen Werkstücks.

The invention will be explained in more detail below with reference to the drawing figures 1 to 6.

FIG. 1 -

shows a longitudinal sectional view through a flow-forming machine which is designed for carrying out the method according to the invention, in Clamping the preform and before bringing the mandrels together,

FIG. 2 -

shows the machine FIG. 1 with clamped preform, before the collapse of the mandrels,

FIG. 3 -

shows the machine FIG. 1 before starting the processing of the preform according to the invention,

FIG. 4 -

shows the forming situation after forming a part of the preform,

FIG. 5 -

shows the Umforsituation towards the end of the deformation of the preform,

FIG. 6 -

shows the machine after removing the finished workpiece,

FIG. 7 -

shows a further embodiment according to the invention with a longitudinal sectional view through a flow-forming machine, which is designed for carrying out the method according to the invention, during clamping of the preform and before the collapse of the mandrels,

FIG. 8 -

shows the machine FIG. 7 with clamped preform before the mandrels come together,

FIG. 9

shows the machine FIG. 7 before starting the processing of the preform according to the invention,

FIG. 10 -

shows the forming situation after forming a part of the preform,

FIG. 11

shows the forming situation towards the end of the deformation of the preform,

FIG. 12 -

shows the machine after removing the finished workpiece,

FIG. 13

shows a third embodiment of the flow-forming machine according to the invention in a longitudinal sectional view, which is designed for the production of bottles with an expanding mandrel, before the clamping of the preform,

FIG. 14 -

shows the machine FIG. 13 with clamped preform,

FIG. 15 -

shows the machine FIG. 13 in a forming situation after forming a part of the preform,

FIG. 16

shows the forming situation towards the end of the deformation of the preform,

FIG. 17

shows the machine when removing the finished workpiece.

In the FIGS. 1 to 6 is a schematically illustrated flow-forming machine, with which the inventive method can be performed.

In the FIG. 1 The device shown has a main spindle box 1 and an associated tool housing 6 with a mandrel 4 guided axially displaceably therein. Tool housing 6 and mandrel 4 lie on a common longitudinal axis MA which passes through the center of the main spindle S1 and tailstock spindle S2. By a hydraulic cylinder H1, the mandrel 4 can be moved axially relative to the tool housing 6. The mandrel 4, as well as the mandrel 3, is each equipped with the negative mold of the inner surface of the finished part 8.2 a and 8.2 b. In this case, the smallest diameter in the plane of the mutually facing end faces 3c and 4c of the mandrels 3 and 4.

The tool housing 6 has opposite the main spindle receiving a receiving bore 6b with a driver 6a. The receiving bore 6b has the outer diameter of the preform 8, so that the preform 8 centered by the receiving bore 6b can be added to the longitudinal axis MA. When inserting the preform 8, FIG. 1 If the preform 8 is pressed in the start-up phase of the forming by the mandrel 3 of the tailstock, the driver 6a takes this with rotation of the main spindle S1 on the tool housing 6 with. During the forming, the axial contact pressure of the preform is taken over by the axial forming force of the spinning rollers 7.

The tailstock 2 with the tailstock spindle S2 and the tool housing 5, depending on the size of the preform to be reshaped 8 also be equipped with a synchronous to the main spindle S1 drive. Tailstock spindle and tool housing 5 lie in the center of the common longitudinal axis MA and rotate around them.

The mandrel 3 in the tool housing 5 is arranged axially displaceable by a hydraulic cylinder H2.

Depending on the type of flow-forming machine main spindle box 1 and tailstock 2 can be moved relative to and independently of each other to the axially positioned pressure rollers 7. Alternatively, there is the constructive solution, the pressure rollers 7 to be arranged displaceable together via an axial feed, in which case the main spindle 1 fixed and the tailstock 2 are arranged movable. The latter solution is in the Figures 1-6 shown.

The mandrel 3 has an axial stop surface 3d and in the negative mold direction an outer diameter 3e which corresponds to the inner diameter of the preform 8. If a preform 8 is received, the mandrel 3 moves into the preform 8 by advancing the hydraulic cylinder H2, centering the outer diameter 3e on the side of the preform 8 facing the mandrel 3, and pushing it into the previously described outer center 6b of the tool holder 6 to press them against the driver 6a with an axial pressure. In this workflow phase, FIG. 2 , the preform is kept centered by hand or by an automatic loading device until the clamping is ensured.

The tool housing 5, as in the Figures 1-6 shown, is required only when the tailstock S2 is driven. If the tailstock spindle is not driven, the mandrel 3 with the hydraulic cylinder H2 assumes the function of a tailstock quill. A corresponding embodiment is in the FIGS. 7 to 12 shown.

After the preform 8 is clamped ( FIG. 2 ), the mandrel 4 moves axially towards the tailstock 2 by the advance of the hydraulic cylinder H1 to form a unit with the mandrel 3. In this case, both sides 3c and 4c of the mandrels 3 and 4 are pressed against each other, wherein the centering projection 3a of the mandrel 3 is inserted into the centering hole 4a of the mandrel 4. This is due to the two mandrels 3 and 4, the negative form formed the inner surface of the finished part. The length of the two proportional negative forms 3b, 4b together corresponds to the length of the finished part, which is formed from the preform 8. If a cylindrical shape 8c with the diameter of the separating surface 3c or 4c is provided between the proportionate negative mold 3b, 4b and separating surface 3c and / or parting surface 4c, then the length of the finished part increases by these amounts.

The same applies if, as in Figure 8.2 shown, a cylindrical shape 8c in the region of the preform end, to the main spindle side, is provided. Alternatively, it is also possible to mold an additional, cylindrical shape 8c towards the tailstock side.

The spinning rollers 7 move radially outside the clamped preform 8 in their positions, and then together in the axial direction to drive against the rotating preform 8, FIG. 3 , The rotation of the unit preform 8, tool housing 5, 6 with the spines 3, 4, the main spindle S1 and tailstock S2 is done by the drive of the main spindle S1 and, depending on the version, also on the synchronlaufenden- drive the tailstock S2.

For forming according to the invention one or preferably a plurality of pressure rollers 7 are arranged on the circumference of the preform 8. The pressure rollers 7 are provided on the circumference in the axial direction in each case with an inlet slope. Radially, the pressure rollers 7 are in position to the outer diameter of the finished part 8.2, which achieved by flow-forming the preform 8 shall be. If the pressure rollers 7 positioned around the center of the longitudinal axis MA of the main spindle S1 are driven jointly in the axial direction x by a common feed on the rotating preform 8, they are rotated by contact with the preform 8 in rotation. In this case, the material is set in a flow state by the axial and radial pressure of the pressure rollers 7 in the region between the pressure rollers 7 and first of all the respective, axial cross-sectional plane of the mandrel 3, FIG. 4 , The material penetrates into the existing free space 9 between the mandrel 3 and the pressure roller 7 in order, after filling the volume of the free space 9, FIG. 5 , in the direction of tailstock 2, with the set outer diameter of the finished part 8.2 and given by the mandrel 3 inner diameter, to evade. By the axial stop 3d on the mandrel 3 of the tailstock 2 of this mandrel 3 is taken by the back-flowing material, as long as material flows back through the displacement. Tolerances in the diameters of the preform 8 are therefore noticeable only in the length of the formed workpiece 8.2.

Since the two mandrels 3, 4 are coupled in the composite, they are pushed together by the displaced material in the tailstock 2, while the spinning rollers 7 move together in the direction of the main spindle box 1. This results from the material displacement from the preform 8, the finished part 8.2, which is reduced in outer diameter relative to the preform 8, with an imprint of the two mandrels 3, 4 as an inner diameter.

The forming is completed when the spinning rollers 7 come close to the outer center 6b of the preform, FIG. 5 , Thereafter, the individual flow-forming rollers 7 return to their radial starting position and together in their axial starting position. The mandrel 4 of the main spindle side is decoupled and retracted, the mandrel 3 of the tailstock side also from the shaped workpiece 8.2. For this purpose, if necessary, provided an externally acting scraper. With the withdrawal of the tailstock 2, the shaped workpiece 8.2 is released, FIG. 6 ,

The shaped workpiece 8.2 is characterized by a reduced outer diameter, and in the inner diameter by the impression of the contour of the two mandrels 3, 4th

In the method according to the invention, concave, conical and cylindrical contours are used on the mandrels. Since the mandrel or the composite of two mandrels during the deformation, in which the material flows, is displaced by the excess material, which forms from the reduction of the cross section of the preform on the cross section of the finished part form, there is no relative movement between the workpiece inner surface and Mandrel.

The mandrel moves axially only in the direction of freedom when a material abundance is present. This means that the reshaped material rolls axially on the mandrel and this pushes further only if enough material is there. There is thus no relative movement between mandrel and material, but only a rolling according to the contour in the axial direction. This rolling of the material in the area of the spinning rollers can be assisted or made more difficult by a hydraulic pressure regulation in the cylinders H1 and H2.

With the rolling of the material and a so-called. Eating between the two elements material and mandrel outer surface during the forming is not possible.

Tolerances in the preform area are absorbed by the extruded material without affecting the nature of the finished workpiece, ie different wall thicknesses of the preforms have no influence on the formed by the spin forming wall thickness of the finished workpiece; the material continues to flow only when the predetermined wall thickness of the finished workpiece is reached in the relevant axial plane. Only the length of the shaped workpiece is therefore predominantly subject to tolerances. The flow rate of the material from the Querschnittreduzierung in the relevant axial plane of the preform, in the cross section of the relevant axial plane of the finished part, is formed from the excess material and the feed rate of the spinning rollers. This means that the axial speed of the displacement of the unit of the two mandrels is dependent on the cross-sectional reduction in the respective axial plane of the preform, at a constant feed rate of the spinning rollers.

Thus, with this method different heels, steps and contours can be formed in the inner surface of a rotationally symmetrical hollow body, when these steps, shoulders and contours taper towards the point of separation of the dowels moved together in diameter.

This also applies when working only with the mandrel of the tailstock side. Furthermore, the method is applicable when only a part of the rotationally symmetrical body in the longitudinal direction, using one or two mandrels, reshaped and thereby applied.

Thus, it is possible, depending on the subsequent load of the workpiece, to form a so-called carrier on two supports with constant resistance moment.

The properties of the cylindrical preformed workpieces produced by the process are particularly suitable for gas cylinders and idlers.

In the FIGS. 7 to 12 a second erfindungsegmäße embodiment of the flow-forming machine is shown. This differs from the arrangement in the FIGS. 1 to 6 merely in that the tailstock side 2 'has the already mentioned above function of a tailstock quill in the tailstock side no tool housing is provided and only the mandrel 3 is mounted displaceably via a hydraulic cylinder H2 in the axial direction x. When forming the mandrel 3 is pushed back by material flow in the direction of the tailstock side 2 'against the force of the hydraulic cylinder. Incidentally, the method is analogous to that described above with reference to FIGS. 1 to 6 described method.

An alternative variant is in the FIGS. 13 to 17 shown. In contrast to the embodiments described above, this device comes with only one main spindle side provided expanding mandrel 4 'from. This variant is provided in particular for forming cylindrical preforms 8, in which one end is closed, such as in gas cylinders.

The expanding mandrel 4 'has a section approximately corresponding to the mandrel 4 of the above embodiments with a conical or conical outer surface 4b' and an adjoining spreading section 4d which has outer surface sections 4b "which act against the machine axis MA via a spreading mechanism 4e can be so that this section is replaced by the shape of the mandrel 3 of the above embodiments.

First, the preform 8 is pushed with its open side on the expanding mandrel 4 ', wherein a mandrel 4' opposite slider 10 engages the closed end of the preform 8 and this deferred until the stop 6a on the tool housing 6 of the main spindle box 1, FIG. 14 , The slider 10 holds the preform 8 against the stop 6a, so that the portion 4f of the mandrel 4 'by means of the spreading mechanism 4e can be spread so that the above-described clearance 9, which corresponds to the negative shape of the inner surface to be formed, is formed by the surfaces 4b 'and 4b "between the inner wall of the preform 8 and the mandrel 4' Material from the preform 8 is forced into the space 9, wherein the mandrel 4 'is moved, FIGS. 15 and 16 , After completion of the forming process, the finished form 8.2 is removed after retraction of the mandrel 4 ', FIG. 17 , and the open end of the mold 8.2 can be further processed, for example, to produce a gas cylinder 8.3.

The forming by spin forming takes place in the described embodiments in two directions, namely in the radial direction by reducing the outer diameter of the preform 8 and in the axial direction by shaping a cylindrical shape with the new, reduced outer diameter. In this case, the spinning rollers 7 advance in the direction of the main spindle box 1 while rotating the preform 8. This causes the material displacement takes place in a spiral shape and thus the displaced material distributed both axially and in the circumferential direction of the mandrel 3, 4, 4 '(tangentially). The reason for this lies in the material displacement from a larger to a smaller diameter with simultaneous rotation of the material.

The material flows radially to the smaller diameter of the mandrel 3, 4, 4 'and fills the cavity; tangential, due to the rolling displacement by the rotation, with simultaneous feed movement in the axial direction; such as axially, opposite to the feed movement, if a sufficient excess material is present.

If, in this situation, the mandrel 3, 4, 4 'secured radially against rotation, the material must move relative to the mandrel 3, 4, 4' in the circumferential direction of the mandrel. The result is a relative movement of the shaped body to the body of the preform 8 on a fixed mandrel.

According to a preferred embodiment, the mandrel 3, 4, 4 'in the circumferential direction and axially freely movable; This allows it to adapt to the movement in the two directions mentioned by the contact with the deformed material unhindered. In this case, takes place in the circumferential direction relative movement in the non-contact region of the preform 8 to the mandrel 4, 4 'on the main spindle side.

LIST OF REFERENCE NUMBERS

1

Headstock

2

tailstock
2 'quill

3

Tailstock mandrel

• 3a pin
• 3b Surface of the tailstock mandrel
• 3c front side of the tailstock pin
• 3d stop
• 3eCenter diameter of the tailstock mandrel

4, 4 '

Main spindle arbor

• 4a hole
• 4b, 4b ', 4b "surface of the main spindle mandrel
• 4c face of the main spindle mandrel
• 4d spreading section
• 4e spreading mechanism

5

Tool housing of the tailstock

6

Tool housing of the main spindle
6a driver

7

jig

8th

preform

8.1

machined preform

• 8.1a first area
• 8.1b transition area
• 8.1c third area

8.2

finished workpiece

• 8.2a first area
• 8.2b second area
• 8.2c third area

9

cavity

10

pusher

A

Longitudinal axis of the preform or of the workpiece

MA

Longitudinal axis of the flow-forming machine

S1

main spindle

S2

Tailstock spindle

H1

Hydraulic cylinder of the main spindle box

H2

Hydraulic cylinder of the reedock

8.3

gas bottle

Claims (16)

1. Method for producing workpieces, in which an essentially cylindrical preform (8) is shaped by means of at least one pressure roller (7) into a finished workpiece (8.2), whereby the following steps are carried out:

   a. pushing of a section of the preform (8) onto at least one first mandrel (3, 4') mounted so as to be displaceable parallel to the longitudinal axis (A) of the preform (8),

   b. arrangement of the mandrel (3, 4') so that its surface (3b, 4b, 4b') lying in the preform (8) forms approximately a negative mould of the inner face to be formed on the preform (8),

   c. realisation of a relative movement between the preform (8) and the pressure roller (7) in a direction parallel to the longitudinal axis (A) with simultaneous pressing of the pressure roller (7) against the preform (8),

   characterised in that
   step c. is carried out so that material of the preform (8) is displaced through the pressure roller (7) in such a way that the mandrel (3, 4') is moved through the displaced material.
2. Method according to claim 1,
   characterised in that
   after step a., the placing of the further section of the preform (8) lying opposite the first section onto a second mandrel (4) mounted so as to be displaceable parallel to the longitudinal axis (A) of the preform (8) is carried out and subsequently the first (4) and the second mandrel (3) are brought together in such a way that their surfaces (3b, 4b) lying in the preform (8) form an approximately negative mould of the inner face to be formed on the preform (8).
3. Method according to claim 2,
   characterised in that
   the mandrels (3, 4) are coupled during the pressing process.
4. Method according to one of the preceding claims,
   characterised in that
   the mandrel(s) (3, 4, 4') is / are axially moved and / or rotated out of the preform (8) in any case for a time through subsequently flowing material.
5. Method according to claim 4,
   characterised in that
   the displacement takes place in the direction of the first tool housing (5) connected to a tailstock (2), in which the first mandrel (3) is mounted so as to be displaceable.
6. Method according to one of the preceding claims,
   characterised in that
   the preform (8) is pushed by means of a entrainment element (6a) situated on a tool housing (5, 6) onto the first mandrel (3).
7. Method according to claim 6,
   characterised in that
   the preform (8) is centred as it is pushed onto the first mandrel (3) by means of centring element (3e) on the first mandrel (3).
8. Method according to one of the preceding claims,
   characterised in that
   at least one mandrel (3, 4) with a tapered or double tapered, conical or double conical outer face (3b, 4b, 4b') is used.
9. Method according to one of the preceding claims,
   wherein merely one section of a rotationally symmetrical preform (8) is shaped.
10. Pressure rolling machine, in particular for carrying out the method according to one of the preceding claims, with at least one mandrel (3, 4, 4') mounted so as to be displaceable parallel to the machine axis (MA), onto which a preform (8) to be shaped is pushed, and with at least one shaping roller (7) for shaping the preform (8), whereby the outer face of the at least one mandrel (3, 4, 4') is designed so that in the region of a pushed- on preform (8) it has a tapering region which forms essentially the negative mould of an inner face to be formed on the preform (8),
    characterised in that
    the at least one mandrel (3, 4, 4') is mounted so that it is displaced and / or rotated, during shaping, through material displaced out of the preform (8) through pressure rolling.
11. Pressure rolling machine according to claim 10,
    characterised in that
    it further comprises a main headstock (1) with a tool housing (6) and an associated further mandrel (4) mounted so as to be displaceable parallel to the machine axis (MA).
12. Pressure rolling machine according to claim 11,
    characterised in that
    furthermore a tailstock (2) is provided with the associated one mandrel (3) mounted so as to be displaceable parallel to the machine axis (MA), whereby the two mandrels (3, 4) are arranged concentrically and whereby the two mandrels (3, 4) face each other with their end faces (3c, 4b) and respectively taper towards their end faces (3c, 4c).
13. Pressure rolling machine according to claim 12,
    characterised in that
    furthermore a tool housing (5) assigned to the tailstock (2) and which is mounted so as to be displaceable parallel to the machine axis (MA) is provided.
14. Pressure rolling machine according to one of the claims 11 to 13,
    characterised in that
    one mandrel (3) comprises a pin element (3a) which can be introduced, for the purpose of centring with the other mandrel (4), into a bore (4a) provided thereon.
15. Pressure rolling machine according to one of the claims 10 to 14,
    characterised in that
    the at least one mandrel (3, 4, 4') comprises a centring element for the preform (8) to be received.
16. Pressure rolling machine according to one of the claims 10 to 15,
    characterised in that
    a mandrel (4') with an expansion element is provided.

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