GB2047585A - Separation of sections from bars or the like - Google Patents

Abstract

A method for the separation of sections (17) from bars (12), wherein the bar and the section are held separately in direct proximity in a force-locking and/or form-locking manner and are separated by torsion. A shearing force may also be applied. An apparatus for carrying out the method comprises two holders (8, 9) lying directly against one another and turnable relative to one another. The shearing force may be applied by arranging the axes of the holders (8, 9) eccentric relative to one another. <IMAGE>

Description

SPECIFICATION Method and apparatus for the separation of sections from bars or the like This invention relates to a method and apparatus for the separation of sections, for example blanks, from bars or the like.

So-called blanks which have been separated from bars or billets of large lengths are processed and machined particularly in the manufacture of drop forgings and extrusion mouldings. Whereas these blanks were previously usually sawn off, they are now separated almost without exception by a shearing operation. Shearing has in comparison with sawing the economic advantage that higher separation performances are achieved and no material losses occur. However, the not inconsiderable disadvantage arises that the sheared blanks do not have planar separation faces, that the separation faces are not exactly perpendicular to the axis of the blank and that crack formation can occur in the separation faces. In addition, upon shearing, the crosssection of the blank or of the bar is deformed in the region near the separation face.

It was established from comprehensive investigations published e.g. in "Industrie-Anzeiger, Volume 97, No. 69 of 29.8.1975, pages 1 538-1 544, and Kurt Lange "Lehrbuch der Umformtechnik, Volume II, 1974, pages 614-629, that the position and the planeness of the separation face can be considerably improved by a particular choice of blade shape, size of the shear gap, shearing speed, temperature and workpiece clamping as well as due to a superimposed axial compressive stress. However, an undesirable deformation of the cross-section still occurs.

There is known from German OLS 1,925,750 a method especially for the separation of short pieces or pressings from a long bar with the use of a separating tool with a fixed section and a separating stamp movable in relation to said section, in which method the separating stamp is exposed temporarily to an impact effect directed to the bar of such strength that it received at least the energy necessary for the separating operation and the movement of the separating stamp is stopped immediately after completion of the separating operation. Despite a high separating speed, a small shear gap, special workpiece bracing and limitation of the separating stamp stroke, the separation faces do not have the required position and planeness. Too large a deformation of the bar cross-section due to the separating operation is also not excluded here.

Furthermore, the known methods of separation require a high consumption of energy and are unsuitable for the separation of sections whose length is equal to or less than the diameter of the bar. Moreover, the known devices work noisily and therefore necessitate special measures for sound-proofing.

The object of the invention is therefore to provide a method and an apparatus for the separation of sections, especially blanks, from bars or the like, which produce the desired planeness and position of the separation faces, avoid a disadvantageous deformation of the cross-section, necessitate a small consumption of energy, work comparatively silently and can be used for the separation of relatively short sections.

According to the invention, there is provided a method for the separation of sections from bars or the like, wherein the bar and the section to be separated are held separately in direct proximity in a force-locking and/or form-locking manner and are separated by torsion.

This method results in a rotationally symmetrical and clean separation face. Due to the rotationally symmetrical introduction of force no noteworthy deformation of the cross-section and no consolidation in the separation or shearing zone occur. The smaller local compressive loads also permit the separation of sections whose length is shorter than the diameter of the profile bar. The consumption of energy required for torsional shearing is significantly smaller than for linear shearing.

Furthermore, the relaxation impact does not arise, since the resistance in the torsional shearing operation is smaller and gradually decreases.

According to a further feature of the invention there is superimposed on the torsion a shearing force which can be derived from the torsion. The stress in the marginal zone of the shear plane is thereby increased and the initiation of the shearing operation is consequently favoured. The separating operation or the torsion is effected at a high angular velocity, thereby improving the quality of the separation faces. If the torsion is effected over a limited angle governable by the cross-sectional size of the profile bar, the largely separated section can still remain on the profile bar.

According to the invention, there is also provided an apparatus for the separation of sections from bars, comprising members turnable relative to one another, each having a force-locking and/or form-locking holder for the bar and the section to be separated, the two holders lying directly against one another.

The invention is described in detail hereinafter with reference to an exemplary embodiment illustrated in a simplified way in a drawing wherein: Figure 1 is a section through an apparatus according to the invention; and Figure 2 is a plan view of the apparatus of Fig. 1.

The apparatus 1 illustrated in the drawing serves for the separation of a section from a profile bar and comprises two members 2, 3, the member 3 of which is arranged fixedly and may be supported bya raachine stand (not shown). On a free end face the member 3 has in the embodiment illustrated a recess 4 in which the member 2 is mounted turnably with a shouldered flange 5. The members 2, 3 each have a continuous opening 6, 7, said openings being aligned with one another at least in the basic position of the member 2 and each accommodating a holder 8, 9 of circular cross-section.

The holders 8, 9 merely suggested in the drawing have through-openings 10, 11 which are aligned with one another likewise in the basic position of the member 2 and into which a profile bar 12, having in this instance a circular cross-section, is pushed from the free side 13 of the member 3 so that, as illustrated, said bar projects by a given amount into the holder 8 of the member 2.

The holders 8, 9 are intended, on the one hand, to permit an axial displacement of the profile bar 12, but, on the other hand, to prevent any turning at least in one direction, the directions in which turning is prevented of the two holders 8, 9 being opposite one another or acting oppositely to one another.

For this purpose, the holders 8, 9 are designed in dependence on the cross-sectional form of the profile bar 12 e.g. as clamping jaws, freewheel systems or profile rings having a profile corresponding to that of the bar 12.

As is illustrated especially clearly in Fig. 2, in this exemplary embodiment the axis of rotation 14 of the member 2 and the axes 15 of the holders 8, 9 are offset to one another, while remaining parallel to one another, that is they are arranged eccentrically to one another. The position or direction of this eccentricity may be as desired, but is selected in dependence on the cross-section and form of the profile bar 12. However, in no case is the eccentricity larger than the largest radius of the profile bar cross-section, so that the axes 15 of the holders 8, 9 are always situated within the profile cross-section.

This eccentric arrangement of the holders 8, 9 necessitates a special construction thereof.

Each holder 8, 9 has in the exemplary embodiment illustrated a shearing element, said shearing element being made in one piece with the holders 8, 9 only the shearing element 16 of the holder 8 being suggested in Fig. 2. These shearing elements 16 extend over only a part of the inner faces of the holders 8, 9. The remaining inner face of the holders 8, 9 serves to transmit the torsional moment and is designed in an appropriate way as a freewheel system 18. The shearing elements 16 are arranged lying opposite one another in relation to the shear plane, that is when, as shown in Fig. 2, the shearing element 16 is situated "at the top" in the holder 8 of the member 2, the shearing element in the holder 9 is situated "at the bottom".

Wot the separating opexation, due to introduction at a high angular velocity of forces e.g. at the points marked with arrows 2a, 2b (Fig. 2), the member 2 is turned through a given angle in an anti-clockwise direction. This results in that the section 17, situated in the holder 8 of the member 2, of the profile bar 12 is turned in relation to the profile bar 12 situated in the holder 9 of the member 3 and is consequently exposed to torsion. However, due to the above-mentioned eccentricity, the holder 8 changes its axis in relation to the holder 9, so that additional shearing forces act via the shearing elements 16 inserted in the holders 8, 9 on the profile bar 12 in the region of the separating line between the member 2 and the member 3 or between the holder 8 and the holder 9.Due to the torsional and shearing forces superim posed on one another the section 17 is separated from the profile bar 12. The resulting separation faces of the section 17 and of the profile bar 12 are planar and extend perpendicularly to the axis of the profile bar 12 and of the section 17. A deformation prejudicing the further processing of the section 17 does not occur in so doing. Upon the further push ing forwards of the profile bar 12 the section 17 is ejected or delivered to a further process ing device.

In a modification of the exemplary embodiment described, the eccentricity between the axis of rotation 14 of the member 2 and the axis 15 of the holders 8, 9 can be "zero".

The separation of the section 17 is then effected only due to torsional forces. The cross-section of the profile bar 12 to be divided may be selected as desired. The holders 8, 9, must, however, be adapted to this crosssection.

Claims (15)

1. Method for the separation of sections from bars or the like, wherein the bar and the section to be separated are held separately in direct proximity in a force-locking and/or form-locking manner and are separated by torsion.

2. Method according to claim 1, wherein a shearing force is superimposed on the torsion.

3. Method according to claim 2, wherein the shearing force is derived from the torsion.

4. Method according to any of claims 1 to 3, wherein the torsion is effected over a limited angle.

5. Method according to any of claims 1 to 4, wherein the torsion is effected at a high angular velocity.

6. Apparatus for the separation of sections from bars, comprising members turnable relative to one another, each having a force locking and/or form-locking holder for the bar and the section to be separated, the two holders lying directly against one another.

7. Apparatus according to claim 6, wherein the axes of the two holders are coaxial with the axis of rotation of the two members.

8. Apparatus according to claim 6, wherein the axes of the two holders are eccentric relative to the axis of rotation of the two members.

9. Apparatus according to claim 8, wherein the eccentricity is equal to or less than the largest radius of the profile bar crosssection.

10. Apparatus according to any of claims 6 to 9, wherein the holders comprise clamping jaws, freewheel systems, or profile rings.

11. Apparatus according to claim 10, wherein at least a part of the holders are constructed as shearing elements.

12. Apparatus according to claim 11, wherein the shearing elements extend in dependence on the eccentricity over an angle of from 30 to 270 .

13. Apparatus according to claim 11 or 12, wherein the holders accommodate the shearing elements lying opposite one another in relation to the shearing plane.

14. Apparatus according to any of claims 11 to 13, wherein the holders and the shearing elements are made in one piece.

15. Apparatus for the separation of sections from bars substantially as herein described with reference to the accompanying drawing.