GB2090190A

GB2090190A - A press

Info

Publication number: GB2090190A
Application number: GB8137822A
Authority: GB
Original assignee: Umformtechnik Herbert Warnke VEB
Current assignee: Umformtechnik Herbert Warnke VEB
Priority date: 1980-12-29
Filing date: 1981-12-15
Publication date: 1982-07-07
Also published as: DE3143690C2; GB2090190B; DE3143690A1; FR2497149A1; DD154080B1; DD154080A1; FR2497149B1

Abstract

A crank-driven press for producing can components has a frame 1 in which a ram 4, 10 is guided via rolling elements 14 for reciprocating motion in guides 2 mounted in the frame 1. The ram comprises a rectangular upper portion 4 and a rectangular lower portion 10 which are integrally connected with each other by means of connection elements 6, 18, 19 and 20 arranged at the respective corners of the upper and lower ram portions. The upper ram portion 4 has a tool clamping surface 5 on which an upper tool part 7 is fastened by means of screws 15. The lower ram portion 10 surrounds a support table 11 which has a clamping surface 12 on which a lower tool part 9 is fastened by means of screws 16. A guide element 13 is carried at each corner of the upper ram portion 4, connecting element and each corner of the lower ram portion 10 and cooperates with the rolling elements 14. The plane of contact of the upper tool part with the lower tool part passes through the point of intersection of the diagonals 25, 26 of the ram. <IMAGE>

Description

SPECIFICATION A press This invention relates to a press, for example a crank-driven press for producing can components, having a ram reciprocable in a press frame and guide means for guiding the ram in the press frame. The invention is applicable to all presses the tools of which must be guided with a high degree of accuracy.

A number of inventions relating to the improvement of the guiding for the press ram in the press frame is known (WP B 30 B/197091).

These inventions constitute an improvement with respect to conventional roller, ball and sliding guides. With eccentric loading of the ram, the latter however assumes an inclined position as a result of the necessary guide play, the ellipticity of the rolling elements and the deformation of the press body. Consequently, the upper tool fastened to the underside of the ram is displaced with respect to the lower tool, as the tilting point of the ram lies far above the plane of the sheet metal.

The further the tilting point of the ram is from the plane of the sheet metal, the greater the displacement. A ram is also known from the Swiss Patent Specification 543 375, and has four additional guide columns disposed on its underside which guide the ram additionally in the region of the plane of the sheet metal. The onesided fastening of the guide columns has a disadvantageous effect in this respect.

The tilting point of the ram lies a long way above the plane of the sheet metal, so that in this case also a slightly oblique positioning of the ram causes a displacement of the upper tool part with respect to the lower tool part and therefore leads to premature wear of the tool parts.

From French Patent Specification 1489878 there is known a ram which is connected to two vertical supports which are guided through the lower portion of the press frame and are connected underneath the press. This construction enables a very long guiding also below the plane of the sheet metal, but is used in slow running presses as a result of its mass and requires high expenditure in this case. The accessibility of the tool is greatly impaired from both sides.

It is an object of the invention to increase the life of conventional press tools, whilst avoiding the drawbacks of the known arrangements, and to provide the requirements for the use of carbide tipped press tools.

The invention aims at providing a ram and guide means in a press which ensures guide pairs with the press frame on both sides of the plane of the sheet metal by means of continuous guides extending over the entire length of the ram and by means of a ram of low mass and having a compact shape.

Accordingly, the present invention consists in a press comprising a press frame, a ram reciprocable in said frame and guide elements mounted within the frame and on the ram for guiding the ram in the frame, wherein a rectangular upper ram portion, having a tool clamping surface on which an upper tool part is fastened by screws, is connected to a rectangular lower ram portion by means of connection elements, and wherein the lower ram portion surrounds a support table having a clamping surface on which a lower tool part is fastened by means of screws, each corner of the upper ram portion, each connection element and each corner of the lower ram portion being provided with a respective ram guide element which co-operates with a respective guide element in the frame to form a rolling guide assembly, the planes of contact of the upper tool part with the lower tool part passing through the point of intersection of the diagonals of the ram. Preferably, the rolling guide assembly is constructed as an eight-fold rolling guide. Conveniently, the plane of contact of the upper tool part with the lower tool part passes through the point of intersection of the diagonals of the ram.

During the downward stroke of the ram there arises in the case of eccentric loading an inclined position which is dependent on the rigidity of the guide elements. In this respect the ram is twisted about the point of intersection of the diagonals lying in the plane of the sheet metal, i.e. in the plane of contact of the upper and lower tool parts.

The cutting process takes place in this plane. The displacement of the upper tool part with respect to the lower tool part is reduced to a small residual amount caused by the deflection from the plane.

The advantage of the invention consists in that a ram of a fast-running press is formed in such a way that the damaging effect of the slightly inclined position on the tool caused by the elastic deformation of the guides and the rolling elements in the case of eccentric loading is prevented.

A further advantage is that the ram constructed in this way is substantially the same as conventional rams in terms of size and volume and is therefore suitable particularly for fast-running presses. The degree of structural complexity therefore remains slight. The ram is formed compactly in one piece.

Advantageously, the guide elements in the press frame are formed in such a way that the ram with its guide elements is guided over its entire length during the entire course of the movement of the ram.

The ram guide elements with the eight-fold rolling guiding are disposed in the top dead centre and in the bottom dead centre of the ram within the guide elements of the press frame. It is not possible for the ram to move out of the guide elements of the press frame.

As a result of the arrangement of the upper ram portion, the lower ram portion and the connection elements, apertures are provided in the plane of the sheet metal. These apertures ensure good accessibility of the tool and for assembly and dismantling and for charging. The simple assembly and dismantling of the ram, which does not differ from the constructions conventionally used, is also advantageous.

In order that the invention may be more readily understood, reference is made to the accompanying drawings which illustrate diagrammatically and by way of example an embodiment thereof, and in which: Fig. 1 is a main view of the ram and the ram guiding in cross-section; Fig. 2 is a cross-section on the line A-A of Fig. 1; Fig. 3 is a cross-section on the line B-B of Fig. 1; and Fig. 4 is a cross-section on the line C-C of Fig. 2.

In Fig. 1 the ram is shown in its lower dead centre position, and in Fig. 2 in its top dead centre position.

The ram, comprising an upper ram portion 4 having a workpiece clamping surface 5, connection elements 6, 8, 1 9, 20 and a lower ram portion 10, is mounted in the press frame 1 having guide bars 2.

An upper tool part 7 of a multiple cavity die is fastened to the clamping surface 5 of the upper ram portion 4 by means of screws 1 5. A lower tool part 9 is connected to a clamping surface 12 of a support table 11, projecting into the lower ram portion 10, by means of screws 1 6. The upper tool part 7 and the lower tool part 9 have additional tool guiding elements 1 7. The support table 11 is rigidly connected to the press frame 1. The ram is connected to the press drive (not shown) by means of a pivot joint 3 fixedly mounted in the upper ram portion 4. The upper ram portion 4, the lower ram portion 10 and the connection elements 6, 18, 19, 20 carry ram guide elements 13 with rolling elements 14.

The guide bars 2 are therefore so constructed that they guide the ram guide elements 1 3 with the rolling elements 14 during the entire stroke of the ram. In this respect the clamping surface 5 of the upper ram portion 4 is arranged such that in the case of the cutting operation shown in Fig.1 the plane of the sheet metal 8 lies in the point of intersection 27 of the ram diagonals 25 and 26 during the engagement of the upper tool part 7 with the lower tool part 9. Apertures 21, 22, 23 and 24 are provided between the connection elements 6, 18, 1 9 and 20.

Claims

1. A press comprising a press frame, a ram reciprocable in said frame and guide elements mounted within the frame and on the ram for guiding the ram in the frame, wherein a rectangular upper ram portion, having a tool clamping surface on which an upper tool part is fastened by screws, is connected to a rectangular lower ram portion by means of connection elements, and wherein the lower ram portion surrounds a support table having a clamping surface on which a lower tool part is fastened by means of screws, each corner of the upper ram portion, each connection element and each corner of the lower ram portion being provided with a respective ram guide element which co-operates with a respective guide element in the frame to form a rolling guide assembly, the planes of contact of the upper tool part with the lower tool part passing through the point of intersection of the diagonals of the ram.

2. A press as claimed in claim 1 , wherein the rolling guide assembly is constructed as an eightfold rolling guide.

3. A press as claimed in claim 1 or 2, wherein the plane of contact of the upper tool part with the lower tool part passes through the point of intersection of the diagonals of the ram.

4. A press as claimed in any of the preceding claims, wherein the guide elements in the press frame are formed such that the ram with its ram guide elements is guided over its entire length during the entire course of movement.

5. A press as claimed in any of the preceding claims, wherein as a result of the arrangement of the upper ram portion, the lower ram portion and the connection elements apertures are formed in the plane of contact of the upper tool part with the lower tool part.

6. A press, substantially as herein described with reference to and as shown in the accompanying drawings.