GB2071553A - Sheet metal-working device - Google Patents

Abstract

A sheet metal-working device comprises a ram 22 driven by a hydraulic cylinder 26. A work surface 20 is arranged in a plane normal to the direction of movement of the ram. The hydraulic cylinder is arranged below the work surface with the ram extending upwardly through an opening 34 in the work surface. Thus, sheet metal on the work surface can be worked by tools carried on the ram. As shown the edge 24b of a circular hole in a workpiece 24c is trimmed by a tool 24a secured to the ram. Alternatively the edge of a hole may be e.g. racked or widened. <IMAGE>

Description

SPECIFICATION Sheet metal working device The invention relates to a sheet metal-working device comprising a ram driven by a hydraulic cylinder, and a work surface lying in a plane normal to the direction of movement of the ram.

Such a device is normally known as a "press", and is conventionally constructed with supports which project upwardly from either a rear edge or two opposite edges of the work surface i.e. the press table", the hydraulic cylinder being mounted on the ends of the support remote from the work surface. The ram performing a working stroke towards the press table as the ram moves out of the drive cylinder, in order, for example, to operate a punching or stamping tool.

The dimensions of metal plates which can be worked on such a press are limited by the free space between the supports. Consequently, metal plates of large area can only be worked on correspondingly large presses, even if the plates are very thin. This is uneconomical, in particular in the case of individual and short-run production, because a considerable time is required to set-up large and correspondingly expensive presses.

Furthermore, if the hydraulic cylinder is required to exert a considerable force on the workpiece, the press frame must be dimensioned to accommodate the equally large reaction forces, so that the load-bearing parts must be heavy and correspondingly expensive, even though the weight of the hydraulic cylinder to be supported is itself comparatively small.

According to the invention, there is provided a sheet metal-working device comprising a ram driven by a hydraulic cylinder, and a work surface arranged in a plane normal to the direction of movement of the ram, the hydraulic cylinder being arranged below the work surface, and the ram extending upwardly through an opening in the work surface for the mounting of working tools thereon.

The following is a more detailed description of one embodiment of the invention, by way of example, reference being made to the accompanying drawings, in which: Figure 1 is a vertical cross-section through a sheet metal-working device, and Figure 2 is a perspective view of the device of Fig. 1 but fitted with a tool which is different from the tool fitted in Fig. 1.

Referring to Fig. 2 the device comprises a frame 12 movable on rollers 10. The frame 12 has side cover plates 14 provided with ventilation slots 16, and has at the front fitted storage compartments 18 for tools, for example. A work surface 20 rests on the frame, and comprises a central opening 34 for a ram 22, on which - in Figure 2 - a square plate 24 is mounted (e.g. to serve as a trimming tool).

As can be seen in Figure 1, a hydraulic cylinder 26 is screwed below the work surface 20 via a mounting plate 30 having an opening 31. A piston rod either forms or carries the ram 22. The assembly of the hydraulic cylinder 26 and the ram 22 is stiffened by triangular ribs 28 and the mounting plate 30, and is screwed to the work surface 20 by screws 32.

The work surface 20 comprises an opening 34 concentric with the ram 22, and is provided with further depressions 36 which increase stepwise in diameter, and into which inserts 38 are fitted (only two are shown). The free end of the ram 22 is provided with a thread 40 in threaded engagement with a knurled head 42 for fixing tools, e.g. a tool 24a for trimming edges 24b of a circular hole in a workpiece 24c. Further tools 62 for co-operating with tools carried by the ram 22 are either supported on the work surface 20 or are in fact formed thereby. The depressions 36 which are exactly concentric to the axis of the ram 22 serve for centering such tools 62.It should be noted that smaller complete tools such as punching shears and stamping tools 68 can also be driven by means of an arm 66 laterally extending from the ram 22, these naturally having their own guide for the upper tool, whereas the lower tool can be fixed to the work surface 20 by means of clamps or the like. The work surface 20 further comprises centering recesses 60 for larger area tools 62. The contour of such a tool 62 is shown in dashed lines.

It is apparent that the device described above with reference to the drawings is of versatile application, and can be of very simple construction.

A pumping assembly 46 (an electric motor plus a hydraulic pump, preferably a high pressure pump for a high pressure cylinder 26) is fitted in the interior of the frame 1 2 as shown in Figure 1 at 44, and is supported on an intermediate floor 48.

The cylinder is in this case shown as a doubleacting cylinder. It can however also be singleacting, and can be returned by means of tension of compression springs. In addition to feed lines 50, 52 from the unit 44 to the cylinder, further lines 54, 56 lead to a pressure connector 58, to which further mobile hydraulic devices can be connected. A control panel 64 is located in a side wall of the frame 12, which is otherwise totally enclosed.

The only structural components which have to absorb the reaction forces arising from working operations are the work surface itself and the hydraulic cylinder suspended directly below it, plus its piston rod and ram, and these parts are correspondingly dimensioned. The work surface is stressed by direct pressure, but is not subjected to bending moments, as in the case of a press frame.

The spaces around the work surface remains completely free.

The limitation in the use of the device described above with reference to the drawings is that a metal plate to be worked must be traversed by the ram (but the plate edge can be worked in the same manner as in conventional presses).

However, the number and type of possible working operations is considerable, such as making holes (of larger dimensions than the ram diameter), working the edges of such holes such as necking, shoulder turning, widening, trimming, and the metal plate does not have to be flat, it being possible even to work pipes.

Claims (7)

1. A sheet metal-working device comprising a ram driven by a hydraulic cylinder, and a work surface arranged in a plane normal to the direction of movement of the ram, the hydraulic cylinder being arranged below the work surface, and the ram extending upwardly through an opening in the work surface for the mounting of working tools thereon.

2. A sheet metal-working device as claimed in claim 1 wherein that the work surface is mounted on a movable frame.

3. A sheet metal-working device as claimed in claim 2 wherein the frame comprises a housing within which is located a hydraulic pump for supplying hydraulic fluid under pressure to the hydraulic cylinder and a control for the hydraulic pump.

4. A sheet metal-working device as claimed in any one of claims 1 to 3 wherein the work surface comprises a series of concentric circular stepped depressions arranged around the opening.

5. A sheet metal-working device as claimed in claim 4 wherein inserts are provided which fit into respective depressions and which have an upper surface level with an upper surface of the associated depression of the work surface.

6. A sheet metal-working device as claimed in any one of claims 1 to 5 wherein the work surface comprises, outside the opening, positioning recesses for carrying counter-tools for cooperating with operating tools mounted on the ram.

7. A sheet metal-working device substantially as hereinbefore described with reference to the accompanying drawings.