GB2110581A

GB2110581A - Sheet metal stamping

Info

Publication number: GB2110581A
Application number: GB08231052A
Authority: GB
Inventors: Dr Klaus E Lang
Original assignee: KARGES HAMMER MASCHF
Current assignee: KARGES HAMMER MASCHF
Priority date: 1981-12-01
Filing date: 1982-10-29
Publication date: 1983-06-22
Also published as: IT1191106B; IT8224527A0; IT8224527A1; DE3147465A1

Abstract

A press 1 comprises an upper part 2 with a slide 8 for a stamping tool 13, and a lower part 3 with a platen 6 for a counterpart tool 7. The up-and-down movement of the slide 8 is guided by columns 14. Metal components such as cans or can lids are fed from a device 4. A wheel 12 adjusts a V-belt 10 from a cone 11 to a flywheel 9. Heating cartridges 15 bring the upper part 2 up to operating temperature before the press 1 is brought into operation so as to reduce registration error. <IMAGE>

Description

SPECIFICATION Sheet metal stamping The invention relates to sheet metal stamping machines and a method of reducing registration error in the operation of such machines.

Sheet metal stamping machines generally comprise a pressing and stamping tool attached to a motor-driven slide in an upper part of a press body which perform an up-and-down movement, and a counterpart tool on a platen in a lower part of the press body. Such machines produce a blank for a can and/or can lid in a single operation from tin plate or tin plate strip. To achieve efficiency in production, can lids are manufactured at a high indexing speed. in order to reduce waste, the machines are loaded with tin plate or tin plate strip cut to very close tolerances, and the machine is required to work with great accuracy. The material used frequently consists of superfine sheets 0.16 to 0.4 mm thick, so it is not unusual for the tools to work with a die clearance of only 0.01 mm.

It has become evident from such stamping machines in operation that their service life is disproportionately short, i.e. that it is necessary after a relatively short time to replace or recondition the tools. For years this wear was thought to be unavoidable due to the high indexing speed. The invention is based on the recognition that the short service life is due also to thermal influences. Investigations have revealed that the generation of heat in the upper part of the press results mainly from friction due to the slide moving in its bearing, and to a certain extent from the friction on the crankshaft or camshaft driving the slide. This may lead to displacement of the upper part of the press relative to its lower part by as much as 0.07 mm. As a result the tool no longer meets the envisaged die clearance, and life of the tool is reduced.

The invention provides a sheet metal stamping machine comprising a slide for a stamping tool, a platen for a counterpart tool, and means for heating the operative parts of the machine to operating temperature before the machine is brought into operation.

The invention includes a method of reducing registration error in a sheet metal stamping machine which comprises heating operative parts of the machine to operating temperature before the machine is brought into operation.

The invention ensures that registration and operation are both performed in the same thermal state, so that the heat generated does not lend to displacement of the tool relative to the counterpart tool. Due to the moving parts in the upper part of the press, a constant temperature is set up, determined by the heat generated by the movement and by the heat transmitted to the surrounding area. By pre-heating the upper part of the press a stable final state can be set up prior to starting the machine, and when the machine is put into operation that state is maintained. This prevents misalignment caused by temperature changes.

Drawings: Figure 1 is a side view of a sheet metal stamping machine according to the invention; and Figure 2 is a section along a line A-B in Figure 1.

The stamping machine illustrated in Figure 1 consists of a press body 1, which is shaped in the form of a sloping 'C', and comprises an upper part 2 and a lower part 3. A device 4 feeds tin plates and/or tin plate strips into a space between the upper part 2 and lower part 3. The machine is controlled from a desk 5 situated on the lower part 3. The lower part 3 comprises a platen 6 on which a counter-part tool 7 is arranged. The upper part 2 comprises a reciprocating slide 8 which is driven from a flywheel 9 connected with an eccentric.

The flywheel 9 in turn is driven by a V-belt 10 from a driving cone 11 coupled to a motor (not shown). The position of the V-belt 10 on the driving cone 11 may be adjusted by means of a crank 12, thus allowing selection of the tansmission ratio between the driving cone 11 and the flywheel 9, and thereby of the rotational speed of the flywheel 9. The slide 8 is fitted with stamping and pressing tool 13, which in conjunction with the counterpart tool 7 stamps out the can lid and presses it into its final shape.

Two guide columns 14 coming from the platen 6 are surrounded by ball bushes thus effecting additional guidance of the slide 8 in relation to the platen 6. Preheating of the lower part 2 in the vicinity of the slide 8 is effected by heating cartridges 15 provided a bearing 17 (Figure 2) for the slide 8. Figure 2 shows that the slide 8 is shaped in the form of an essentially rectangular frame with angled projections 16 extending parallel to its longitudinal axis on the side walls in a bearing 17 having a prismatic guide.

The heat generated by the movement of the slide 8 in operation is produced on the friction surface between the projections 16 and the bearings 17. Figure 2 shows that the heating cartridges 15 are arranged in the immediate vicinity of the bearing 1 7. Thus the upper part 2 is heated in the area of the bearing 17 to the temperature reached during operation before the machine is put into operation.

1. A sheet metal stamping machine comprising a slide for a stamping tool, a platen for a counterpart tool, and means for heating the operative parts of the machine to operating temperature before the machine is brought into operation.

2. A machine according to claim 1 in which the said means comprises holes for heating cartridges adjacent a bearing for the slide.

3. A sheet metal stamping machine as herein described with reference to the drawings.

4. A method of reducing registration error in a sheet metal stamping machine which comprises heating operative parts of the machine to

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Sheet metal stamping The invention relates to sheet metal stamping machines and a method of reducing registration error in the operation of such machines. Sheet metal stamping machines generally comprise a pressing and stamping tool attached to a motor-driven slide in an upper part of a press body which perform an up-and-down movement, and a counterpart tool on a platen in a lower part of the press body. Such machines produce a blank for a can and/or can lid in a single operation from tin plate or tin plate strip. To achieve efficiency in production, can lids are manufactured at a high indexing speed. in order to reduce waste, the machines are loaded with tin plate or tin plate strip cut to very close tolerances, and the machine is required to work with great accuracy. The material used frequently consists of superfine sheets 0.16 to 0.4 mm thick, so it is not unusual for the tools to work with a die clearance of only 0.01 mm. It has become evident from such stamping machines in operation that their service life is disproportionately short, i.e. that it is necessary after a relatively short time to replace or recondition the tools. For years this wear was thought to be unavoidable due to the high indexing speed. The invention is based on the recognition that the short service life is due also to thermal influences. Investigations have revealed that the generation of heat in the upper part of the press results mainly from friction due to the slide moving in its bearing, and to a certain extent from the friction on the crankshaft or camshaft driving the slide. This may lead to displacement of the upper part of the press relative to its lower part by as much as 0.07 mm. As a result the tool no longer meets the envisaged die clearance, and life of the tool is reduced. The invention provides a sheet metal stamping machine comprising a slide for a stamping tool, a platen for a counterpart tool, and means for heating the operative parts of the machine to operating temperature before the machine is brought into operation. The invention includes a method of reducing registration error in a sheet metal stamping machine which comprises heating operative parts of the machine to operating temperature before the machine is brought into operation. The invention ensures that registration and operation are both performed in the same thermal state, so that the heat generated does not lend to displacement of the tool relative to the counterpart tool. Due to the moving parts in the upper part of the press, a constant temperature is set up, determined by the heat generated by the movement and by the heat transmitted to the surrounding area. By pre-heating the upper part of the press a stable final state can be set up prior to starting the machine, and when the machine is put into operation that state is maintained. This prevents misalignment caused by temperature changes. Drawings: Figure 1 is a side view of a sheet metal stamping machine according to the invention; and Figure 2 is a section along a line A-B in Figure 1. The stamping machine illustrated in Figure 1 consists of a press body 1, which is shaped in the form of a sloping 'C', and comprises an upper part 2 and a lower part 3. A device 4 feeds tin plates and/or tin plate strips into a space between the upper part 2 and lower part 3. The machine is controlled from a desk 5 situated on the lower part 3. The lower part 3 comprises a platen 6 on which a counter-part tool 7 is arranged. The upper part 2 comprises a reciprocating slide 8 which is driven from a flywheel 9 connected with an eccentric. The flywheel 9 in turn is driven by a V-belt 10 from a driving cone 11 coupled to a motor (not shown). The position of the V-belt 10 on the driving cone 11 may be adjusted by means of a crank 12, thus allowing selection of the tansmission ratio between the driving cone 11 and the flywheel 9, and thereby of the rotational speed of the flywheel 9. The slide 8 is fitted with stamping and pressing tool 13, which in conjunction with the counterpart tool 7 stamps out the can lid and presses it into its final shape. Two guide columns 14 coming from the platen 6 are surrounded by ball bushes thus effecting additional guidance of the slide 8 in relation to the platen 6. Preheating of the lower part 2 in the vicinity of the slide 8 is effected by heating cartridges 15 provided a bearing 17 (Figure 2) for the slide 8. Figure 2 shows that the slide 8 is shaped in the form of an essentially rectangular frame with angled projections 16 extending parallel to its longitudinal axis on the side walls in a bearing 17 having a prismatic guide. The heat generated by the movement of the slide 8 in operation is produced on the friction surface between the projections 16 and the bearings 17. Figure 2 shows that the heating cartridges 15 are arranged in the immediate vicinity of the bearing 1 7. Thus the upper part 2 is heated in the area of the bearing 17 to the temperature reached during operation before the machine is put into operation. CLAIMS

4. A method of reducing registration error in a sheet metal stamping machine which comprises heating operative parts of the machine to operating temperature before the machine is brought into operation.

5. A method of reducing registration error in a sheet metal stamping machine as herein described.