DE2364729A1 - Safety guard interlock for press tool operation - A guard operates in parallel with the tool and trips limit switches - Google Patents

Abstract

Safety interlock facilities are provided for manufacturing processes where components must be manipulated by hand. A reciprocating press tool member is driven by an hydraulic cylinder to carry out a forming operation on sheet metal components. A safety guard actuated by two cylinders operates parallel to the moving press tool to prevent the possibility of an operators fingers being under the tool. The guard moves a distance such that the access gap is large enough for insertion of components, but too small for finger insertion. In operation the guard moves down and providing there is no obstruction trips limit switches. The limit switch signals then initiate actuation of the tool and completion of this is confirmed by a limit switch to repeat the cycle.

Description

Licentia Patent Verwaltungs-G.m.b.H. 6 Prankfurt / Main 70, Theodor-Stern-Kai 1

Unger / cr FBE 73/44

December 19, 1973 =========

"Facility. For industrial accident protection for hand-operated machine tools "

The invention relates to a device for industrial accident protection in hand-operated machine tools with a protective grille using a safety device in two-hand control.

When working with hand-operated machine tools, it is often necessary that during a working stroke of the tool the workpiece is guided by hand. Here makes the use of a safety device with two-hand operation Trouble. Protective grids are often attached to such machine tools, but such protective grids prevent even if they are attached to the machine tool so that they can be opened, the manipulation of the workpiece is considerable.

There are so-called "safety two-hand circuits on power-operated Pressing by the safety regulations of the commercial trade association, Central Office for Accident Prevention, Specialized Committee for Iron and "Metal, Pressing, Issue 1. 1972"

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required. Compliance with these regulations for press brakes but requires that for the safety two-hand control used special devices and control devices must be provided so that when Bending an edge the workpiece can be carried by hand can.

The invention is based on the object of providing a device for industrial accident protection in hand-operated machine tools with a protective grille using a safety device as described above in two-hand control to create in which the workpiece is completely safe and without risk during a working stroke of the tool Obstruction through the protective grille as well as without additional facilities can be carried out by hand, with the pace of work is not noticeably slowed down compared to an unprotected machine tool, and accordingly The control is designed in accordance with the safety rules for controls on power-operated presses in metalworking is that failure of a component does not result in an inadvertent pass and after failure of one Component of the control, another working stroke cannot be triggered.

According to the invention, this object is achieved in that the protective grille is designed in the shape of a comb and attached to rods with which the protective grille is held in its initial position and the protective grille comb on the operator's side of the tool of the machine tool is arranged that further the protective grille by actuating a first foot switch can be lowered from the starting position into the protective position, in which a safety distance is provided by means of stops the teeth of the protective mesh comb from the tool table

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PBE 7-3 / 44

the machine tool is adhered to and at the same time two spaced-apart limit switches of the safety device are actuated, which then triggers a working stroke of the tool, and that during a working stroke a stop of the tool at a distance between an exposed edge of the tool on the operator side and the workpiece table a limit switch is actuated by a maximum of 8 mm, whereby the protective grille is raised again to the rest position will.

In order to quickly process one and the same workpiece several times with a corresponding number of working strokes of the tool mask to be able to, whereby the workpiece must be brought into a different machining position, is after another Embodiment of the invention, the width of a comb gap is at least equal to the sum of a tooth width and twice that Dimension workpiece thickness,

namely 1 ^ ζ + 2 d,

and the tooth height is at least equal to the difference between the maximum edge height and the safety distance between the comb teeth dimensioned from the workpiece table,

H ^ h - b,

where ζ the tooth width, 1 the width of a comb gap, d the sheet metal piece thickness, H the tooth height and h the edge height of the Workpiece mean.

Whenever you start machining workpieces that were previously machined in terms of dimensions or material Differentiate workpieces, it is usually necessary, for. B. the pressure, the force or the speed of the tool to adapt to the workpiece to be machined. Around

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PBE 73/44

To make this possible is, according to a further embodiment of the invention, a prior to actuation of the first foot switch operable second foot switch provided, by actuating the tool when it is in the protective position Protective grille is lowered to a distance of the exposed edge from the workpiece table less than 8 mm which by actuating the limit switch, the tool is stopped and the protective grille is raised back to the rest position will, and. then a working stroke of the tool is triggered again by actuating the first foot switch.

In order to prevent the protective mesh comb from being hit and damaged when the workpiece is manipulated, lies according to one embodiment of the invention, the protective mesh comb directly on the operating side of the tool.

Otherwise and according to another embodiment of the invention the protective mesh comb is in one of the distance of the teeth from the workpiece table and of the width of the tooth gaps arranged depending on the distance from the operating side of the tool.

The advantages achievable by the invention are for example evident when processing sheet metal with so-called press brakes. Here the edges are all around by means of one after the other following work cycles each e.g. B. bent at right angles, the non-bent part of a sheet metal is moved out of the usually horizontal processing position and must be carried by hand. A at the device according to the invention used safety device in two-hand control with the associated limit switches does not prevent manual guidance of these sheet metal parts and no special devices and control

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I ¹ BE 73/44

facilities are created. Bas workpiece can work with both Hands are carried.

The safety distance between the teeth of the protective mesh comb and the workpiece table and the gaps depending on the distance between the protective mesh comb from the operating side of the tool are dimensioned so that a pinger of the operator touches the tool can not achieve.

For large presses for bending thick sheet metal, the minimum width is the tooth gaps of the protective mesh comb determined by the sheet thickness.

An exemplary embodiment is shown below with reference to the drawing the invention described in a press brake. The drawing shows a perspective view of a device according to the invention. A cross-section through the device is shown in a secondary sketch of the drawing.

Based on the drawing it can be seen that a with the piston shaft 71 of the in a cylinder 7 z. B. hydraulically moved back and forth piston 72 connected folding tool 3 with a pressing edge 34 for folding sheet metal workpieces 2 is formed. The workpiece table of the press brake is a die 8 with an incision 81. A sheet metal 2 is also on the die. brought into the machining position by means of a stop 82. The press brake is provided with a protective grille 1 which is designed in the shape of a comb at its lower part in the drawing and which almost rests with this lower part on the operating side of the tool 3. With the help of the rods 11, 11 ^f , the protective grille is held in the starting position A shown. The rods are held by means of drivers 93 »93 *, which are attached to the piston shafts 91» 91 * of the pistons 92, 92 'which can be moved pneumatically to and fro ^{in two cylinders 9 »9 1}

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236472S

- 6 - PBE 73/44

are, ^ he movement of the linkage is due to a raising and lowering limited by a Pührngeirorrlichtung P.

When lowering the rods 11, 11 'and the protective grille 1 stops 12, 12 'are reached, which limit the lowering ^ and two limit switches 5 and 5 'of a safety device are used when the stops are reached operated in two-hand control, which are arranged parallel to the die 8 and with a sufficiently large distance from each other are attached. The lowering path is denoted by s. When it is hit, the protective grille 1 assumes protective layer B. Here are the teeth Z of the protective mesh comb 13 at a distance b from the die 8, which is smaller than one Finger height f is.

The lowering of the protective grille 1 is triggered before the execution of a working stroke of the folding tool 3 by actuating a first foot switch 4, whereby the overpressure is released in the cylinders 9 »9 * below the pistons 92, 92 'and let in above. If the protective grille then moves into protective position B, the limit switches 5 and 5 ^r are actuated simultaneously and the working stroke of the tool 3 is triggered. The operator's fingers are protected from the tool by the protective grille. The sheet 2 bends when it is folded by the tool into the position shown in dashed lines and can be safely guided with both hands. The tool 3 is provided with a stop 32, which actuates a limit switch 6 on the working stroke as soon as the edge 33 exposed on the operating side 31 has taken a distance a from the workpiece table which is at most 8 mm and thus also less than a finger height f. By actuating the limit switch 6, a lifting movement of the protective grille into the rest position A is triggered ^{by means of the cylinders 9, 9 1,}

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- 7 - PBE 75/44

so that the subsequently edged workpiece without the protective grille to damage, can go into the dashed position. The tool is then brought back into the balanced position. The sheet metal folded on one side can be easily removed from the die 8 of the press brake and brought into the machining position with another sheet metal side, which is now to be folded. In this way, unhindered machining of workpieces is possible without the risk of accidents. The weight of the protective grille 1 and the linkage 11, 11 · can be so small be measured in such a way that pinger injuries are excluded.

Whenever, while working with a press brake, the processing of a new workpiece series is started which differs significantly from the previously processed series in terms of dimensions and material type, so that the previously applied force or the pressure of the press brake is foreseeably insufficient to make the workpiece like If a second foot switch 4 ^{1 is} also provided, the folding tool 3 can be lowered to a distance of no more than 8 mm from the workpiece table so that a workpiece that has already been folded can be processed further without a protective grille interfering here. A dangerous closing movement is ended when moving and fixed parts of a press have approached a distance = 8 mm. A protective device is no longer required for pressing movements shorter than 8 mm, since injuries are no longer possible. The workpiece is placed with the folded part to the workpiece table, so that the comb of the protective grille does not abut on / lowering from ^ urch the operation of the Pußschalters 4 ^f is first the protective grid 1 into the "taken chutzlage B?. The subsequent lowering of the tool is set with the help of the limit switch 6 in the position

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Z364729

- 8 - FBE 75/44

ended, in which the protective grille 1 is raised again. Then the workpiece is hand-edged in brought the incision 8t and edged by pressing the foot switch 4. The trial press brake or press brakes can be carried out unhindered with changed force and without the risk of injuring a finger will.

As already mentioned, the gaps L and the distance between the teeth Z of the protective mesh comb 13 from the workpiece table can be larger than a finger's width or height »if the protective mesh comb is far away from the tool is arranged.

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Claims (5)

-S- FBE 73/44 Claims Device for industrial accident protection in hand-operated machine tools with a protective grille using a safety device in two-hand control, characterized in that the protective grille (1) is designed in the shape of a comb and attached to rods (11, 11 ') with which the protective grille is held in its initial position A. and the protective grille comb (13) is arranged on the operating side (31) of the tool (3) of the machine tool, so that the protective grille (1) can also be lowered from the starting position (A) into the protective position (B) by actuating a first foot switch (4) in which a safety distance (b) between the teeth (Z) of the protective mesh comb (13) and the workpiece table of the machine tool is maintained by means of stops (12, 12) and two limit switches (5> 5 ¹ ) of the safety device that are spaced apart from one another are actuated at the same time , whereby dam a working stroke of the tool is triggered, and that a stop (32) de during a working stroke s tool at a distance (a) of an exposed edge (33) of the tool from the workpiece table (8) of no more than 8 mm, a limit switch (6) is actuated, whereby the protective grille is raised again to the rest position. 2. Device according to claim 1, characterized in that the width (1) of a comb gap (L) is at least equal to The sum of a face width (z) and twice the workpiece thickness (d) is measured, namely 1 ^ ζ + 2 d, 50 9 8 27/0106 and that the height (H) is at least equal to -the -difference the maximum edge height (h) and the safety distance (b) of the comb teeth (Z) from the workpiece table is measured, namely H ^ h - b, where ζ the tooth width, 1 the width of a comb gap, d the sheet metal piece thickness, H the tooth height and h the edge height of the workpiece mean. 3. Device according to claim 1, characterized in that a before actuation of the first foot switch (4) can be actuated a second foot switch (4 ··) is provided, which actuates the tool (3) when in the protective position (B) located protective grille (1) lowered to the distance (a) of the exposed edge (33) from the workpiece table is, in which by actuating the limit switch (6) the tool is stopped and the protective grille is raised again to the rest position, and that then again by actuating the first foot switch (4) The working stroke of the tool is triggered. 4. Device according to claim 1, characterized in that the protective mesh comb (13) directly on the operating side (31) of the tool (3) is applied. 5. Device according to claim 1, characterized in that that the protective mesh comb (13) in one of the distance between the teeth (Z) of the comb (13) from the workpiece table and from the Width (1) of the gaps (L) of the comb (13) depending on the distance is arranged from the operating side (31) of the tool (3). 509827/0106