GB1600288A - Spot welding and other machines - Google Patents

Description

(54) AN IMPROVEMENT IN OR RELATING TO SPOT WELDING AND OTHER MACHINES (71) We, SPEEDWELL REIN FORCEMENT LIMITED, a British Com- pany, of 37 Exchange Street, Sheffield 2, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to spot welding and other machines of the kind having an anvil or worktable and a toolhead or the like movable towards and away from the anvil or worktable.

Machines of the kind referred to do not lend themselves readily to guarding by means of total enclosure using fixed or interlocking guard mechanisms because of the need for the operator to have frequent access to the work area to reposition the workpiece or to adjust a new workpiece in position and also because of the need for the operator to have an unobstructed view of the work area.

According to the invention there is provided a machine of the kind referred to, having an anvil or worktable and a toolhead or electrode holder movable towards and away from the anvil or worktable, there being provided a guard in the form of a fence for surrounding the work area during a power stroke of the toolhead or electrode holder, the guard being slidable towards and away from the anvil or worktable, independently or the tbolhead or electrode holder, by power operated means and being connected to means for opening an electric switch to interrupt the power to the toolhead or electrode holder the arrangement being such that until the guard is less than a pre-determined distance from the anvil or worktable a power stroke of the toolhead or electrode holder cannot take place, the guard depending from the toolhead or electrode holder on vertically located suspension rods which extend slidably through guides on the front face of the toolhead or electrode holder, the power operated means for moving the guard relative to the toolhead or electrode holder being constituted by a pneumatic ram which when actuated lifts the guard clear of the work area.

Preferably the guard will be made of a transparent plastics material.

In order that the invention may be fully understood and readily carried into effect, the same will now be described, by way of example only, with reference to the accompanying drawing which is a perspective view of a wire mesh welding machine embodying the invention.

Referring now to the drawing, the machine there illustrated is a wire mesh welding machine for the production of welded mesh from wires crossing one another and welded together at their crossover points. The wires 10 from which the mesh is to be made are position in channels 12 in a jig which is mounted on a worktable 14. An electrode 16 is mounted beneath a toolhead 18 and can be brought down onto the transverse wires in turn as the jig is progressed across the worktable by an operative. A power stroke of the electrode can be initiated by the depression of a foot pedal 20.

A guard 22 which is provided to safeguard the operator from injury is in the form of a fence surrounding the work area during a power stroke of the toolhead. The guard is made of a transparent plastics material and depends from the toolhead on suspension rod 30 which are connected to a crosshead member (26 and 34). A pneumatic ram 28 which is carried on the front face of the toolhead is connected to the crosshead so that actuation of the ram causes the guard to be raised clear of the work area. When the ram is retracted, the guard falls back to a position in which it is spaced less than 5 m.m. from the jig (that is to say a distance less than the thickness of an operatives finger).

The suspension rods 30 extend slidably through guides 32 on the front face of the toolhead, the rods being connected at their lower ends to the guard 22 and at their upper ends to bars 26 and 34 constituting the crosshead member, 26 having a turned down end for the on/off lever of a microswitch 36, said micro-switch being arranged to interrupt the power supply to the toolhead when open.

The arrangement is such that only when the guard is in its operative position, the micro-switch 36 is closed and the foot pedal 20 is rendered operable so that a power stroke can be initiated. When the operative needs to raise the guard so that he has greater access to the work area, he can do this by opening a valve 38 which operates the pneumatic ram 28. This causes the micro-switch 36 to be opened and renders the foot pedal inoperative. Thus it will be seen that the machine is very safe and that even if the operative by inadvertence depresses the foot pedal whilst the guard is raised he cannot injure himself. In other words, a power stroke cannot be initiated until the guard is in its lowered position and the guard cannot return to its lowered position whilst the operatives hand or even a finger is in the way.

Various modifications may be made without departing from the scope of the invention. For example, screwthreaded adjustment may be provided for varying the length of the suspension rods 30 on which the guard is suspended. It will of course be understood that the invention may be used on other machines such as riveting machines.

WHAT WE CLAIM IS: 1. A machine of the kind referred to having an anvil or worktable and a toolhead or electrode holder movable towards and away from the anvil or worktable there being provided a guard in the form of a fence for surrounding the work area during a power stroke of the toolhead or electrode holder, the guard being slidable towards and away from the anvil or worktable, independentlv of the toolhead or electrode holder, by power operated means and being connected to means for opening an electric switch to interrupt the power to the toolhead or electrode holder, the arrangement being such that until the guard is less than a pre-determined distance from the anvil or worktable a power stroke of the toolhead or electrode holder cannot take place, the guard depending from the toolhead or electrode holder on vertically located suspension rods which extend slidably through guides on the front face of the toolhead or electrode holder, the power operated means for moving the guard relative to the toolhead or electrode holder being constituted by a pneumatic ram which when actuated lifts the guard clear of the work area.

2. A machine according to claim 1, in which the guard is made of a transparent plastics material.

3. A machine constructed, arranged and adapted to operate substantially as hereinbefore described with reference to and as illustrated by the accompanying drawings.

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

Claims (3)

**WARNING** start of CLMS field may overlap end of DESC **. less than the thickness of an operatives finger). The suspension rods 30 extend slidably through guides 32 on the front face of the toolhead, the rods being connected at their lower ends to the guard 22 and at their upper ends to bars 26 and 34 constituting the crosshead member, 26 having a turned down end for the on/off lever of a microswitch 36, said micro-switch being arranged to interrupt the power supply to the toolhead when open. The arrangement is such that only when the guard is in its operative position, the micro-switch 36 is closed and the foot pedal 20 is rendered operable so that a power stroke can be initiated. When the operative needs to raise the guard so that he has greater access to the work area, he can do this by opening a valve 38 which operates the pneumatic ram 28. This causes the micro-switch 36 to be opened and renders the foot pedal inoperative. Thus it will be seen that the machine is very safe and that even if the operative by inadvertence depresses the foot pedal whilst the guard is raised he cannot injure himself. In other words, a power stroke cannot be initiated until the guard is in its lowered position and the guard cannot return to its lowered position whilst the operatives hand or even a finger is in the way. Various modifications may be made without departing from the scope of the invention. For example, screwthreaded adjustment may be provided for varying the length of the suspension rods 30 on which the guard is suspended. It will of course be understood that the invention may be used on other machines such as riveting machines. WHAT WE CLAIM IS:

1. A machine of the kind referred to having an anvil or worktable and a toolhead or electrode holder movable towards and away from the anvil or worktable there being provided a guard in the form of a fence for surrounding the work area during a power stroke of the toolhead or electrode holder, the guard being slidable towards and away from the anvil or worktable, independentlv of the toolhead or electrode holder, by power operated means and being connected to means for opening an electric switch to interrupt the power to the toolhead or electrode holder, the arrangement being such that until the guard is less than a pre-determined distance from the anvil or worktable a power stroke of the toolhead or electrode holder cannot take place, the guard depending from the toolhead or electrode holder on vertically located suspension rods which extend slidably through guides on the front face of the toolhead or electrode holder, the power operated means for moving the guard relative to the toolhead or electrode holder being constituted by a pneumatic ram which when actuated lifts the guard clear of the work area.

2. A machine according to claim 1, in which the guard is made of a transparent plastics material.

3. A machine constructed, arranged and adapted to operate substantially as hereinbefore described with reference to and as illustrated by the accompanying drawings.