GB1558513A - Machine tool guards - Google Patents

Description

(54) IMPROVEMENTS RELATING TO MACHINE TOOL GUARDS (71) We, AID FABRICATIONS LIMITED, a British Company, of Oak Tree Bungalow Ladywood, Nr. Droitwich, Worcestershirc, 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: This invention relates to machine tool guards.

Automatic machine tools designed and manufactured today for operations such as turning, drilling, boring threading and so on have guards built in. They are generally in the form of an overall sliding guard which totally encloses all moving parts when the machine is operating. However, there are a great number of machine tools which have been, or are capable of being, converted to automatic operation, and these require to be guarded. It is not always convenient or practical to mount a guard on the machine itself, and the way it was built as a handoperated machine precludes this in some cases.

It is an object of this invention to provide a machine tool guard which is applicable to a great range of machine tools convertible or converted to automatic operation.

According to the present invention there is provided a machine tool guard comprising at least two generally vertical supports adapted for attachment to a base on the ground laterally clear of a machine tool, an arm projecting from the upper part of each support, a track extending between the arms, and a shield suspended from the track and arranged for travel along it.

Preferably a further parallel track is secured to the supports and serves to stabilise the shield. The first or each track may be adjustable in height and/or distance from the supports, so that the guard does not have to be 'custom-made' for each tool.

Conveniently, the shield comprises a frame covered in sheet material, a portion of which is transparent, so that the work can be visually checked.

The guard may operate in combination with a control system for the machine tool it protects. In this case, as the shield attains a guarding position a switch may be arringed to be operated, thereby to enable one mode of operation of the tool, while a locking device is actuated to secure the shield in that guarding position until the end of that mode of operation.

The shield may be manually or power operated.

For a better understanding of the invention one embodiment will now be described, by way of example, with reference to the accompanying drawing, in which the single figure is a diagrammatic perspective view, partly cut away, of a machine tool guard according to the invention.

The guard has two similar supports 1 each with a base plate 2 which is secured, by bolts for example, to the floor behind a machine tool (not shown). A vertical column 3 extends upwardly from each base plate 2 and arms 4, each supported by an angled strut 5, project horizontally from the upper ends of the columns, partially to overhang the machine tool. Each arm 4 and strut 5 is secured to a vertical strip 6 which is clamped to the associated column 3 by bolts 7 and pads 8. This enables the height to be readily adjusted, without making tracks or apertures in the column 3. A bar 9 extends between and beyond the extremities of the arms 4 and is attached beneath them.

A track 10, in the form of a tube of generally square section with a longitudinal slot in its underside, is secured by brackets 11 to the bar 9 and receives lugs with rollers (not shown) by which a shield 12 can be suspended in balanced fashion and travel along it. The shield is stabilised by a further track 13, parallel to the track 10 and secured to the struts 5. The track 13 is simply a channel section member in which one or more rollers or followers (not shown) on the rear side of the shield can engage.

Normally there will be little or no force on its flanges. The track 13 is held in place by countersunk screws through the web of its channel engaging in slots in depending fingers 14 clamped to the struts 5. The slots and the clamping give some adjustability to the position of the track 13.

The shield 12 may take various forms but will generally be of inverted U-shape as shown. It is formed by a metal frame 15 to which is secured sheet material, preferably transparent over the front part. This transparent section 16 may be a polycarbonate glazing material such as "Makrolon" or "Lexan" (both Registered Trade Marks) which gives strength and visibility. The rear section 17 may simply be sheet metal.

A flexible skirt 1S, of neoprene for example, depends from the lower front edge of the shield. These sections and the skirt can readily be replaced, and indeed the guard as a whole can easily be removed if there is a keep at one end of the track which can be displaced for sliding out the supporting rollers. It may be beneficial to have different shapes of guards for different jobs.

The shield is arranged to operate a safety system whereby the machine tool is inoperative for auto-cycling unless the shield is in the guarding position (to the left as shown in the Figure). When it achieves this position it operates a switch 19, which enables auto-cycling to commence. In the nonoperated condition manual operation of the machine tool will be possible. At the same time as, or fractionally before, the switch is operated, a plunger 20 snaps over a cam 21 on the shield 12 and positively retains the shield in the guarding position. The end of an auto-cycle signals the plunger, which may be air or electrically operated, to be raised and the shield can be drawn clear.

The shield is manually moved, by handle 22, but it can readily be powered, with its movements governed by the auto-cycle control.

It will be understood that modifications of this guard may include more than two supports, particularly if the travel of the shield is long. Also provision may be made for adjusting the overhanging ends of the arms 4 horizontally, transverse to the direction of shield movement, and this will adjust the position of the track 10. The arms may be made telescopic for this purpose.

WHAT WE CLAIM IS:- 1. A machine tool guard comprising at least two generally vertical supports adapted for attachment to a base on the ground laterally clear of a machine tool, an arm projecting from the upper part of each support, a track extending between the arms, and a shield suspended from the track and arranged for travel along it.

2. A guard as claimed in claim 1, wherein a further, parallel track is secured to the supports and serves to stabilise the shield.

3. A guard as claimed in claim 1 or 2, wherein the first or each track is adjustable in height and/or distance from the supports.

4. A guard as claimed in claim 1, 2 or 3, wherein the shield comprises a frame covered in sheet material, a portion of which is transparent.

5. A guard as claimed in any preceding claim, in combination with a control system for a machine tool to be guarded, wherein as the shield attains a guarding position, a switch is arranged to be operated, thereby to enable one mode of operation of the machine tool, and a locking device is activated to secure the shield in that guarding position until the end of that mode of operation.

6. A guard as claimed in any preceding claim, wherein the shield is manually traversed between a guarding and an open position.

7. A guard as claimed in any one of claims 1 to 5, wherein the shield is power operated.

8. A machine tool guard substantially as hereinbefore described with reference to the accompanying drawing.

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

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. and the clamping give some adjustability to the position of the track 13. The shield 12 may take various forms but will generally be of inverted U-shape as shown. It is formed by a metal frame 15 to which is secured sheet material, preferably transparent over the front part. This transparent section 16 may be a polycarbonate glazing material such as "Makrolon" or "Lexan" (both Registered Trade Marks) which gives strength and visibility. The rear section 17 may simply be sheet metal. A flexible skirt 1S, of neoprene for example, depends from the lower front edge of the shield. These sections and the skirt can readily be replaced, and indeed the guard as a whole can easily be removed if there is a keep at one end of the track which can be displaced for sliding out the supporting rollers. It may be beneficial to have different shapes of guards for different jobs. The shield is arranged to operate a safety system whereby the machine tool is inoperative for auto-cycling unless the shield is in the guarding position (to the left as shown in the Figure). When it achieves this position it operates a switch 19, which enables auto-cycling to commence. In the nonoperated condition manual operation of the machine tool will be possible. At the same time as, or fractionally before, the switch is operated, a plunger 20 snaps over a cam 21 on the shield 12 and positively retains the shield in the guarding position. The end of an auto-cycle signals the plunger, which may be air or electrically operated, to be raised and the shield can be drawn clear. The shield is manually moved, by handle 22, but it can readily be powered, with its movements governed by the auto-cycle control. It will be understood that modifications of this guard may include more than two supports, particularly if the travel of the shield is long. Also provision may be made for adjusting the overhanging ends of the arms 4 horizontally, transverse to the direction of shield movement, and this will adjust the position of the track 10. The arms may be made telescopic for this purpose. WHAT WE CLAIM IS:-

1. A machine tool guard comprising at least two generally vertical supports adapted for attachment to a base on the ground laterally clear of a machine tool, an arm projecting from the upper part of each support, a track extending between the arms, and a shield suspended from the track and arranged for travel along it.

2. A guard as claimed in claim 1, wherein a further, parallel track is secured to the supports and serves to stabilise the shield.

3. A guard as claimed in claim 1 or 2, wherein the first or each track is adjustable in height and/or distance from the supports.

4. A guard as claimed in claim 1, 2 or 3, wherein the shield comprises a frame covered in sheet material, a portion of which is transparent.

5. A guard as claimed in any preceding claim, in combination with a control system for a machine tool to be guarded, wherein as the shield attains a guarding position, a switch is arranged to be operated, thereby to enable one mode of operation of the machine tool, and a locking device is activated to secure the shield in that guarding position until the end of that mode of operation.

6. A guard as claimed in any preceding claim, wherein the shield is manually traversed between a guarding and an open position.

7. A guard as claimed in any one of claims 1 to 5, wherein the shield is power operated.

8. A machine tool guard substantially as hereinbefore described with reference to the accompanying drawing.