GB2063153A - Improvements relating to sawing machines - Google Patents

Abstract

To enable the position of a workpiece (18) to be adjusted relative to the saw blade in order to make maximum use of the working length of the blade, an auxiliary jaw (30) is provided for location between the workpiece (18) and the fixed jaw (15) of a work holder. The auxiliary jaw (30) comprises two parts (34, 36) which can be adjusted in telescopic manner and secured in a selected position of adjustment. <IMAGE>

Description

SPECIFICATION Improvements relating to sawing machines This invention relates to sawing machines (particularly hacksawing machines) of the kind having a reciprocating holder for mounting a saw blade and a vice assembly for holding a workpiece securely during the sawing operation so that the workpiece extends transversely of the reciprocating saw blade holder. Such sawing machines are hereinafter referred to as being of the kind specified.

The vice assembly of such machines in general comprises two pairs of vice jaws so as to grip the workpiece at spaced positions along its length, one pair of jaws (the front pair) being located nearer to the blade holder than the other (rear) pair. Usually, the rear pair of jaws is mounted for movement as a unit lengthwise of the workpiece so that the rear pair can be used to feed the workpiece relative to the holder.

As far as I am aware, hitherto each pair of jaws has comprised a fixed jaw and a movable jaw. This fact, coupled with the need for the length of the saw blade to be sufficiently long for use with a wide range of workpiece diameters, has meant that in many instances the blade has to be renewed even though it has become worn over only a small part of its working length, for example in circumstances where a large number of sawing operations are carried out on small diameter workpieces. Although this problem of blade replacement after only limited wear has existed for many decades, I am not aware of any commercially acceptable solutions to the problem if indeed the problem has been recognised as such.

The object of the present invention is to provide means for adapting a sawing machine of the kind specified in order to enable the working life of the saw blades to be increased especially when a large number of small diameter cut-off operations have to be made.

According to one aspect of the present invention there is provided a method of adapting a sawing machine of the kind specified to lengthen the working life of its blade comprising providing the or each fixed jaw thereof with a removable auxiliary jaw whereby the position of the clamped workpiece relative to the length of the blade is adjusted.

According to a second aspect of the present invention there is provided a sawing machine of the kind specified wherein said vice assembly comprises at least one pair of jaws of which one is fixed and the other is movable, characterised by the provision of a removable auxiliary jaw for the or each fixed jaw whereby the clamping position of the workpiece is adjustable.

Preferably the or each auxiliary jaw is adjustable so that when assembled to the respective fixed jaw, the spacing of the auxiliary gripping face relative to the fixed gripping face can be varied.

Preferably the auxiliary jaw comprises two parts coupled together in telescopic fashion and means is provided for locking the telescoping parts in selected positions of adjustment. The locking means may be such that the parts can be locked in any one of a number of finite positions of adjustment or alternatively the parts may be in finitely adjustable relative to one another and the locking means may be arranged to secure the parts together in any selected position of adjustment.

To stabilize the auxiliary jaw when mounted on the machine, it may be provided with means for connecting it to the respective fixed jaw and/or other fixed structure of the machine. In general, sawing machines of the kind specified include a slidewayfor the or each movable jaw and each slideway incorporates a channel or groove in which a lead-screw is accommodated, the lead-screw being coupled to the movable jaw. Although jaw configurations of conventional sawing machines vary widely, all such machines are provided with a lead-screw channel extending between the fixed and movable jaws and, as a general rule, it is only the width of the channel that varies from one machine to another. In the presently preferred embodiment of the invention, each auxiliary jaw is provided with location means for engaging in said channel in order to stabilize the auxiliary jaw.Such location means is conveniently of adjustable dimensions widthwise of the channel so that the auxiliary jaw can be used with machines having lead-screw channels of differing widths.

It will be understood that by means of the auxiliary jaws, the position of the workpieces can be adjusted after one section of the blade has become worn so as to bring the workpieces into registry with an unworn section of the same blade and where the workpieces are exceptionally small, this adjustment procedure can be repeated several times thereby prolonging blade life considerably.

One embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a front elevation of a conventional hacksawing machine provided with auxiliary jaws in accordance with the invention; Figure 2 is a plan view of the machine shown in Figure 1; and Figure 3 is a perspective view of one of the auxiliary jaws.

Referring now to the drawings, the hacksawing machine illustrated is of conventional construction and comprises a reciprocably driven arm 10 carrying a replaceable blade 12, a front pair of vice jaws 14, 15 and a rear pair of vice jaws 16, 17 for clamping an elongate workpiece 18 at spaced positions along its length in order to hold the workpiece stationary while the arm 10 reciprocates transversely of the workpiece to effect a sawing operation. The rear pair of jaws 16, 17 may be displaceable as a unit lengthwise of the workpiece (as indicated by arrows A) to effect feed of the workpiece in conventional manner. Such displacement may be effected by suitable hydraulic means (not shown) for instance.

The jaws 15, 17 are fixed relative to the bed 20 of the machine and the jaws 14, 16 are slidable along slideways 22, 24 towards and away from the respective jaws 15,17 under the control of suitable means such as lead-screws (not shown) accommodated in channels 26,28 in the slideways 22, 24. Arrows B in Figure 2 indicate the directions of movement of the jaws 14, 16. Numerals 30, 32 depict the auxiliary jaws of the present invention.

It will be understood that hitherto the position of the clamped workpiece was dictated by the fixed jaws 15, 17 so that, in the absence of the auxiliary jaws 30, 32 the workpiece 1 8-regardless of its size would be clamped with one side thereof in direct abutment with the fixed jaws 15, 17. As a consequence wear of the blade 12 would be confined to a region adjacent the fixed jaws 15,17 especiallyfor small diameterworkpieces. In the past, this has meant that frequently a worn blade has had to be replaced through wear adjacent one end even the remaining length of the blade had been unused.

Referring now to Figure 3, each auxiliary jaw 30, 32 comprises two parts 34, 36 which are slidably engageable in telescopic manner. For this purpose, the part 36 is provided with angle section portions 38 for slidably receiving the top and bottom edges of the side walls 40 of the part 36. Thus, the spacing between the front wall 42 of the part 34 may be varied relative to the rear wall 44 of the part 36 by sliding the parts 34, 36 relative to each other. Means is provided for securing the parts 34, 36 in selected positions of adjustment and such means may be such that the parts can be secured together in any position of sliding adjustment.In the illustrated embodiments, the arrangement is such that the parts 34, 36 can be secured at a number of well defined positions and for this purpose each auxiliary jaw includes a locking pin 46 for engagement in aligned holes 48 in side walls 40 and any one of three pairs of aligned holes 50 in side walls 52. As shown in Figures 1 and 2, the locking pin 46 is engaged with the middle pair of holes 50 in the part 36.

It will be understood that, with the aid of the auxiliary jaws 30, 32, the position of the workpiece 18 may be varied lengthwise of the blade 12 according to the adjusted setting of the parts 34, 36 and by periodically repositioning the workpiece transversely of its length by adjustment of the auxiliary jaws (and removal of the auxiliary jaws), the life of the blade can be considerably lengthened by making use of its full working length.

Means is provided for stabilizing the auxiliary jaws and such means may be in the form of formations provided on the part 36 so as to engage with the jaws 15,17. As mentioned previously however, the vice jaws may vary in configuration from one machine to another and for this reason in the preferred embodiment the stabilizing means is conveniently cooperable with the slideways of the machine and in particular with the channels 26, 28.

This is implemented in the illustrated embodiment by provision of two pairs of tongues 54, 56 mounted on and depending below the respective parts 34, 36.

To enable the tongues to be adjusted to takeup play in the channels 26, 28, the tongues are mounted on non-rotatable screwthreaded rods 58, 60 between pairs of nuts 62, 64 so that by appropriate manipulation of the nuts the positions of the tongues can be adjusted lengthwise of the rods 58 until they abut opposite sides of the channels 26, 28, as shown in Figure 2. The nuts 62, 64 are readily accessible for this purpose because the parts 34, 36 are open at top and bottom. Otherforms of mounting arrangements for the tongues are of course possible; for example, the arrangement may be such that the rods 58,60 are rotatably mounted in the side walls 40 and 52 and turning of each rod, e.g. by means of a handle or the like, causes the respective tongues to move towards or away from each other according to the direction in which turning takes place.

The side walls 52 of the jaw part 36 are cut away at 66 for the receiption of the ends of the rod 58 so that the jaw can be retracted at such an extent that the wall 42 engages the front wall 68 of the part 36. To facilitate entry of a workpiece between the movable jaws 14, 16 and the auxiliary jaws, the front walls 42 are conveniently bevelled, chamfered or otherwise relieved along one edge 70 thereof to provide a "lead-in".

Claims (10)

1. A method of adapting a sawing machine of the kind specified to lengthen the working life of its blade comprising providing the or each fixed jaw thereof with a removable auxiliary jaw whereby the position of the clamped workpiece relative to the length of the blade is adjusted.

2. A sawing machine of the kind specified where in said vice assembly comprises at least one pair of jaws of which one is fixed and the other is movable, characterised by the provision of a removable auxiliary jaw for the or each fixed jaw whereby the clamping position of the workpiece is adjustable.

3. A machine as claimed in Claim 2 in which the or each auxiliary jaw is adjustable so that when assembled to the respective fixed jaw, the spacing of the auxiliary gripping face relative to the fixed gripping face can be varied.

4. A machine as claimed in Claim 3 in which the auxiliary jaw comprises two parts coupled together in telescopic fashion and means is provided for locking the telescoping parts thereof in selected positions of adjustment.

5. A machine as claimed in Claim 2,3 or 4 in which means is provided for connecting the or each auxiliary jaw to the respective fixed jaw andlor other fixed structure of the machine.

6. A machine as claimed in Claim 5 in which the or each auxiliary jaw is provided with location means for engaging in a channel in order to stabilise the auxiliary jaw.

7. A machine as claimed in Claim 6 in which said location means is of adjustable dimensions widthwise of said channel which extends between the movable and fixed jaws of the machine.

8. A machine as claimed in Claim 7 in which said location means comprises depending tongues which are spaced transversely of the direction of telescopic adjustment, means being provided for varying the spacing between said tongues.

9. A sawing machine substantially as hereinbe fore described with reference to, and as shown in, the accompanying drawings.

10. A method of sawing workpieces comprising clamping successive workpieces between at least one pair of jaws of which one is fixed and the other is movable and subjecting the clamped workpiece to the action of a reciprocating saw blade whose length is equal to at least a major part of the maximum spacing between said jaws, characterised by effecting a number of the sawing operations with the clamped workpiece directly in contact with said jaws and effecting the remainder of said sawing operations with a workpiece clamped in abutment with an auxiliary jaw located between the workpiece and the fixed jaw, the auxiliary jaw being adjustable in length as considered in the direction of movement of the movable jaw.