GB2059851A - Chain-type tube cutter - Google Patents

Abstract

A chain-type tube cutter comprising a plier arrangement having a linked chain with cutting rollers carried on the link pins has an adjustable pivot. Because of the cutting rollers 12 pivoted on the link pins 11 of the chain, the chain has a relatively coarse pitch and therefore a relatively coarse adjustment to accommodate different sizes of tube 13. The adjustable pivot gives an adjustment intermediate that provided by notching different links of the chain in one of the jaws of the plier arrangement. <IMAGE>

Description

SPECIFICATION Chain-type tube cutter This invention relates to a chain-type tube cutter, of the kind comprising two plier members, relatively pivotable on a pivot pin, having, on one side of the pivot, hand grips, on the other side, jaws and a linked chain with cutting rollers carried on the link pins thereof, in which the chain, at one end, is pivoted, but not readily removable from one of the jaws, and the other jaw has two forks in which different link pins can be selectably notched.

Such a chain-type cutter can be used for a number of different tube diameters and materials such as metal, plastic, etc. For the purpose of adjustment to a different tube diameter the link pin notched into the forks on the one plier member is taken out and another link pin notched in its place. By squeezing together the two plier members, the chain and the cutting rollers are tensioned around the tube so that by twisting, especially twisting toand-fro, a clean separation of the tube is effected. Because of the necessarily quite coarse pitch of the linked chain, occasioned by the diameter of the cutting rollers and hence the spacing of the link pins, known chain-type tube cutters have only a coarse adjustability.This means that with a substantial number of tube diameters, the plier levers have to be spread wide apart at the start of the cutting process which does not allow the optimum application of force. If the next wider spaced link pin is notched in the forks, the plier members can certainly be put in an advantageous relative position at the beginning of the cutting process, but then it can happen cspecially with thick-walled tubes~ that the cutting process cannot be carried through to the end, because the plier levers have closed part way through.

The invention comprises a chain-type tube cutter comprising a plier arrangement having a linked chain with cutting rollers carried on the link pins, characterised in that the plier arrangement has an adjustable pivot. The extent of the pivot adjustment is particularly useful if it is about half the spacing of the link pins. In this way it turns out that for the majority of tube diameters for which the chain is provided it is always possible to have a nearly optimum pre-adjustment of the plier members. This gives the possibility in each case of single handed operation of the pliers, so that the user has his other hand free, for example to hold the tube to be cut.

It is particularly advantageous if the pivot pin has a non-circular cross-section and is fixed in one plier member, is located on both sides in an approximately figure "8" shaped slot in the other plier member, of which slot the longest axis runs across the plier member.

The cross-section of the pivot pin has, advantageously, the form of a segment of a circle which amounts to more than half the circle cross section. The slot then has the form of an "8", that is to say, the circumference comprises substantially two laterally displaced circular arcs between which is arranged a constricting nose behind which the pivot pin can be passed with the plier members open.

One embodiment of the invention will now be more particularly described with reference to the single figure, which is a view in the direction of the pivot axis.

In the figure, a chain-type tube cutter is shown which comprises two plier members 2 and 3 pivotable on a pivot pin 1. The plier members have hand grips 4 and 5, and jaws 6 and 7. The plier members are arranged so that by squeezing together the hand grips 4 and 5 the jaws 6 and 7 also move towards each other. On the jaw 7 a linked chain 8 is fastened which comprises links 9 and 10 arranged in two rows which are pivotally connected together by link pins 11. On the link pins 11, cutting rollers 12 are rotatably carried.

In the illustrated arrangement, the chain 8 surrounds the major part of a tube 13 and is at its other end notched by the link pin 11 a in two forks 14, which wrap around the chain 8 on both sides and symmetrically, and of which, in the figure, only the nearer one is visible. The forks 14 form the end of the (doubled) jaw 6. It is to be understood that it does not have to be the last link pin 11 a that is notched in the forks 14, but that, with correspondingly smaller tube diameters, most of the other link pins can be notched in the forks 14, so that a part of the chain hangs out to the side of the jaw 6. The pivot pin 1 is fixed, that is to say neither rotatable nor displaceable in the plier member 2 and, where it projects through the member 3, has a non-circular cross-section, shown as a hatched region, a major segment of a circle.

The chord 15 runs substantially parallel to the handgrip 4. The plier member 2 is also at this place formed double-sided and fits around the plier member 3 that is flattened at this point.

In this member 2 a slot 16 is arranged whose periphery is made up of two nearly completely circular arcs 17 and 18 in the form of a figure "8". In the passage between the circular arcs there is at least at one side a constricting nose 19, which so limits the cross-section of the slot at this point that the pivot pin 1 can be slid through to the other side of the nose 19 in the position of its smallest cross-section normal to the chord 15.

It is seen that the pivot pin 1 can be freely rotated in the shown position in the right hand part of the slot 16. By widely spreading the two plier members, however, the pivot pin 1 can be slid to the left hand side of the slot 16, that is to say behind the nose 19, and is there likewise freely rotatable to an adequate extent. The plier member 2 can thus be brought into the position 2a shown in broken line from which a cutting operation can start.

Claims (5)

1. A chain-type tube cutter comprising a plier arrangement having a linked chain with cutting rollers carried on the link pins, characterised in that the plier arrangement has an adjustable pivot.

2. A chain-type tube cutter according to Claim 1, characterised in that the pivot comprises a pin having a non-circular cross-section fixed in one plier member and located in a roughly figure "8" shaped slot in the other plier member.

3. A chain-type tube cutter according to Claim 2, characterised in that the said slot has a constricting nose behind which the pivot pin can be passed with the plier members open.

4. A chain-type tube cutter according to Claim 3, characterised in that the extent of adjustment of the pivot pin in the said slot is about half the spacing of the link pins.

5. A chain-type tube cutter according to Claim 1, characterised in that the plier members are made of sheet metal.