Pivot Assembly For Tools And The Like

Abstract

A compound pivot, pliers-type cutter having noncrossing jaws and handles and a pivot defined by arcuate channels in opposite faces of the jaws and rings disposed in the channels.

Description

This invention relates to pivots for tools and more particularly to an improved tool of the pliers type having non-crossing jaws positioned by relatively movable non-crossing handles.

One of the major problems in tools of the so-called "pliers type," e.g. grippers, cutters, etc., arises out of the wear qualities of the common pivot pin which extends between and pivotally interconnects the crossing jaws or handles. In the case of a high-quality cutter the pivot pin which extends between the crossing jaws often wears such that after only a modest period of operation the cutter edges no longer mate satisfactorly and thus no longer satisfactorly perform the cutting operation. As a consequence, the tool is usually scrapped at this point since repair and reassembly is generally not economically feasible.

The present invention provides a pivot for tools of the pliers type which pivot eliminates the common pivot pin and the problems typically associated therewith and provides long wear qualities so as to be particularly useful in a precision cutter. In general, the pivot interconnects two elements such as jaws for relative pivotal displacement about a pivot axis. The axis is generally concentric with arcuate grooves formed in opposite faces of the pivotal elements such that when the elements are adjacent in the assembled position the grooves form first and second substantially continuous channels. Rings are disposed in the channels to provide a large bearing diameter having a relatively large bearing surface about the pivot axis.

Another feature of the invention is the provision of a pliers type tool, preferably a cutter of the compound type for providing a substantial mechanical advantage, ease of assembly, and for eliminating the usual pivot pin. In general, this tool comprises a pair of laterally adjacent jaws, a pair of laterally adjacent handles, means for pivotally connecting the jaws for rotation about one axis, means for pivotally connecting the handles for rotation about a second axis and structural means interconnecting the handles and the jaws to maintain the combination in an integral assembly.

The various additional features and advantages of the invention will be best understood by reference to the following specification which sets forth in clear and concise terms a detailed description of a specific embodiment. This specification is to be taken with the accompanying drawings of which:

FIG. 1 is a plan view of an illustrative embodiment of the invention in a working position;

FIG. 2 is a side view of the embodiment of FIG. 1;

FIG. 3 is a sectional view along a line 3--3 of FIG. 1;

FIG. 4 is a sectional view along a line 4--4 of FIG. 1;

FIG. 5 is an enlarged view of several details of the embodiment of FIG. 1; and

FIG. 6 is an exploded perspective view of the jaw, jaw pivot, and retainer plate combination of the embodiment of FIG. 1.

Referring to the drawings, the invention is illustrated by a cutter tool 10 of the type having laterally adjacent, and non-crossing cutter jaws 12 and 14 which are manually positioned by relatively movable non-crossing handles 16 and 18 having suitable plastic sheaths disposed thereover. Handles 16 and 18 are reversely outwardly bowed for manual operation. Jaws 12 and 14 and handles 16 and 18 are secured together in an integral assembly by means of plates 20 and 22 which overlie the opposite plane faces of the jaws 12 and 14 as best shown in FIG. 2. The plates 20 and 22 are secured together by means of a rivet 24 which lies along the pivot axis of the jaws 12 and 14 also by rivets 26 and 28 which lie along pivot axes of the handles 16 and 18 relative to the plates 20 and 22. Handles 16 and 18 are pivotal relative to one another about an axis disposed equidistant between the rivets 26 and 28, this axis being defined by the center line of a pin 30. The jaws 12 and 14 and the handles 16 and 18 are shown in the closed position in FIGS. 1 and 5, from which the handles 16 and 18 are biased apart by means of a small spring 32. Using the relative dimensions of FIGS. 1 and 5 provides a cutter with an 11:1 mechanical advantage. Other ratios are obtainable. Moreover, the pivot of tool 10 is not limited to either compound pivot tools or non-crossing element tools but may also be employed in simple pivot tools with crossing elements.

Looking to the enlarged detailed view of FIG. 5, the jaws 12 and 14 of tool 10 are shown to comprise forwardly tapering cutter portions 34 and 36 which are ground or otherwise formed in reversely symmetrical relationship to define cutting edges which mate at 38 when the handles 16 and 18 are closed, i.e., worked toward one another. Jaws 12 and 14 comprise integral rearwardly tapering legs 38 and 40 having diverging inner surfaces 42 and 44, respectively, contiguous with lesser diverging surfaces 58 and 60 which are spaced apart, as shown in FIG. 5, whenever the cutting edges are mated at 38 but which are brought together to act as a mechanical stop when the cutting edges are spaced apart by the action of the bias spring 32. A complemented mechanical stop is provided by surfaces 61 and 63 forwardly of openings 54 and 56. The surfaces 61 and 63 limit the degree of closing of jaws 12 and 14 and may serve to prevent dulling of a sharp cutting edge due to edge-mating in operation.

The opposite, parallel plane surfaces of jaws 12 and 14 have formed therein shallow arcuate grooves of generally rectangular cross-section which are concentric about the rivet 24. Jaw 12 has a groove 46 formed in the upper plane surface thereof and an identical unnumbered groove oppositely formed in the lower plane surface. Both grooves terminate at the rearward ends at the boundary of surface 58. Similarly, jaw 14 has formed in the lower plane surface thereof a groove 48 and a similar unnumbered groove formed in the upper plane surface. Both grooves terminate at the rear at the boundary of surface 60. To form a large diameter pivot having a substantially large bearing surface, rings 50 and 52 are slidably disposed in the opposite combinations of the grooves in the jaws 12 and 14 and secured in position by plates 20 and 22. The rings 50 and 52 are preferably slidable in both jaws but may be made conversely slidable in one jaw and fixed to the other.

More specifically, the grooves 46 and 48 together with the unnumbered grooves in the jaws 12 and 14 form substantially continuous circular channels when the jaws are placed in the laterally adjacent position shown in FIG. 5. The discontinuity in the circular channels occurs between the surfaces 58 and 60 in FIG. 5 when the handles are brought together and between surfaces 61 and 63 when the handles are apart. The rings 50 and 52 may be lightly lubricated and placed in the grooves for sliding motion therebetween. Alternatively, ring 50 may be secured only to jaw 12 and ring 52 only to jaw 14. In a still further alternative, rings 50 and 52 may be made integral with plates 22 and 20, respectively, to rest in the grooves when assembled. In any of these constructions, jaws 12 and 14 are relatively pivoted such that the rearwardly extending legs 38 and 40 are brought together as shown in FIG. 5 to open the cutter portions 34 and 36 and spread apart to close the cutter portions 34 and 36. It will be appreciated that the grooves and rings are not necessarily of square or rectangular cross section but may be round or elliptical if desired.

Jaws 12 and 14 have formed therein semi-cylindrical openings 54 and 56, respectively, concentric with the pivot grooves to receive the rivet 24 which interconnects the retainer plates 20 and 22 as best illustrated in FIG. 6. The rivet 24 does not serve as the pivot pin for the jaws 12 and 14 and thus no close tolerance in the formation of the rivet relative to the openings 54 and 56 need be observed in the fabrication of the tool 10.

Looking again to FIG. 5, handle 16 is shown to comprise at the forward portion thereof an enlarged hub section 62 having in the end thereof a notch 64. The notch 64 receives the end of the tapered leg 38 of jaw 12. Similarly, handle 18 has an enlarged hub section 66 with an end-disposed notch 68 for receiving the tapered end 40 of jaw 14. A pin 30 is disposed between the handles 16 and 18 to permit relative rotation therebetween. Holes 70 and 72 are formed in the retainer plates 20 and 22 to overlie the hub sections 62 and 66 of the handles 16 and 18 and to receive and permit passage of the rivets 26 and 28. Handles 16 and 18 also have formed therein suitable cavities 74 and 76 for receiving the bias spring 32. The handles 16 and 18 may be identical and simply reversed for assembly.

To fabricate the tool 10 the jaws 12 and 14 and the handles 16 and 18 are formed by suitable operations such as forging and grinding. The grooves 46 and 48 and the unnumbered grooves are formed in the opposite plane surfaces of the jaws 12 and 14. Rings 50 and 52 are disposed in the unnumbered grooves of the jaws 12 and 14, respectively, and lightly lubricated. As previously mentioned, a mechanical operation may be performed on the rings to nonslidably fix the rings to opposite jaws, if desired. For example, a punch or other device may be employed to expand or deform the rings 50 and 52 to create a tight nonmovable relationship between the material of the ring and the surrounding material of the jaw. The jaws 12 and 14 are then placed in the laterally adjacent orientation shown in FIG. 5, the ring 52 fitting into the groove 46 and the ring 50 fitting into the groove 48. The handles 16 and 18 are brought into suitable relationship with the legs 38 and 40 of the jaws 12 and 14, respectively, the retainer plates 20 and 22 are placed in position and the rivets 24, 26 and 28 are applied. The spring 32 may be placed in position either during or after this operation.

It is to be understood that the foregoing description is illustrative in character and is not to be construed in a limiting sense.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A pivot comprising: first and second adjacent elements each having opposite plane faces, arcuate grooves formed in said faces first and second rings disposed in said grooves, each ring being continuous through a groove in each of the elements to provide pivotal motion of the elements about an axis commonly concentric with the rings, first and second retainer members disposed in overlying relationship with said opposite plane faces to retain said rings in said grooves, and means for securing said members and said elements together in an operative assembly.

2. The pivot defined in claim 1 further including: at least one pair stop surfaces formed on and integral with respective elements so as to be brought into mating relationship with one another at a predetermined angular orientation of the elements relative to one another.

3. A tool comprising first and second adjacent jaws having mating edges and opposite plane face, arcuate grooves formed in each of the faces to form first and second substantially contiguous circular channels when the jaws are adjacent, first and second rings coaxially disposed in the channels and slidable relative to at least one of the elements, and means separate from and overlying each of said rings and faces for maintaining the jaws and rings in integral relationship.

4. A tool as defined in claim 3 including a pair of handles separate from said jaws and disposed in laterally adjacent relationship and pivotal relative to one another about a point spaced from the axis of said rings, the handles engaging the jaws for engaging and disengaging the mating edges.

5. A tool as defined in claim 4 wherein the means for maintaining comprises a pair of plates overlying the faces and portions of said handles, and means for interconnecting the plates with the jaws and the handles to form an operative assembly.

6. A tool as defined in claim 3 wherein each of the jaws is of an elongated and tapered configuration to define laterally spaced rearward legs; a pair of handles separate from said jaws and disposed in laterally adjacent and non-crossing relationship; means for pivotally interconnecting the handles for pivotal motion about an axis spaced from the axis of the rings, the handles having portions engaging the rearward legs such that working the handles toward one another causes the mating edges of the jaws to converge.

7. A tool as defined in claim 6 wherein the handles are reversely bowed.

8. A tool as defined in claim 6 wherein the means for maintaining comprises a pair of plates overlying the faces of the jaws and secured together by means of a fastener extending therebetween along the axis of the rings, the plates being pivotally connected to each of the handles.

9. A tool as defined in claim 8 including bias means for urging the handles apart.

10. The tool defined in claim 3 wherein said mating edges of said adjacent jaws are sharpened for cutting purposes, and an additional pair of opposite and mating stop surfaces formed on an integral with respective jaws and adjacent to the cutting edges so as to be brought into mating relationship with one another as said cutting edges are also brought into mating relationship with one another to prevent loading of said cutting edges when said jaws are closed.

11. The tool defined in claim 10 further including a second pair of stop surfaces formed on an integral with the jaws and disposed so as to be brought into mating relationship with one another as said jaws are opened thereby to limit the degree of opening of said jaws.