WO1994012320A1

WO1994012320A1 - A tool

Info

Publication number: WO1994012320A1
Application number: PCT/NZ1993/000119
Authority: WO
Inventors: Neville John Leenstra
Original assignee: Neville John Leenstra
Priority date: 1992-11-26
Filing date: 1993-11-26
Publication date: 1994-06-09
Also published as: CA2128893A1; AU5579694A

Abstract

A tool for tensioning wire, in the form of three flat plates comprising a fixed member (20), a first movable member (30) pivotably connected (40) to the fixed member (20), a link system (70) to link the fixed member (20) and the first movable member (30), the link system (40) consisting of a second movable member (60) pivotally connected to the fixed member (20) by a second pivot (50). The middle plate has apertures (70a and 50a).

Description

The Tool This invention relates to a tool.

For convenience only the invention will predominantly be described as a tool for tensioning wire to be joined, for which the invention may be particularly suitable. However it is to be understood that it is not to be limited as such. Moreover,^" because the invention may have many other . applications, the prior art and possible applications of the invention discussed below, are given by way of example only.

There are a number of known tools used for tensioning wire when the wire is being joined. For example, NZ Patent Application No. 240183 discloses a tool which uses a single pivoted lever type mechanism wherein one end of the wire to be joined is attached to a fitting on a fixed member of the tool, while the other end to be joined is gripped by sliding collets provided on the movable lever of the tool. The wire is thus able to be drawn through a wire retaining device by successive movement of the movable lever, and the end secured at the wire retaining device. With this tool, force is applied to the wire retaining device through a simple lever comprising a single pivot, point, with a movable member pivoting about this point. The mechanical advantage of such a tool is thus limited to that of a single pivot lever mechanism. The tool may therefore not be suitable for applying a high tension to a wire, unless a sufficiently long arm is provided to give the required leverage. Consequently a compact design may not be possible.

The tool of the present invention may be suitab le for a numbe r o f applications where a mechanical advantage greater than that of a single lever mechanism is required. For example, the principle may be suitable for use with tools such as tin snips, bolt cutters, heavy duty pop rivetors, clamping pliers, and crimping tools.

1 Conventional tools for these applications either comprise a complicated linkage mechanism to provide the required mechanical advantage, or u.se a simple single lever mechanism which requires a sufficiently long lever arm to obtain the required capacity. Hence, with conventional systems the tool is either expensive due to the complex linkage mechanism, or in the case of a single lever mechanism, is either limited in capacity or requires a large lever arm.

The tool of the present invention may also be suitable for applications where amplification of movement is required with a negative mechanical advantage, that is, a mechanical advantage less than one.

It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.

Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.

According to one aspect of the present invention there is provided a tool comprising a fixed member,

a first movable member, said first movable member being pivota l ly connected to said fixed member by a first pivot means provided between said fixed member and said first movable member,

a link means for linking between said fixed member and said first movable member, said link means comprising at least;

a second movable member, said second movable member being pivotally connected to said fixed member by a second pivot means, and

2 means for connecting between said first and second movable members,

the arrangement and construction being such that pivotal movemen t of said second movable member about said second pivot means and said first movable member about said first pivot means is communicated between said first and second movable members by said link means.

According to another aspect of the present invention there is provided a tool substantially as described above, wherein said link means comprises at least;

means for connecting between said first and second movable members , and

a third movable member, said third movable member being pivotal ly connected to said fixed member by a third pivot means, and means for connecting between said second and third movable members,

the arrangement and construction being such that pivotal movement of said third movable member about said third pivot means and said first movable member about said first pivot means if communicated between first and third movable members by said link means.

According to another aspect of the present invention there is provided a tool substantially as described above, wherein said link means comprises a mechanical linkage. According to yet another aspect of the present invention there is provided a tool substantially as described above, wherein said mechan ical linkage comprises a single pivot pin and/or pivotal surface.

According to even yet another aspect of the present invention there i.s provided a tool substantially as described above, wherein said first movable member is provided with an elongated aperture, and said second pivot means comprises a pivot pin which is disposed in said aperture.

According to even yet another aspect of the present invention there is provided a tool substantially as described above, wherein said second movable member is provided with an elongated aperture, and said fi rst pivot means comprises a pivot pin which is disposed in said aperture.

According to yet another aspect of the present invention ther i s provided a tool substanti al ly as described above , wherein said f irst movable member i s provided wi th apertures to accomodate plasti c embodiments which are disposed in said aperture .

According to another aspect of the present invention there is provided a method of moving a movable member of a tool relative to a fixed member of the tool, said movable member and fixed member being pivotal ly connected by a pivot member comprising the steps of:

(i⁾ providing a linkage means between said fixed and movable members, and

(ii) moving a movable member of said link means so as to cause said movable member to pivot relative to said fixed member. According to yet another aspect of the present invention there is provided a method of tensioning or joining wire using a tool substantially as described above comprising the steps of: -

(i) attaching a portion of the wire to said fixed member,

(ii) attaching the other end of the wire to said movable member.

(iii) moving said second movable member relative to said fixed member, so that said first movable member moves relative to said fixed member, the ratio of angular movement of said first movable member relative to the angular movement of said second movable member, being a predetermined ratio less than one.

With the tool of the present invention as described above, the provision of the linkage system enables an increase or decrease in the mechanical advantage related to moving the movable member relative to the fixed member, depending on the location of pivot points of the pivot means and link means. Hence, in the case of an increased mechanical advantage arrangement, a greater force may be applied to objects connected by means of the fixed member and movable member, without the requirement for a large lever as would be the case with a single lever system, or without the requirement for a complicated linkage such as is used with tools such as bolt cutters and the like. A relatively low cost compact tool may thus ho produced.

Alternatively, with a decreased mechanical advantage arrangement of the pivot points, amplification of movement may be obtained.

With the above mechanism, the link means may comprise any suitable

5 means wh ereby a positive or negative mechani ca l advantage may h obtained. For example, this may involve a fluid medium such as with a hydraulic system, or may involve a mechanical system.

I n the case of a mech anical system, th is may com prise gea r or ca m means, or a pin connection with or without a link rod, or any combination of these.

Furthermore, any number of combinations of link means may be provided to increase the positive or negative mechanical advantage. That is to say, a second link means may be p^'rovided between the second movable member of a first link means, and the fixed member. The second link means may operate on the same or a different principle to that of the first link means. Also, to obtain mechanisms having different characteristics, link means may be provided between any of the movable members that are able to move relative to each other. For example, a link means may be provided between the first movable member and second movable member.

In the case of a link rod, this may be connected between portions of the first movable member and the second movable member by pivotal connection means such as pivot pins or bearing surfaces. Alternatively, the two movable members may be linked together by a single pivot pin and/or pivotal surface.

With this arrangemen t, in order to obtain an increase in mechanica l advantage, the second pivot means may be arranged closer to th e single p iv o t pin a n d/or pivo ta l su rfa c e th a n i s th e fi rs t p ivo t m e a n s . Alternatively, to obtain a decrease in mechanical advantage for situations where the ratio of angular movement of the first movable member to the second movable member relative to the fixed member is greater than one,

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SUBSTITUTE SHEET the first pivot means may be arranged closer to the single pivot and/or pivotal surface than is the second pivot means. Of course, the mechanical advantage of the link means will be zero if the pivot points of the first and second pivot means coincide.

With the tool of the present invention, for use as a tensioning device, the rotation of the first and second pivotal members is preferably in the same sense relative to the fixed member. Hence, the second pivot means should be positioned so that its distance from the first pivot means is less than the distance of the single pivot pin and/or pivotal surface from the first pivot means.

Furthermore, the second pivot means may preferably be provided on the fixed member at a position relative to the first pivot means such that said pivot pin and/or pivotal surface passes through a line through said first and second pivot means during movement of saidΛϊrst and second movable members. With this arrangement, sliding motion on the pivotal surface may be kept to a minimum. The invention however is not limited to this, and with certain arrangements, it may be desirable to have a link means wherein movement of said second movable member relative to said first movable member involves significant sliding at said pivotal surface therebetween. Such an arrangement may involve a cam surface.

I n the case of the link means comprising a combination of link means, these may be based on the sa me principle and may be arranged with respective movable members formed as pla te members wh ich may be s ta cked side by side , s o that a compact design may be achieved . Furthermore, optional pivot points may be provided on the respective movable members so that the mechanical advantage characteristics of the link means may be varied as required or desired.

In the case of a tool requiring large movement output for a small input movement (negative mechanical advantage), this may be described as for a positive mechanical advantage tool by considering the first movable member to be the input member and the movable member of the linkage means to be the output member.

Wi th the tool of the present invention, the movable members ma be provided with an aperture or apertures to accomodate pl ast i embodiments which are disposed in said aperture to reduce the frictional surface contact between the plates . The invention however i s not l imited to thi s , it may be desirable to have plasti c embodiments either side of said movable members . Further aspects of the present invention will become apparent from the ensuing description which is given by way of example only and with reference to the accompanying drawings in which:

Figure 1: is a schematic diagram of a tool according to an embodiment of the present invention, and

Figure 2: is a schematic diagram of another tool according to an embodiment of the present invention, wherein the first movable member is the input member and the second movable member is the output member, so that operation of the tool amplifies the movement of the first movable member, and

Figure 3: is a schematic diagram of a tool according to another embodiment of the present invention showing a possible combined linkage means.

With respect to figure 1 there is provided a tool generally indicated by

SUBSTITUTE SHEET arrow 1. The tool 1 comprises a fixed member 2 an d a first movabl e member 3. The first movable member 3 is pivotally connected to the fixed member 2 by means of a pivot pin 4 fixedly attached to the fixed member 2. The tool 1 is further provided with a linkage for connecting between the fixed member 2 and the first movable member 3. The linkage comprises a second pivot pin 5 removably attached to the fixed member 2, a second movable arm 6 which is pivotal about the pivot pin 5, and a connecting pin 7 which provides a pivotal connection between the second movable member 6 and the first movable member 3. The first movable member 3 is provided with an elongated aperture 5a so that it may pivot about the pivot pin 4 without interference with the pivot pin 5. Furthermore a hole 7a in the first movable member 3, for accommodating the connecting pi n 7 is slightly elongated to allow for the variation in distance between pivot pin 4, and connecting pin 7, and between pivot pin 5 and connecting pin 7 as the first movable member 3 pivots about pivot pin 4. The hole 7a thus acts as a pivotal surface which allows sliding and rolling pivotal movement.

With this arrangement, movement of the second movable membe r 6 relative to the fixed member 2 causes the first movable member 3 to pivot about the pivot pin 4 relative to the fixed member 2. The arrangement of the pivot pins 4, 5 and 7 is such that with clockwise rotation of the second movable member 6 about the pivot pin 5, the first movable member 3 also turns clockwise about the first pivot pin 4. Furthermore, since the second pivot pin 5 is located closer to the connecting pin 7 than is the first pivot pin 4, the ratio of angular movement of the first movable member 3 about the fixed member 2 to the angular movement of the second movable member G about the fixed member 2 is less than 1. Hence a mechanical advantage is obtained. As a result, compared to a single lever device, the lever arm length of the second movable member 6 may be shorter to obtain the same force at the tip of the movable/fixed members.

As shown in figure 1, the tool is adapted for use in tensioning and tying wire. The fixed member 2 is provided with a connector fitting 10 which has a yoked end portion 11 sized to accommodate a wire connecting device 12. The movable member 3 is provided with a wire gripping device 15 which is fitted with spring loaded collets in a similar arrangement to a standard pup rivet grip.

When using the tool, one end 1G of a wire is fixedly attached to the connector device 12 , while the other end 17 of the wire is threaded through the connector device 12, then through the gripping device 15. The movable member 3 is then moved away from the fixed member 2 by operating the second movable member 6, s o that the wire is drawn through the connector device 12 and thereby tensioned. During the tension ing ope rati on , the wire is grippe d by a fitting 18 which co mprises a mechanism similar to that of the gripping device 15, while the movable member 3 is being moved towards the fixed member 2. When sufficient tension has been obtained, the end 17 is withdrawn from the gripping device 15 and bent back on the device 12 so as to fix the wire thereto.

The fixed and movable members 2 and 3 of the tool 1 may also be provided with other suitable fittings. For example, these may comprise the jaw elements of a crimping tool, with one jaw element attached to an extension of the fixed member 2 which extends out to the other side of the movable member 3. With this arrangement, a crimping action may be obtained between the movable members 3 and the jaw element with anti-clockwise movement of the second movable member 6.

10 Figure 2 shows anothe r e mbodiment of the present inven tion used to provide an amplification of movement (negative mechanical advantage). A tool 100 comprises a fixed member 20 and a first movable member 30. The first movable member 30 is pivotally connected to the fixed member 20 by means of a pivot pin 40 fixedly attached to the fixed member 20. The tool 100 is further provided with a linkage for connecting between the fixed member 20 and the first movable member 30. The linkage comprises a second pivot pin 50 removably attached to the fixed member 20, a second movable arm 60 which is pivotal about the pivot pin 50, and a connecting pin 70 which provides a pivotal connection between the second movable member 60 and the first movable member 30. The second movable member 60 is provided with an elongated aperture 50a so that it may pivot about the pivot pin 50 wi thout in te rfe ren ce wi th the pivot pin 40. F u r th erm o re a h o l e 70 a in th e fi rs t m ov ab l e m e mb e r 60 , for accommodating the connecting pin 70 is slightly elongated to allow for the variation in distance between pivot pin 40, and connecting pin 70, and between pivot pin 50 and connecting pin 70 as the first movable member 30 pivots about pivot pin 40. The hole 70a thus acts as a pivotal surface which allows sliding and rolling pivotal movement.

With this arrangement, movement of the second movable member 60 relative to the fixed member 20 causes the first movable member! 0 to pivot about the pivot pin 40 relative to the fixed member 20. The arrangement of the pivot pins 40, 50 and 70 is such that with clockwise rotation of the second movable member 60 about the pivot pin 50, the first movab le member 30 also turns clockwise about the first pivot pin 40. Furthermore, since the second pivot pin 50 is located further from the connecting pin 70 than is the first pivot pin 40, the ratio of angular movement of the first

11 movable member iϋ about the lixed member 2 ' 0, to the angu lar movement of the second movable member 60 about the fixed member 20 is greater than 1. Hence a negative mechanical advantage is obtained. Various attachments may be fitted to the first movable member 30 and the fixed member 20, depending on the use which the tool 100 is to be put.

Figure 3 shows a tool generally indicated by arrow 200 according to a third embodiment of the present invention. In this figure, components having the same function as thos e of figure 1 are identified with the same numerals and description is omitted for brevity. The linkage for connecting between the fixed member 2 and the first movable member 3 comprises the linkage of figure 1 with an additional linkage for connecting between the movable arm 6 and the fixed member 2. The second linkage comprises a third movable arm 160 which is pivotal about a pivot pin 150, and a connecting pin 170 which provides a pivotal connection between the third movable member 160 and the second movable member 6. The second movable member 6 is provided with an elongated aperture 150a so that it may pivot about the pivot pin 5 without interference with the pivot pin 150. Furthermore, a hole 170a provided in the second movable member 6, for accommodating the connecting pin 170 is slightly elongated to allow for the variation in distance between pivot pin 5 and connecting pin 170 and between pivot pin 150 and connecting pin 170 as the second movable member 6 pivots about pivot pin 5. The hole 170a thus acts as a pivotal surface which allows sliding and rolling pivotal movements.

With this arrangement, movement of the third movable member 160 relative to the fixed member 2 causes the second movable member 6 to pivot about the pivot pin 5 relative to the fixed member 2 which in turn causes the first movable member to pivot about the pivot pin 4 relative to the fixed member.

12 This embodiment shows how the linkage means of the present invention may be increased to provide an increase in positive or negative mechanical advantage.

I believe the advantages of my invention to be as follows however it should be appreciated that all such advantages may not be realised on a l l embodiments of the invention, and the following list is given by way of example only as being indicative of potential advantages of the present invention. Furthermore, it is not intended that the advantages of the present invention be restricted to those of the list which follows: -

1. The provision of a link means between the movable member and the fixed member enables the mechanical advantage of the single pivot to be increased, or decreased,. depending on whether a higher load is to be applied to the movable member, or whether the movable member is required to move through a greater angle than the movement of the link means lever respectively.

2. The components of the tool may be designed so that a simple three plate type device is obtained. This minimises the number of components, making a more compact and lower priced device possible.

3. The design also facilitates the addition of combinations of linkages between members movable relative to each other, since these may be simply provided in the form of flat plates stacked one beside the other, with pin connections therebetween.

4. The principle of the invention may be equally applied to a tool wherein the first movable member is required to move in an opposite sense to movement of the second movable member, by appropriate positioning of the second pivot relative to the first pivot and linkage pivot.

13 5. The tool may be easily provided with a variety of attachments to increase the versatility. For example a combination of pop rivet and wire cutting attachments may be provided so that closing of the operating member towards the fixed member may result in both a tensioning force on the pop rivet and a compression force on the cutting attachment.

6. The tool may be used for work where amplification of movement is required. For example, the tool may be fitted with a mechanism which enables a threaded nut to be rotated several turns for a small movement of the operating handle. In this application, the tool may have facility for varying the location of the pivot points so that a positive mechanical advantage may be used to unload a nut. The pivot point locations may then be changed to give a negative mechanical advantage (ie. a large movement for small movement of the operating handle).

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the spirit or scope thereof.

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T TE SHEET

Claims

WHAT 1 CLAIM IS :

1. A tool comprising a fixed member, a first movable member, said first movable member being pivotally connected to said fixed member by a first pivot means provided between said fixed member and said first movable member, a link means for linking between said fixed member and said first movable member, said link means comprising at least; a second movable member, said second movable member being pivotally connected to said fixed member by second pivot means, and means for connecting between said first movable members, the arrangement and construction being such that pivotal movement of said second movable member about said second pivot means and said first movable member about said first pivot means is communicated between said first and second movable members by said link means.

2. A tool as claimed in claim 1, wherein said link means comprises at least; a second movable member, said second movable member being pivotally connected to said fixed member by a second pivot means, and means for connecting between said first and second movable members, and a third movable member, said third movable member being pivotally connected to said fixed member by a third pivot means, and means for connecting between said second and third movable members, the arrangement and construction being such that pivotal movement of said third moveable member about said third pivot means and said first movable member about said first pivot means is communicated

15 between first and third movable members by said link means.

3. A tool as claimed in claim 1 or claim 2, wherein said link means comprises a mechanical linkage.

4. A tool as claimed in claim 3, wherein said mechanical linkage comprises a single pivot pin and/or pivotal surface.

5. A tool as claimed in any one of claims 1 to 4, wherein said first movable member is provided with an elongated aperture, and said second pivot means comprises α pivot pin which is disposed and said aperture.

6. A tool as claimed in any one of claims 1 to 5, wherein said second movable member is provided with an elongated aperture, and said first pivot means comprises a pivot pin which is disposed in said aperture.

7. A tool as claimed in any one of claims 1 to 6, wherein said first and/or second movable members are provided with apertures to accomodate plastic embodiments which are disposed in said aperture.

8. A method of moving a movable member of a tool relative to a fixed member of the tool as claimed in any one of claims 1 to 6, said movable member and fixed member being pivotally connected by a pivot member comprising the steps of:

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ITUTE SHEET (ij providing a linkage means between said fixed and movable members, and

(ii) moving a movable member of said link means so as to cause said movable member to pivot relative to said fixed member.

9. A method of tensioning or joining wire using a tool as claimed in any one. of claims 1 to 6, comprising the steps of :-

(ij attaching a portion of the wire to said fixed member,

(ii) attaching the other end of the wire to said first movable member,

(iii) moving said second movable member relative to said fixed member, so that said first movable member moves relative to said fixed member, the ratio of angular movement of said first movable member relative to the angular movement of said second movable member, being a predetermind ratio less than one.

10. A tool substantially as described herein with reference to the accompanying drawings.

11. A method of moving a movable member of a tool relative to a fixed member, substantially as herein described with reference to the accompanying drawings.

12. A method of tenisoning or joining wire substantially as herein described with reference to the accompanying drawings.

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