AU2005100643B4 - Blade clamp for reciprocating saw - Google Patents

Description

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AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR AN INNOVATION DIVISIONAL PATENT Name of Applicant: Actual Inventor(s): Address for Service: Invention Title: Black Decker, Inc.

Mike Wilson DAVIES COLLISON CAVE, Patent Attorneys, of 1 Nicholson Street, Melbourne, Victoria 3000, Australia "Blade clamp for reciprocating saw" The following statement is a full description of this invention, including the best method of performing it known to us: P:\OPERRSH\12647590-B&D Innovation doc.5S0805 -1- The present invention relates to a clamp assembly for a working member of a 00 reciprocating tool and relates particularly, but not exclusively, to a clamp assembly for the blade of a reciprocating jigsaw.

Jigsaws are power tools which comprise a reciprocating saw blade for cutting a work piece of wood or other material. Most jigsaws comprise a plastic housing containing an electric motor. The rotary output of the motor is geared to a drive conversion mechanism which converts rotary motion of the motor output into reciprocating motion of C an output shaft to cause reciprocating motion of a saw blade.

Jigsaws are usually designed to enable the blade to be removed from the output shaft. This serves two purposes. Firstly, due to the high frictional forces encountered when in use, jigsaw blades are subject to wear and tear and have limited lifetimes, so that there is a necessity to enable the blade to be easily replaced. Secondly, several different types of blade may be supplied with the jigsaw to enable it to be used to cut a variety of different types of workpiece, or cut the workpiece in a variety of ways.

European Patent Application EP0792713 describes a jigsaw blade clamp which comprises a channel formed in a jigsaw output shaft shaped to accommodate a jigsaw blade and a pin that is urged into contact with the blade by a spring, such that the pin forces the blade into the channel thereby holding it in place. This prior art clamp suffers from the drawback that if sufficient force is applied to the blade, it can still slip out of place and even be pulled away from the jigsaw.

Preferred embodiments of the present invention seek to overcome the above disadvantage of the prior art.

According to an aspect of the present invention in relation to one embodiment, there is provided a clamp assembly for removably mounting a working member of a reciprocating tool to a reciprocating output shaft, the assembly comprising: a body member adapted to be mounted to said output shaft; two engaging members, each engaging member being capable of limited pivotal movement relative to the other engaging member about a common axis; P:\OPERRSH\12647590.B&D Innovaion,.do-05o08/05 -2each engaging member having a first engaging portion adapted to be located at 00 least partially in front of a respective second engaging portion on the working member in the direction of reciprocation of the working member; ¢€3 each engaging portion comprising a cam surface for engaging its respective second engaging portion on the working member; n wherein the engaging members are pivotable in use relative to said body member between a first position, in which the cam surfaces of each first engaging portions engage with their second engaging portions on the working member to retain the working member in position on the output shaft, and a second position in which the working member is removable from the output shaft; and first biasing means for urging the engaging members towards the first position; wherein application of a force to the working member tending to remove the working member from the body member when the engaging members are in the first position thereof causes movement of the second engaging portions to be prevented by the cam surfaces being urged further into engagement with their corresponding second engaging portions.

By providing a clamp assembly in which at least one first engaging portion of an engaging member is adapted to be located partially in front of a respective second engaging portion on the working member (in the direction of reciprocation of the working member), this provides the advantage that the working member can be more effectively held in position on the tool than a clamp assembly using friction alone.

The assembly may comprise at least one first said engaging member having a respective protrusion, and at least one corresponding second said engaging member having a respective recess for receiving at least one respective said protrusion, wherein at least one said recess permits limited pivotal movement of the corresponding said protrusion therein such that the corresponding said first engaging member is pivotable about said common axis.

P:\OPER\RSH12647590-B&D Innovalion.doc-05/O8/5 -3- This provides the advantage that manufacturing tolerances can be accommodated 00 by enabling a plurality of the engaging members to be pivotable about a common axis relative to each other, while enabling pivoting of a single engaging member by a user to cause pivoting of more than one engaging member.

In a preferred embodiment, at least one said engaging member further comprises at least one elongate protrusion adapted to enable the user to pivot said engaging means towards said second position.

This provides the advantage that it is made easier for the user to release the blade from the clamp by minimising the force which the user needs to apply to the engaging member because of leverage obtained by the elongate protrusion.

At least one said elongate protrusion may be formed on a corresponding said first engaging member.

Said first biasing means may comprise at least one torsional spring adapted to engage at least one said elongate protrusion and said body member.

In a preferred embodiment, at least one said first engaging portion comprises at least one respective cam surface for engaging the working member wherein application of a force to said working member so as to remove the working member from the output shaft urges at least one said cam surface further into engagement with said working member.

This provides the advantage that if the working member is pulled outwardly of the tool, the grip provided by the clamp on the working member is tightened.

The or each said engaging member may be adapted to be displaced from the first position thereof by movement of the working member towards the output shaft to enable mounting of the working member to the assembly by such movement thereof.

Preferred embodiments of the present invention will now be described, by way of example only and not in any limitative sense, with reference to the accompanying drawings in which: P \OPERRSH\I12647590-B&D Innovationdox-05/85 S-4- Figure 1 is a perspective side view of a jigsaw; 0 Figure 2a is a front and side perspective view of a jigsaw drive shaft and blade clamp of a first embodiment of the present invention; Figure 2b is a rear and side perspective view of the jigsaw blade clamp and drive shaft of Figure 2a; Figure 2c is a front perspective view of the jigsaw drive shaft and blade clamp of Figure 2a; Figure 3 is a side view of a blade to be used with the blade clamp of Figure 2; SFigure 4a is a sideways perspective view of a body of the blade clamp of Figure 2; Figure 4b is a front view of the blade clamp body of Figure 4a; Figure 4c is a side view of the blade clamp body of Figure 4a; Figure 4d is a rear view of the blade clamp body of Figure 4a; Figure 5 is a perspective view of a cam body of the blade clamp of Figure 2; Figure 6 is a side cross sectional view of the blade of Figure 3 mounted to the blade clamp body of Figure 4; Figure 7 is a front view of the blade and blade clamp of Figure 2; Figure 8 is a cross sectional view of the upper part of the blade of Figure 3 received in the blade clamp of Figure 2; Figure 9a is a side perspective view of a first part of a cam body of a second embodiment of the invention; Figure 9b is a side view of the cam body of Figure 9a; Figure 9c is a bottom view of the cam body of Figure 9a; Figure 9d is a front view of the cam body of Figure 9a; Figure lOa is a side perspective view of a second part of the cam body of the embodiment of Figure 9; Figure lOb is a side view of the cam body of Figure Figure 10c is a bottom view of the cam body of Figure lOa; Figure lOd is a front view of the cam body of Figure lOa; Figure 11 is a partially cut away side perspective view of the first cam part of Figure 9 and the second cam part of Figure 10 mounted in the clamp body of Figure 4; Figure 12a is a side view of a first spring for use with the embodiment of Figures 9 to 11; P:\OPER\RSM12647590.B&D Innovationdoc.050J8/O5 ;Figure 12b is a front view of the spring of Figure 12a; 00 Figure 13a is a side view of a second spring for use with the embodiment of the Figures 9 to 11; Figure 13b is a front view of the spring of Figure 13a; and Figure 14 is a side view of a cam body pin of the embodiment of Figures 9 to 13.

Referring to Figure 1, a jigsaw shown generally by 1 has a housing 2 of durable plastics material, with a motor (not shown) disposed therein. The motor has a rotary output shaft (not shown) geared to a drive mechanism which converts the rotary output of the motor into vertical reciprocating motion of a drive shaft (not shown). The housing 2 is mounted on a shoe 4 which rests on a workpiece and provides a reaction force for the blade 3 during upward movement thereof. The blade 3 is attached to the drive shaft (not shown) by a blade clamp Referring now to Figure 3, a blade to be used with the present invention will now be described. The blade shown generally by 3 has a cutting portion 8 of length defined by 6 and width defined by W. As will be appreciated by persons skilled in the art, one edge of the blade is provided with cutting teeth (not shown). At the upper end of the cutting portion 8 the width of the blade is reduced at a portion of the blade defined by 7, to form two indents 9. Above the indents 9 is a portion of the upper part of the blade as shown by 10 which has width less than W.

Referring now to Figures 2a to 2c, the jigsaw drive shaft 11 is connected to the blade 3 by a jigsaw blade clamp 5 embodying the present invention. Referring also to Figures 4a to 4d, the jigsaw blade clamp comprises a blade clamp body 12 which is mounted securely to the drive shaft 11 by means of a bracket 13. The blade clamp body 12 has a hollow interior 14 formed to receive the upper portion 7 of the jigsaw blade (Figure This is shown best in Figure 6, in which the upper part of the blade 3 is received fully in the hollow portion 14. The blade clamp body 12 also includes a hollow tubular extension Referring to Figure 5, a cam body 16 for cooperating with the clamp body 12 is shown. The cam body 16 comprises two cam surfaces 17 and an elongate P \OPER\RSH\1264590-B&D Innovation do-05/O08/O05 S-6- ;protrusion 18. An indentation 19 is formed on the protrusion 18, the purpose of 00 which will be described in greater detail below. The cam body 16 also comprises a cylindrical bore 20. The cam body 16 is formed such that it can be inserted into the Shollow portion 14 of the clamp body 12. This is shown best in Figures 2a and 2c.

When the cam body 16 is fully received in the clamp body 12 the cylindrical bore Sof the cam body 16 is aligned with the hollow tubular extension 15 of the clamp body 12. A pin (not shown) is inserted such that it passes through the hollow tubular Sextension 15, and through the cylindrical bore 20, to enable the cam body 16 to be C. pivoted relative to the clamp body 12. A torsional spring 21 is mounted co axially on tubular extension 15. A first end 22 of the torsional spring 21 is securely received in a slot 23 formed in the clamp body 12. A second end 24 of the spring 21 rests in the indentation 19 formed in the protrusion 18 of the cam body 16.

The operation of the jigsaw blade clamp will now be described.

Referring to Figure 7, the cam body 16 is able to pivot about an axis through the cylindrical bore 20 such that the cam surfaces 17 move in and out of contact with the rear surface of the hollow portion 14 of the clamp body 12. By virtue of the resilient action of spring 21, the cam body 16 is urged into the clamp body 12. In order to pivot the cam surfaces 17 away from the clamp body 12, the user must press on protrusion 18 in the direction of the blade such that the cam body 16 is pivoted out of clamp body 12 against the action of spring 21.

When a blade is mounted in the hollow portion of the clamp body 12, as shown in Figure 6, the cam surfaces 17 engage indents 9 of blade 3. The blade 3 is prevented from slipping out of the clamp body 12 as the cam surfaces 17 are received in indents 9 and therefore are in contact with the protrusions 10 of the blade 3. If the blade 3 is pulled in a downward direction, the force exerted on cam surfaces 17 by projections 10 causes the cam surfaces 17 to be pivoted into further engagement with the blade 3, thereby tightening the grip of the blade clamp 5 on the blade 3.

In order to effect the release of the blade 3 from the blade clamp 5, the cam body 16 is pivoted out of clamp body 12 by pressing on protrusion 18, such that the P \OPERRSH\I2647590-B&D Innovatm doC.05/8/05 cK1 -7cam surfaces 17 move out of engagement with indentations 9 of the blade 3. Referring to 00 Figure 8, which shows the top of blade 3 engaged in the clamp body 12, a leaf spring contacts the top edge of the blade 3, such that when the clamp 5 is opened the compressed leaf spring 25 extends, thus pushing the blade 3 out of engagement with clamp body 12.

This not only facilitates removal of the blade from the clamp 5, but also ensures the blade _3 is correctly engaged with clamp 5 until the protrusion 18 is pressed.

This first embodiment of the invention is included for reference purposes and does CI not fall within the scope of the claims of this present innovation patent application.

Referring now to Figures 9 to 14, a second embodiment of the present invention is shown with parts common to the embodiment of Figures 1 to 8 denoted by like reference numerals but increased by 100.

Referring to Figures 9a to 9d, the cam body of this embodiment is formed from two separate parts. A first cam body part 130 is formed from durable plastics material. The first cam body part 130 comprises a first cam surface 134 for engaging a blade indent 9 of the blade 3 in the same way as the cam surfaces 17 engage the blade of the embodiment of Figures 1 to 8. An elongate protrusion 118 extends from the first cam body part 130 and is provided to enable a user to easily pivot the cam body part 130. The first cam body part 130 has a first cylindrical bore 138 for receiving a pin (not shown) to enable the cam body part 130 to be pivoted about an axis through the bore 138. A ridge 142 is formed around the circumference of cylindrical bore 138, the purpose of which will be described below. A peg 146 is also formed integrally with the first cam body part 130, the purpose of which will also be described below.

Referring now to Figures 10a to 10d, the second cam body part 132 comprises a second cam surface 136 for engagement with an indent 9 of blade 3. A second cylindrical bore 140 is formed with a circular recess 144 adapted to receive ridge 142 of the first cam body part 130, such that when the first and second cam body parts 130, 132 are mounted to each other, the first and second cylindrical bores 138, 140 form a continuous single cylindrical bore with a common axis. The second cam body part 132 is also provided with an aperture 148 in which peg 146 is received when the first and second cam body parts 130, 132 are attached to one another.

P \OPER\RSH\I2647590-B&D Innovation doc5/IO08(1J5 -8- The first and second cam body parts 130, 132 are adapted to be mounted on a 0 pin 150 (Figure 14) such that the pin 150 passes through first and second cylindrical bores 138, 140 and each cam body part 130, 132 is independently pivotable to a ¢q limited extent about the pin 150.

IN4D Referring to Figure 11, the first and second cam body parts 130, 132 are shown mounted in a blade clamp body 112. The blade clamp body 112 is identical to the blade clamp body 12 from the first embodiment of the invention. Coil springs 152, ri 154 (Figures 12 and 13) are mounted on the cylindrical bore portions 138, 140 of the cam body parts 130, 132 respectively such that the coiled portions 156, 158 of the springs are coaxial with the cylindrical bore of the assembly. Each coil spring has a first end 160, 162 which is secured to the respective cam body part 130, 132 and a second end 164, 166 secured to the blade clamp body 112.

The operation of the jigsaw blade clamp of Figures 9 to 14 will now be described.

Referring to Figure 11, in order to release a blade from the blade clamp, the user depresses elongate protrusion 118 to pivot first cam body part 130 about pin 150. This moves the first cam surface 134 out of engagement with the indentation 9 of blade 3. At the same time, peg 146 moves in the aperture 148 of the second cam body part 132 until the first cam body part 130 has moved sufficiently about the axis such that the peg 146 abuts the edge of the aperture 148. Further depression of elongate protrusion 118 then also causes second cam body part 132 to pivot about pin 150, thus moving the second cam surface 136 out of engagement with the other indentation 9 of blade 3. When the elongate protrusion 118 has been fully compressed, the blade is released.

As the peg 146 has a limited amount of travel in aperture 148, each cam body part 130, 132 is independently pivotable to a limited extent about the pin 150.

However the user only has to move the first cam body part 130 in order to effect eventual movement of the second cam body part 132. Independent movement of the first and second cam body parts 130, 132 will therefore absorb any manufacturing tolerances in the cam surfaces themselves or the indentations of the blades.

P:\OPER\RSH\12647590-B&D Innovaliondoc-05/08/05 -9- It will be appreciated by persons skilled in the art that the above embodiments have 00 been described by way of example only and not in any limitative sense, and various 0 alterations and modifications are possible without departure from the scope of the c invention as defined by the appended claims.

5 Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and itt "comprising", will be understood to imply the inclusion of a states integer or step or group 0of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that that prior art forms part of the common general knowledge in Australia.

Claims (4)

1. A clamp assembly for removably mounting a working member of a reciprocating tool to a reciprocating output shaft, the assembly comprising: O a body member adapted to be mounted to said output shaft; two engaging members, each engaging member being capable of limited pivotal n movement relative to the other engaging member about a common axis; each engaging member having a first engaging portion adapted to be located at least partially in front of a respective second engaging portion on the working member in the direction of reciprocation of the working member; each engaging portion comprising a cam surface for engaging its respective second engaging portion on the working member; wherein the engaging members are pivotable in use relative to said body member between a first position, in which the cam surfaces of each first engaging portions engage with their second engaging portions on the working member to retain the working member in position on the output shaft, and a second position in which the working member is removable from the output shaft; and first biasing means for urging the engaging members towards the first position; wherein application of a force to the working member tending to remove the working member from the body member when the engaging members are in the first position thereof causes movement of the second engaging portions to be prevented by the cam surfaces being urged further into engagement with their corresponding second engaging portions.

2. An assembly according to claim 1 wherein one of the engaging members has a respective protrusion and the other engaging member has a respective recess for receiving the respective protrusion, wherein the recess permits limited relative pivotal movement of the protrusion therein such that one engaging member is pivotable about said common axis relative to the other. P:\OPER\RSH\2647590-B&D Innovation doc.-08/05 S-11- (N

3. An assembly according to any one of the preceding claims, wherein at least one of 00 the engaging members further comprises at least one elongate protrusion adapted to enable O the user to pivot the two engaging members towards the second position.

4. An assembly according to any one of the preceding claims, wherein the engaging Io members are adapted to be displaced from the first position thereof by movement of the working member towards the output shaft to enable mounting of the working member to Sthe assembly by such movement thereof. A reciprocating tool comprising: a body; a motor having a rotary shaft; drive means for converting rotary movement of said rotary shaft to reciprocating movement of an output shaft; and a clamp assembly according to any one of the preceding claims. DATED this 8 th day of August 2005 Black Decker, Inc. by their Patent Attorneys DAVIES COLLISON CAVE