Technical Field

The invention relates to a saw blade clamping device for a hand-held machine tool, in particular to a saw blade clamping device which can be used in a hand-held linearly reciprocating type sawing machine and is able to clamp two types of saw blades.

Background Art

Figures la and lb show a saw blade clamping device 100' used in a hand-held linearly reciprocating type sawing machine according to prior art. The saw blade clamping device is able to clamp either of a jigsaw blade 10 and a reciprocating saw blade 20 which have different shanks as shown in Figure 2. The saw blade clamping device 100' comprises a first clamping plate 30' , a second clamping plate 40' , a first driving element 50' , a second driving element 60' , and a fixing pin 31 ' assembled to the first clamping plate 30' , wherein the second clamping plate 40' is provided with a slot 4Γ having a shape matching with that of the shank 11 of the jigsaw blade 10.

The first driving element 50' and the second driving element 60' are configured to be able to clamp the first clamping plate 30' and the second clamping plate 40' together. When a jigsaw blade 10 is inserted into the clamping device 100' , the shank 11 of the jigsaw blade 10 is located in the slot 4Γ of the second clamping plate 40' , and the first clamping plate 30' and the second clamping plate 40' are fastened together by means of the first driving element 50' and the second driving element 60' , so that the jigsaw blade 10 is clamped in the clamping device 100' . On the other hand, when a reciprocating saw blade 20 is inserted into the clamping device 100' , the fixing pin 3 Γ is inserted through a through hole 32' of the first clamping plate into a circular hole 22 in the shank 21 of the reciprocating saw blade 20, and the first clamping plate 30' and the second clamping plate 40' are fastened together by means of the first driving element 50' and the second driving element 60' , so that the reciprocating saw blade 20 is clamped in the clamping device 100' .

A defect in such a clamping device 100' is that it is difficult for an operator to insert a corresponding saw blade to an accurate position, which may result in that the first driving element 50' and the second driving element 60' fail to drive the first clamping plate 30' and the second clamping plate 40' into correct clamping condition.

Thus, it is desirable to solve the above problem found in the prior art.

Summary of the Invention

An object of the invention is to provide a saw blade clamping device for a linearly reciprocating type sawing machine, which has a simple structure and is easy to be operated.

For this end, the invention provides a saw blade clamping device for a linearly reciprocating type sawing machine, the saw blade clamping device being able to clamp at least two types of saw blades and comprising a clamping seat having a connecting portion configured to be driven by the linearly reciprocating type sawing machine and a loading portion formed by extending from the connecting portion, the loading portion being provided with a loading slot; an operating member comprising an operating portion as well as an assembling end and a loading end formed on opposite ends of the operating portion respectively, the operating portion being assembled around the loading portion of the clamping seat by the help of the assembling end, and the loading end being provided with a loading port; and an abutting element disposed between the operating member and the clamping seat, the abutting element having an abutting end which can extend into the loading slot; wherein the operating member is able to be rotated with respect to the loading portion, an inner wall of the operating member is provided with a driving surface formed in the form of a curved surface, the abutting element is provided with a driving end which abuts against the driving surface, and the abutting end of the abutting element can be driven by the driving surface during the rotation of the operating member to move in a direction of extending into the loading slot.

In the saw blade clamping device according to the invention, the operating member is provided with the driving surface, by means of which an operator can perform operation easily. Thus, the saw blade clamping device of the invention is easy to be operated.

In this way, the invention provides an advantageous option to users.

Brief Description of the Drawings

Figure la is an exploded perspective view of a saw blade clamping device of the prior art;

Figure lb shows in perspective views a component of the saw blade clamping device of the prior art;

Figure 2 shows in front views a jigsaw blade and a reciprocating saw blade;

Figure 3a is an exploded perspective view of a saw blade clamping device of the invention;

Figure 3b is an exploded perspective view of a part of the saw blade clamping device of the invention;

Figure 4 shows in a sectional view and a front view respectively the initial position of the saw blade clamping device of the invention;

Figure 5 shows in a sectional view and a front view respectively the loading position of the saw blade clamping device of the invention;

Figure 6 shows in sectional views and a front view respectively the saw blade clamping device of the invention when a reciprocating saw blade is in a loaded state;

Figure 7 is a perspective view of the saw blade clamping device of the invention when the reciprocating saw blade is in the loaded state;

Figure 8 shows in sectional views and a front view respectively the saw blade clamping device of the invention when a jigsaw blade is in a loaded state; and

Figure 9 is a perspective view of the saw blade clamping device of the invention when the jigsaw blade is in the loaded state.

Detailed Description of Preferred Embodiments

Now the principle of a saw blade clamping device according to the invention will be described with reference to the drawings.

The invention relates to a saw blade clamping device 100 which is mainly used with linearly reciprocating type sawing machines, such as jigsaws or reciprocating saws, for loading saw blades therein, so that cutting operations can be performed by using the linearly reciprocating type sawing machines.

As shown in Figure 2, a jigsaw blade 10 and a reciprocating saw blade 20 have shanks of different shapes, and the saw blade clamping device 100 of the invention is able to clamp the shank 11 of the jigsaw blade 10 as well as the shank 21 of the reciprocating saw blade 20. As shown in Figures 3a and 3b, the saw blade clamping device 100 of the invention comprises a clamping seat 30, an abutting element comprising a U-shaped member 40 and a fixing pin 50, an elastic member 60, a holding member 70, and an operating member 80.

The clamping seat 30 comprises a cylindrical connecting portion 31 which is coupled with a stroke rod of a linearly reciprocating type sawing machine, by means of which the linearly reciprocating type sawing machine drives a saw blade loaded in the clamping device 100 to move in a linearly reciprocating way, so that a cutting operation is performed. A cylindrical loading portion 32 is formed by extending from the cylindrical connecting portion 31 in the longitudinal direction thereof, a stop part 36 being formed between the connecting portion 31 and the loading portion 32. The stop part 36 is in the form of a circular ring around the cylindrical portions, having a cross sectional area which is larger than either of that of the connecting portion 31 and that of the loading portion 32. The loading portion 32 comprises a first clamping piece 33 and a second clamping piece 34, a loading slot 35 being formed between the first clamping piece 33 and the second clamping piece 34. The first clamping piece 33 and the second clamping piece 34 are each of the shape of a semi-cylinder and are opposed to each other. The loading slot 35 is defined by facing planes of the first clamping piece 33 and the second clamping piece 34, and an opening 350 of the loading slot 35 is defined between free tip ends of the first clamping piece 33 and the second clamping piece 34. A corresponding notch 330 is formed on each of opposite lateral sides of the first clamping piece 33, with both the notches 330 on the opposite sides of the first clamping piece 33 being communicated with the loading slot 35. A through hole 340 extending through the second clamping piece 34 is formed in a middle portion of the second clamping piece 34. The through hole 340 is also communicated with the loading slot 35.

The U-shaped member 40 comprises a U-shaped portion 41 and branched arms 42 extending in parallel from opposite ends of the U-shaped portion 41, wherein a protrusion 410 is formed on a middle portion of the U-shaped portion 41. The U-shaped member 40 is assembled to the first clamping piece 33, wherein the two branched arms 42 of the U-shaped member 40 are received in the opposite notches 33 of the first clamping piece 33 respectively, and tip ends 420 of the two branched arms 42 are configured as abutting ends which are able to abut against the plane of the second clamping piece 34.

The fixing pin 50 comprises a cylindrical pin body 51 and a first top end 52 and a second top end 53 forming opposite ends of the pin body 51. The first top end 52 and the second top end 53 forming the opposite ends each has a cross sectional area that is decreased gradually in a direction away from the pin body 51. The fixing pin 50 is received in the through hole 340 of the second clamping piece 34. The distance between the first top end 52 and the second top end 53 of the fixing pin 50 is larger than the sum of the depth of the loading slot 35 and the maximum thickness of the second clamping piece 34. The first top end 52 of the fixing pin 50 extends through the second clamping piece 34 and abuts against the plane of the first clamping piece 33.

The elastic member 60 is in the form of a helical spring which is able to provide a spring force in its helical direction and comprises a helical body 61 , a first fixing leg 62, and a second fixing leg 63. The elastic member 60 is assembled around the loading portion 32 and abuts against the stop part 36. The second fixing leg 63 is received in the loading slot 35 within the inner most end of the loading slot 35 which is longitudinally opposite to the opening 350.

The holding member 70 is in the form of a cylindrical sleeve and comprises a sleeve body 71 which is formed with a through cut 710 and an aperture 711. The sleeve body is assembled around the loading portion 32. In the assembled state, the through cut 710 of the sleeve body 71 is aligned with the notches 330 of the first clamping piece 33, and the aperture 711 is aligned with the through hole 340 of the second clamping piece 34. The U-shaped member 40 is assembled to the first clamping piece 33 through the through cut 710 of the holding member 70, and the fixing pin 50 is received in the through hole 340 of the second clamping piece 34 through the aperture 711.

The operating member 80 is in the form of a cylindrical sleeve and comprises an operating portion 81 defined by a sleeve body, and a loading end 82 and an assembling end 83 formed on opposite ends of the operating portion 81. The assembling end 83 defines an opening, so that the operating member 80, by means of the assembling end 83, is assembled around the loading portion 32 which is already assembled with the U-shaped member 40, the fixing pin 50, the elastic member 60 and the holding member 70 as described above. The inner wall 84 of the operating member 80 is formed with a narrow slot 840 for receiving the first fixing leg 62 of the elastic member 60. Both the protrusion 410 on the U-shaped member 40 and the second top end 53 of the fixing pin abut against the inner wall 84 of the operating member 80 and are able to slide along the wall surface of the inner wall 84. The inner wall 84 is provided with a first driving surface 842 and a second driving surface 843 each formed by a curved surface, the first driving surface 842 comprising a start end 841, and the second driving surface 843 comprising a terminal end 844. The first driving surface 842 and the second driving surface 843 are formed in an opposed manner in the inner wall 84 of the operating member 80. In addition, in the direction reverse to the direction A shown in Figure 4, the first driving surface 842 and the second driving surface 843 are each defined by a curved trajectory surface which is formed by varying the wall thickness at the inner wall 84 of the operating member 80, wherein the start end 841 is at a location on the first driving surface 842 where the operating member presents a maximum wall thickness, and the terminal end 844 is at a location on the second driving surface 843 where the operating member presents a minimum wall thickness. The operating member 80 can be rotated when the operating portion 81 is manipulated, and after rotation, the operating member 80 can return to its original position under the spring force of the elastic member 60. The operating member 80 is coaxial with the loading portion 32, so that the operating member returns to its original position around a central axis. The loading end 82 of the operating member 80 is provided with a loading port 820 which is composed of a first sector opening 821 and a second sector opening 822. The first sector opening 821 is formed by two opposing sector surfaces having the same radius and extending through the same radian, while the second sector opening 822 is formed by another two opposing sector surfaces having the same radius and extending through the same radian. The first sector opening 821 and the second sector opening 822 share the same symmetric center O, and an angle B is formed between the radial or longitudinal symmetric lines of the first sector opening 821 and the second sector opening 822. The first sector opening 821 forms an effective portion of the loading port 82 which has a width larger than that of the effective portion of the loading port 82 formed by the second sector opening 822. The first sector opening 821 and the second sector opening 822 may be formed as a narrow slot which allows the shank of a saw blade to be inserted in, or be formed as other similar structures. The width of the effective portion of the loading port is defined as the maximum allowance width of the overlap area between the first sector opening 821 or the second sector opening 822 and the opening 350 of the loading slot 35. The radian of each of the first sector opening 821 and the second sector opening 822 is larger than the depth of the opening 350 of the loading slot 35.

As shown in Figure 4, the initial position of the saw blade clamping device 100 of the invention is illustrated. In this condition, the protrusion 410 of the U-shaped member 40 abuts against the start end 841 which is on the first driving surface 842, with the tip ends 420 of the branched arms 42 of the U-shaped member 40 extending into the loading slot 350 and abutting against the plane of the second clamping piece 34. Of course, There may be a gap between the tip ends 420 and the plane of the second clamping piece 34, providing that the depth of this gap is smaller than the depth of the thinnest saw blade among a group of saw blades. The first top end 52 of the fixing pin 50 extends into the loading slot 35, and the second top end 53 abuts against the portion of the second driving surface 843 where it has the most wall thickness. The second sector opening 822 overlaps the opening 350 of the loading slot 35. By means of the start end 841, it is able to prevent the operating member from rotating in the direction reverse to the direction A, and the elastic member 60 provides a pre-applied spring force to the operating member 80 in the direction reverse to the direction A, by means of which spring force, the start end 841 of the operating member 80 and the protrusion 410 abut against each other, so that the saw blade clamping device 100 of the invention is kept in its initial position shown in Figure 4.

During operation, when an operator rotates the operating member 80 by the help of the operating portion 81 in the direction A, the operating member 80 is driven to rotate in the direction A with respect to the loading portion 32. In this condition, the protrusion 410 and the second top end 53 slide along the first driving surface 842 and the second driving surface 843 respectively. As mentioned above, the wall thicknesses at the first driving surface 842 and the second driving surface 843 are varied in the direction A according to the curved trajectory surface, thus, during sliding, spaces that allow the U-shaped member 40 and the fixing pin 50 to move in directions away from the first clamping piece 33 and the second clamping piece 34 respectively are provided. As shown in Figure 5, a loading position of the saw blade clamping device 100 of the invention is illustrated. In this condition, the second top end 53 of the fixing pin 50 abuts against the terminal end 844, so that the operating member 80 is prevented from rotating further in the direction A. The tip ends 420 of the branched arms 42 and the first top end 52 of the fixing pin 50 are withdrawn from the loading slot 350, and the first sector opening 821 overlaps the opening 350 of the loading slot 35.

Now a saw blade to be used can be loaded into the saw blade clamping device 100 of the invention. When a reciprocating saw blade 20 is to be loaded, the shank 21 of the reciprocating saw blade 20 is inserted into the loading port 820. Since the operating member 80 is in the loading position, the shank 21 of the reciprocating saw blade 20 is inserted into the loading slot 350 through the effective portion of the loading port where the first sector opening 821 overlaps the opening 350 of the loading slot 35. During insertion, the U-shaped member 40 and the fixing pin 50 move in directions away from the first clamping piece 33 and the second clamping piece 34 respectively. When the shank 21 of the reciprocating saw blade 20 is inserted into a proper position, the operating member 80 is released to allow it to rotate backwardly in the direction reverse to the direction A under the spring force of the elastic member 60. During the backward rotation, the first driving surface 842 and the second driving surface 843 of the operating member 80 drive the tip ends 420 of the U-shaped member 40 and the first top end 52 of the fixing pin 50 to extend into the loading slot 350 respectively. When the operating member 80 is rotated back to a clamping position, the two tip ends 420 of the U-shaped member 40 abut against opposite side edge portions of the shank 21 of the reciprocating saw blade 20 respectively, the first top end 52 of the fixing pin 50 is inserted into a circular hole 22 formed in the shank, and the shank 21 of the reciprocating saw blade 20 is in the first sector opening 821 of the loading port 820. The holding member 70 has an internal diameter which corresponds to the width of the shank 21 of the reciprocating saw blade 20, as shown in Figure 7. When the shank 21 of the reciprocating saw blade 20 is inserted into the loading slot 35, the reciprocating saw blade 20 can be prevented, by the holding member 70, from swing in the lateral direction. The radian of the first sector opening 821 should be larger than the rotational allowance of the operating member 80, to avoid the condition that the rotation of the operating member 80 is blocked by the first sector opening 821 which may result in that the tip ends 420 and the first top end 52 cannot come into correct positions. The width of the first sector opening 821 corresponds to that of the shank 21 of the reciprocating saw blade 20, so that the stability degree of the reciprocating saw in the clamping device 100 is increased.

As shown in Figures 8 and 9, when a jigsaw blade 10 is to be loaded, the shank 11 of the jigsaw blade 10 is inserted into the loading port 820. Since the operating member 80 is in the loading position, the shank 11 of the jigsaw blade 10 is inserted into the loading slot 350 through the effective portion of the loading port where the first sector opening 821 overlaps the opening 350 of the loading slot 35. During insertion, the fixing pin 50 moves in the direction away from the second clamping piece 34. When the shank 11 of the jigsaw blade 10 is inserted into a proper position, the operating member 80 is released so that it is rotated in the direction reverse to the direction A under the spring force of the elastic member 60. During the backward rotation, the first driving surface 842 and the second driving surface 843 of the operating member 80 drive the tip ends 420 of the U-shaped member 40 and the first top end 52 of the fixing pin 50 to extend into the loading slot 350 respectively. The distance between the two tip ends 420 of the U-shaped member 40 is larger than the width of the shank 11 of the jigsaw blade 10. After the operating member 80 is rotated back to the clamping position, once the two tip ends 420 of the U-shaped member 40 extend into the loading slot 35, internal side surfaces of the two tip ends 420 abut against opposite sides of the shank 11 of the jigsaw blade 10. The first top end 52 of the fixing pin 50 abuts against the shank 11 of the jigsaw blade 10 and pushes the shank 11 of the jigsaw blade 10 against the inner wall of the first clamping piece 33 tightly. The shank 11 of the jigsaw blade 10 is in the second sector opening 822 of the loading port 820. As shown in Figure 8, a pair of stops 12 are formed on opposite sides of the shank 11 of the jigsaw blade 10, the width between the two stops 12 being larger than the width of the second sector opening 822. After loading, the two stops 12 interfere with the second sector opening 822, and the top end of the shank 11 of the jigsaw blade 10 abuts against the bottom of the loading slot 35, so that the jigsaw blade 10 is fixedly held in the saw blade clamping device 100. The radian of the first sector opening 821 should be smaller than the rotational allowance of the operating member 80, to avoid the condition that the shank 11 of the jigsaw blade 10 cannot interfere with the second sector opening 822 which may result in that the jigsaw blade 10 cannot be fixedly held in the clamping device 100.

When the operating member 80 is in the initial position, the elastic member 60 provides a pre-pressing force, and when the operating member 80 is in the clamping position, the elastic member 60 provides pressing forces to corresponding elements to force them to abut against the saw blade. It is conceived that the same effect can be achieved by screw fitting between the clamping seat 30 and the operating member 80. In this case, when the operating member 80 is in the initial position, the clamping seat 30 and the operating member 80 can be kept stably in this position by means of engaged screws therebetween. On the other hand, when the operating member 80 is in the clamping position, pressing forces which force corresponding elements to abut against the saw blade can be provided by fastening the engaged screws between the clamping seat 30 and the operating member 80. In this configuration, the loading port 820 of the operating member 80 may be provided by a separate member, to ensure that the screws between the operating member 80 and the clamping seat 30 can be engaged with each other in a free manner. Any other configurations can be used alternatively, only if the loading port 820 is composed of the first sector opening 821 and the second sector opening 822 and the same effects of the above embodiments can be achieved. Of course, further effects can be provided by remaining the elastic member 60 in the configuration in which screws are provided between the clamping seat 30 and the operating member 80.

While certain embodiments of the invention have been described here, they are presented by way of explanation only and are not intended to limit the scope of the invention. Various modifications, substitutions and changes can be made by those skilled in the art within the scope and spirit of the invention as defined in the attached claims and their equivalents.