Oscillating saw

Abstract

Provided is an oscillating saw that achieves a reduction in impact force in cutting. An oscillating saw (100) comprises a saw blade (1) and a drive device (2) that causes the saw blade to oscillate so as to swing about an axial position. The path of a tooth tip (12a) of the saw blade has: an arc-shaped first path that overlaps in reciprocating oscillations; and a second path located behind a virtual line at the end of an oscillation, the virtual line obtained by extending the first path to the end of the oscillation.

Description

vibrating saw

[0001] The present invention relates to an oscillating saw.

[0002] Conventionally, there is known an electric oscillating saw that cuts an object by oscillating a saw blade in a swinging manner. Such oscillating saws are particularly used for cutting hard tissue (e.g., bone) in surgical operations. Oscillating saws that can swing the saw blade a short distance are effectively used for cutting hard tissue, where it is necessary to avoid damaging the surrounding soft tissue.

[0003] The trajectory of the saw blade is typically an arc-shaped trajectory. In addition, Patent Documents 1 to 5 listed below propose various trajectories of the saw blade that are not limited to an arc-shaped trajectory, with the aim of improving workability for the surgeon (user).

[0004] Japanese Patent Application Laid-Open No. 2008-29848, U.S. Patent No. 9,579,105, U.S. Patent No. 9,572,585, U.S. Patent No. 9,975,191, Japanese Patent No. 6,852,152

[0005] Han Wang, Urara Satake, Toshiyuki Enomoto: Modeling of oscillating bone sawing forces with instantaneous cutting speed and depth of cut, Journal of Materials Processing Technology, 324 (2024) 118225.

[0006] However, the above-mentioned Patent Documents 1 to 5 leave room for improvement in terms of improving the processing accuracy of the cutting work and reducing wear on the tooth tips of the saw blade. The reasons for this will be explained below.

[0007] In a cutting operation in which an oscillating saw cuts a workpiece to form a groove, continuous chips may be generated during the cutting. These chips may be pushed into the end of the groove by the reciprocating motion of the saw blade during the cutting operation. This increases the impact force generated when the outer teeth of the saw blade come into contact with the end face of the groove. This increase in impact force can cause a decrease in the processing accuracy of the cutting operation. The oscillating saws disclosed in the above-mentioned Patent Documents 1 to 5 cannot adequately deal with continuous chips generated during the cutting operation.

[0008] An object of one aspect of the present invention is to provide an oscillating saw that can reduce impact forces during cutting.

[0009] In order to solve the above problem, an oscillating saw according to aspect 1 of the present invention comprises a saw blade having a tooth tip at its front end, and a drive device that vibrates the saw blade so that it swings around an axial position located rearward of the tooth tip, and the orbit of the tooth tip has a first arc-shaped orbit that overlaps during the round trip of vibration, and a second orbit that is located rearward of an imaginary line extending the first orbit to the end of vibration at the end of vibration, and the orbit of the second orbit toward the center of vibration does not lie between the imaginary line and the orbit of the second orbit toward the end of vibration.

[0010] In order to solve the above problem, an oscillating saw according to a fifth aspect of the present invention comprises a saw blade having a tooth tip at its front end, and a drive device that oscillates the saw blade so as to swing around an axial position located rearward of the tooth tip, wherein the saw blade has at least one first tooth having the tooth tip located on one side of the swing at its front end, and at least one second tooth having the tooth tip located on the other side of the swing at its front end, wherein the trajectory of the first tooth in the first direction of the swing is located forward of the trajectory of the first tooth in the second direction of the swing, and the trajectory of the second tooth in the first direction of the swing is located rearward of the trajectory of the second tooth in the second direction of the swing, the trajectory of the first tooth in the first direction of the swing and the trajectory of the second tooth in the first direction of the swing are trajectories at the same time, and the trajectory of the first tooth in the second direction of the swing and the trajectory of the second tooth in the second direction of the swing are trajectories at the same time.

[0011] In order to solve the above problem, an oscillating saw according to aspect 10 of the present invention comprises a saw blade having a tooth tip at its front end and vibrating to swing around an axial position located rearward of the tooth tip, the tooth tip having a positive or zero cutting face and a negative cutting face, the saw blade having a blade main body portion, a plurality of teeth having the tooth tip, and an elastic hinge portion connecting each of the plurality of teeth to the blade main body portion and elastically deforming during cutting to displace the plurality of teeth in the forward and backward directions, and the plurality of teeth have extension portions extending forward to the tooth tip.

[0012] According to one aspect of the present invention, it is possible to reduce the impact force during cutting.

[0013] 10 is a diagram showing how a groove is formed by cutting an object to be cut with an oscillatory saw according to Reference Form 1. FIG. 11 is a diagram showing how a groove is formed by cutting an object to be cut with an oscillatory saw according to Embodiment 1. FIG. 12 is a perspective view showing the overall configuration of the oscillatory saw. FIG. 13 is an exploded perspective view showing a partial configuration of a drive device for the oscillatory saw. FIG. 14 is an exploded perspective view showing a partial configuration of a drive device for the oscillatory saw. FIG. 15 is a perspective view and a top view illustrating the relationship between a first shaft portion and a third shaft portion of the drive device. FIG. 16 is a perspective view illustrating the relationship between a second shaft portion and a third shaft portion of the drive device. FIG. 17 is a top view illustrating the relationship between a grooved cam and a roller of the drive device. FIG. 18 is a graph showing an example of a trajectory along which the tip of the saw blade moves due to a drive head transmission unit having the grooved cam. FIG. 19 is a graph showing another example of a trajectory along which the tip of the saw blade moves due to a drive head transmission unit having the grooved cam. FIG. 19 is a diagram showing the shape of the distal end of the saw blade and how the saw blade is vibrated along an arc-shaped trajectory to cut an object to be cut OB. FIG. 19 is a diagram showing how the saw blade is vibrated along the trajectory of the saw blade shown in FIG. 10 is a diagram showing how the saw blade is vibrated along the trajectory of the saw blade shown in FIG. 11 to cut an object to be cut. 1 is a diagram showing another example of the shape of the distal end of a saw blade that can be used in combination with the drive head transmission unit having the groove cam. FIG. 2 is a diagram showing how a groove is formed by cutting a cutting object using an oscillating saw according to a second embodiment. FIG. 3 is a diagram showing the trajectory of the saw blade in the oscillating saw. FIG. 4 is a diagram showing the trajectory of the saw blade in the oscillating saw according to the second embodiment. FIG. 5 is a perspective view showing the overall configuration of the oscillating saw. FIG. 6 is an exploded perspective view showing a partial configuration of the drive unit of the oscillating saw. FIG. 7 is a longitudinal sectional view of the drive unit. FIG. 8 is an exploded perspective view, side view, and sectional view taken along arrows A-A illustrating the relationship between the rotation shaft of the drive unit and the first oscillation shaft. FIG. 9 is an exploded perspective view, side view, and sectional view taken along arrows B-B illustrating the relationship between the rotation shaft of the drive unit and the second oscillation shaft. FIG. 10 is a schematic view showing the trajectory of the axis of the second oscillation shaft in the oscillating saw. FIG. 11 is a schematic view showing the trajectory of the saw blade in the oscillating saw. FIG. 12 is a conceptual view showing the relative eccentric angle between the first eccentric wheel and the second eccentric wheel. FIG. 13 is a diagram showing the trajectory of the saw blade relative to the relative eccentric angle. FIG. 14 is a diagram showing an example of the trajectory of the saw blade in the oscillating saw.10 is a diagram showing another example of the trajectory of the saw blade in the oscillating saw; FIG. 11 is a perspective view showing the overall configuration of the oscillating saw according to a third embodiment; FIG. 12 is an exploded perspective view showing the configuration of a support unit in a drive device for the oscillating saw; FIG. 13 is an exploded perspective view showing the configuration of a drive unit in a drive device for the oscillating saw; FIG. 14 is a diagram showing narrow deep groove cutting with a saw blade according to a fourth embodiment; FIG. 15 is a front view of a saw blade for narrow deep groove cutting, a partial rear view of a distal end of the saw blade, and a partial perspective view of the distal end of the saw blade; FIG. 16 is a diagram showing narrow groove cutting with a saw blade according to the fourth embodiment; FIG. 17 is a perspective view of a saw blade for narrow groove cutting, a cross-sectional view of a second tooth of the saw blade, and a cross-sectional view of a first tooth of the saw blade; FIG. 18 is a diagram showing cutting of an object with an oscillating saw according to a fifth embodiment; FIG. 19 is a plan view showing an example of the configuration of the saw blade of the oscillating saw; FIG. 19 is an enlarged plan view of the distal end of the saw blade; FIG. 19 is an enlarged plan view of one tooth of the saw blade and one corresponding elastic hinge portion; FIG. 19 is a diagram showing displacement of the tooth of the saw blade in the front-to-rear direction due to elastic deformation of the elastic hinge portion. Fig. 1 is an enlarged plan view of the distal end of a saw blade showing another example of the saw blade configuration; Fig. 2 is an enlarged plan view of one tooth of the saw blade and one corresponding elastic hinge portion; Fig. 3 is a diagram showing displacement of the tooth of the saw blade in the front-to-rear direction due to elastic deformation of the elastic hinge portion; Fig. 4 is a diagram showing yet another example of the saw blade configuration; Fig. 5 is a diagram showing yet another example of the saw blade configuration; Fig. 6 is a diagram showing yet another example of the saw blade configuration; Fig. 7 is a diagram showing yet another example of the saw blade configuration;

[0014] [Reference Form 1] Prior to describing the vibration saw 100 according to embodiment 1, a description will be given of a vibration saw 100s according to reference form 1. For ease of explanation, components having the same functions as those described in the reference form will be denoted by the same reference numerals in the following embodiments, and their description will not be repeated.

[0015] (Issues of the Oscillating Saw 100s) FIG. 1 illustrates the process of cutting an object (OB) to form a groove using an oscillating saw 100s. The oscillating saw 100s is a device that cuts an object (OB) (workpiece) by vibrating a saw blade 1 having a plurality of teeth 12 at its distal end in a swinging motion. The oscillating saw 100s is used, for example, to cut hard tissue in surgical operations or industrial materials (wood, metal materials, resin materials, ceramic materials, etc.). Specifically, the saw blade 1 swings so that the plurality of teeth 12 trace an arc-shaped trajectory. The detailed configuration of the oscillating saw 100s is described in the aforementioned Non-Patent Document 1. For simplicity, the trajectory traced by the tips of the saw blade's teeth due to the swinging motion of the saw blade will be simply referred to as the "saw blade trajectory."

[0016] Reference numeral 1001 in FIG. 1 is an overall view showing the oscillating saw 100s cutting an object to be cut (OB) (bone in the example shown in FIG. 1 ), and reference numeral 1002 in FIG. 1 is an enlarged view of the portion of reference numeral 1001 in FIG. 1 where the saw blade 1 abuts on the work surface of the object to be cut (OB). As shown by reference numerals 1001 and 1002 in FIG. 1 , during cutting operations using the oscillating saw 100s, the saw blade 1 swings so that the multiple teeth 12 trace an arc-shaped trajectory. Furthermore, along with the swinging motion, the saw blade 1 gradually moves toward the work surface of the object to be cut (OB). This cuts the object to be cut (OB) and forms a groove on the work surface of the object to be cut (OB). When the outer teeth collide with the end face of the groove, an impact force is generated. Typically, the impact force increases dramatically as the groove depth increases.

[0017] Reference numerals 1003 and 1004 in Fig. 1 are enlarged views of the tooth tips of the saw blade 1 indicated by reference numeral 1002 in Fig. 1. Reference numerals 1005 and 1006 in Fig. 1 respectively show how the tooth tips of the saw blade 1 indicated by reference numerals 1003 and 1004 in Fig. 1 collide with the end faces of the grooves. Here, the depth h indicated by reference numerals 1005 and 1006 in Fig. 1 is the depth cut by the saw blade 1 for each reciprocation.

[0018] 1 indicates a case where the teeth at one end of the saw blade 1 in the vibration direction are facing the other end of the vibration direction. In this case, as shown by the reference numeral 1003 in FIG. 1, when the saw blade 1 moves in one direction in the vibration direction and the negative rake face of the saw blade 1 collides with the end face of the groove, a strong impact force is generated.

[0019] Reference numeral 1004 in FIG. 1 indicates a case where the teeth at one end of the saw blade 1 in the vibration direction are facing in the same direction. In this case, as shown by reference numeral 1004 in FIG. 1 , when the saw blade 1 moves in one direction in the vibration direction, the positive rake face of the tooth cuts the object OB. At this time, as shown by reference numeral 1006 in FIG. 1 , at the start of cutting, the impact force when the tooth tips of the saw blade 1 collide with the end face of the groove is small. However, as cutting progresses, multiple continuous chips are pushed into the end of the groove by the swinging motion of the saw blade 1 without being cut at the end of the groove. Therefore, as cutting progresses, a strong impact force is generated when the tooth tips of the saw blade 1 collide with the end face of the groove.

[0020] Such an increase in impact force can cause a decrease in the processing accuracy of the cutting work. Furthermore, when the oscillating saw is used for cutting bones in a surgical operation, such an increase in impact force can adversely affect the sensation in the surgeon's hands and increase fatigue in the surgeon's hands.

[0021] [Embodiment 1] (Regarding Features of One Aspect of the Present Invention) The inventors have discovered that the above-mentioned increase in impact force can be suppressed by using an oscillating saw 100 having the features described below instead of the oscillating saw 100s according to Reference Example 1. Specifically, the inventors propose an oscillating saw 100 in which the trajectory of the saw blade 1 has a first trajectory and a second trajectory. The first trajectory is an arc-shaped trajectory that overlaps during the reciprocating vibration. The second trajectory is a trajectory that is located at the end of the vibration, rearward (toward the base end of the saw blade 1) of an imaginary line extending from the first trajectory to the end of the vibration. The inventors have discovered that by defining the trajectory of the saw blade 1 as described above, it is possible to suppress the increase in impact force that occurs when the outer teeth of the saw blade contact the end face of the groove when cutting an object OB with the positive rake face (therefore, improving the processing accuracy of the cutting operation and preventing damage to the workpiece).

[0022] Furthermore, the trajectory toward the center of vibration in the second trajectory does not lie between the imaginary line of the first trajectory and the trajectory toward the end of vibration in the second trajectory, so that the tooth tip of the saw blade 1 does not cut the cutting object in the trajectory toward the center of vibration in the second trajectory, thereby reducing cutting resistance.

[0023] 2 is a diagram showing how the oscillating saw 100 cuts the object OB to form a groove. Reference numeral 2001 in Fig. 2 indicates a first trajectory and a second trajectory along which the saw blade 1 can move when the tip of the saw blade 1 reaches the end face of the groove. Reference numeral 2002 in Fig. 2 indicates how the tip of the saw blade 1 hits the end face of the groove.

[0024] For example, the saw blade 1 of the oscillating saw 100 moves along an arc-shaped trajectory (first trajectory) similar to that of the oscillating saw 100s during a first swing motion in a cutting operation. At this time, one continuous chip is pushed into the end of the groove. Next, during a second swing motion in a cutting operation, the saw blade 1 moves along the arc-shaped trajectory (first trajectory) and then moves along a trajectory (second trajectory) that moves away from the cutting surface near the end face of the groove.

[0025] As the saw blade 1 moves along the second orbit, the tooth tips of the saw blade 1 cut off the continuous chips (that were connected to the end faces of the groove) generated by the first and second swing motions and discharge them to the outside of the groove, as shown by reference numeral 2001 in Fig. 2. Therefore, as shown by reference numeral 2002 in Fig. 2, multiple continuous chips are not pushed into the end of the groove, and an increase in the impact force generated when the outer teeth of the saw blade 1 come into contact with the end face of the groove can be suppressed.

[0026] A specific configuration for realizing such an oscillation saw 100 will be described below.

[0027] (Schematic Configuration of Oscillating Saw 100) Figure 3 is a perspective view (reference numeral 3001) showing the overall configuration of the oscillating saw 100 and an enlarged top view (reference numeral 3002) of the saw blade 1. As shown by reference numeral 3001 in Figure 3, the oscillating saw 100 includes the saw blade 1, a drive unit 2, a handle unit 3, and a battery unit 4.

[0028] The saw blade 1 has a blade body 11 and a plurality of teeth 12. The blade body 11 is a flat plate member extending in a predetermined direction, with a plurality of teeth 12 provided at its distal end. The blade body 11 is made of stainless steel, for example, with a thickness of approximately 0.5 mm to 2 mm. Hereinafter, unless otherwise specified, the long axis direction of the blade body 11 in the oscillating saw 100 will be referred to as the front-to-rear direction, the short axis direction as the left-to-right direction, and the thickness direction as the up-to-down direction. Furthermore, the direction toward the distal end of the blade body 11 will be referred to as the front, and the direction toward the proximal end as the rear. Furthermore, the left-to-right direction, the front-to-rear direction, and the up-to-down direction will also be referred to as the X-axis direction, the Y-axis direction, and the Z-axis direction, respectively.

[0029] As shown by reference numeral 3002 in FIG. 3 , the plurality of teeth 12 include at least one or more first teeth 12A and at least one or more second teeth 12B. The first teeth 12A are disposed on the left side of the front end of the saw blade 1, with their tips facing leftward. The first teeth 12A cut the object to be cut OB with their positive cutting faces when the saw blade 1 moves leftward. The second teeth 12B are disposed on the right side of the front end of the saw blade 1, with their tips facing rightward. The second teeth 12B cut the object to be cut OB with their positive cutting faces when the saw blade 1 moves rightward.

[0030] The drive unit 2 is a device for vibrating the saw blade 1 so that it swings around an axis located rearward of the tooth tip. A drive head transmission unit 2A is provided at the front of the drive unit 2, which drives the saw blade 1 to move along the first and second orbits. A motor 2B is provided at the rear of the drive unit 2, which drives the drive head transmission unit 2A. A housing 20 of the drive unit 2 has a drive head 20A that houses the drive head transmission unit 2A and a motor housing 20B that houses the motor 2B.

[0031] The drive head transmission unit 2A vibrates the saw blade 1 in the left-right direction so that the saw blade 1 swings about the axis position. The drive head transmission unit 2A also moves the saw blade 1 so that the distance from the axis position to the tooth tip of the saw blade 1 when it moves along the second orbit is shorter than the distance from the axis position to the tooth tip of the saw blade 1 when it moves along the first orbit.

[0032] Here, the axial position refers to the position of the axis C3 (see FIGS. 3 to 5) of the third shaft portion 24 in the drive head transmission unit 2A. The saw blade 1 is fixed to the third shaft portion 24 at its proximal end and swings in response to the rotation of the third shaft portion 24. The detailed configuration of the drive device 2 will be described later with reference to FIGS. 3 to 9.

[0033] The handle 3 is a portion that a user grips to operate the oscillating saw 100. The handle 3 extends downward from the drive unit 2. The handle 3 may also be provided with a trigger 31 on its front surface that is operated by the user to activate the drive unit 2.

[0034] The battery unit 4 is a power source that operates the motor 2B of the drive unit 2. The battery unit 4 is provided below the handle unit 3 and applies a voltage to the drive unit 2 via wiring arranged within the handle unit 3. The battery unit 4 can use a known power source.

[0035] (Detailed Configuration of Drive Unit 2) Figures 4 and 5 are exploded perspective views of a portion of the configuration of the drive unit 2. Figure 4 shows the drive unit 2 with the drive head 20A removed. Figure 5 shows the drive unit 2 with the bearings 26a to 26f also removed. Note that Figures 4 and 5 omit illustration of the motor 2B and motor housing 20B provided at the rear of the drive unit 2. Figure 5 also omits illustration of the drive head 20A.

[0036] As shown in Figures 4 and 5, the drive head transmission unit 2A includes a drive shaft 21, a first shaft portion 22, a second shaft portion 23, a third shaft portion 24 (vibration shaft), and a vibration shank 25 (vibration member).

[0037] The drive shaft 21 is a shaft that extends in the front-rear direction. The rear end of the drive shaft 21 meshes with the motor 2B and is driven to rotate by the motor 2B. The drive shaft 21 has a bevel gear 21a. The bevel gear 21a is provided at the front end of the drive shaft 21.

[0038] The first shaft portion 22, the second shaft portion 23, and the third shaft portion 24 have shafts that extend in the up-down direction. The first shaft portion 22, the second shaft portion 23, and the third shaft portion 24 are arranged in this order from the rear side along the front-rear direction.

[0039] The first shaft portion 22 has a bevel gear 22a, a spur gear 22b, and an eccentric wheel 22c. The bevel gear 22a is provided at the lower end of the first shaft portion 22 and meshes with the bevel gear 21a of the drive shaft 21. As a result, rotation of the drive shaft 21 around its longitudinal axis is transmitted to the first shaft portion 22 as rotation of the first shaft portion 22 around its vertical axis. The spur gear 22b is provided at the vertical center of the first shaft portion 22. The eccentric wheel 22c is provided above the spur gear 22b on the first shaft portion 22. The eccentric wheel 22c has a larger diameter than the shaft of the first shaft portion 22 and has an axis that is offset from the axis C1 of the first shaft portion 22. The eccentric wheel 22c is fixed to the first shaft portion 22 and, like the first shaft portion 22, is rotated in accordance with the rotation of the drive shaft 21.

[0040] The second shaft portion 23 has a spur gear 23a and a grooved cam 23b. The spur gear 23a is provided in the center of the second shaft portion 23 in the vertical direction and meshes with the spur gear 22b of the first shaft portion 22. As a result, rotation of the first shaft portion 22 about its vertical axis is transmitted to the second shaft portion 23 as rotation of the second shaft portion 23 about its vertical axis. The reduction ratio of the spur gear 23a to the spur gear 22b is, for example, 1 / 2. In other words, for every two rotations of the first shaft portion 22, the second shaft portion 23 rotates once. The grooved cam 23b is provided at the upper end of the second shaft portion 23. A detailed configuration of the grooved cam 23b will be described later with reference to FIGS. 7 and 8.

[0041] The third shaft portion 24 has a rail portion 24a (oscillating member) and a saw blade fixing portion 24b (oscillating member). The rail portion 24a is provided at the upper end of the third shaft portion 24. The saw blade fixing portion 24b is provided above the rail portion 24a and is slidable in the front-to-rear direction relative to the rail portion 24a. The saw blade 1 is fixed (for example, by tightening a bolt) above the saw blade fixing portion 24b. That is, the saw blade 1 is slidable in the front-to-rear direction.

[0042] The vibration shank 25 is a flat plate member extending in the front-rear direction. The vibration shank 25 has a slot 25a and a through hole 25b. The slot 25a is formed to extend forward from the rear end of the vibration shank 25. The eccentric wheel 22c of the first shaft portion 22 is disposed in the slot 25a. The through hole 25b is formed in the center of the vibration shank 25 in the front-rear direction. The second shaft portion 23 passes through the through hole 25b. The vibration shank 25 is also fixed to the third shaft portion 24 at its front.

[0043] The drive head transmission unit 2A further includes six bearings 26a to 26f (a first bearing 26a, a second bearing 26b, a third bearing 26c, a fourth bearing 26d, a fifth bearing 26e, and a sixth bearing 26f). The drive head 20A also includes an upper cover 20Aa and a lower cover 20Ab.

[0044] The first bearing 26a and the fourth bearing 26d rotatably support the first shaft portion 22 relative to the upper cover 20Aa and the lower cover 20Ab, respectively. The second bearing 26b and the fifth bearing 26e rotatably support the second shaft portion 23 relative to the upper cover 20Aa and the lower cover 20Ab, respectively. The third bearing 26c and the sixth bearing 26f rotatably support the third shaft portion 24 relative to the upper cover 20Aa and the lower cover 20Ab, respectively.

[0045] 6 is a perspective view (reference numeral 6001) and a top view (reference numeral 6002) illustrating the relationship between the first shaft portion 22 and the third shaft portion 24. For simplicity, only the first shaft portion 22, the third shaft portion 24, and the vibration shank 25 of the drive head transmission unit 2A are shown in FIG.

[0046] As shown in FIG. 6 , an eccentric ring 22c is disposed in the slot 25a of the vibration shank 25. The width of the slot 25a in the left-right direction is approximately equal to the diameter of the eccentric ring 22c. That is, the outer peripheral surface of the eccentric ring 22c contacts a pair of surfaces extending in the front-rear direction of the slot 25a. When the first shaft portion 22 rotates around its axis, the eccentric ring 22c rotates around an axis offset from the axis of the eccentric ring 22c. Therefore, the eccentric ring 22c vibrates the vibration shank 25 so that it swings around the third shaft portion 24. The third shaft portion 24 rotates in accordance with the swing of the vibration shank 25.

[0047] As described above, rotation of the first shaft portion 22 around its axis drives the third shaft portion 24 to swing, and ultimately causes the saw blade 1 fixed to the third shaft portion 24 to vibrate so as to swing around the axis C3 of the third shaft portion 24.

[0048] Furthermore, the through hole 25b of the vibration shank 25 is sized so that the second shaft portion 23 does not come into contact with the inner peripheral surface of the through hole 25b and inhibit the swing of the vibration shank 25.

[0049] Fig. 7 is a perspective view illustrating the relationship between the second shaft portion 23 and the third shaft portion 24. For simplicity, Fig. 7 only illustrates the second shaft portion 23, the third shaft portion 24, and the vibration shank 25 in the drive head transmission unit 2A.

[0050] 7, the grooved cam 23b of the second shaft portion 23 is a cylindrical member with an annular groove formed downward from the upper surface thereof. The grooved cam 23b is fixed to the second shaft portion 23, and is therefore driven to rotate in accordance with the rotation of the first shaft portion 22 about its axis.

[0051] The third shaft portion 24 also has a cam follower 24c. A cam follower mounting hole 24ba for mounting the cam follower 24c is formed in the rear portion of the saw blade fixing portion 24b. The cam follower 24c engages with the cam follower mounting hole 24ba and extends downward to the groove of the grooved cam 23b. In other words, the cam follower 24c is fixed to the saw blade 1 and disposed in the groove of the grooved cam 23b. Specifically, a roller 24ca is formed at the lower end of the cam follower 24c, and the roller 24ca is rotatably fitted into the groove of the grooved cam 23b.

[0052] 8 is a top view illustrating the relationship between the grooved cam 23b and the roller 24ca. As shown in FIG. 8, the axis C4 of the roller 24ca vibrates over the swing angle range of the vibration shank 25 (hereinafter referred to as the vibration angle range) as the third shaft portion 24 oscillates. Furthermore, the axis C4 of the roller 24ca moves in the front-to-rear direction as the second shaft portion 23 rotates. Specifically, the axis C4 of the roller 24ca moves (relative to the grooved cam 23b) on a pitch curve that corresponds to the shape of the groove in the grooved cam 23b.

[0053] The grooved cam 23b has a first groove corresponding to the first track and a second groove corresponding to the second track. The second groove is shaped so that the axis C4 of the roller 24ca passing through the second groove is recessed. For example, when the roller 24ca is positioned in the front portion of the grooved cam 23b, the second groove is located closer to the rotation axis of the grooved cam 23b (axis C2 of the second shaft portion 23) than the first groove. As a result, when the roller 24ca moves through the first groove, the distance from the axis C3 of the third shaft portion 24 to the tooth tip is maintained. That is, the distance from the axis C3 of the third shaft portion 24 to the axis C4 of the roller 24ca is maintained. Furthermore, when the roller 24ca moves through the second groove, the distance from the axis C3 of the third shaft portion 24 to the tooth tip is shortened. That is, the distance from the axis C3 of the third shaft portion 24 to the axis C4 of the roller 24ca is lengthened.

[0054] An example of the shape of the groove of the grooved cam 23b will be described below with reference to FIG. 8. In the example shown in FIG. 8, the roller 24ca is positioned in front of the groove of the grooved cam 23b. In this example, the pitch curve of the grooved cam 23b is divided into four arcs (arcs AB, BC, CD, and DA in FIG. 8). Arcs DA and BC are parts of a circle with a radius R1 centered on the axis C2 of the second shaft portion 23. Arcs AB and CD are curves with a radius of curvature R2 larger than the radius R1. In other words, when the axis of the roller 24ca passes through arc DA or arc BC, the distance R1 is maintained between the axis C4 of the roller 24ca and the axis C2 of the second shaft portion 23. When the axis of the roller 24ca passes through arc AB or arc CD, the distance R1 is reduced. Arc AB or arc CD may be a straight line.

[0055] Therefore, when the axis of the roller 24ca passes through the arc DA or the arc BC, the saw blade 1 passes through the first track, and when the axis of the roller 24ca passes through the arc AB or the arc CD, the saw blade 1 passes through the second track. In other words, the groove in which the arc DA or the arc BC is the pitch curve is the first groove, and the groove in which the arc AB or the arc CD is the pitch curve is the second groove.

[0056] (Trajectory of saw blade 1 in oscillating saw 100) Figure 9 is a graph showing an example of a trajectory of the tooth tip of the saw blade 1 moved by the drive head transmission unit 2A having the grooved cam 23b shown in Figure 8. Reference numeral 9001 in Figure 9 indicates the trajectory of the saw blade 1 in the first swing motion. Reference numeral 9002 in Figure 9 indicates the trajectory of the saw blade 1 in the second swing motion. Reference numeral 9003 in Figure 9 indicates the trajectory of the saw blade 1 in the first and second swing motions when there is a feed speed (when the saw blade 1 is moved forward).

[0057] The trajectory shown in Figure 9 is the trajectory of the saw blade 1 when the positional relationship between the grooved cam 23b and the roller 24ca is set as follows: When the third shaft portion 24 oscillates to the end on one side (right side) of the oscillation, the axis C4 of the roller 24ca coincides with point F (see Figure 8), which is the center of the arc CD. When the third shaft portion 24 oscillates to the end on the other side (left side) of the oscillation, the axis C4 of the roller 24ca coincides with point E (see Figure 8), which is the center of the arc AB.

[0058] As shown by reference numeral 9001 in Fig. 9 , the trajectory of the saw blade 1 during the first swing motion is a first arc-shaped trajectory that overlaps with the reciprocating oscillation. As shown by reference numeral 9002 in Fig. 9 , the trajectory of the saw blade 1 during the second swing motion includes the first trajectory and a second trajectory that is located behind an imaginary line extending the first trajectory to the end of the oscillation at the end of the oscillation. That is, during the second swing motion, the saw blade 1 retreats at the end of the oscillation.

[0059] As shown by reference numeral 9003 in Fig. 9, when an appropriate feed rate is set, two types of trajectories are generated alternately, and the two types of trajectories intersect at the end of the vibration (see the dotted frame around reference numeral 9003). As a result, when the oscillating saw 100 cuts the object OB to form a groove, the tooth tips of the saw blade 1 cut and discharge the continuous chips generated by the first and second swing motions to the outside of the groove. This reduces the impact force generated when the outer teeth of the saw blade 1 contact the end face of the groove.

[0060] FIG. 10 is a graph showing another example of the trajectory of the tooth tip of the saw blade 1 moved by the drive head transmission unit 2A having the grooved cam 23b shown in FIG. 8. The trajectory shown in FIG. 10 is the trajectory of the saw blade 1 when the positional relationship between the grooved cam 23b and the roller 24ca is set as follows: When the third shaft portion 24 oscillates to one end of the oscillation, the axis C4 of the roller 24ca coincides with a point on the side of point D relative to point F at the center of the arc CD. When the third shaft portion 24 oscillates to the other end of the oscillation, the axis C4 of the roller 24ca coincides with a point on the side of point B relative to point E at the center of the arc AB. In other words, compared to the trajectory shown in FIG. 9, the trajectory shown in FIG. 10 is the trajectory when the phase of the rotation of the grooved cam 23b slightly lags behind the phase of the swing motion of the saw blade 1.

[0061] By setting the positional relationship between the grooved cam 23b and the roller 24ca as described above, the trajectory of the saw blade 1 as shown in FIG. 10 can be realized.

[0062] As shown in Figures 9 and 10, the orbit toward the center of the vibration in the second orbit does not fall between the imaginary line of the first orbit and the orbit toward the end of the vibration in the second orbit. In the example shown in Figure 9, the orbit toward the center of the vibration in the second orbit coincides with the orbit toward the end of the vibration in the second orbit. In the example shown in Figure 10, the orbit toward the center of the vibration in the second orbit is located closer to the center of the vibration than the orbit toward the end of the vibration in the second orbit.

[0063] The trajectory of the saw blade 1 is not limited to the trajectory shown in FIGS. 9 and 10 . For example, the second trajectory may be located further rearward or forward than the trajectories shown in FIGS. 9 and 10 . This can be achieved, for example, by changing the radius of curvature R2 of the arcs AB and CD. Furthermore, the saw blade 1 may retract at the end of oscillation based on the second trajectory for each swing of the saw blade 1. This can be achieved, for example, by dividing the pitch curve of the groove cam 23b into eight arcs, and arranging the arcs corresponding to the first groove and the arcs corresponding to the second groove alternately. This can also be achieved by setting the rotational speeds of the first shaft portion 22 and the second shaft portion 23 to be the same.

[0064] (Advantages of the Oscillating Saw 100) With the above configuration, the orbit of the saw blade 1 has a second orbit that retracts the tooth tips at the end of the vibration. This allows the tooth tips of the saw blade 1 to cut and discharge the continuous chips that are generated at the end of the groove during the cutting operation of cutting the cutting object to form a groove. This prevents an increase in the impact force that occurs when the outer teeth of the saw blade 1 come into contact with the end face of the groove.

[0065] Furthermore, the trajectory toward the center of vibration in the second trajectory does not fall between the virtual line of the first trajectory and the trajectory toward the end of vibration in the second trajectory. As a result, the tooth tip of the saw blade 1 does not cut the workpiece in the trajectory toward the center of vibration in the second trajectory, thereby reducing cutting resistance. In particular, when the tooth tip of the saw blade 1 has a positive rake face and a negative rake face, after cutting the workpiece with the positive rake face in the first trajectory, the workpiece is not cut with the negative rake face in the trajectory toward the center of vibration in the second trajectory. As a result, cutting resistance can be reduced.

[0066] The saw blade 1 has a circular arc-shaped first orbit that overlaps during the reciprocating vibration. As a result, by providing the saw blade 1 with first teeth 12A and second teeth 12B that have inward-facing tooth tips 12a and are located on the left side (one side of the swing) and the right side (the other side of the swing), respectively, the surface of the object to be cut OB can be efficiently cut during the reciprocating vibration.

[0067] (Modification) Reference numeral 1101 in Fig. 11 is a diagram showing the shape of the distal end of the saw blade 1 that can be used in combination with the drive head transmission unit 2A having the grooved cam 23b shown in Fig. 8. Reference numeral 1102 in Fig. 11 is a diagram showing how the saw blade 1 shown in Fig. 11 is oscillated along an arc-shaped trajectory to cut the object OB. Figures 12 and 13 are diagrams showing how the saw blade 1 shown in Fig. 11 by reference numeral 1101 is oscillated along the trajectories of the saw blade 1 shown in Figs. 9 and 10 to cut the object OB, respectively.

[0068] As shown by reference numeral 1101 in FIG. 11 , the leftmost tooth 12A-1 of the first teeth 12A and the rightmost tooth 12B-1 of the second teeth 12B may each have two opposing tooth tips (an inward tooth tip 12a and an outward tooth tip 12b). The leftmost tooth 12A-1 and the rightmost tooth 12B-1 have substantially the same vibration radius (the distance from the tooth tip to the axis C3 of the third shaft portion 24). The other teeth only have inward tooth tips 12a. A line tangent to the inward tooth tips 12a of the multiple teeth 12 is perpendicular to the center line of the saw blade 1.

[0069] As shown by reference numeral 1102 in Fig. 11, when the saw blade 1 shown by reference numeral 1101 in Fig. 11 is oscillated along a path having only the first path (a circular path), the oscillation radius of the outer tooth tips is larger than that of the inner tooth tips, so that the outer tooth tips form stop grooves (stepped corners) near the maximum oscillation angle. When the tooth tips of the saw blade 1 contact the stop grooves, high impact resistance is generated.

[0070] On the other hand, as shown in Fig. 12, when the saw blade 1 indicated by reference numeral 1101 in Fig. 11 is vibrated along the path of the saw blade 1 shown in Fig. 9, the tooth tips recede at the end of the vibration. Therefore, the path of the tooth tips intersects with the path of the adjacent tooth tips in the swing direction. Therefore, the outer tooth tips do not form the stop grooves. Therefore, the generation of impact resistance can be suppressed.

[0071] Furthermore, as shown in Fig. 13, when the saw blade 1 indicated by reference numeral 1101 in Fig. 11 is vibrated along the path of the saw blade 1 shown in Fig. 10, the tooth tips continue to retract even when they reach the maximum vibration angle position. As a result, not only do the outer tooth tips not form the stop grooves, but the negative rake face can be prevented from contacting the work surface of the object OB. This reduces the pressing force of the negative rake face of the saw blade 1.

[0072] Figure 14 is a diagram showing another example of the shape of the distal end of the saw blade 1 that can be used in combination with the drive head transmission unit 2A having the grooved cam 23b shown in Figure 8. As shown in Figure 14, all of the first teeth 12A and all of the second teeth 12B may each have two opposing tooth tips.

[0073] [Reference Form 2] Prior to describing the vibration saw 200 according to embodiment 2, a vibration saw 200s according to reference form 2 will be described. For ease of explanation, components having the same functions as those described in the reference form will be denoted by the same reference numerals in the following embodiments, and their descriptions will not be repeated.

[0074] FIG. 15 is a diagram showing how the vibration saw 200s cuts the object OB. Reference numerals 15001 and 15002 in FIG. 15 respectively show how the positive and negative rake faces of the teeth 12 of the saw blade 1 of the vibration saw 200s cut the object OB. As shown by reference numeral 15001 in FIG. 15, when the positive rake face cuts into the machined surface of the object OB, chips are generated and the cutting resistance is small. On the other hand, as shown by reference numeral 15002 in FIG. 15, when the negative rake face cuts into the machined surface of the object OB, the negative rake face presses down on the machined surface, making it difficult to generate chips and resulting in a large cutting resistance. This not only reduces cutting efficiency but also increases the force required during cutting.

[0075] Furthermore, when the oscillating saw is used to cut bones in a surgical operation, such an increase in cutting resistance can adversely affect the sensation in the surgeon's hands and increase fatigue in the surgeon's hands.

[0076] Fig. 16 is a diagram showing the trajectory of the saw blade 1 in the vibration saw 200s. As shown in Fig. 16, the saw blade 1 moves along an arc-shaped trajectory by swinging about an axis position located rearward of the tooth tip. In this case, if the positive rake face cuts the object OB on the forward path, the negative rake face comes into contact with the object OB on the return path. This causes an increase in cutting resistance.

[0077] [Embodiment 2] Another embodiment of the present invention will be described below. For ease of explanation, the same reference numerals will be used to designate components having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

[0078] (Regarding the characteristics of one aspect of the present invention) The inventors have discovered that the increase in cutting resistance described above can be suppressed by using a vibration saw 200 having the characteristics described below instead of the vibration saw 200s of reference form 2.

[0079] Specifically, the inventors propose an oscillating saw 200 in which the saw blade 1 moves along a circular (e.g., elliptical) path. According to the oscillating saw 200, the teeth 12 of the saw blade 1 contact the object to be cut OB when the positive rake face is on the side of the swing direction of the saw blade 1, and move away from the object to be cut OB when the negative rake face is on the side of the swing direction of the saw blade 1. This reduces the cutting resistance during cutting compared to the oscillating saw 200s according to the reference embodiment.

[0080] Fig. 17 is a diagram showing the trajectory of the saw blade 1 in the oscillating saw 200. As shown in Fig. 17, the saw blade 1 has at least one or more first teeth 12A arranged on the left side of the front end (one side of the swing) and at least one or more second teeth 12B arranged on the right side of the front end (the other side of the swing).

[0081] 17, the tips of the first tooth 12A and the second tooth 12B face outward, i.e., the positive rake face is formed on the left side of the first tooth 12A, and the positive rake face is formed on the right side of the second tooth 12B.

[0082] The saw blade 1 moves along a circular path by swinging around an axis located rearward of the tooth tips. Specifically, the path of the first tooth 12A in the leftward direction (first swing direction) is located forward of the path of the first tooth 12A in the rightward direction (second swing direction). The path of the second tooth 12B in the leftward direction (first swing direction) is located rearward of the path of the second tooth 12B in the rightward direction (second swing direction). The path of the first tooth 12A in the leftward direction and the path of the second tooth 12B in the leftward direction are trajectories at the same time. The path of the first tooth 12A in the rightward direction and the path of the second tooth 12B in the rightward direction are trajectories at the same time. In other words, the first tooth 12A moves along a clockwise circular path, and the second tooth 12B moves along a counterclockwise circular path.

[0083] By moving the saw blade 1 in a circular orbit, when the saw blade 1 moves leftward, the first teeth 12A are moved away from the object to be cut OB, preventing the negative rake face from contacting the object to be cut OB. Furthermore, when the saw blade 1 moves rightward, the first teeth 12A are caused to cut into the object to be cut OB, allowing the positive rake face to perform cutting. At the same time, when the saw blade 1 moves leftward, the second teeth 12B are caused to cut into the object to be cut OB, allowing the positive rake face to perform cutting. Furthermore, when the saw blade 1 moves rightward, the second teeth 12B are moved away from the object to be cut OB, preventing the negative rake face from contacting the object to be cut OB. Therefore, an increase in cutting resistance due to the negative rake faces of the first teeth 12A and the second teeth 12B contacting the object to be cut OB can be suppressed, and the object to be cut OB can be efficiently cut by the two types of teeth, the first teeth 12A and the second teeth 12B.

[0084] A specific configuration for realizing such an oscillating saw 200 will be described below.

[0085] 18 is a perspective view showing the overall configuration of the vibration saw 200. As shown in FIG. 18, the vibration saw 200 includes a saw blade 1, a drive unit 202, a handle unit 3, and a battery unit 4.

[0086] The driving device 202 is a device for vibrating the saw blade 1 so that it swings around an axis located rearward of the tooth tip. A drive head transmission unit 202A is provided at the front of the driving device 202, which drives the saw blade 1 to move along a circular track. A motor 2B is provided at the rear of the driving device 202, which drives the drive head transmission unit 202A. The housing 20 of the driving device 202 has a drive head 220A that houses the drive head transmission unit 202A and a motor housing 20B that houses the motor 2B.

[0087] (Detailed configuration of drive unit 202) Fig. 19 is an exploded perspective view of a portion of the configuration of drive unit 202. Fig. 19 shows the drive unit 202 with the drive head 220A removed. Fig. 20 is a vertical cross-sectional view of drive unit 202. Note that Figs. 19 and 20 omit illustration of motor 2B and motor housing 20B provided at the rear of drive unit 202.

[0088] As shown in Figures 19 and 20, the drive head transmission unit 202A includes a drive shaft 21, a rotating shaft 222, a first vibration shaft 223, a second vibration shaft 224, a first vibration shank 225 (first vibration member), and a second vibration shank 226 (second vibration member).

[0089] The rotation shaft 222, the first vibration shaft 223, and the second vibration shaft 224 have shafts that extend in the up-down direction. The rotation shaft 222, the first vibration shaft 223, and the second vibration shaft 224 are arranged in this order from the rear side along the front-rear direction.

[0090] The rotating shaft 222 has a bevel gear 22a, a first eccentric ring 222b, and a second eccentric ring 222c. The bevel gear 22a is provided at the lower end of the rotating shaft 222 and meshes with the bevel gear 21a of the drive shaft 21. As a result, rotation of the drive shaft 21 around its longitudinal axis is transmitted to the rotating shaft 222 as rotation of the rotating shaft 222 around its vertical axis. The first eccentric ring 222b and the second eccentric ring 222c are provided above the bevel gear 21a and are provided on the shaft of the rotating shaft 222 in this order from the top. The first eccentric ring 222b and the second eccentric ring 222c have diameters larger than the shaft of the rotating shaft 222 and have axes that are offset from the axis C21 of the rotating shaft 222. The first eccentric wheel 222b and the second eccentric wheel 222c are fixed to the rotary shaft 222 and are driven to rotate in accordance with the rotation of the drive shaft 21, similar to the rotary shaft 222.

[0091] The first vibration shaft 223 has a first base portion 223a (first vibration member). The first base portion 223a is a flat plate member that is provided at the upper end of the first vibration shaft 223 and extends forward of the shaft of the second vibration shaft 224. A through-hole 223aa for passing the second vibration shaft 224 is formed in the front portion of the first base portion 223a.

[0092] The second vibration shaft 224 has a second base portion 224a. The second base portion 224a is provided at the upper end of the second vibration shaft 224. The saw blade 1 is fixed (for example, by bolting) to an upper portion of the second base portion 224a.

[0093] The first vibrating shank 225 and the second vibrating shank 226 are flat plate members extending in the front-rear direction. The first vibrating shank 225 is disposed above the second vibrating shank 226. The first vibrating shank 225 is fixed to the first vibrating shaft 223 (e.g., via a shaft retaining ring 229). The second vibrating shank 226 is fixed to the second vibrating shaft 224 (e.g., via a shaft retaining ring 229).

[0094] The drive head transmission unit 202A further includes eight bearings 227a to 227h (first bearing 227a, second bearing 227b, third bearing 227c, fourth bearing 227d, fifth bearing 227e, sixth bearing 227f, seventh bearing 227g, and eighth bearing 227h). The drive head transmission unit 202A may further include a bearing cover 228. The drive head 220A also includes an upper cover 220Aa and a lower cover 220Ab.

[0095] The first bearing 227a and the second bearing 227b rotatably support the rotating shaft 222 relative to the upper cover 220Aa. The third bearing 227c and the fourth bearing 227d rotatably support the first vibration shaft 223 relative to the upper cover 220Aa. The fifth bearing 227e and the sixth bearing 227f rotatably support the second vibration shaft 224 relative to the first base portion 223a and the first vibration shank 225 (i.e., the first vibrating member), respectively. The seventh bearing 227g rotatably supports the first eccentric ring 222b relative to the first vibration shank 225. The eighth bearing 227h rotatably supports the second eccentric ring 222c relative to the second vibration shank 226.

[0096] The bearing cover 228 is provided on the upper part of the first bearing 227a to prevent the first bearing 227a from being displaced in the axial direction. The lower cover 220Ab is used to protect the mounting space of the drive head transmission part 202A.

[0097] 21 is an exploded perspective view (reference numeral 21001), a side view (reference numeral 21002), and a cross-sectional view (reference numeral 21003) taken along the line A-A at reference numeral 21002, which explain the relationship between the rotating shaft 222 and the first vibrating shaft 223. For simplicity, FIG. 21 only illustrates the rotating shaft 222, the first vibrating shaft 223, the second vibrating shaft 224, and the first vibrating shank 225 of the drive head transmission unit 202A, and further illustrates a state in which the second vibrating shaft 224 has been removed.

[0098] As shown in FIG. 21 , the first vibration shank 225 has a slot 225a and a through hole 225b. The slot 225a is formed to extend forward from the rear end of the first vibration shank 225. The first eccentric wheel 222b of the rotation shaft 222 is disposed in the slot 225a. The through hole 225b is formed in the front portion of the first vibration shank 225. The second vibration shaft 224 passes through the through hole 225b. The first vibration shaft 223 is fixed to the center of the first vibration shank 225 in the front-rear direction. For example, as shown by reference numeral 21003 in FIG. 21 , the first vibration shank 225 may have a rectangular hole disposed in the center in the front-rear direction, and the first vibration shaft 223 may have a fitting portion having a cross-sectional shape that fits into the rectangular hole.

[0099] The seventh bearing 227g rotatably supports the first eccentric ring 222b within the slot 225a. Specifically, the outer peripheral surface of the seventh bearing 227g attached to the first eccentric ring 222b contacts a pair of surfaces extending in the front-rear direction of the slot 225a. When the rotating shaft 222 rotates around its axis, the first eccentric ring 222b rotates around an axis that is offset from the axis of the first eccentric ring 222b. Therefore, the first eccentric ring 222b vibrates the first vibrating shank 225 so that it swings around the first vibrating shaft 223. The first vibrating shaft 223 rotates in accordance with the swing of the first vibrating shank 225.

[0100] The second vibration shaft 224 passes through the through hole 223aa of the first base portion 223a and the through hole 225b of the first vibration shank 225. The fifth bearing 227e and the sixth bearing 227f rotatably support the second vibration shaft 224 inside the through hole 223aa and the through hole 225b, respectively.

[0101] As described above, the rotation of the rotary shaft 222 around its axis drives the first vibration shaft 223 to oscillate, and in turn vibrates the second vibration shaft 224 so as to swing around the axis C22 of the first vibration shaft 223.

[0102] 22 is an exploded perspective view (reference numeral 22001), a side view (reference numeral 22002), and a cross-sectional view (reference numeral 22003) taken along the line B-B of reference numeral 22002, which explain the relationship between the rotating shaft 222 and the second vibrating shaft 224. For simplicity, only the rotating shaft 222, the second vibrating shaft 224, and the second vibrating shank 226 of the drive head transmission unit 202A are shown in FIG.

[0103] As shown in FIG. 22 , the second vibration shank 226 has a slot 226a and a through hole 226b. The slot 226a is formed to extend forward from the rear end of the second vibration shank 226. The second eccentric wheel 222c of the rotation shaft 222 is disposed in the slot 226a. The through hole 226b is formed in the center of the second vibration shank 226 in the front-rear direction. The first vibration shaft 223 passes through the through hole 226b. A second vibration shaft 224 is fixed to the front of the second vibration shank 226. For example, as shown by reference numeral 21003 in FIG. 22 , the second vibration shank 226 may have a D-shaped hole in its front portion, and the second vibration shaft 224 may have a fitting portion having a cross-sectional shape that fits into the D-shaped hole.

[0104] The eighth bearing 227h rotatably supports the second eccentric ring 222c within the slot 226a. Specifically, the outer peripheral surface of the eighth bearing 227h attached to the second eccentric ring 222c contacts a pair of surfaces extending in the front-rear direction of the slot 226a. When the rotating shaft 222 rotates around its axis, the second eccentric ring 222c rotates around an axis that is offset from the axis of the second eccentric ring 222c. Therefore, the second eccentric ring 222c vibrates the second vibration shank 226 so that it swings around the second vibration shaft 224. The second vibration shaft 224 rotates in accordance with the swing of the second vibration shank 226.

[0105] As described above, the rotation of the rotation shaft 222 about its axis not only drives and oscillates the first oscillation shaft 223, but also drives and oscillates the second oscillation shaft 224. Therefore, the rotation of the rotation shaft 222 about its axis vibrates the second oscillation shaft 224 so as to swing about the axis C22 of the first oscillation shaft 223, and at the same time vibrates the saw blade 1 fixed to the second oscillation shaft 224 so as to swing about the axis C23 of the second oscillation shaft 224.

[0106] Furthermore, the through hole 226b of the second vibration shank 226 is large enough so that the first vibration shaft 223 does not come into contact with the inner circumferential surface of the through hole 226b and inhibit the swing of the second vibration shank 226.

[0107] (Trajectory of saw blade 1 in oscillating saw 200) Figure 23 is a schematic diagram showing the trajectory of the axis C23 of the second oscillating shaft 224 in the oscillating saw 200. Figure 24 is a schematic diagram showing the trajectory of the saw blade 1 in the oscillating saw 200. The principle by which the circular trajectory of the saw blade 1 can be achieved by the oscillating saw 200 equipped with the drive head transmission unit 202A described above will be described below.

[0108] 23 , rotation of the first eccentric wheel 222b causes the first vibration shank 225 to vibrate so as to swing around the axis C22 of the first vibration shaft 223. Therefore, the axis C23 of the second vibration shaft 224 fixed to the first vibration shank 225 follows an arc-shaped path. The vibration angle θ1 of the first vibration shaft 223 is the rotation angle of the first vibration shank 225 with respect to a line passing through the axis C21 of the rotation shaft 222 and the axis C22 of the first vibration shaft 223.

[0109] Furthermore, due to the rotation of the second eccentric wheel 222c, the second vibration shank 226 vibrates so as to swing around the axis C23 of the second vibration shaft 224. The vibration angle θ2 of the second vibration shaft 224 is the rotation angle of the second vibration shank 226 with respect to a line passing through the axis C22 of the first vibration shaft 223 and the axis C23 of the second vibration shaft 224.

[0110] The vibration angle θ3 of the saw blade 1 fixed to the second vibration shank 226 is the difference between the vibration angle θ1 of the first vibration shaft 223 and the vibration angle θ2 of the second vibration shaft 224.

[0111] 24, a solid line extending forward relative to the axis C23 of the second vibration shaft 224 indicates the position of the saw blade 1 of the vibration saw 200 equipped with the drive head transmission unit 202A. Furthermore, a dashed line extending forward relative to the axis C23 of the second vibration shaft 224 indicates the position of the saw blade 1 of the vibration saw 200s according to Reference Form 2. Hereinafter, for ease of explanation, "'" will be added to the reference numerals of the components of the vibration saw 200s to distinguish them from the components of the vibration saw 200.

[0112] In the oscillating saw 200s, the saw blade 1' oscillates so as to swing about an axis (corresponding to the axis C22 of the first oscillation shaft 223 in FIG. 24) that is stationary relative to the housing. That is, in FIG. 24, θ1 = θ3. Therefore, the trajectory of the saw blade 1' is an arc.

[0113] On the other hand, in the oscillating saw 200, the saw blade 1 is offset from the saw blade 1' by the oscillation angle θ2 of the second oscillation shaft 224. Therefore, the orbit of the saw blade 1 is circular (particularly elliptical). As shown in FIG. 24 , when θ2 > 0, the first teeth 12A are positioned rearward relative to the first teeth 12A', and the second teeth 12B are positioned forward relative to the second teeth 12B'. On the other hand, when the saw blade 1 swings in the opposite direction from the state shown in FIG. 24 around the axis C22 of the first oscillation shaft 223, θ2 < 0. At this time, the first teeth 12A are positioned forward relative to the first teeth 12A', and the second teeth 12B are positioned rearward relative to the second teeth 12B'. In other words, one of the first teeth 12A and the second teeth 12B moves clockwise along the elliptical orbit, and the other of the first teeth 12A and the second teeth 12B moves counterclockwise along the elliptical orbit.

[0114] Fig. 25 is a conceptual diagram showing the relative eccentric angle between the first eccentric ring 222b and the second eccentric ring 222c. Fig. 26 is a diagram showing the trajectory of the saw blade 1 relative to the relative eccentric angle. The relative eccentric angle is an angle indicating the phase difference between the first eccentric ring 222b and the second eccentric ring 222c.

[0115] 25 and 26, when the relative eccentric angle is zero, the orbit of the saw blade 1 is an arc, and when the relative eccentric angle is greater than zero, the orbit of the saw blade 1 is elliptical. As the relative eccentric angle increases, the minor axis of the elliptical orbit increases and the major axis (i.e., the range of the vibration angle θ3 of the saw blade 1) decreases.

[0116] The larger the minor axis of the elliptical orbit, the farther the negative rake face is from the machining surface, making it easier to remove chips. On the other hand, the larger the major axis of the elliptical orbit, the wider the cutting range of the oscillating saw 200. Therefore, by appropriately setting the relative eccentricity angle, it is possible to provide an oscillating saw 200 that meets specific needs.

[0117] FIG. 27 is a diagram showing an example of the trajectory of the saw blade 1 in the oscillating saw 200. FIG. 28 is a diagram showing another example of the trajectory of the saw blade 1 in the oscillating saw 200. As shown in FIG. 27 , the positive rake face of the first tooth 12A is on the left side of the first tooth 12A (one side of the swing), and the positive rake face of the second tooth 12B is on the right side of the second tooth 12B (the other side of the swing). That is, the tips of the first tooth 12A and the second tooth 12B are formed to face outward. Alternatively, as shown in FIG. 28 , the positive rake face of the first tooth 12A is on the right side of the first tooth 12A (the other side of the swing), and the positive rake face of the second tooth 12B is on the left side of the second tooth 12B (one side of the swing). That is, the tips of the first tooth 12A and the second tooth 12B are formed to face inward.

[0118] As shown in FIG. 27 , when the tips of the first tooth 12A and the second tooth 12B are formed so that they face outward, the first tooth 12A can be moved along a clockwise elliptical orbit, and the second tooth 12B can be moved along a counterclockwise elliptical orbit. Also, as shown in FIG. 28 , when the tips of the first tooth 12A and the second tooth 12B are formed so that they face inward, the first tooth 12A can be moved along a counterclockwise elliptical orbit, and the second tooth 12B can be moved along a clockwise elliptical orbit. This allows the first tooth 12A and the second tooth 12B to cut the workpiece OB using only the positive rake face, preventing the negative rake face from contacting the workpiece OB. Therefore, an increase in cutting resistance due to contact of the negative rake face of the first tooth 12A and the second tooth 12B with the workpiece OB can be suppressed. Furthermore, by changing the trajectories of the first and second teeth between the forward and backward paths, chips generated during cutting can be appropriately discharged.

[0119] [Embodiment 3] Another embodiment of the present invention will be described below. For ease of explanation, the same reference numerals will be used to designate components having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

[0120] 29 is a perspective view showing the overall configuration of an oscillation saw 300 according to embodiment 3. The oscillation saw 300 differs from the oscillation saw 200 according to embodiment 2 in that it includes a drive unit 302 in which two rotation shafts are driven by two motors, respectively.

[0121] 29 , the drive device 302 includes a drive unit 320 that drives the saw blade 1 to move along the circular track, and a support unit 340 that supports the drive unit 320. The drive unit 320 includes a first motor 321 (relative eccentricity angle adjuster), a second motor 322 (relative eccentricity angle adjuster), a first rotation shaft 323, a second rotation shaft 324, a first vibration shaft 223, a second vibration shaft 224, a first vibration shank 225, and a second vibration shank 226. The support unit 340 includes a first shaft holder 341, a second shaft holder 342, a motor holder 343, and a base 344. In this embodiment only, the extension direction of the first rotation shaft 323 is defined as the left-right direction, and the side of the first rotation shaft 323 on which the first motor 321 is located is defined as the right side.

[0122] FIG. 30 is an exploded perspective view showing the configuration of the support unit 340 in the drive unit 302. As shown in FIG. 30 , the first shaft holder 341, the second shaft holder 342, and the motor holder 343 are fixed to a base 344. The first shaft holder 341 and the second shaft holder 342 have mounting holes for mounting the first rotating shaft 323, the second rotating shaft 324, and the first vibrating shaft 223 via bearings 305, respectively. The support unit 340 further has a bearing cover 345 on the left side of the first shaft holder 341 to limit axial movement of the bearing 305. The left sides of the first rotating shaft 323 and the second rotating shaft 324 are fixed to the first shaft holder 341 by lock nuts 306. The motor holder 343 secures the first motor 321 and the second motor 322.

[0123] Figure 31 is an exploded perspective view showing the configuration of the drive unit 320 in the drive device 302. As shown in Figure 31, the first vibration shaft 223 is fixed to the first vibration shank 225 at its center in the left-right direction, and both ends are fixed to the vibration shaft holder 307 with lock nuts 306. The second vibration shaft 224 is fixed to the second vibration shank 226 at its center in the extension direction, and both ends are fitted into mounting holes in the vibration shaft holder 307 via bearings 305.

[0124] The first motor 321 and the second motor 322 are respectively coupled to a first rotating shaft 323 and a second rotating shaft 324 by a coupling 308. The first rotating shaft 323 has a first eccentric ring 222b in its left-right center that is fixed to a first vibrating shank 225 via a bearing 305. The second rotating shaft 324 has a second eccentric ring 222c in its left-right center (more specifically, to the left of the first eccentric ring 222b) that is fixed to a second vibrating shank 226 via a bearing 305.

[0125] According to the oscillating saw 300, by driving two motors (first motor 321 and second motor 322), the saw blade 1 can be moved along an elliptical orbit, similar to the oscillating saw 200. Furthermore, by controlling the relative rotation angle of the two motors, the magnitude of the relative eccentric angle of the two eccentric wheels (first eccentric wheel 222b and second eccentric wheel 222c) can be controlled. Therefore, the range of the oscillation angle θ3 of the saw blade 1 can be adjusted (see FIG. 26 ). In other words, the shape of the elliptical orbit of the saw blade 1 can be changed as shown in FIG. 26 .

[0126] [Embodiment 4] Another embodiment of the present invention will be described below. For ease of explanation, the same reference numerals will be used to designate components having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

[0127] In this embodiment, an oscillating saw suitable for narrow deep groove cutting and narrow elongated groove cutting will be described. The oscillating saw suitable for narrow deep groove cutting is oscillating saws 200 and 300 having the above-described saw blade 1. The oscillating saw suitable for narrow elongated groove cutting is oscillating saw 400, which differs from oscillating saws 200 and 300 in that it has saw blade 401 instead of saw blade 1.

[0128] FIG. 32 is a diagram showing how a narrow, deep groove is machined by a saw blade 1. Note that FIG. 32 shows only the trajectories of one of the first teeth 12A and one of the second teeth 12B. As shown in FIG. 32, when the feed direction of the saw blade 1 is perpendicular to the vibration direction of the saw blade 1, the vibration saws 200, 300 machine deep grooves. In this case, to prevent the negative rake face of the saw blade 1 from contacting the end face of the narrow, deep groove and generating large cutting resistance, the trajectory of the saw blade 1 and the direction of the teeth of the saw blade 1 must have the relationship shown in FIG. 27.

[0129] FIG. 33 shows a front view (reference numeral 33001) of a saw blade 1 for narrow, deep groove machining, a partial rear view (reference numeral 33002) of the distal end of the saw blade 1, and a partial perspective view (reference numeral 33003) of the distal end of the saw blade 1. As shown in FIG. 33 , the tips of the first teeth 12A face left, and the tips of the second teeth 12B face right. The saw blade 1 may further include discharge grooves 13 for discharging chips generated during cutting. The discharge grooves 13 extend from recesses between the teeth 12 toward the blade body 11 on either the first main surface or the second main surface opposite the first main surface of the saw blade 1. The discharge grooves 13 on the first main surface and the discharge grooves 13 on the second main surface are alternately formed in the recesses between the teeth 12.

[0130] FIG. 34 illustrates narrow groove machining using a saw blade 401. As shown in FIG. 34 , when the feed direction of the saw blade 401 is parallel to the vibration direction of the saw blade 401, the vibration saw 400 performs narrow groove machining. The saw blade 401 has fine abrasive grains 121 on the left side and coarse abrasive grains 122 on the right side. By using the saw blade 401 so that the coarse abrasive grains 122 are positioned in the feed direction of the saw blade 401, rough machining and finish machining can be performed in a single groove machining operation. In rough machining, the second teeth 12D, on which the coarse abrasive grains 122 are formed, are primarily used to groove the workpiece OB. In finish machining, the first teeth 12C, on which the fine abrasive grains 121 are primarily formed on the side surfaces, are used to finish the walls of the groove after cutting. In narrow groove machining using the saw blade 401, moving the saw blade 401 along a circular orbit achieves the following effects. That is, by changing the trajectory of the second tooth 12D between the forward path and the backward path, chips generated during cutting can be appropriately discharged.

[0131] 35 shows a perspective view (reference numeral 35001) of a saw blade 401 for narrow groove cutting, a cross-sectional view (reference numeral 35002) of the second tooth 12D of the saw blade 401, and a cross-sectional view (reference numeral 35003) of the first tooth 12C of the saw blade 401. Like the saw blade 1, the saw blade 401 is fixed to a driving device at its proximal end and has the second tooth 12D for rough cutting and the first tooth 12C for finish cutting at its distal end. The saw blade 401 for narrow groove cutting does not need to penetrate deeply into the grooves of the cutting surface. Therefore, the blade body 11 of the saw blade 401 may be formed thicker than the blade body 11 of the saw blade 1 to increase blade rigidity.

[0132] The second teeth 12D are coarser than the first teeth 12C. Specifically, coarse abrasive grains 122 are formed on the end faces of the second teeth 12D. Fine abrasive grains 121 are formed on the end faces and side surfaces of the first teeth 12C. The first teeth 12C and the second teeth 12D are, for example, very thin grindstones such as dicing blades. The first teeth 12C and the second teeth 12D have, for example, arc-shaped end faces. A large number of very small abrasive grains are distributed on the end faces.

[0133] The second teeth 12D for rough machining have coarse abrasive grains, and no abrasive grains protrude from the sides of the second teeth 12D. This allows for faster groove machining. Furthermore, because groove walls machined with coarse abrasive grains may develop microcracks, it is preferable to perform finish machining.

[0134] The first teeth 12C for finishing have fine abrasive grains, and the abrasive grains protrude from the side surfaces of the first teeth 12C, which can reduce microcracks on the groove wall surface, resulting in excellent machining results.

[0135] [Embodiment 5] Another embodiment of the present invention will be described below. For the sake of convenience, the same reference numerals will be used to designate components having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

[0136] (Regarding the characteristics of one aspect of the present invention) The inventors further discovered that the increase in cutting resistance described above can be suppressed by using a vibration saw 500 having the characteristics described below instead of the vibration saw 200s of reference form 2.

[0137] Specifically, the inventors propose an oscillating saw 500 in which a saw blade 501 is provided with an elastic hinge portion 14 that elastically deforms during cutting, displacing the teeth 12 in the forward and backward directions. When force is applied to the negative rake face of the oscillating saw 500, the teeth 12 rotate so that the negative rake face moves away from the workpiece surface, reducing the cutting depth of the negative rake face. This reduces cutting resistance during cutting.

[0138] FIG. 36 is a diagram showing how the oscillating saw 500 cuts the object OB. Reference numerals 36001 and 36002 in FIG. 36 respectively indicate how the positive rake face and negative rake face of the tooth 12 of the saw blade 501 cut the object OB. As shown in FIG. 36 , the saw blade 501 includes, in addition to the blade body 11 and a plurality of teeth 12, elastic hinge portions 14 that connect each of the plurality of teeth 12 to the blade body 11. The elastic hinge portions 14 elastically deform during cutting, displacing the plurality of teeth 12 in the forward and backward directions. For simplicity, FIG. 36 shows only one tooth 12 and one corresponding elastic hinge portion 14.

[0139] As shown by reference numeral 36002 in Figure 36, when the negative rake face comes into contact with the object to be cut OB, a force is applied to the negative rake face. At this time, the elastic hinge portion 14 is slightly elastically deformed, and the teeth 12 rotate so that the negative rake face moves away from the machining surface. This reduces the cutting depth of the negative rake face. Therefore, cutting resistance can be reduced.

[0140] On the other hand, as shown by reference numeral 36001 in FIG. 36 , when the positive rake face cuts into the work surface of the workpiece OB, a force is applied to the positive rake face. At this time, the elastic hinge portion 14 is slightly elastically deformed, and the multiple teeth 12 rotate so that the positive rake face cuts deeper into the work surface. As a result, the cutting depth of the positive rake face increases on the forward pass, and the cutting depth of the negative rake face decreases further on the return pass. Therefore, cutting resistance can be further reduced. In addition, since the cutting depth of the negative rake face can be reduced without reducing the cutting depth of the positive rake face, cutting efficiency is not reduced.

[0141] Several example configurations of such saw blades 501 are described below.

[0142] (Configuration Example of Saw Blade 501) Figure 37 is a plan view showing an example of the configuration of saw blade 501. Figure 38 is an enlarged plan view of the distal end of saw blade 501.

[0143] 37 and 38, saw blade 501 has blade body 11, a plurality of teeth 12 disposed at the distal end (front end), and the above-mentioned elastic hinge portion 14. The plurality of teeth 12 have inward-facing tooth tips 12a and extension portions 12c that connect to elastic hinge portion 14 and extend forward to tooth tips 12a.

[0144] Here, the width d1 of the elastic hinge portion 14 is preferably smaller than the width d2 of the extension portion 12c. This allows the elastic hinge portion 14 to elastically deform more easily than at least the blade body 11 and the plurality of teeth 12 when a predetermined force is applied to the saw blade 501. Furthermore, because the plurality of teeth 12 are provided at the front ends of the extension portions 12c extending in the front-rear direction, the amount of front-rear displacement of the tooth tips 12a of the plurality of teeth 12 is even greater. Note that the elastic hinge portion 14 only needs to be able to elastically deform at least during cutting to displace the plurality of teeth 12 in the front-rear direction (relative to the blade body 11); for example, d1 = d2 may be satisfied. Alternatively, multiple elastic hinge portions 14 may be provided between the blade body 11 and the extension portion 12c. Furthermore, the width d2 of the extension portion 12c may be variable (by elastic deformation).

[0145] Furthermore, the direction in which the width of the elastic hinge portion 14 is smallest in a plane perpendicular to the thickness direction of the saw blade 501 intersects the vibration direction (left-right direction). Specifically, the side surface of the extension portion 12c on the positive rake face side is longer in the extension direction of the extension portion 12c than the side surface of the extension portion 12c on the negative rake face side. With this configuration, the amount of rearward displacement of the tip 12a when force is applied to the negative rake face is increased, thereby further reducing the cutting depth of the negative rake face.

[0146] 39 is an enlarged plan view of one tooth 12 and one corresponding elastic hinge portion 14 of saw blade 501. As shown in FIG. 39 , blade body 11 may include deformation limiting portions adjacent to each of teeth 12, which limit the range of displacement of teeth 12 due to elastic deformation. With this configuration, the deformation limiting portions can prevent damage to teeth 12 due to excessive elastic deformation of elastic hinge portion 14.

[0147] In the example shown in Figure 39, the deformation limiting portion is a side wall 11a that faces the rear of the side surface of the extension portion 12c. A slit-like gap is formed between the side wall 11a and the side surface of the extension portion 12c. The width of the gap determines the range of rotation of the multiple teeth 12, i.e., the amount of displacement of the tooth tips 12a in the front-to-rear direction. The side wall 11a may also be thicker (in the vertical direction) than the extension portion 12c. This prevents the multiple teeth 12 from climbing up or down the side wall 11a due to elastic deformation of the elastic hinge portion 14.

[0148] In addition, notches 15 are formed on both sides of the elastic hinge portion 14. In other words, a pair of notches 15 are formed in the blade body portion 11, and the elastic hinge portion 14 is provided between the pair of notches 15. The width of the notches is greater than the width of the slit-shaped gap. This achieves an elastic hinge portion 14 that is narrower than the extension portion 12c. The notches 15 may be circular. By making the notches 15 circular, the possibility of cracks occurring from the notches 15 due to elastic deformation of the elastic hinge portion 14 can be reduced.

[0149] Figure 40 is a diagram showing the forward / backward displacement of the tooth 12 of the saw blade 501 shown in Figures 37 to 39 due to elastic deformation of the elastic hinge portion 14. Reference numerals 40001 and 40002 in Figure 40 respectively indicate the forward / backward displacement of the tooth 12 when cutting resistance is applied to the negative rake face and the positive rake face of the tooth 12 of the saw blade 501. Note that the solid lines in Figure 40 indicate the position of the tooth 12 and the trajectory of the tooth tip 12a before the cutting resistance is applied, and the dashed lines in Figure 40 indicate the position of the tooth 12 and the trajectory of the tooth tip 12a after the cutting resistance is applied.

[0150] As shown by reference numeral 40001 in Figure 40, when the negative rake face cuts the object to be cut OB, the elastic hinge portion 14 and the extension portion 12c are elastically deformed due to the cutting resistance generated when the negative rake face comes into contact with the object to be cut OB. As a result, the trajectory of the tooth tip 12a moves backward. In other words, the trajectory of the tooth tip 12a moves away from the machined surface of the object to be cut OB. Therefore, the cutting resistance can be reduced.

[0151] As shown by reference numeral 40002 in FIG. 40 , when the positive rake face cuts the object OB, the elastic hinge portion 14 and the extension portion 12c are elastically deformed due to the cutting resistance generated when the positive rake face contacts the object OB. As a result, the trajectory of the tooth tip 12a moves forward. The trajectory of the tooth tip 12a becomes deeper relative to the machining surface. As a result, the cutting depth of the positive rake face increases on the forward pass, and the cutting depth of the negative rake face decreases further on the return pass. Therefore, the cutting resistance can be further reduced.

[0152] Note that the displacement of the tooth tip 12 a in the front-to-rear direction when the cutting object OB is cut by the positive cutting face is smaller than the displacement of the tooth tip 12 a in the front-to-rear direction when the cutting object OB is cut by the negative cutting face. Therefore, the increase in cutting resistance caused by an increase in the cutting depth of the positive cutting face is slight compared to the reduction in cutting resistance caused by a decrease in the cutting depth of the negative cutting face.

[0153] Figure 41 is an enlarged plan view of the distal end of a saw blade, showing another example of the saw blade configuration. As the saw blade provided in the oscillating saw 500, a saw blade 501A shown in Figure 41 may be adopted instead of the saw blade 501 shown in Figures 36 to 38. As shown in Figure 41, saw blade 501A differs from saw blade 501 in that each of the multiple teeth 12 has two opposing tooth tips (tooth tip 12a and tooth tip 12b).

[0154] Figure 42 is an enlarged plan view of one tooth 12 and one corresponding elastic hinge portion 14 of saw blade 501A. As shown in Figure 42, two opposing tooth tips are located on the left and right sides of the front end of tooth 12. The tooth tip located on the left side of the front end of tooth 12 faces left, and the tooth tip located on the right side of the front end of tooth 12 faces right. Each tooth tip has a positive rake face and a negative rake face.

[0155] FIG. 43 is a diagram showing the forward / backward displacement of the teeth 12 of the saw blade 501A shown in FIGS. 41 and 42 due to elastic deformation of the elastic hinge portion 14. As shown in FIG. 43 , when the saw blade 501A vibrates to the right, the positive rake face of the right tooth tip of the two opposing tooth tips cuts the object to be cut OB, and the negative rake face of the left tooth tip of the two opposing tooth tips cuts the object to be cut OB. At this time, the cutting resistance generated when the right tooth tip contacts the object to be cut OB causes the elastic hinge portion 14 and the extension portion 12c to elastically deform. Specifically, the elastic hinge portion 14 and the extension portion 12c elastically deform so that the teeth 12 tilt leftward. As a result, the trajectory of the right tooth tip moves forward, and the trajectory of the left tooth tip moves backward. This reduces the cutting resistance.

[0156] In the saw blade 501A having symmetrical tooth tips, the direction in which the width of the elastic hinge portion 14 is smallest in a plane perpendicular to the thickness direction of the saw blade 501A is preferably along the vibration direction (left-right direction), thereby enabling the cutting resistance to be reduced in the same manner in both reciprocating motions of the saw blade 501A.

[0157] Figure 44 is a diagram showing yet another example of the configuration of a saw blade. As the saw blade provided in the oscillating saw 500, a saw blade 501B shown in Figure 44 may be adopted instead of the saw blade 501 shown in Figures 36 to 38. As shown in Figure 44, saw blade 501B differs from saw blade 501 in that a plurality of teeth 12 are provided on either the left or right end face from the proximal end to the distal end of the blade body 11. In this case, saw blade 501B vibrates in the front-to-rear direction.

[0158] Figure 45 is a diagram showing yet another example of the configuration of a saw blade. As the saw blade provided in the oscillating saw 500, a saw blade 501C shown in Figure 45 may be adopted instead of the saw blade 501 shown in Figures 36 to 38. As shown in Figure 45, saw blade 501C differs from saw blade 501A in that a plurality of teeth 12 are provided on either the left or right end face from the proximal end to the distal end of the blade body 11. In this case, saw blade 501C vibrates in the front-to-rear direction.

[0159] Figure 46 shows yet another example of a saw blade configuration, where reference numeral 46001 in Figure 46 shows a perspective view of saw blade 501D, reference numeral 46002 in Figure 46 shows an enlarged plan view of the distal end of saw blade 501D, and reference numeral 46003 in Figure 46 shows an enlarged plan view of one tooth of saw blade 501D.

[0160] As the saw blade provided in the oscillating saw 500, a saw blade 501D shown in Fig. 46 may be used instead of the saw blade 501 shown in Figs. 36 to 38. As shown in Fig. 46, the saw blade 501D differs from the saw blade 501A in that the blade body 11 is a tubular member. In this case, the saw blade 501D rotates and vibrates around its axis. A rotary vibration handpiece is connected to the proximal end of the blade body 11.

[0161] A plurality of teeth 12 are provided at the distal end of the blade body 11. The extensions 12c of the plurality of teeth 12 extend along the axial direction of the saw blade 501D. By the rotational vibration of the saw blade 501D, the plurality of teeth 12 can form annular grooves in the cutting object OB until a through hole is formed in the cutting object OB.

[0162] Figure 47 shows yet another example of a saw blade configuration, where reference numeral 47001 in Figure 47 shows a perspective view of the saw blade 501E, reference numeral 47002 in Figure 47 shows an enlarged plan view of the distal end of the saw blade 501E, and reference numeral 47003 in Figure 47 shows an enlarged plan view of one tooth of the saw blade 501E.

[0163] As the saw blade provided in the oscillating saw 500, a saw blade 501E shown in Fig. 47 may be adopted instead of the saw blade 501 shown in Fig. 36 to Fig. 38. As shown in Fig. 47, the saw blade 501E differs from the saw blade 501D in that the blade body 11 is a cylindrical member and the extensions 12c of the multiple teeth 12 extend radially outward from the saw blade 501D.

[0164] FIG. 48 is a diagram showing yet another example of the configuration of a saw blade. As shown in FIG. 48 , a saw blade 501F includes a tooth structure 50 that is separate from the blade body 11 and has a plurality of teeth 12 and an elastic hinge portion 14. The blade body 11 also has a fitting groove 60 into which the tooth structure 50 fits. Reference numeral 48001 in FIG. 48 is a plan view of the saw blade 501F with the plurality of tooth structures 50 fitted into the fitting groove 60. Reference numeral 48002 in FIG. 48 is an enlarged plan view of one tooth structure 50 of the saw blade 501F. Reference numeral 48003 in FIG. 48 is a plan view of the blade body 11 without the plurality of tooth structures 50 fitted therein. Reference numeral 48004 in FIG. 48 is a plan view of the tooth structure 50. The tooth structure 50 is fitted into the fitting groove 60 of the blade body 11 by press-fitting.

[0165] 48 , the fitting groove 60 has a fitting portion 61 formed at the proximal end of the saw blade 501F and a linear portion 62 extending from the distal end of the saw blade 501F to the fitting portion 61. The fitting portion 61 includes a portion having a larger inner diameter than the linear portion 62.

[0166] As shown by reference numeral 48004 in Figure 48, the tooth structure 50 has a wide portion 51 that fits into the fitting portion 61 on the side opposite to the side where the tooth 12 is located, with the elastic hinge portion 14 in between. The wide portion 51 includes a portion whose inner diameter is larger than that of the extension portion 12c. The wide portion 51 fits into the fitting portion 61, preventing the tooth structure 50 from slipping out of the fitting groove 60. The elastic hinge portion 14 is provided between the extension portion 12c and the wide portion 51. The elastic hinge portion 14 has an inner diameter smaller than that of the wide portion 51 and the extension portion 12c so that the elastic hinge portion 14 elastically deforms during cutting, displacing the tooth 12 in the front-rear direction.

[0167] Furthermore, as shown by reference numeral 48002 in FIG. 48 , when the tooth structure 50 is fitted into the fitting groove 60, a gap is formed between the side surface of the extension 12c on the positive rake face side (the right side in FIG. 48 ) and the linear portion 62. As a result, when the negative rake face contacts the cutting object OB, the extension 12c elastically deforms toward the positive rake face side, and the trajectory of the tooth tip 12a moves away from the machining surface of the cutting object OB. This reduces cutting resistance. Note that a gap may be formed between the side surface of the extension 12c on the negative rake face side (the left side in FIG. 48 ) and the linear portion 62, or gaps may be formed on both sides.

[0168] Furthermore, the blade body 11 and the tooth structure 50 may be made of the same material or different materials.

[0169] (Summary) The oscillating saw according to aspect 1 of the present invention comprises a saw blade with a tooth tip at its front end, and a drive device that vibrates the saw blade so that it swings around an axial position located rearward of the tooth tip, and the orbit of the tooth tip has a first arc-shaped orbit that overlaps during the round trip of vibration, and a second orbit that is located at the end of vibration behind an imaginary line that extends the first orbit to the end of vibration, and the orbit of the second orbit that leads toward the center of vibration does not lie between the imaginary line and the orbit of the second orbit that leads toward the end of vibration.

[0170] In an oscillating saw according to aspect 2 of the present invention, in the above-mentioned aspect 1, the distance from the axial position to the tooth tip when the tooth tip moves along the second orbit may be shorter than the distance from the axial position to the tooth tip when the tooth tip moves along the first orbit.

[0171] In an oscillating saw according to aspect 3 of the present invention, in the above-mentioned aspects 1 or 2, the drive device may include a rotationally driven grooved cam and a cam follower fixed to the saw blade and positioned in the groove of the grooved cam, and the saw blade may be slidable in the forward and backward directions.

[0172] In an oscillating saw according to aspect 4 of the present invention, in the above-mentioned aspect 3, the drive device may further include an eccentric wheel that is driven to rotate, an oscillating shaft, and an oscillating member that is fixed to the oscillating shaft and oscillates around the oscillating shaft as the eccentric wheel rotates, and the saw blade may be slidably fixed to the oscillating member.

[0173] An oscillating saw according to aspect 5 of the present invention comprises a saw blade having a tooth tip at its front end, and a drive device that oscillates the saw blade so as to swing around an axial position located rearward of the tooth tip, wherein the saw blade has at least one first tooth having the tooth tip located on one side of the swing at its front end, and at least one second tooth having the tooth tip located on the other side of the swing at its front end, wherein the trajectory of the first tooth in the first direction of the swing is located forward of the trajectory of the first tooth in the second direction of the swing, and the trajectory of the second tooth in the first direction of the swing is located rearward of the trajectory of the second tooth in the second direction of the swing, the trajectory of the first tooth in the first direction of the swing and the trajectory of the second tooth in the first direction of the swing are trajectories at the same time, and the trajectory of the first tooth in the second direction of the swing and the trajectory of the second tooth in the second direction of the swing are trajectories at the same time.

[0174] In an oscillating saw according to aspect 6 of the present invention, in the above-mentioned aspect 5, the drive device may include a first eccentric wheel and a second eccentric wheel that are driven to rotate, a first vibration shaft, a first vibration member fixed to the first vibration shaft and vibrating around the first vibration shaft as the first eccentric wheel rotates, a second vibration shaft rotatably connected to the first vibration member, and a second vibration member fixed to the second vibration shaft and vibrating around the second vibration shaft as the second eccentric wheel rotates, and the saw blade may be fixed to the second vibration member.

[0175] In an oscillating saw according to Aspect 7 of the present invention, in the above-described Aspect 6, the drive device may further include a relative eccentric angle adjuster that can adjust the relative eccentric angle between the first eccentric wheel and the second eccentric wheel.

[0176] In an oscillating saw according to aspect 8 of the present invention, in any of aspects 5 to 7 above, the positive cutting surface of the first tooth may be on one side of the swing of the first tooth, and the positive cutting surface of the second tooth may be on the other side of the swing of the second tooth, or the positive cutting surface of the first tooth may be on the other side of the swing of the first tooth, and the positive cutting surface of the second tooth may be on one side of the swing of the second tooth.

[0177] In the oscillating saw according to Aspect 9 of the present invention, in any one of Aspects 5 to 7, the second teeth may be coarser than the first teeth.

[0178] An oscillating saw according to aspect 10 of the present invention comprises a saw blade having a tooth tip at its front end and vibrating to swing around an axial position located rearward of the tooth tip, the tooth tip having a positive or zero cutting face and a negative cutting face, the saw blade having a blade body portion, a plurality of teeth having the tooth tip, and an elastic hinge portion connecting each of the plurality of teeth to the blade body portion and elastically deforming during cutting to displace the plurality of teeth in the forward and backward directions, the plurality of teeth having extension portions extending forward to the tooth tip.

[0179] In an oscillating saw according to an eleventh aspect of the present invention, in the above-mentioned tenth aspect, the width of the elastic hinge portion may be smaller than the width of the extension portion.

[0180] In the vibration saw according to aspect 12 of the present invention, in the above-mentioned aspects 10 or 11, the direction in which the width of the elastic hinge portion is smallest in a plane perpendicular to the thickness direction of the saw blade may intersect with the vibration direction.

[0181] The oscillating saw according to aspect 13 of the present invention may be any of aspects 10 to 12 above, further comprising a deformation limiting portion adjacent to each of the plurality of teeth, which limits the range of displacement of the plurality of teeth due to elastic deformation.

[0182] The oscillating saw according to Aspect 14 of the present invention is the oscillating saw of any one of Aspects 10 to 13, wherein notches may be formed on both sides of the elastic hinge portion.

[0183] In an oscillating saw according to aspect 14 of the present invention, in any of aspects 10 to 14 above, the saw blade may have a tooth structure separate from the blade body portion, having each of the plurality of teeth and the elastic hinge portion, and the blade body portion may have a mating groove into which the tooth structure fits.

[0184] [Additional Notes] The cutting target of the oscillating saws in the above-described embodiments (oscillating saws 100, 200, 300, 400, and 500) is not limited to hard tissue (e.g., bone) in surgical operations. The oscillating saws can also be used to cut wood, metal, resin, or ceramic materials.

[0185] Also, in each of the above-described embodiments, the tip of the saw blade may have a zero rake face (i.e., a face perpendicular to the surface to be cut) instead of a positive rake face.

[0186] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0187] 100, 200, 300, 400, 500 Oscillating saw 1, 401, 501, 501A, 501B, 501C, 501D, 501E Saw blade 2, 202, 302 Drive device 11 Blade body 12 Multiple teeth 12A First tooth 12B Second tooth 12a, 12b Tooth tip 12c Extension portion 14 Elastic hinge portion 22c Eccentric wheel 23b Grooved cam 24 Third shaft portion (oscillating shaft) 24c Cam follower 25 Oscillating shank (oscillating member) 222b First eccentric wheel 222c Second eccentric wheel 223 First oscillating shaft 224 Second oscillating shaft 225 First oscillating shank (first oscillating member) 226 Second oscillating shank (second oscillating member) 321 First motor (relative eccentric angle adjustment unit) 322 Second motor (relative eccentric angle adjustment unit) 50 Tooth structure 60 Fitting groove

Claims

1. A reciprocating saw comprising a saw blade having a cutting edge disposed at a front end thereof, and a driving device configured to vibrate the saw blade so as to swing about an axis position located rearward of the cutting edge, wherein a trajectory of the cutting edge has an arcuate first trajectory that overlaps in reciprocation of the vibration, and a second trajectory that is located rearward of a virtual line obtained by extending the first trajectory to an end of the vibration at an end of the vibration, and a trajectory of the cutting edge toward the center of the vibration in the second trajectory does not enter between the virtual line and a trajectory of the cutting edge toward the end of the vibration in the second trajectory.

2. The reciprocating saw according to claim 1, wherein a distance from the axis position to the cutting edge when the cutting edge moves along the second trajectory is shorter than a distance from the axis position to the cutting edge when the cutting edge moves along the first trajectory.

3. The reciprocating saw according to claim 1 or 2, wherein the driving device includes a grooved cam that is rotationally driven, and a cam follower that is fixed to the saw blade and disposed in a groove of the grooved cam, and the saw blade is slidable in a front-rear direction.

4. The reciprocating saw according to claim 3, wherein the driving device further includes an eccentric wheel that is rotationally driven, a vibration shaft, and a vibration member that is fixed to the vibration shaft and vibrates about the vibration shaft as the eccentric wheel rotates, and the saw blade is slidably fixed to the vibration member.

5. A saw blade having tooth tips disposed at the front end, and a driving device configured to vibrate the saw blade so as to swing about an axis position located rearward of the tooth tips. The saw blade has at least one or more first teeth having the tooth tips disposed on one side of the swing at the front end, and at least one or more second teeth having the tooth tips disposed on the other side of the swing at the front end. The orbit of the first teeth in the first direction of the swing is located forward of the orbit of the first teeth in the second direction of the swing. The orbit of the second teeth in the first direction of the swing is located rearward of the orbit of the second teeth in the second direction of the swing. The orbit of the first teeth in the first direction of the swing and the orbit of the second teeth in the first direction of the swing are orbits at the same timing, and the orbit of the first teeth in the second direction of the swing and the orbit of the second teeth in the second direction of the swing are orbits at the same timing. A vibrating saw.

6. The driving device includes a first eccentric wheel and a second eccentric wheel that are rotationally driven, a first vibration shaft, a first vibration member fixed to the first vibration shaft and vibrating about the first vibration shaft as the first eccentric wheel rotates, a second vibration shaft rotatably connected to the first vibration member, and a second vibration member fixed to the second vibration shaft and vibrating about the second vibration shaft as the second eccentric wheel rotates. The saw blade is fixed to the second vibration member. The vibrating saw according to claim 5.

7. The driving device further includes a relative eccentric angle adjustment unit capable of adjusting a relative eccentric angle between the first eccentric wheel and the second eccentric wheel. The vibrating saw according to claim 6.

8. The positive rake face of the first teeth is on one side of the swing in the first teeth, and the positive rake face of the second teeth is on the other side of the swing in the second teeth, or the positive rake face of the first teeth is on the other side of the swing in the first teeth, and the positive rake face of the second teeth is on one side of the swing in the second teeth. The vibrating saw according to any one of claims 5 to 7.

9. The second teeth are coarser than the first teeth. The vibrating saw according to any one of claims 5 to 7.

10. A vibrating saw blade having a cutting edge disposed at the front end and vibrating so as to swing about an axis position located behind the cutting edge, the cutting edge having a positive or zero rake face and a negative rake face, the saw blade including a blade body portion, a plurality of teeth having the cutting edges, and elastic hinge portions connecting respective ones of the plurality of teeth to the blade body portion and elastically deforming during cutting to displace the plurality of teeth in the front-rear direction, the plurality of teeth having an extension portion extending forward to the cutting edge.

11. The vibrating saw according to claim 10, wherein a width of the elastic hinge portion is smaller than a width of the extension portion.

12. The vibrating saw according to claim 10, wherein a direction in which the width of the elastic hinge portion is minimized in a plane perpendicular to a thickness direction of the saw blade intersects with a vibration direction.

13. The vibrating saw according to claim 10, further including a deformation restricting portion adjacent to each of the plurality of teeth and restricting a displacement range of the plurality of teeth due to elastic deformation.

14. The vibrating saw according to claim 10, wherein circular notches are formed on both sides of the elastic hinge portion.

15. The vibrating saw according to claim 10, wherein the saw blade includes a tooth structure separate from the blade body portion and having each of the plurality of teeth and the elastic hinge portions, the blade body portion having a fitting groove into which the tooth structure fits.

Images