Impact Tools

Abstract

The present invention provides an impact tool. The hammer drill (1) is constructed to include: a cylindrical top tool holding component (10) that holds a top tool (T); a piston (16) that moves forward and backward with the rotation of a motor (4); an impact piece (18) that moves forward and backward in conjunction with the piston; an intermediate piece (20) that is housed between the impact piece and the top tool in a manner that allows it to move forward and backward in the top tool holding component, and that abuts against the rear end of the top tool during normal impact to indirectly transmit the impact from the impact piece to the top tool, and two metal front rings (42) and rear rings (43) are housed on the front side of the intermediate piece in the top tool holding component and between the top tool holding component and the intermediate piece so as to be movable in the forward and backward directions. According to the present invention, even a tool that restricts the movement of the intermediate piece toward the impact piece can exert a stable anti-air strike function.

Description

Technical Field

[0001] The invention relates to an impact tool such as an electric hammer and a hammer drill. Background Art

[0002] Impact tools such as electric hammers and hammer drills convert the rotation from the motor into the forward and backward movement of the piston through a crank mechanism, and the impact piece that moves forward and backward in the cylinder and the top tool holding component in conjunction with the piston indirectly impacts the rear end of the top tool installed on the top tool holding component through the intermediate piece, thereby enabling impact action.

[0003] As such an impact tool, an impact tool having an anti-air strike mechanism is known, so that when the top tool is not mounted on the top tool holding component or the top tool is not pushed onto the processed surface (hereinafter referred to as "non-impact state"), even if the piston reciprocates, the impact piece will not impact the middle piece. For example, Patent Document 1 describes a technical solution in which a locking O-ring is provided at the top of the cylinder, a conical surface is formed on the middle piece, and in the non-impact state, in the initial air strike, the locking O-ring is engaged with the conical surface of the middle piece that is more advanced than in the normal impact, and resistance is applied to the forward and backward movement of the middle piece, thereby limiting the movement of the middle piece toward the impact piece side and preventing subsequent air strikes.

[0004] [Prior art literature]

[0005] [Patent Literature]

[0006] Patent Document 1: Japanese Patent Publication No. 3369844 Summary of the invention

[0007] [Technical problem to be solved by the invention]

[0008] However, in the technical solution of Patent Document 1, the movement of the middle piece is directly restricted by an O-ring, i.e., an elastic body. Therefore, there is a concern that the O-ring may be worn or deteriorated due to repeated contact with the middle piece, and the resistance applied to the middle piece may decrease, resulting in the inability to perform the anti-airstrike function.

[0009] Therefore, an object of the present invention is to provide an impact tool that can exhibit a stable anti-runaway function even if it is a tool that restricts the movement of an intermediate piece toward the impact piece.

[0010] [Technical solutions for solving technical problems]

[0011] In order to achieve the above-mentioned purpose, the invention described in technical solution 1 is an impact tool having an impact mechanism, which is composed of a cylindrical top tool holding component, a piston, an impact piece and an intermediate piece, wherein the top tool holding component holds the top tool; the piston moves forward and backward with the rotation from the motor; the impact piece moves forward and backward in conjunction with the piston; the intermediate piece is housed between the impact piece and the top tool in a manner that allows it to move forward and backward in the top tool holding component, and abuts against the rear end of the top tool during normal impact to indirectly transmit the impact from the impact piece to the top tool, and the impact tool is characterized in that,

[0012] At least two annular members are housed in the tip tool holding member, on the front side of the intermediate member and between the tip tool holding member and the intermediate member. The annular members are housed in a state movable in the front-rear direction, and at least one of them is made of metal.

[0013] The invention described in claim 2 is characterized in that, in addition to the structure of claim 1, there are two annular members.

[0014] The invention described in claim 3 is characterized in that, based on the structure of claim 2, all the annular members are made of metal.

[0015] The invention described in Technical Solution 4 is based on the structure of any one of Technical Solutions 1 to 3, and is characterized in that the intermediate piece is constructed to include a large diameter portion and a small diameter portion, wherein the large diameter portion slides relative to the inner surface of the top tool holding component; and the small diameter portion protrudes forward from the large diameter portion and is loosely inserted into the annular component.

[0016] The invention described in Technical Solution 5 is based on the structure of any one of Technical Solutions 1 to 4, and is characterized in that a thin annular step portion with a tip is formed on the top tool holding component, and the front surface of the annular component at the frontmost position is a conical surface that abuts against the step portion and has the same shape as the step portion.

[0017] The invention described in technical solution 6 is based on the structure of any one of technical solutions 1 to 5, and is characterized in that a resistance body is provided on the top tool holding component, and in a non-impact state, the resistance body abuts against the intermediate piece and can apply resistance to the forward and backward movement of the intermediate piece.

[0018] The invention described in claim 7 is characterized in that, in addition to the structure of claim 1 or 2, one of the annular members is formed of an elastic material.

[0019] The invention described in claim 8 is characterized in that, based on the structure of claim 7, the outer periphery of the annular member formed of elastic material contacts the inner surface of the tip tool holding member, and the inner periphery of the annular member contacts the outer surface of the intermediate member.

[0020] [Effects of the invention]

[0021] According to the invention described in technical solution 1, at least two annular components are housed in the top tool holding component, on the front side of the intermediate component and between the top tool holding component and the intermediate component, so that they can move in the forward and backward directions. Thus, by generating a small gap between the annular components, the rebound of the intermediate component becomes irregular and the rebound amount becomes small. Therefore, even if the tool is used to limit the movement of the intermediate component to the impact component side, a stable anti-air strike function can be exerted.

[0022] According to the invention described in claim 2, in addition to being able to obtain the effects of claim 1, since the number of the annular members is two, the anti-dry-strike function can be achieved with minimal addition of parts.

[0023] According to the invention described in claim 3, in addition to the effect of claim 2, since both of the two annular members are made of metal, durability can be ensured.

[0024] According to the invention described in claim 4, in addition to achieving the effects of any one of claims 1 to 3, since the intermediate piece is constructed as a component including a large diameter portion and a small diameter portion, the annular component can be reliably arranged toward the front side by the small diameter portion.

[0025] According to the invention described in technical solution 5, in addition to being able to obtain the effect of any one of technical solutions 1 to 4, since the front surface of the annular component at the frontmost position is a conical surface of the same shape as the top tip annular step portion formed on the top tool retaining component, the annular component can be arranged in the top tool retaining component in an appropriate posture.

[0026] According to the invention described in technical solution 6, in addition to being able to obtain the effects of any one of technical solutions 1 to 5, since a resistance body is provided on the top tool holding component, which can abut against the middle piece in a non-impact state and apply resistance to the forward and backward movement of the middle piece, it is possible to reduce the power of the middle piece moving forward due to empty hitting and more effectively suppress rebound.

[0027] According to the invention described in claim 7, in addition to the effects of claim 1 or 2, since one of the annular members is formed of an elastic material, the momentum of the advancing intermediate member can be absorbed.

[0028] According to the invention described in Technical Solution 8, in addition to being able to obtain the effects of Technical Solution 7, since the outer periphery of the annular component formed by the elastic material contacts the inner surface of the top tool holding component, and the inner periphery of the annular component contacts the outer surface of the middle piece, it is possible to suppress the deformation of the annular component, maintain durability, and make the space between the annular component and the middle piece airtight, thereby obtaining a buffering effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a partial central longitudinal section view of the hammer drill (usually during impact).

[0030] Figure 2 It is a partial central longitudinal section view of the hammer drill (non-impact state).

[0031] [Description of Reference Numerals]

[0032] 1: hammer drill; 2: main body shell; 3: motor shell; 4: motor; 5: output shaft; 10: top tool holding part; 14: eccentric pin; 15: connecting rod; 16: piston; 17: air chamber; 18: impact piece; 20: intermediate piece; 21: large diameter part; 23: small diameter part; 36: resistance pin; 40: top part; 41: step part; 42: front ring; 43: rear ring; 44: tapered surface; T: top tool. DETAILED DESCRIPTION

[0033] Hereinafter, embodiments of the present invention will be described based on the drawings.

[0034] Figure 1 It is a central longitudinal sectional view showing an example of a hammer drill 1 as an impact tool.

[0035] In the hammer drill 1, a motor housing 3 housing a motor 4 with an output shaft 5 facing upward is connected in the up-down direction to the front lower part of the main body housing 2, and a gear housing 6 housing a crank shaft 7 and an intermediate shaft 8 respectively meshing with the output shaft 5 is provided above the motor housing 3. A front housing 9 housing a cylindrical top tool holding member 10 facing forward is assembled to the front side of the gear housing 6. A handle housing (not shown) with a switch and a switch operating handle and connected to a power cord is connected to the rear part of the main body housing 2, and a housing cover 11 covering the front housing 9 is connected to the front part of the main body housing 2.

[0036] The intermediate shaft 8 meshes with a bevel gear 12 provided at the rear end of a tip tool holding member 10 , and a tip tool T such as a drill can be mounted on the tip of the tip tool holding member 10 via an operating sleeve 13 .

[0037] A piston 16 is provided in the top tool holding member 10, and the piston 16 is connected to the eccentric pin 14 of the crankshaft 7 via a connecting rod 15 so as to reciprocate. In front of the piston 16, an impact piece 18 and an intermediate piece 20 are housed in a manner that they can move forward and backward respectively via an air chamber 17, thereby forming an impact mechanism, wherein the impact piece 18 has a front shaft portion 19 protruding forward, and the intermediate piece 20 is located in front of the impact piece 18.

[0038] The middle part of the intermediate member 12 is a large diameter portion 21 that slides relative to the inner surface of the top tool holding member 10, and a rear shaft portion 22 is formed at the rear of the intermediate member 20. The rear shaft portion 22 gradually decreases in diameter as it moves toward the rear and protrudes rearward coaxially with the large diameter portion 21. A small diameter portion 23 having a smaller diameter than the large diameter portion 21 is also coaxially protruded at the front of the intermediate member 20.

[0039] On the other hand, a rear guide surface 24 and a front guide surface 25 are formed on the inner circumference of the top tool holding member 10, wherein the rear guide surface 24 receives the piston 16 and the impact member 18; the front guide surface 25 receives the intermediate member 20 and has a smaller diameter than the rear guide surface 24. Figure 1 As shown, a non-guide surface 26 is locally provided at a position closer to the front side of the advancing position of the impact member 18 during normal impact. The diameter of the non-guide surface 26 is larger than the inner diameter of the rear guide surface 24. The non-guide surface 26 is in a non-contact state with the outer peripheral surface of the impact member 18 that advances during idle striking. At the position of the non-guide surface 26, exhaust holes 27, 27 are formed through the top tool holding component 10 to connect the inside and outside of the top tool holding component 10.

[0040] Furthermore, in the top tool holding member 10, a front support ring 28 is provided at the front end of the rear guide surface 24, through which the rear shaft portion 22 of the intermediate member 20 passes and supports the rear surface of the large diameter portion 21, and a grip ring 29 is provided behind the front support ring 28, which grips the front shaft portion 19 of the impact member 18 when the impact member 18 moves forward due to the empty strike. In addition, a rear support ring 30 is provided behind the grip ring 29, through which the front shaft portion 19 passes and supports the front surface of the impact member 18.

[0041] In a state where the front support ring 28 abuts against the step portion formed between the rear guide surface 24 and the front guide surface 25 and is restricted from moving forward, the front support ring 28, the holding ring 29 and the rear support ring 30 are housed in the order of the holding ring 29 and the rear support ring 30, and the rear support ring 30 is restricted from moving backward by the locking ring 31 that is locked to the rear guide surface 24, thereby positioning the front support ring 28, the holding ring 29 and the rear support ring 30 in the front-to-back direction.

[0042] On the other hand, a through hole 35 is formed along the radial direction at the rear end of the front guide surface 25 on the top tool holding member 10, and a resistor pin 36 is inserted into the through hole 35, wherein the through hole 35 is tapered from the outside to the inside in the radial direction and the top end becomes thinner. The resistor pin 36 is a metal shaft body formed into a tapered shape corresponding to the through hole 35, and its thinned top end is formed into a hemispherical shape.

[0043] At the position of the resistance pin 36, a leaf spring 37 is installed on the outer periphery of the top tool holding component 10. The leaf spring 37 is a spring formed by bending a strip of metal plate into a C-shape, and the base end of the resistance pin 36 is inserted into the end of the leaf spring 37 in the length direction, thereby, the leaf spring 37 pushes the resistance pin 36 toward the center side of the top tool holding component 10, and applies force to make it protrude from the through hole 35 to the inside.

[0044] Furthermore, on the top tool holding component 10, a small-diameter top portion 40 is formed in front of the intermediate piece 20 into which the top tool T and the small-diameter portion 23 can be loosely inserted, and an annular step portion 41 that tapers toward the front top is formed between the top portion 40 and the front guide surface 25.

[0045] Behind the step 41, a front ring 42 and a rear ring 43 are housed on the front side of the intermediate member 20 so as to be movable forward and backward. The two rings 42 and 43 are made of metal and have an inner diameter into which the small diameter portion 23 of the intermediate member 20 can be loosely inserted. The front ring 42 is formed longer than the rear ring 43 in the axial direction, and a tapered annular surface 44 having a tapered tip corresponding to the inclination of the inner surface side of the step 41 is formed on the front surface of the front ring 42.

[0046] Therefore, when the intermediate member 20 moves forward from the normal impact, the intermediate member 20 does not directly abut against the step portion 41 but abuts against the rear ring 43 .

[0047] In the hammer drill 1 constructed as described above, a hammer mode, a drilling mode and a hammer drill mode can be selected by a switching operating handle (not shown) provided on the left side of the main body shell 2, wherein the hammer mode is a mode in which the crank shaft 7 is rotated to apply an impact to the top tool T; the drilling mode is a mode in which the intermediate shaft 8 is rotated to rotate the top tool T together with the top tool holding component 10; and the hammer drill mode is a mode in which the crank shaft 7 and the intermediate shaft 8 are rotated simultaneously to apply an impact and rotate the top tool T.

[0048] Here, when the tip tool T is inserted into the tip of the tip tool holding member 10 and the tip of the tip tool T is pressed against the workpiece surface, the tip tool T is pushed in and the intermediate piece 20 is retracted. Figure 1 The retracted position shown is limited in thrust, wherein Figure 1 The retracted position shown is a position where the intermediate member 20 abuts against the front support ring 28 and the rear shaft portion 22 faces the inside of the rear support ring 30. In this retracted position, the tip portion of the resistance pin 36 protruding into the tip tool holding component 10 abuts against the large diameter portion 21 of the intermediate member 20, so that the resistance pin 36 is in a state of overcoming the force of the leaf spring 37 and retreating radially outward in the through hole 35, so that the tip is pushed by the outer periphery of the large diameter portion 21.

[0049] Next, when the switch operating handle is pushed in and the switch is turned on in a state where the hammer mode or the hammer drill mode is selected by the switching operating handle, the motor 4 is driven to rotate the output shaft 5, thereby rotating the crankshaft 7. Therefore, due to the eccentric movement of the eccentric pin 14, the piston 16 moves forward and backward through the connecting rod 15, and the impact piece 18 moves forward and backward through the air chamber 17, so that the front shaft portion 19 of the impact piece 18 impacts the rear shaft portion 22 of the intermediate piece 20 in the rear support ring 30. In this way, the impact piece 18 indirectly impacts the top tool T through the intermediate piece 20, and the top tool T can perform cutting of the workpiece surface. At this time, the large diameter portion 21 of the intermediate piece 20 is separated from the rear ring 43, so that the front ring 42 and the rear ring 43 are in a state where the front and rear movements are not restricted.

[0050] Furthermore, when the switch operating handle is pushed in in a non-impact state without pressing the top tool T against the processed surface (or without installing the top tool T on the top tool holding member 10), as shown in FIG. Figure 2 As shown, the intermediate member 20 moves forward from the retracted position due to the initial impact (dry strike) performed by the impact member 18. At this time, the intermediate member 20 advances under the state where resistance is applied by the resistance pin 36 from the radially outer side, and therefore, the momentum of its advancement is weakened.

[0051] In addition, the advanced intermediate piece 20 abuts against the rear ring 43, but as described above, the front and rear rings 42 and 43 are not restricted in their forward and backward movement in the top tool holding member 10, so that when the top tool T is pushed in, etc., it is easy to generate gaps between the step portion 41 and the front ring 42, and between the front ring 42 and the rear ring 43. Therefore, when the rear ring 43 abutted by the intermediate piece 20 abuts against the front ring 42 or the front ring 42 abuts against the step portion 41, the rebound of the intermediate piece 20 becomes irregular, the rebound amount becomes small, and the subsequent empty hitting is prevented.

[0052] Furthermore, even if the intermediate piece 20 rebounds, the top end of the resistance pin 36 that returns to the protruding position due to the advancement of the intermediate piece 20 engages with the rear end of the large diameter portion 21 from behind, thereby limiting the retreat of the intermediate piece 20 and preventing it from returning to the retreated position.

[0053] On the other hand, the impact piece 18 that advances in the initial empty driving advances to the position where the tip of the front shaft portion 19 reaches the inside of the front support ring 28. Here, since a plurality of vent holes 32, 32 ... (which are opened by the advancement of the impact piece 18) are formed in the circumferential direction on the tip tool holding member 10, Figure 2 ), so the air chamber 17 is connected to the outside of the top tool holding component 10 and loses the effect of the air spring. Accordingly, the impact member 18 is held at the position where the front end of the front shaft portion 19 is embedded in the grip ring 29 and the linkage with the piston 16 is blocked.

[0054] In addition, a non-guide surface 26 having a larger diameter than the impact piece 18 is formed on the rear guide surface 24 of the top tool holding member 10. Therefore, when the impact piece 18 advances in the initial empty strike, the impact piece 18 enters the inner side of the non-guide surface 26 and the rear guide surface 24 cannot guide the forward movement. Accordingly, the impact piece 18 is easily tilted from the axis of the forward and backward movement during normal impact, and the impact force itself of the initial empty strike on the intermediate piece 20 is weakened. In addition, the front end surface of the front shaft portion 19 of the impact piece 18 and the rear end surface of the rear shaft portion 22 of the intermediate piece 20 are spherical surfaces that bulge toward each other. Therefore, even if the impact piece 18 is slightly tilted, it is possible to ensure that the front shaft portion 19 is properly abutted against the rear shaft portion 22.

[0055] Thus, according to the hammer drill 1 of the above-mentioned embodiment, the two front rings 42 and the rear ring 43 (ring-shaped members) are housed in a state of being movable in the front and rear directions between the top tool holding member 10 and the middle member 20, respectively, on the front side of the middle member 20. Therefore, due to the small gap between the two front rings 42 and the rear ring 43, the rebound of the middle member 20 becomes irregular and the rebound amount becomes small. Therefore, even if the tool is implemented to restrict the movement of the middle member 20 to the impact member 18 side, a stable anti-air strike function can be exerted.

[0056] In particular, here, since both the front ring 42 and the rear ring 43 are used as the annular members, the anti-dry strike function can be exhibited with minimal addition of parts.

[0057] Furthermore, since both the front ring 42 and the rear ring 43 are made of metal, durability can also be ensured.

[0058] Furthermore, since the intermediate member 20 is configured to include a large diameter portion 21 that slides relative to the inner surface of the top tool holding portion 10 and a small diameter portion 23 that protrudes forward from the large diameter portion 21 and is loosely inserted into the front ring 42 and the rear ring 43, the front ring 42 and the rear ring 43 can be reliably configured toward the front side by the small diameter portion 23.

[0059] On the other hand, since the front surface of the front ring 42 at the most forward position is set to abut against the tapered surface 44 of the same shape as the tip pointed ring-shaped step portion 41 formed on the tip tool holding component 10, the front ring 42 can be arranged in the tip tool holding component 10 in an appropriate posture.

[0060] In addition, since a resistance pin 36 (resistance body) is provided on the top tool holding component 10, which can abut against the intermediate piece 20 in a non-impact state and apply resistance to the forward and backward movement of the intermediate piece 20, the power of the intermediate piece 20 moving forward due to empty hitting can be weakened and rebound can be more effectively suppressed.

[0061] In addition, the resistance body is not limited to a component that applies resistance to the intermediate piece, and may also be a component that applies resistance to the top tool. The number and configuration of the resistance bodies may also be appropriately changed. However, the resistance body may be omitted. The non-guide surface may also be omitted.

[0062] Furthermore, in the above-described embodiment, two annular members are provided, but three or more annular members may be provided, and the shape of each annular member may be changed as appropriate.

[0063] In addition, if the annular parts are all made of metal, durability can be obtained, but one of the annular parts can also be formed of an elastic material such as rubber. If it is set to an elastic material, the momentum of the intermediate piece moving forward can be absorbed. In this case, the annular part of the elastic material can be located at the front side.

[0064] Furthermore, the outer periphery of the annular component formed of an elastic material preferably contacts the inner surface of the top tool holding component, and the inner periphery of the annular component contacts the outer surface of the intermediate component. In this way, the deformation of the annular component can be suppressed, the durability can be maintained, and the space between the annular component and the intermediate component can be sealed, thereby obtaining a buffering effect.

[0065] In addition, even in the case of a hammer drill, for example, the impact mechanism is configured such that the arm is swingably provided on a protruding sleeve provided on an intermediate shaft parallel to the top tool holding member via a swash plate bearing with an axis tilted, and the piston cylinder connected to the arm moves forward and backward, the annular member on the front side of the intermediate member can be used. In addition, the direction and type of the motor are not limited to the above-mentioned method, and it is also possible to use a DC motor equipped with a battery pack instead of an AC motor.

[0066] Furthermore, the impact tool is not limited to the hammer drill, and the present invention can be applied even to an electric hammer having only an impact mechanism.

Claims

1. An impact tool having an impact mechanism, the impact mechanism being composed of a cylindrical top tool holding member, a piston, an impact piece and an intermediate piece, wherein: The top tool holding component holds the top tool; the piston moves forward and backward with the rotation from the motor; the impact piece moves forward and backward in conjunction with the piston; the intermediate piece is housed between the impact piece and the top tool in a manner that it can move forward and backward in the top tool holding component, and abuts against the rear end of the top tool during normal impact to indirectly transmit the impact from the impact piece to the top tool, and the impact tool is characterized in that, In the top tool holding component, at least two annular components are housed on the front side of the intermediate component and between the top tool holding component and the intermediate component. The annular components are housed in a state where they can move in the forward and backward directions and a gap is formed between them due to their movement. The annular components are all made of metal, and there is no spacer between adjacent annular components. The rear end of the top tool is inserted into the annular member at the frontmost position, when the middle member is in a state where the middle member retreats to a position where the pushing is restricted due to the pushing of the top tool, and the annular member at the frontmost position is in a state where the forward movement is restricted due to the abutment with the step portion formed by the top tool holding member, When the intermediate piece is separated from the annular member at the rearmost position, the rearward movement of the annular member is not restricted.

2. The impact tool according to claim 1, characterized in that There are two annular parts.

3. The impact tool according to claim 1 or 2, characterized in that: The intermediate member is configured to include a large diameter portion and a small diameter portion, wherein the large diameter portion slides relative to the inner surface of the tip tool holding member; and the small diameter portion protrudes forward from the large diameter portion and is loosely inserted into the annular member.

4. The impact tool according to claim 1 or 2, characterized in that: The tip tool holding member is provided with a tapered annular step portion, and the front surface of the annular member at the frontmost position is a tapered surface that abuts against the step portion and has the same shape as the step portion.

5. The impact tool according to claim 1 or 2, characterized in that: The tip tool holding member is provided with a resistance body, which abuts against the intermediate member in a non-impact state and can apply resistance to the forward and backward movement of the intermediate member.

6. The impact tool according to claim 1 or 2, characterized in that: The outer periphery of the annular member contacts the inner surface of the tip tool holding member, and the inner periphery of the annular member contacts the outer surface of the intermediate member.

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