JP7094036B2 - Impact tool - Google Patents

Description

The present invention relates to an impact tool that intermittently engages a hammer that repeats rotation and forward / backward movement with the rotation of the drive shaft with an anvil of the output shaft to give an impact to the output shaft.

Conventionally, impact tools such as impact wrenches and impact drivers intermittently engage anvils formed on the output shaft with a hammer that repeats rotation and forward / backward movement in the direction of the output shaft as the drive shaft rotates. As a result, an impact in the rotational direction is given to the output shaft.

In a conventional impact tool, a thrust plate is interposed between the anvil formed on the output shaft and the casing so that the thrust plate receives the load (impact) in the output shaft direction generated when the hammer engages with the anvil. (See, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 7-52062

However, in the above-mentioned conventional impact tool, since the thrust plate is interposed between the anvil formed on the output shaft and the casing, the impact in the output shaft direction is transmitted through the thrust plate when the hammer and the anvil are engaged. Was transmitted to the casing.

Therefore, vibration (impact) is transmitted to the body such as the worker's hand through the casing, which may cause an accident such as injury to the worker.

In addition, noise is generated by the impact transmitted to the casing and the rotational impact, which may cause noise at the work site.

As described above, the conventional impact tool may cause a decrease in safety during work and a decrease in the work environment.

Therefore, in the present invention according to claim 1, the drive source is used in an impact tool in which a hammer that repeats rotation and forward / backward movement with the rotation of the drive shaft is intermittently engaged with the anvil of the output shaft to give an impact to the output shaft. The drive shaft connected to the drive shaft, the hollow hammer cage provided on the drive shaft, the output shaft rotatably provided in the hollow portion of the hammer cage, the cam ball that rotates with the hammer cage, and the rear end of the output shaft. A cam ball pilot that holds the cam ball rotatably and guides the cam ball in the direction of rotation, a hammer cam that repeatedly moves forward and backward along the output shaft as the cam ball rotates, and a cam spring that urges the hammer cam to retract. A hammer that moves forward and backward with the hammer cam and engages with the anvil of the output shaft by advancing, a thrust plate that receives a load in the direction of the output shaft of the anvil due to engagement with the hammer, and a rotation seal provided on the output shaft. It has a cage cap that seals the hollow part of the hammer cage and a casing that accommodates each of the above parts with the front end of the output shaft protruding, and the thrust plate is sandwiched between the anvil and the cage cap, while the cage cap and casing. It was decided to form a gap between the and, so that the impact applied to the thrust plate when the hammer and the anvil are engaged is received by the cage cap and not transmitted to the casing.

Further, in the present invention according to claim 2, in the present invention according to claim 1, the cage cap is detachably attached to the hammer cage, and the lubricating oil is injected into the hollow portion of the hammer cage sealed by the cage cap. I made it.

Then, in the present invention, the effects described below are obtained.

That is, in the present invention, while the anvil and the cage cap sandwich the thrust plate, a gap is formed between the cage cap and the casing, and the impact applied to the thrust plate when the hammer and the anvil are engaged is applied by the cage cap. Since it is configured so that it is received and not transmitted to the casing, it is possible to prevent vibration (impact) from being transmitted to the worker's body and to reduce noise generated during work. , It is possible to improve the safety and working environment during work.

In particular, if the cage cap is detachably attached to the hammer cage and the lubricating oil is injected into the hollow portion of the hammer cage sealed by the cage cap, each part such as the output shaft housed in the hollow portion of the hammer cage is to be injected. The rotation of the tool becomes smooth, and failure can be prevented without frequent maintenance of the impact tool.

A partially enlarged sectional view showing an impact tool according to the present invention. Partially enlarged cross-sectional view at the same impact.

For impact tools such as impact wrenches and impact drivers, a hammer that repeatedly rotates and moves forward and backward as the drive shaft rotates is intermittently engaged with the anvil of the output shaft when moving forward to output. A configuration that generates an impact that forcibly rotates a shaft is known.

In the present invention, the mechanism for generating the impact of the impact tool having the above configuration (impact generation mechanism) is the most characteristic.

Hereinafter, a specific configuration of the impact generation mechanism of the impact tool according to the present invention will be described with reference to the drawings.

As shown in FIGS. 1 and 2, the impact generation mechanism 2 of the impact tool 1 is housed inside the front end portion of the casing 3.

Inside the rear portion of the casing 3, a drive shaft 4 connected to a drive source such as a pneumatic motor or an electric motor is housed. On the other hand, inside the front portion of the casing 3, the output shaft 5 is housed on the same axis as the drive shaft 4 with the front end portion protruding forward. The drive shaft 4 is rotatably held inside the casing 3 via a bearing 6. Further, the output shaft 5 is rotatably held at the front end portion of the casing 3 via a cylindrical bearing 7. The drive shaft 4 and the output shaft 5 are connected via an impact generation mechanism 2. In the case of an impact wrench, the output shaft 5 is formed with a square drive 8 to which a socket is mounted at the tip, but in the case of an impact driver, the tip is formed into various driver shapes, and various types are formed at the tip. Driver bit is attached detachably.

The impact generation mechanism 2 attaches a rear end portion of a hollow cylindrical hammer cage 9 having a front end opened to the front end of the drive shaft 4, and rotatably accommodates the rear portion of the output shaft 5 in the hollow portion of the hammer cage 9. ..

A cam ball pilot 10 is attached to the rear end of the hollow portion of the hammer cage 9. The cam ball pilot 10 has a through hole 11 formed in the central portion in the front-rear direction to rotatably hold the rear end of the output shaft 5, and a semicircle formed on the outer peripheral surface along the circumferential direction. The cam ball 13 is slidably held by the arc-shaped recess 12. The cam ball 13 is held at the rear end of the hollow portion of the hammer cage 9, and is guided by the recess 12 of the cam ball pilot 10 to rotate together with the hammer cage 9.

Further, in the hollow portion of the hammer cage 9, the hammer cam 14 is mounted on the rear portion of the output shaft 5 so as to be slidable back and forth. The hammer cam 14 is spline-coupled to the outer peripheral surface of the output shaft 5 on the inner peripheral surface of the through hole 15 formed in the central portion in the front-rear direction. As a result, the hammer cam 14 can rotate together with the output shaft 5 and at the same time move forward and backward along the output shaft 5. Further, the hammer cam 14 forms a protruding cam 16 projecting rearward at the rear end. This cam 16 has a shape in which the height (the amount of protrusion to the rear) gradually changes in one cycle of minimum → maximum → minimum in the circumferential direction of the hammer cam 14, and the cam ball at the rear end portion. Engage with 13. A cam spring 18 for urging the hammer cam 14 in the retracting direction is provided between the hammer cam 14 and the anvil 17 formed in a crossguard shape on the outer peripheral portion of the output shaft 5. As a result, as the cam ball 13 rotates around the output shaft 5, the hammer cam 14 is pressed by the cam ball 13 toward the front, and the hammer cam 14 rotates with the output shaft 5 to the output shaft 5. After that, the hammer cam 14 rotates with the output shaft 5 due to the repulsive force (urging force) of the cam spring 18 and retreats along the output shaft 5.

The hammer cam 14 is formed with a crossguard-shaped convex portion 19 protruding in the radial direction along the circumferential direction on the outer circumference.

Further, in the hollow portion of the hammer cage 9, the hammer 20 is provided so as to be able to move forward and backward along a guide groove 28 formed on the inner peripheral surface of the hollow portion in the front-rear direction. The hammer 20 has a concave groove 21 formed on the outer periphery of the rear end portion in the radial direction along the circumferential direction.

Then, the convex portion 19 of the hammer cam 14 and the groove 21 of the hammer 20 are engaged with each other. As a result, as the hammer cam 14 moves forward and backward, the hammer 20 is also guided by the inner peripheral surface of the hollow portion of the hammer cage 9 and moves forward and backward along the output shaft 5.

When the hammer 20 moves forward, it is inserted into the recess 22 formed at the outer peripheral end of the anvil 17 of the output shaft 5. As a result, the hammer 20 can forcibly rotate the output shaft 5 by engaging with the recess 22 of the anvil 17 and give an impact to the output shaft 5. At the time of this impact, the anvil 17 is loaded with a load in the direction of the output shaft acting forward along the output shaft 5 due to the engagement with the hammer 20, and the thrust plate 23 is placed on the anvil 17 to receive the load. It is provided in front.

The thrust plate 23 is formed in the shape of an annulus plate and is rotatably engaged with the outer periphery of the output shaft 5.

The impact generation mechanism 2 is configured as described above, and each component (output shaft 5, cam ball pilot 10, cam ball 13, hammer cam 14, anvil 17, cam spring 18, hammer 20, thrust plate 23) is configured. , The front end portion of the output shaft 5 is housed in the hollow portion of the hammer cage 9 in a state of protruding forward. A cage cap 24 is detachably screwed into the front opening of the hammer cage 9.

The cage cap 24 is provided on the outer periphery of the output shaft 5 (in front of the thrust plate 23) via the rotary seal 25, and is provided in the front opening of the hammer cage 9 via the packing 26. As a result, the cage cap 24 seals the hollow portion of the hammer cage 9. Lubricating oil is injected (enclosed) in the hollow portion of the sealed hammer cage 9.

Then, in the impact tool 1, each of the above parts (output shaft 5, bearings 6, 7, hammer cage 9, cam ball pilot 10, cam ball 13, hammer cam 14, anvil 17, cam spring) with the front end of the output shaft 5 protruding. 18, hammer 20, thrust plate 23, cage cap 24, rotary seal 25, packing 26) are housed inside the casing 3.

Moreover, in the impact tool 1, the thrust plate 23 is sandwiched between the anvil 17 of the output shaft 5 and the cage cap 24, while a gap 27 is formed between the cage cap 24 and the casing 3.

As a result, in the impact tool 1, the impact applied to the thrust plate 23 when the hammer 20 and the anvil 17 are engaged is received by the cage cap 24, and the impact is not transmitted to the casing 3 by the gap 27.

The impact tool 1 is configured as described above, and when no load (torque) is applied to the output shaft 5 during the fastening work, as shown in FIG. 1, the hammer cage is accompanied by the rotation of the drive shaft 4. The 9 and the cam ball 13 and the hammer cam 14 rotate, and the output shaft 5 spline-coupled to the hammer cam 14 rotates. On the other hand, when a load (torque) is applied to the output shaft 5, as shown in FIG. 2, a load is applied to the hammer cam 14 together with the output shaft 5 in the rotational direction, and the cam ball 13 and the hammer cam 14 are relatively relative to each other. Rotates, which causes the cam ball 13 to move the hammer cam 14 forward through the cam 16 and the hammer 20 to move forward along with the hammer cam 14 to engage the recess 22 of the anvil 17 of the output shaft 5 with the output shaft. An impact (impact) that forcibly rotates 5 is given (Fig. 2), and then the hammer 20 and the hammer cam 14 retract due to the urging force of the cam spring 18 (Fig. 1), and the impact operation due to the forward / backward movement of the hammer 20 is performed. This is repeated until the rotation of the drive shaft 4 is stopped. Although one hammer 20 and a recess 22 are shown in FIGS. 1 and 2 for ease of explanation, two hammers 20 and a recess 22 are provided in the circumferential direction of the output shaft 5. Has been done.

In this way, in the impact tool 1, during the fastening work, the hammer 20 that repeats rotation and forward / backward movement with the rotation of the drive shaft 4 is intermittently engaged with the anvil 17 of the output shaft 5 to give an impact to the output shaft 5. By giving, the fastener can be fastened with a predetermined torque.

As described above, the impact tool 1 is rotatably provided in the drive shaft 4 connected to the drive source, the hollow hammer cage 9 provided in the drive shaft 4, and the hollow portion of the hammer cage 9. Along with the rotation of the output shaft 5, the cam ball 13 that rotates together with the hammer cage 9, the cam ball pilot 10 that rotatably holds the rear end of the output shaft 5 and guides the cam ball 13 in the rotational direction, and the cam ball 13. A hammer cam 14 that repeatedly moves forward and backward along the output shaft 5, a cam spring 18 that urges the hammer cam 14 to move backward, and a hammer that moves forward and backward together with the hammer cam 14 and engages with the anvil 17 of the output shaft 5 by moving forward. A thrust plate 23 that receives a load in the output shaft direction of the anvil 17 due to engagement with the hammer 20 and a cage cap 24 that is provided on the output shaft 5 via a rotary seal 25 and seals the hollow portion of the hammer cage 9. And a casing 3 for accommodating each of the above parts with the front end of the output shaft 5 protruding, and the thrust plate 23 is sandwiched between the anvil 17 and the cage cap 24, while the cage cap 24 and the casing 3 are used. A gap 27 is formed between them so that the impact applied to the thrust plate 23 when the hammer 20 and the anvil 17 are engaged is received by the cage cap 24 and is not transmitted to the casing 3.

Therefore, the impact tool 1 having the above configuration can prevent vibration (impact) from being transmitted to the worker's body and can reduce noise generated during work, thereby ensuring safety during work. And the working environment can be improved.

Further, the impact tool 1 has a configuration in which the cage cap 24 is detachably attached to the hammer cage 9.

Therefore, in the impact tool 1 having the above configuration, maintenance of each part such as the output shaft 5 housed in the hollow portion of the hammer cage 9 becomes easy, and this also causes a failure of the impact tool 1 (impact generation mechanism 2). It is possible to prevent damage.

Further, the impact tool 1 has a configuration in which lubricating oil is injected (enclosed) into a hollow portion of a hammer cage 9 sealed with a cage cap 24, a rotary seal 25, and a packing 26.

Therefore, in the impact tool 1 having the above configuration, the striking noise generated when the hammer 20 and the anvil 17 are engaged (at the time of impact) can be reduced by the lubricating oil and can be sealed in the hollow portion of the sealed hammer cage 9. In addition, the rotation and impact of each part such as the output shaft 5 housed in the hollow portion of the hammer cage 9 becomes smooth, and the frequency of maintenance of the impact tool 1 can be reduced (it can be expected to be maintenance-free). ), It is possible to prevent the impact tool 1 (impact generation mechanism 2) from failing or being damaged (expected to extend the life of the impact tool 1). Further, since the lubricating oil can be filled only inside the hammer cage 9, when an electric motor is used as a drive source, a cooling opening can be formed in the casing 3.

In the impact tool, the striking sound generated at the time of impact becomes a problem, but in the above impact tool 1, the hammer 20 and the anvil 17 engaged at the time of impact are housed in the hammer cage 9, and the hammer cage 9 is housed in the rotary seal 25 and the packing 26. Since it is sealed with oil and the oil is sealed inside, the impact sound generating part is further sealed with oil in the hammer cage 9, so that the sound deadening effect like a double window structure by the hammer cage 9 and oil is achieved. It is possible to demonstrate and extremely reduce the sound of the impact tool 1.

1 Impact tool 2 Impact generation mechanism 3 Casing 4 Drive shaft 5 Output shaft 6 Bearing 7 Bearing Octagonal drive 9 Hammer cage 10 Cam ball pilot
11 Through hole 12 Recess
13 cam ball 14 hammer cam
15 through hole 16 cam
17 anvil 18 cam spring
19 Convex part 20 Hammer
21 Groove 22 Recess
23 Thrust plate 24 Cage cap
25 Rotating seal 26 Packing
27 Gap 28 Guide groove

Claims (2)

In an impact tool that gives an impact to the output shaft by intermittently engaging the hammer that repeats rotation and forward / backward movement with the rotation of the drive shaft to the anvil of the output shaft.
The drive shaft connected to the drive source and
A hollow hammer cage provided on the drive shaft and
An output shaft rotatably provided in the hollow part of the hammer cage,
A cam ball that rotates with the hammer cage,
A cam ball pilot that rotatably holds the rear end of the output shaft and guides the cam ball in the direction of rotation.
A hammer cam that repeatedly moves forward and backward along the output axis as the cam ball rotates,
A cam spring that urges the hammer cam to retract, and
A hammer that moves forward and backward with the hammer cam and engages with the anvil of the output shaft by moving forward.
A thrust plate that receives a load in the output axis direction of the anvil due to engagement with the hammer,
A cage cap that is provided on the output shaft via a rotary seal and seals the hollow part of the hammer cage.
A casing that accommodates each of the above parts with the front end of the output shaft protruding.
Have,
While the thrust plate is sandwiched between the anvil and the cage cap, a gap is formed between the cage cap and the casing, and the impact applied to the thrust plate when the hammer and the anvil are engaged is received by the cage cap and transmitted to the casing. An impact tool characterized by being configured so as not to let it. The impact tool according to claim 1, wherein a cage cap is detachably attached to the hammer cage, and lubricating oil is injected into a hollow portion of the hammer cage sealed by the cage cap.

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