JP2002154063A - Hammering clamping tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To clamp a screw or the like with desired tightening torque even if a hammer collides with an anvil due to a burr or the like before the screw or the like is seated, in a hammering clamping tool for clamping the screw or the like by rotating the anvil by the free rotation and the collision of the hammer with the anvil when force of a predetermined value or more acts between the hammer and the anvil. SOLUTION: This hammering clamping tool is operated based on the collision detected by a detection means 30 for detecting the collision of the hammer 4 with the anvil, and provided with switch means 38, 114 and 40 for stopping the driving source of the hammer at predetermined timing after the detection of the collision. The switch means 38, 114 and 40 are reset when it is determined that the collision of the hammer 4 with the anvil detected by the detection means 30 occurred before the screw or the like is seated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an impact tightening tool such as an impact wrench or an impact driver.

[0002]

2. Description of the Related Art Impact wrenches, impact drivers, and the like are often used as impact tightening tools for securely tightening screws such as bolts and nuts. This type of tool includes, for example, a hammer that is rotated by a drive source such as an electric motor or an air motor, and an anvil that engages with the screws and rotates the screws. The hammer and anvil engage with each other so that the hammer rotates the anvil. When a force equal to or more than a predetermined value acts between the hammer and the anvil, the hammer is linked to the anvil such that the hammer idles. With such a configuration, while the screw is screwed with a light load (before the screw bottom surface comes into contact with the object to be tightened (before seating)), the hammer continuously rotates the anvil to continuously rotate the screw. Tighten to When the screws are tightened and a force equal to or greater than a predetermined value acts between the anvil and the hammer (after the screw bottom comes into contact with the tightened object (so-called after seating)), the hammer starts to idle and has a predetermined angle. After idling, it will collide with the anvil. By repeating the operation of the idle rotation and the collision, the anvil rotates each time the hammer collides, and the screws are tightened each time.

As is apparent from the above description, in this type of impact tightening tool, the tightening torque of the screws depends on the amount of collision between the hammer and the anvil (the number of collisions). For this reason, if the amount of collision between the hammer and the anvil becomes too large, the tightening torque acting on the screws becomes too large, and the screws may be damaged. Therefore, in order to prevent such a situation, a collision between the hammer and the anvil has been conventionally detected,
Various techniques for automatically stopping the drive source of the hammer based on the detection of the collision have been developed (for example, see Japanese Unexamined Patent Application Publication No.
No. 2006677). One of the prior arts is provided with a detection sensor for detecting a collision between the hammer and the anvil. When the collision between the hammer and the anvil detected by the detection sensor reaches a preset number of times, the driving source of the hammer is changed. Stop. Further, another one of the prior arts is provided with a detection sensor for detecting a collision between the hammer and the anvil, and automatically detects a collision between the hammer and the anvil by a predetermined time after detecting the collision between the hammer and the anvil. It was a technology to stop. According to these conventional techniques, the driving source of the hammer is automatically stopped at a predetermined timing after detecting the collision between the hammer and the anvil (after the first collision is detected). Does not act, and damage to the screws is prevented.

[0004]

However, when there are burrs or the like on the screws and / or the member to be tightened, a force of a predetermined value or more acts between the anvil and the hammer before the screws are seated by the burrs. In some cases. In such a case, the hammer collides with the anvil before the screws are seated. However, in the related art, when a collision between the hammer and the anvil (first collision) is detected, the driving source of the hammer is automatically stopped at a predetermined timing after the detection of the collision. Therefore, when the hammer collides with the anvil before the screws are seated due to the above-mentioned burrs or the like, the driving source of the hammer is stopped based on the collision before seating. For this reason, with a conventional impact tightening tool of the type that stops when the number of collisions reaches the set number of times, the number of collisions before sitting is counted. In addition, in a conventional impact tightening tool of a type in which the driving source of the hammer is stopped a predetermined time after the collision between the hammer and the anvil (the first collision), the driving of the hammer is performed a predetermined time after the collision before sitting. Since the power source is stopped, the tightening torque of the screws may be insufficient, or the drive source may stop before the screws are seated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a desired tightening torque even when a collision of a hammer and an anvil occurs before screws are seated by burrs or the like. A hitting tightening tool capable of tightening screws is realized.

[0006]

Means for Solving the Problems, Functions and Effects In order to solve the above problems, the impact tightening tool according to the first aspect of the present invention provides a tool for tightening an anvil when a force greater than a predetermined value acts between the hammer and the anvil. A hitting tool for tightening screws by rotating the anvil by hitting the anvil after the hammer idles and rotating the hammer at a predetermined angle, and a detecting means for detecting a collision between the hammer and the anvil. And switch means for stopping the drive source of the hammer at a predetermined timing after the collision is detected, based on the collision between the hammer and the anvil detected by the detection means. Further, the impact tightening tool further includes a determination unit that determines whether the collision between the hammer and the anvil detected by the detection unit is before or after the screws are seated, and the determination unit determines whether the collision between the hammer and the anvil occurs. And reset means for resetting the switch means when it is determined that the screws are not yet seated. In the above-described impact tightening tool, when a collision between the hammer and the anvil is detected by the detection unit, a switch unit for stopping the driving source of the hammer is activated based on the detection. If it is determined that the seat is not yet seated, the operation of the switch means is reset by the reset means. For this reason, when a collision between the hammer and the anvil is detected before sitting due to a burr or the like, even if the switch means for stopping the driving source of the hammer is operated based on the detection, the operation is reset. Therefore, the driving source of the hammer is not stopped based on the collision before sitting. Therefore, the screws can be tightened with a desired tightening torque.

Here, the "detecting means" may be any means as long as it can detect a collision between the hammer and the anvil. For example, an acceleration sensor that detects the collision by detecting the acceleration of the hammer, It can be configured by a proximity sensor that detects a collision based on the position of a hammer, a sound sensor (for example, a condenser microphone, a microphone, or the like) that detects a collision by detecting a collision sound between the hammer and the anvil. Further, the method of determining whether the seat is before or after sitting by the “determining means” may be performed by any logic, for example, within a predetermined time (an average time from the start of tightening to seating) from the start of tightening. The logic that determines that a collision is before seating, the logic that determines by the time interval between collisions and the next collision (the time interval between collisions after sitting is short), and the logic that determines the time interval between collisions A logic that determines based on a change (the collision interval after sitting decreases monotonously) (that is, a logic that determines that the seating is before seating when the collision interval becomes longer) or the like can be used.

[0008] The impact tightening tool according to claim 1,
The determination means determines that the collision between the hammer and the anvil is before the screw is seated when the collision between the next hammer and the anvil is not detected within a predetermined time from the detection of the collision between the hammer and the anvil by the detection means. (Claim 2). That is, in the above-described impact tightening tool, the property that the collision between the hammer and the anvil occurs at a relatively short time interval after sitting (the property that the force acting between the hammer and the anvil becomes a predetermined value or more in a short time). Use According to such a method, it is possible to accurately determine whether before or after sitting by relatively simple logic.

[0009] The above object can also be solved by a striking tool according to the third aspect. That is, claim 3
The hammer tightening tool described in (1), when a force greater than a predetermined value acts between the hammer and the anvil, the hammer idles on the anvil, and after the hammer idles by a predetermined angle, the hammer collides with the anvil and the anvil is hit. A hitting tightening tool for tightening screws by rotating the screw, detecting means for detecting collision between the hammer and the anvil, and detecting collision between the hammer and anvil detected by the detecting means before or after the screw is seated. Determining means for determining whether or not the hammer and the anvil have collided after the screws have been seated, and a switch for stopping the drive source of the hammer based on the collision determined to be after seating. Means. In the above impact tightening tool, when a collision between the hammer and the anvil is detected, it is determined whether the detected collision is before or after sitting. Then, when it is determined that the seat has been seated, the switch means for stopping the drive source of the hammer based on the collision is activated, and the drive source of the hammer is stopped. Therefore, the driving source of the hammer is not stopped based on the collision before sitting, so that the screws can be tightened with a desired tightening torque.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The impact tightening tool described in the above-mentioned claims can be suitably implemented in the following forms. (Mode 1) The impact tightening tool according to claim 1,
The switch means includes a timer that is triggered by a collision between the hammer and the anvil detected by the detection means, and a switch circuit that stops the drive source when a predetermined time is counted by the timer. May be. In this embodiment, a timer is activated when a collision is detected, but the timer is reset when the collision between the hammer and the anvil is before seating. Therefore, the driving source of the hammer is driven for a predetermined time after the screws are seated, so that the screws can be securely tightened. (Mode 2) The impact tightening tool according to claim 1,
The switch means includes a count means for counting a collision between the hammer and the anvil detected by the detection means, and a switch circuit for stopping the drive source when the count number of the count means matches a set number. May be configured. According to this aspect, when a collision between the hammer and the anvil is detected, the collision is counted by the counting means. When the collision is before the seating, the counted number of collisions is reset. Therefore, since the hammer and the anvil collide with each other a set number of times after seating, the screws can be tightened with an accurate tightening torque.

[0011]

Next, a tightening tool according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a partial cross-sectional side view of the impact wrench 1. In the figure, reference numeral 3 denotes a housing in which a motor 22 as a driving source is housed and fixed. A gear is formed on the output shaft 20 (supported by the bearing 19) of the motor 22, and a plurality of planet gears 12 mesh with this gear. The planetary gear 12 has a pin 14 as an axis, and the pin 14 is fixed to the spindle 8 supported by a bearing 23. The planetary gear 12 meshes with an internal gear 16 fixed to an internal gear case 18. These gear trains constitute a reduction mechanism for reducing the rotation of the motor 22, and the spindle 8 is rotationally driven by the reduction mechanism.

A plurality of grooves 8a are formed in the spindle 8 in a V-shape, and the hammer 4 can freely rotate on the spindle 8. The ball 6 is interposed between the hammer 4 and the groove 8a. A cam mechanism is constituted by the groove 8a and the ball 6, and the hammer 4 is relatively movable with respect to the spindle 8 along the groove 8a. A ball 51 and a washer 4 are provided between the hammer 4 and the spindle 8.
The spring 10 is housed in a compressed state via the spring 9, and the hammer 4 is constantly urged rightward in the figure. An anvil 2 is rotatably attached to the housing 3 on the tip side of the hammer 4. The tip 2a of the anvil 2 has a polygonal cross section, and a box (not shown) for engaging with the heads of nuts is attached thereto. A pair of ridges 2b, 2c extending in the diameter direction are formed on the rear end surface of the anvil 2. Protrusions 4b, 4c extending in the diameter direction are also formed on the tip end surface of the hammer 4, and the side surfaces of the protrusions 2b, 2c and 4b, 4c abut.

Next, the operation of the above-described tightening mechanism will be described. When the nuts are tightened with a light load in the above-described tightening mechanism (before the nuts are seated), the force acting between the ridges of the anvil 2 and the hammer 4, that is, the ball 6 between the spindle 8 and the hammer 4 The hammer 4 is pressed against the anvil 2 by the force of the spring 10. Therefore, the rotation of the spindle 8 is continuously transmitted to the hammer 4 and the anvil 2, and the nuts (not shown) are continuously tightened. On the other hand, when the tightening force of the nuts is increased (when the nuts are seated and the tightening force is increased), a large force acts between the protrusions of the anvil 2 and the hammer 4, and the spindle 8 and the A large force acts between the hammers 4 via the balls 6.
Therefore, the force for moving the hammer 4 to the rear side of the spindle 8 along the groove 8a also increases. That is, when a force equal to or more than a predetermined value acts between the anvil 2 and the hammer 4, the hammer 4 retreats and the abutting relationship between the ridges 2b, 2c and the ridges 4b, 4c is lost. Idle.
When the ridges 4b and 4c exceed the ridges 2b and 2c, the hammer 4 moves forward by the spring 10. For this reason, the hammer 4 collides with the anvil 2 after rotating by a predetermined angle with respect to the anvil 2. This phenomenon of idle rotation and collision is repeated, and the nuts are more firmly tightened at each collision.

Next, components such as switches provided on the handle portion 3a will be described with reference to FIGS. Here, FIG. 2 is a diagram of the battery pack 122 removed from the impact wrench 1 and viewed from the II direction in FIG. 1 (from below the impact wrench 1). As shown in FIG.
The handle 3 a is provided with a main switch 48 for starting the motor 22 and a forward / reverse switch 24 for switching the rotation direction of the motor 22. Further, a dial setting section 34 is provided at a lower end of the handle section 3a. As shown in FIG. 2, the dial setting unit 34 includes a first setting dial 33 and a second setting dial 3.
5 are provided. The first setting dial 33 has 0
Numeral scales of 9 to 9 and alphabet scales of A to F are provided, and the second setting dial 35 is provided with numerical scales of 0 to 9. In the present embodiment, by appropriately setting these dials 33 and 35, the time from when the collision between the hammer 4 and the anvil 2 is detected to when the motor 22 is stopped can be appropriately set. Here, as is apparent from FIG. 1, the dial setting unit 34 sets each dial 3 only when the battery pack 122 is removed.
It has a structure in which the settings of 3, 35 can be changed. This is to prevent an unintended setting change of the operator. As shown in FIG. 2, a contact 42 is provided at the lower end of the handle portion 3a, and a contact (not shown) of the battery pack 122 is brought into contact with the contact 42. .

A control board 36 is mounted at a position from the lower end in the handle portion 3a as shown in FIG. 1, on which electronic components such as a microcomputer 38 and a switching circuit 114 are mounted. . The control board 36 incorporates a sound receiving unit 30 (such as a piezoelectric buzzer) that receives a collision sound between the hammer 4 and the anvil 2.

Next, the configuration of a control circuit of the main tightening tool 1 will be described with reference to FIG. The control circuit of the tightening tool 1 is mainly composed of a sound receiving unit 30 attached to a control board 36 and a microcomputer 38. The microcomputer 38 includes a CPU 110, a ROM 118, a RAM 120
And the I / O 108 are microcomputers integrated into one chip, and are connected as shown in FIG. The ROM 38 of the microcomputer 38 includes a sound receiving unit 30.
A control program or the like for stopping the motor 22 based on the collision sound between the hammer 4 and the anvil 2 detected in the above is stored. On the other hand, the sound receiving unit 30 is connected to one terminal of the comparator 104 via the filter 102. Comparator 10
The voltage V3 of the reference voltage generator 112 is input to the other terminal of the reference numeral 4. The output voltage of the comparator 104 is input to the microcomputer 38. The battery pack 122 serving as a power supply is connected to the microcomputer 38 and also connected to the motor 22 via the main switch 48, the forward / reverse switch 24, and the switching element 40. This switching element 4
0 is connected to the microcomputer 38 via the switching circuit 114, and is turned on / off by an output signal from the microcomputer 38.
The microcomputer 38 also has a setting dial 3
4 are connected.

In the above-described circuit, when sound is detected by the sound receiving unit 30, a voltage V1 is generated from the sound receiving unit 30. The low-frequency noise is removed from the voltage V1 by the filter 102, and the voltage V1 is output to the comparator 104 as the voltage V2. The comparator 104 outputs a pulse wave by turning on from off when the voltage V2 output from the filter 102 becomes higher than the other comparison voltage V3. The pulse wave output from the comparator 104 is detected by the microcomputer 38. Therefore, when the collision sound between the hammer 4 and the anvil 2 is detected by the sound receiving section 30, a pulse wave is output from the comparator 104, and the microcomputer 38 causes the microcomputer 38 to collide with the hammer 4 and the anvil 2. Will be recognized.

Next, the operation of the microcomputer 38 when the nuts are tightened using the main tightening tool 1 having the above-described configuration will be described with reference to the flowchart shown in FIG. FIG. 4 shows a flowchart of the processing performed by the microcomputer 38. In order to tighten the nuts using the tightening tool 1, first, an operator engages the nuts with a box attached to the tip of the anvil 2. Next, the main switch 48 is turned on. When the main switch 48 is turned on, the microcomputer 38 drives the motor 22 to rotate to tighten the nuts. At this time, the microcomputer 3
At 8, the process described below is performed.

When the main switch 48 is turned on, the microcomputer 38 first reads the numerical value "xy" set in the dial setting section 34 (S10). That is, in the present embodiment, the collision between the hammer 4 and the anvil 2 is detected based on the numerical value “x” set by the first setting dial 33 and the numerical value “y” set by the second setting dial 35. After that, the time from when the motor 22 is stopped is set. Therefore, when the main switch 48 is turned on,
First, the microcomputer 38 controls the dial setting unit 34.
Is read, and the time until the motor 22 is stopped is calculated. Specifically, the set time Tset is (10 × x + y) × 0.02 seconds.
When the numerical value of the dial setting unit 34 is read in step S10, the microcomputer 38 outputs a signal to the switching element 40 via the switching circuit 114, and starts rotation of the motor 22 (S12). As a result, the motor 22 rotates and the fastening of the screws is started.

Next, the microcomputer 38
It is determined whether or not the collision between the anvil 2 and the ma 4 has been detected.
(S14). Specifically, the microcomputer 38
Whether the pulse wave output from the comparator 104 has been input
To judge. Detecting collision between hammer 4 and anvil 2
If not (if NO in step S14), the hammer
Step S14 until a collision between the anvil 2 and the anvil 2 is detected.
(That is, the hammer 4 and the anvil 2
Wait in that state until a collision is detected). Conversely, Han
When a collision between the lug 4 and the anvil 2 is detected [Step S1
4 is YES), the timer T for auto-stop
_autoAnd the collision interval calculation timer T_{widt h}Reset
(S16), these timers T_autoAnd T_widthThe star
(S20). Where the auto-stop timer
T_autoMeans that the motor 22 is stopped after the collision is detected.
Is a timer that measures the time at
Ma T _widthIs whether the collision detected in step S14 is before seating
A timer that measures the time to determine whether it is after sitting
It is.

When the step S20 is completed, the microcomputer 38 next sets the auto stop timer T _auto
Is longer than the time set by the dial setting unit 34 (that is, the time calculated by the numerical value “xy” read in step S10) (S22). If the auto-stop timer T _auto is equal to or greater than the set value [YES in step S22], it is determined that the nuts have been sufficiently tightened and the drive of the motor 22 is stopped (S32). Specifically, the microcomputer 3
8 turns off the switching element 40 by stopping the signal output to the switching element 40. On the other hand, if the timer T _auto for _auto stop is not equal to or greater than the set value (if step S22 is NO), the microcomputer 38 next proceeds with the hammer 4 and the anvil 2
It is determined whether or not a new collision has been detected (S24).
If a collision between the hammer 4 and the anvil 2 has been detected (YES in step S24), the collision interval calculation timer T _width is reset (S28). Then, the collision interval calculation timer T _width is started again (S3).
0), the processing from step S22 is repeated. Conversely, if the collision between the hammer 4 and the anvil 2 is not detected (NO in step S24), it is next determined whether or not the collision interval calculation timer T _width has exceeded a predetermined value (S26). ). Here, the collision interval calculation timer T
_The predetermined value to be compared with the _width time is a time several times the collision interval after the nuts are seated (in this embodiment,
0.1 seconds (5 for normal collision interval of 0.02 seconds after sitting)
Times)]. Therefore, in the present embodiment, when the collision interval calculation timer T _width is equal to or more than a predetermined value, that is, when a new collision cannot be detected even after a predetermined time has elapsed since the detection of the collision [Y in step S26]
In the case of ES], it is determined that the collision detected in step S14 is before seating, and the process returns to step S14 and the processing from step S14 is repeated. Note that the predetermined value to be compared with the collision interval calculation timer T _width can be appropriately set according to the specifications (diameter, material, etc.) of the nuts to be tightened. Conversely, if the collision interval calculation timer T _width is not equal to or greater than the predetermined value (NO in step S26), the process proceeds to step S22.
And the process from step S22 is repeated.

As is clear from the above description, in the fastening tool 1 according to the present embodiment, when the collision between the hammer 4 and the anvil 2 is detected, a timer different from the _auto stop timer T _auto (that is, the collision interval calculation) is used. Timer T _width ) starts. If the next collision is not detected while the collision interval calculation timer T _{width measures the} predetermined time, the detected collision (each of the timers T _auto , T _auto
it is determined that the collision has become due to start the _width) it is before sitting again auto stop timer T _auto collision interval calculation timer T _auto when it detects a next collision
Will be reset and restarted. Therefore, based on the collision before seating, the timer T
_{The auto} is not activated and the motor 22 is not stopped, and the motor 22 is stopped based on the collision after sitting. Therefore, according to the tightening tool 1 of the present embodiment, even when a collision occurs before seating due to a burr or the like, the motor 22 continues to be driven for a predetermined time (time set by the dial setting unit 34) after seating. Therefore, the screws can be tightened with a desired torque.

The preferred embodiment of the present invention has been described in detail above, but this is merely an example, and the present invention may be embodied in various modified and improved forms based on the knowledge of those skilled in the art. Can be. For example, in the above-described embodiment, the present invention is applied to the tightening tool that stops the motor 22 after a predetermined time from detecting the collision between the hammer 4 and the anvil 2, but the present invention is not limited to such a form. No hammer 4
The present invention can be applied to various types of tightening tools having a function of stopping the rotation of the motor 22 based on the collision of the motor 22 and the anvil 2 (so-called automatic stop function). For example, the present invention can be applied to a fastening tool of a type that stops the motor 22 when the number of collisions between the hammer 4 and the anvil 2 reaches a preset number. For these types,
When it is determined that the detected collision is before seating, the collision may be invalidated (the count number is decremented by 1), or the previous count number may be reset. In short, a method of resetting the counted number of collisions may be adopted in accordance with the timing (logic) of the judgment before sitting or after sitting. In the above-described embodiment, the automatic stop timer is activated when a collision is detected, and the timer is reset when the collision is before the seating. However, the present invention is not limited to such a configuration, and the collision is performed after the seating. After the determination is made, the automatic stop timer may be operated. In such a mode, the time to be measured by the auto-stop timer may be determined in consideration of the time required to determine that the collision is after seating (for example, in the above-described embodiment, the time set by the dial setting unit 34 is set). Is programmed to count 0.1 seconds from the elapsed time).

In the embodiment described above, an example in which the present invention is applied to an impact wrench has been described. However, the present invention is not limited to such a tool but can be applied to various impact tightening tools. . For example, the present invention can be applied to a soft impact driver, a striking tool such as a torque wrench, or the like.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional side view of a tightening tool according to the present embodiment.

FIG. 2 is a view of the battery pack removed from the tightening tool of the embodiment and viewed from below (from the direction II in FIG. 1).

FIG. 3 is a block diagram showing a circuit configuration of the tightening tool according to the embodiment.

FIG. 4 is a flowchart for explaining the operation of the tightening tool according to the embodiment.

[Explanation of symbols]

 2 Anvil 4 Hammer 30 Sound receiving part 34 Dial setting part 38 Microcomputer 48 Main switch

Claims (3)

[Claims] 1. A method in which a hammer idles on an anvil when a force equal to or more than a predetermined value acts between the hammer and anvil, and after the hammer idles at a predetermined angle, the hammer collides with the anvil to rotate the anvil. And a detecting means for detecting a collision between the hammer and the anvil, and a predetermined timing after the collision is detected based on the collision between the hammer and the anvil detected by the detecting means. A switch means for stopping the drive source of the hammer by means of: a judging means for judging whether the collision between the hammer and the anvil detected by the detecting means is before or after the screws are seated; a collision between the hammer and the anvil by the judging means And a reset means for resetting the switch means when it is determined that the screws are not seated yet. 2. A striking tool according to claim 1, wherein said judging means does not detect a collision between the next hammer and the anvil within a predetermined time after the collision between the hammer and the anvil is detected by the detecting means. A striking tool that determines that the collision between the hammer and the anvil is before the screws are seated. 3. A hammer idles on the anvil when a force greater than a predetermined value acts between the hammer and the anvil, and after the hammer idles by a predetermined angle, the hammer collides with the anvil to rotate the anvil. And a detecting means for detecting a collision between the hammer and the anvil, and judging whether the collision between the hammer and the anvil detected by the detecting means is before or after the screws are seated. And a switch for stopping the drive source of the hammer based on the collision determined to be after seating when the collision between the hammer and the anvil is determined to be after seating of the screws by the determination unit. Hammering tightening tool.