JP2012139767A - Driving tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving tool that generates extremely small striking noise, that can drive a bolt or a screw in one strike, and that generates small reaction.SOLUTION: A motor 30 is a brushless motor and is provided with an electric-current detecting device (not shown) that is capable of detecting electric current flowing through the motor 30. The electric-current detecting device (not shown) is electrically connected to a control circuit 15, so as to detect an electric current value in the control circuit 15. A weight engaging section 34 engages with an engaging concave section 40a of a weight 40, and as a result, the weight 40 and an output shaft 31 are integrally rotatable. Rotational energy transmitted to an end-bit per driving torque of 1 Nm by rotation of the weight 40 is 0.2 J to 0.4 J, and a motor rotational speed and a moment of inertia of the weight 40 are respectively 350 rad/s to 500 rad/s and 80 kg×mto 150 kg×m. By these values, rotational energy of the end-bit (not shown) can be controlled to 8 J to 16 J.

Description

  The present invention relates to a tightening tool, and more particularly to a tightening tool for tightening a screw, a bolt, or the like with a tip tool.

  Conventionally, tightening tools as so-called impact tools for tightening screws, bolts and the like are known. As an impact tool, one having a configuration in which a striking force is transmitted to an output shaft in a rotational direction by a rotational impact force of a hammer is known. The impact tool having this configuration includes a motor, a hammer, and an anvil.

  In the impact tool, the motor installed in the housing is driven using the power supplied from a rechargeable battery or the power supplied from the outside by an AC or DC power cord (not shown). The spindle is rotated by the motor via the speed reduction mechanism. Then, tightening is performed by striking the anvil with a hammer that is rotatable on the spindle and movable in the axial direction via a steel ball inserted into a cam groove formed on the spindle.

  The hammer is pushed forward by a spring arranged between the speed reduction mechanism and the spindle, and if the rotational resistance increases after the screw is seated, the rotation of the anvil is suppressed, and the hammer gets over the hammer collision part of the anvil. Accelerate and hit the anvil again. In this manner, several to ten and several times of rotational impact force is transmitted continuously or intermittently to a tip tool (not shown) such as a hexagon socket, and operations such as nut tightening and bolt tightening are performed. Such a tightening tool is described in, for example, JP-A-2005-022082 (Patent Document 1).

  However, with a tightening tool of this configuration, the hammer and anvil are generally made of metal, so the impact effect is great, but the noise at the time of collision is very large, and it can be used in environments where low noise is required. It becomes difficult.

  Therefore, an oil pulse tool having an oil pulse mechanism is known as a mechanism for transmitting rotation of a motor as a tightening tool with reduced noise. The oil pulse unit of the oil pulse tool is composed of two parts: a drive part that rotates in synchronization with the motor and an output part that rotates in synchronization with the output shaft to which the tip tool is attached. Each time the drive portion makes one revolution, the oil pressure suddenly rises at a position where the oil provided at one position for the one revolution is sealed, an impact pulse is generated, and the output shaft tightening torque is transmitted. As a result, a rotating impact force of several to ten and several times is transmitted continuously or intermittently to a tip tool (not shown) such as a hexagon socket to perform operations such as nut tightening and bolt tightening. Such a tightening tool is described in, for example, Japanese Patent Application Laid-Open No. 2003-039341 (Patent Document 2).

JP 2005-022082 A JP 2003-039341 A

  However, although the oil pulse tool described in Patent Document 2 has a noise level lower than that of the impact tool described in Patent Document 1, generally, when a bolt or the like is tightened, the tightening is performed by several to dozens of impacts. The noise is conspicuous in a difficult place. In addition, when installing parts in a factory, etc., there is a case where the installation is confirmed by sound. If an oil pulse tool is used in such a factory, the noise of the oil pulse tool may hinder the work. is there. Therefore, there is a demand for a tool with lower noise than oil pulse tools.

  Here, the noise reduction means to reduce the sound generated at the time of one hit and to reduce the number of times the sound is generated by reducing the number of hits as much as possible.

  In the case of reducing the number of hits, for example, if a motor having a configuration in which a motor and a tip tool are connected via a reduction mechanism is used, screwing can be performed with one hit. However, the tightening torque is less than or equal to one-tenth for an impact tool using the same motor, and the reaction transmitted to the hand becomes very large, which is dangerous. In the case of a general cordless oil pulse tool, the danger is smaller than that of an impact tool, but the reaction that is transmitted to the hand during bolting is still a burden during continuous operation.

  Therefore, an object of the present invention is to provide a tightening tool that can tighten a bolt or a screw with a very small impact sound and can be fastened with a single impact, and has a small reaction.

  In order to achieve the above object, the present invention includes a motor having an output shaft, a housing that houses the motor, a tip tool holding unit that is connected to the motor and is driven to rotate by the motor, and a rotation reduction mechanism. A clamping tool comprising a weight that can be connected to the output shaft without intervention and that can rotate integrally with the output shaft of the motor, and the weight and the tip tool holding portion are configured to be integrally rotatable. Is provided.

  The weight that can rotate integrally with the output shaft of the motor includes a weight that rotates around the output shaft of the motor.

  The weight can be connected to the output shaft and can rotate integrally with the output shaft of the motor. In addition, it is possible to perform only one blow in the rotation direction. For this reason, since an impact does not arise inside the tightening tool, the impact sound is small, and the reaction transmitted to the hand can be suppressed. Further, the torque can be controlled by adjusting the rotational speed by electrical control. Further, since the rotation speed reduction mechanism is not provided between the motor and the output shaft, the reaction transmitted to the hand can be suppressed as much as possible.

  Here, the control of rotating the motor at a constant speed after the start of driving of the motor, and the supply of current to the motor is interrupted when the current value flowing through the motor becomes a predetermined value or more during the constant rotation of the motor. Alternatively, it is preferable to have a control means for performing the control of decreasing.

  Control to rotate the motor at a constant speed after the motor starts driving, and control to interrupt or reduce the supply of current to the motor when the value of the current flowing through the motor exceeds a predetermined value during the constant rotation of the motor. Since it has a control means, after seating is completed after tightening the fastening tool to be fastened by the tip tool held by the tip tool holding part, the motor rotation is stopped or the motor rotation number is reduced to waste power. This can be prevented.

  Moreover, it is preferable that the rotational energy of the tip tool holding portion per tightening torque of 1 Nm of the fastening tool fastened by the tip tool held by the tip tool holding portion is 0.2 J or more and 0.4 J or less. Since the rotational energy of the tip tool holding portion per 1 Nm of tightening torque of the fastener tightened by the tip tool held by the tip tool holding portion is 0.2 J or more and 0.4 J or less, based on this value, the target The rotational speed of the tip tool can be easily set according to the tightening torque value.

Further, the inertia moment of the weight is 80 kg · m ² or more and 150 kg · m ² or less, and the motor can rotate the tip tool holding portion at a rotational speed of 350 rad / s or more and 500 rad / s or less. The rotational energy of the holding part is preferably 8J or more and 16J or less.

The inertia moment of the weight is 80 kg · m ² or more and 150 kg · m ² or less, and the motor can rotate the tip tool holding portion at a rotational speed of 350 rad / s or more and 500 rad / s or less, and the rotational energy of the tip tool holding portion is Since it is 8 J or more and 16 J or less, high torque fastening can be efficiently realized even with a low noise and low reaction fastening tool.

  Further, it is preferable that the weight is directly connected and fixed to the output shaft of the motor. Since the weight is directly connected and fixed to the output shaft of the motor, the configuration of the weight that rotates integrally with the output shaft of the motor can be simplified.

  Further, it is preferable that a plurality of weights are provided. Since a plurality of weights are provided, it is possible to disperse and reduce a burden on a member that supports the weight, for example, an output shaft of a motor. For this reason, it can suppress that the output shaft of a motor breaks. Moreover, the slip which arises between an output shaft and a weight can be suppressed, and an energy loss can be suppressed.

  And a rotation start delay means for connecting the tip tool holding portion and the weight and rotating the tip tool holding portion and the weight integrally after rotating by a predetermined angle after the weight starts to rotate. Is preferred.

  Since there is a rotation start delay means for connecting the tip tool holding part and the weight and rotating the tip tool holding part and the weight integrally after rotating by a predetermined angle after the weight starts to rotate, the weight starts to rotate. The weight of rotation can be applied to the weight until the weight and the tip tool start to rotate integrally. For this reason, for some reason, the fastening tool tightened with the tip tool held by the tip tool holding portion does not become a so-called free-run state in which a load is hardly applied to rotate while the tightening is not completed. If the rotation stops at this time, it is possible to escape from such a state and return to a free-run state. Moreover, it is possible to follow up the fastening tool once fastened.

  As described above, the present invention can provide a tightening tool that has a very low impact sound and that can fasten bolts and screws with a single impact and that has a small reaction.

Sectional drawing which shows the clamping tool by embodiment of this invention. The front view which shows the front-end part of the output shaft of the motor of the clamping tool by embodiment of this invention. The graph which shows the relationship between the electric current value of the motor in the fastening tool by embodiment of this invention, torque, and rotational speed. The graph which shows the relationship between the inertia moment of the weight of the fastening tool by embodiment of this invention, and rotational speed. The flowchart which shows operation | movement of the clamping tool by embodiment of this invention, and control of a control circuit. Sectional drawing which shows the modification of the clamping tool by embodiment of this invention. FIG. 7 is a cross-sectional view of a main part along VII-VII in FIG. 6.

  An embodiment of a tightening tool according to the present invention will be described with reference to FIGS. As shown in FIG. 1, the tightening tool 1 is specifically a tightening tool for tightening a screw, and includes a housing 10, a motor 30, and a weight 40. A "screw" that is tightened with a tightening tool is a bolt that is screwed onto a nut. Specifically, there is little load to rotate at the start of tightening, and the load suddenly increases when tightening is completed. Means.

  The housing 10 includes a body housing part 11 and a handle housing part 12, and the body housing part 11 and the handle housing part 12 are integrally formed of resin and are integrally connected to each other. The body housing part 11 has a substantially cylindrical shape, and the motor 30 and the weight 40 are arranged side by side in the body housing part 11. In the following description, the side on which the weight 40 is disposed with respect to the motor 30 is defined as the front side, and the side on which the motor 30 is disposed with respect to the weight 40 is defined as the rear side. Further, description will be made by defining the upper side of FIG.

  The handle housing portion 12 incorporates a control circuit 15 and a storage device (not shown), and a trigger 13 is provided at the upper end portion of the handle housing portion 12. A storage device (not shown) stores in advance an upper limit value of the current flowing through the motor 30 when the screw is seated as will be described later. A rechargeable battery 14 is detachably attached to the handle housing portion 12 at the lower end portion of the handle housing portion 12. The battery 14 can supply power to the motor 30 and the control circuit 15. The control circuit 15 is configured to supply power to the motor 30 when the trigger 13 is operated by an operator.

  An operation unit (not shown) that can set the number of rotations of the motor 30, the value of the current flowing through the motor 30, and the like is provided outside the body housing unit 11. An operation unit (not shown) is electrically connected to the control circuit 15.

  Further, an inner cover 36 is provided in a portion of the body housing portion 11 that accommodates a weight 40 described later. A metal bearing 37 is provided at the rear of the inner cover 36. The metal bearing 37 rotatably supports a rear end portion of a weight 40 described later. A hammer case 38 is connected to the inner cover 36, and the inner cover 36 and the hammer case 38 define a space for accommodating the weight 40.

  A seal member (not shown) is provided at a portion where the inner cover 36 and the hammer case 38 overlap in the vertical direction so as to be sandwiched between the inner cover 36 and the hammer case 38. A seal member (not shown) seals the internal lubricating oil so as not to leak out. A metal bearing 39 is provided on the inner peripheral surface of the front portion of the hammer case 38, and the metal bearing 39 supports the front portion of the weight 40 so as to be rotatable.

  The motor 30 is configured by a brushless motor, and a current detection device (not shown) capable of detecting a current flowing through the motor 30 is provided. A current detection device (not shown) is electrically connected to the control circuit 15 so that the control circuit 15 can detect a current value. The motor 30 includes an output shaft 31 extending in the front-rear direction. The output shaft 31 is supported by the body housing part 11 via a bearing 32 so as to be rotatable with respect to the body housing part 11. The output shaft 31 of the motor 30 can rotate at a maximum of 500 rad / s. A fan 33 is provided in the portion of the output shaft 31 that is located in front of the motor 30. The fan 33 is fixed to the output shaft 31 so as to be integrally rotatable with the output shaft 31. The mass of the fan 33 is 120 g.

  A weight engaging portion 34 is provided at the front end portion of the output shaft 31. As shown in FIG. 2, the weight engaging portion 34 has a pair of parallel sides 34 </ b> A and a pair of arcs 34 </ b> B connecting the ends of the pair of sides 34 </ b> A. The output shaft 31 is fixed at the center position.

  As shown in FIG. 1, the weight 40 is disposed in the inner front space of the body housing portion 11, and an engagement recess 40 a is formed at the rear end thereof. The engaging recess 40a has substantially the same shape as the weight engaging portion 34, and the weight engaging portion 34 is engaged with the engaging recess 40a. The front end portion 40A of the weight 40 forms a tool driving unit and has a substantially cylindrical shape with the rear side closed. The front end portion 40 </ b> A of the weight 40 is exposed from the front end of the body housing portion 11 to the outside of the body housing portion 11 and protrudes forward from the body housing portion 11.

  The front end portion 40A of the weight 40 is provided with a sleeve 41 having a substantially cylindrical shape so as to wrap around the front end portion 40A of the weight 40. A convex portion 41A that protrudes inward in the radial direction of the sleeve 41 is provided on the inner peripheral surface of the sleeve 41, and the sleeve 41 can move within a predetermined range in the front-rear direction. Further, the internal space of the front end portion 40A of the weight 40 having a substantially cylindrical shape forms a tip tool engagement recess 40b that can engage a rear end portion of a tip tool (not shown) such as a hexagon socket.

  Further, a plurality of ball holding holes 40c are formed in the front end portion 40A of the weight 40 to communicate the external space and the internal space of the front end portion 40A. One ball 42 is disposed in each of the plurality of ball holding holes 40c. The ball 42 can move outward in the radial direction of the front end portion 40A of the weight 40 when the sleeve 41 is not in contact with the convex portion 41A of the sleeve 41 due to the movement of the sleeve 41 in the front-rear direction. At this time, the rear end portion of the tip tool (not shown) is inserted into the tip tool engagement recess 40b, and the ball 42 is engaged with the recess (not shown) formed in the rear end portion. Thereafter, the sleeve 41 is moved so that the ball 42 is in contact with the convex portion 41A of the sleeve 41, whereby the ball 42 is restricted from moving outwardly in the radial direction of the front end portion 40A of the weight 40. The front end tool is connected to the front end portion 40A so as not to come off from the front end portion 40A of the weight 40. The tip tool (not shown) has a hexagonal recess that is substantially the same shape as the screw head at the tip, and the motor 30 is driven with the screw head engaged in the recess. The screw can be tightened by rotating the tool. The front end portion 40A corresponds to a tip tool holding portion.

  The mass of the weight 40 is about 330 g. A tightening torque for tightening a screw or the like by a tip tool (not shown) varies depending on the rotational energy of the tip tool. Large rotational energy is required to obtain a large tightening torque. The relationship between torque and rotational energy varies depending on the size of the screw to be tightened, the rigidity at the time of screw seating, the resistance during screw rotation, and the like, but in the tightening tool 1, it is transmitted to the tip tool per tightening torque of 1 Nm. The rotational energy is set to 0.2J to 0.4J. The conventional rotational energy per 1 Nm is 0.1 or less in the oil pulse tool, and about 0.02 in the conventional impact tool. Therefore, the rotational energy in the tightening tool 1 of the present embodiment, in other words, the rotational speed and the moment of inertia are much larger than those of conventional impact tools and oil pulse tools.

  In the graph of FIG. 4, the tightening tool 1 of the present embodiment is A, and the relationship between the rotational speed of the motor 30 and the weight 40 and the inertia moment of the weight 40 is shown. Also, the relationship between the rotation speed of the hammer and the moment of inertia of the hammer is shown with B as the conventional impact tool. In addition, the relationship between the rotational speed of the drive portion that rotates in synchronization with the motor 30 and the moment of inertia of the portion is shown with C as the conventional oil pulse tool. It can be seen from the graph shown in FIG. 4 that the tightening tool 1 performs screw tightening by rotating a large moment of inertia at a high rotational speed.

The tightening torque value is determined to some extent by the rotational energy value, but not only the rotational energy value but also the rotational speed value and the moment of inertia value suitable for the size of the motor 30 must be determined. For example the rotational speed in the case of targeting about tightening torque 30Nm tightening moment of inertia of the weight 40, in this embodiment respectively ^{350rad / s~500rad / s, 80kg ·} m 2 ~150kg · m 2. More preferably, it is 400 rad / s and 100 kg · m ² .

If the weight 40 becomes too heavy, it takes time to reach the target rotational speed at the time of activation. Accordingly, the upper limit value of the inertia moment of the weight is 150 kg · m ² and the lower limit value of the rotational speed is 500 rad / s. On the other hand, if it is too light, the number of rotations of the motor 30 must be increased, and the efficiency is reduced due to an increase in mechanical loss of the fan 33 and the like, and the torque of the motor 30 is also reduced. Disappear. Therefore, the lower limit value of the inertia moment of weight is 80 kg · m ² and the lower limit value of the rotational speed is 350 rad / s. By setting these values, the rotational energy of the tip tool (not shown) can be set to 8J to 16J, and the tightening performance can be efficiently exhibited in the configuration of the tightening tool 1 of the present embodiment.

  The control by the control circuit 15 and the operation of the tightening tool 1 when the screws are tightened by the tightening tool 1 are as shown in FIG. First, the rotational speed of the motor 30 and the upper limit value of the current flowing through the motor 30 are input and set from an operation unit (not shown) (S1). Next, the operator operates the trigger 13 to start driving the motor 30 (S2). When the drive of the motor 30 is started, the screw rotates in a state where there is almost no resistance to tightening the screw when the screw is rotating, that is, in a free-run state, and the rotational speed is increased (S3). Thereafter, when the rotation speed of the motor 30 set in S1 is reached, the motor 30 continues to rotate at a constant rotation speed until the screw is seated as described later (S4, section A in FIG. 3).

  Next, when the screw is seated and the rotation of the screw is stopped (S5, point B in FIG. 3), the current value detected by a current detection device (not shown) increases rapidly, the torque increases rapidly, and the rotation The speed decreases rapidly (S6, section C in FIG. 3). When the current value becomes larger than the upper limit value of the current stored in the storage device (not shown) (S6, point D in FIG. 3), the supply of current to the motor 30 is stopped or the electronic A clutch is performed (S7). Here, the electronic clutch means that a low current is supplied to the motor 30 under the control of the control circuit 15 to cause the motor 30 to perform forward and reverse operations in small increments.

  In the present embodiment, since the weight 40 having a large moment of inertia is rotated at a high speed, it is difficult to control the tightening torque. In addition, when a screw generates resistance before it is seated due to a dimensional error between the screw and the hole or when foreign matter is caught between the screw and the hole during screw tightening, the required rotational speed cannot be obtained and the screw The tightening performance is expected to decrease. Further, the rotational energy at the time of sitting also decreases when the rigidity of the tightened object to which the screw or the like is tightened is low.

  However, since the control is performed by the control circuit 15 as shown in the above flowchart, a slight difference in resistance at the time of screw tightening can be adjusted. Further, if the current supplied to the motor 30 at the time of sitting exceeds the upper limit value, the excess rotational energy can be cut off by interrupting or reducing the supply of electric power (electronic clutch).

  Since the weight 40 is connected to the output shaft 31 of the motor 30 and can rotate integrally coaxially with the output shaft 31, the screw tightened by the rotation of the tip tool is finally tightened, and only one impact is applied in the rotational direction. A blow can be made.

  For this reason, since an impact does not arise inside the tightening tool 1, the impact sound is small, and the reaction transmitted to the hand can be suppressed. Further, the torque can be controlled by adjusting the rotational speed by electrical control. Moreover, since the rotation speed reduction mechanism is not provided between the output shaft 31 of the motor 30, the reaction transmitted to a hand can be suppressed as much as possible.

  In addition, since the rotational energy of the tool per 1 Nm of the tightening torque for tightening the screw is 0.2 J or more and 0.4 J or less, based on this value, the motor 30 and the tip tool are set according to the target tightening torque value. The number of rotations can be set easily.

Further, the moment of inertia of the weight 40 is ^{80kg · m 2 ~150kg · m 2} , the motor 30 is rotatable at a rotational speed of 350rad / s~500rad / s the tool, rotational energy of the tool 8J than 16J less Therefore, even with the low noise and low recoil tightening tool 1, high torque tightening can be efficiently realized.

  Further, since the weight 40 is directly connected and fixed to the output shaft 31 of the motor 30, the configuration of the weight 40 that rotates integrally with the output shaft 31 of the motor 30 can be simplified.

  The tightening tool of the present invention is not limited to the above-described embodiment, and various modifications and improvements can be made within the scope described in the claims. For example, in the present embodiment, the tip tool (not shown) is detachably attached to the tool drive unit that is the front end portion 40A of the weight 40, but the present invention is not limited to this configuration. For example, as shown in FIGS. 6 and 7, the weight 140 of the tightening tool 101 and the tip tool attaching portion 140 </ b> A that is a tool driving portion may be configured separately, and these may be integrally rotated.

  Specifically, the front end surface of the weight 140 is provided with a pair of weight-side convex portions 141 </ b> C protruding forward at a diametrical position centered on the axis of the weight 140. As shown in FIG. 7, the weight-side convex portion 141 </ b> C has a fan-shaped cross section cut by a plane perpendicular to the front-rear direction. A rear end surface of the tip tool attachment portion 140A is provided with a pair of fan-shaped attachment portion-side convex portions 140B that protrude rearward at a diametrical position centered on the axis of the weight 140. When the weight 140 rotates integrally with the output shaft 31 of the motor 30, the weight-side convex portion 141C rotates around the axis of the weight 140, contacts the mounting portion-side convex portion 140B, and makes the mounting portion-side convex portion 140B the weight 140. , The tip tool mounting portion 140A is rotated coaxially and integrally with the weight 140 and the output shaft 31 of the motor 30. The weight side convex portion 141C and the attachment portion side convex portion 140B correspond to rotation start delay means.

  With such a configuration, the tip tool mounting portion 140A can be made to play with respect to the rotation of the weight 140, and after the weight 140 starts to rotate, the weight side convex portion 141C becomes the mounting portion side convex portion 140A. The momentum of rotation can be applied to the weight 140 until it comes into contact with the weight 140. For this reason, if for some reason the screw that is tightened with the tip tool (not shown) has not been completely tightened and has not stopped running, it has escaped from such a state, and again It can be in a free-run state. Moreover, the screw once fastened can be tightened.

  Moreover, you may comprise a tool drive part and a front-end tool integrally.

  Further, in this embodiment, the weight 40 can be integrally rotated with the output shaft 31 of the motor 30 by being directly fixed to the rotating shaft of the motor 30, but may not be directly fixed. Moreover, although one weight 40 is provided, it is not limited to one. For example, a plurality of weights are provided, a weight support portion is connected to the output shaft 31 of the motor 30, a plurality of weights are respectively fixed to the weight support portions, and a plurality of weights are rotated around the output shaft 31 of the motor 30. It is good also as a structure which can be moved or rotated.

  Since a plurality of weights 40 are provided, the burden on the member that supports the weights 40, for example, the output shaft 31 of the motor 30, can be distributed and reduced. For this reason, it is possible to prevent the output shaft 31 of the motor 30 from being damaged. Moreover, the slip produced between the output shaft 31 and the weight 40 can be suppressed, and energy loss can be suppressed.

  In the present embodiment, the weight 40 and the output shaft 31 of the motor 30 are directly connected and fixed to rotate integrally, but the present invention is not limited to this configuration. For example, the weight and the output shaft of the motor are connected and rotated integrally until the tightening is completed after the screw starts rotating, and then the weight and the output shaft of the motor are disconnected and do not rotate integrally. Also good.

  In the present embodiment, the number of rotations of the motor 30 is controlled and the current value supplied to the motor 30 is changed depending on the magnitude of the current value flowing through the motor 30. However, the present invention is limited to both the number of rotations and the current value. Instead, only one of them may be controlled.

  In the present embodiment, the brushless motor 30 that is an electric motor is used. However, the present invention is not limited to the brushless motor 30. For example, an air motor or the like may be used.

  In the present embodiment, the “screw” tightened with the tightening tool 1 is specifically a bolt, but is not limited to a bolt. Any load may be used as long as the load for rotating is hardly applied at the start of tightening and the load is rapidly increased when the tightening is completed.

  The tightening tool of the present invention is particularly useful in the field of tightening tools for tightening screws and bolts.

DESCRIPTION OF SYMBOLS 1,101 ... Tightening tool 10 ... Housing 30 ... Motor 31 ... Output shaft 40, 140 ... Weight

Claims (7)

A motor having an output shaft;
A housing for housing the motor;
A tip tool holder connected to the motor and driven to rotate by the motor;
A weight that can be connected to the output shaft without using a rotation speed reduction mechanism and that can rotate integrally with the output shaft of the motor;
The tightening tool, wherein the weight and the tip tool holding portion are configured to be integrally rotatable.   Control that rotates the motor at a constant speed after the motor starts driving, and interrupts or reduces the supply of current to the motor when the value of the current flowing through the motor exceeds a predetermined value during the constant rotation of the motor The tightening tool according to claim 1, further comprising control means for performing control.   The rotational energy of the tip tool holding portion per 1 Nm of tightening torque of a fastener fastened by the tip tool held by the tip tool holding portion is 0.2 J or more and 0.4 J or less. The tightening tool according to 1. An inertia moment of the weight is 80 kg · m ² or more and 150 kg · m ² or less, and the motor can rotate the tip tool holding portion at a rotational speed of 350 rad / s or more and 500 rad / s or less, and the tip tool holding portion The tightening tool according to claim 3, wherein the rotational energy of is not less than 8 J and not more than 16 J.   2. The tightening tool according to claim 1, wherein the weight is directly connected and fixed to the output shaft of the motor.   2. The tightening tool according to claim 1, wherein a plurality of weights are provided.   And a rotation start delay means for connecting the tip tool holding portion and the weight and rotating the tip tool holding portion and the weight integrally after the weight starts to rotate by a predetermined angle. The fastening tool according to claim 1.

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