JP2007245284A - Rotary fastening tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotary fastening tool capable of effectively reducing a reaction force in fastening work transmitted to a worker holding the rotary fastening tool. <P>SOLUTION: The rotary fastening tool 10 is equipped with a motor 1, a reducer 2 composed of a planetary gear mechanism mounted to a rotary shaft 11 of the motor 1, an output shaft 51 mounted to the reducer 2, a fixing member 52 which is mounted to the tip end of the output shaft 51 and fixes a fastened member (a), and a control means for variably adjusting the rotational speed of the rotary shaft 11 by a pulse signal. The planetary gear mechanism is composed of a sun gear 21 fixedly provided on the rotary shaft 11, a plurality of planetary gears 22, 22 moving around the sun gear rotating on the outer periphery, and an outer ring gear 24 serving as a housing and rotating on an outer hull of an orbital track of the planetary gears 22, 22. An annular member 4 is fixedly provided on the motor 1, and the outer ring gear 24 is surrounded by the annular member 4 in a mechanically separated attitude. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a rotary tightening tool used for tightening bolts, nuts, and the like, and in particular, effectively reduces a reaction force at the time of tightening transmitted to an operator holding the rotary tightening tool. The present invention relates to a rotary fastening tool that can be used.

  When tightening bolts and nuts, hand-held rotary tightening tools are frequently used. The rotary tightening tool has a motor and a speed reducer that reduces the rotational speed and converts it to high torque, and can be used to fasten bolts or the like to any workpiece at a constant rotational speed. it can. At the time of this rotary tightening, since the reaction force at the time of tightening is transmitted to the worker holding the rotary tightening tool, when the reaction force is large, Depending on the situation, it may impose a mental burden. Therefore, the torque range of the hand-held rotary tightening tool must be narrowed.

  In response to the above problem, it is common to attach a reaction force receiver to the rotary tightening tool and tighten the bolts etc. with the reaction force receiver installed on the workpiece. Therefore, it is necessary for the reaction force receiver to comply with the restrictions due to the shape of the workpiece to be installed. Therefore, the reaction force receiver according to the restrictions on the workpiece side will be applied, but the shape on the workpiece side will be changed variously depending on the tightening part such as bolts, so prepare a reaction force receiver applicable each time. Is too expensive in terms of cost.

  On the other hand, a striking tool that is provided with a piston that reciprocates when driven by a motor and that strikes a workpiece while striking a bolt or the like with a stroke of the piston is well known. In the case of this impact tool, the reaction force is smaller than that of the rotary tightening tool, and therefore it is possible to take a wider torque range. However, since the generated tightening torque is caused by the impact force, Variations in tightening torque increase due to the rigidity of the screw, and it is difficult to apply it to parts that require torque management accuracy.

  By the way, patent document 1 can be mentioned as a conventionally disclosed technique regarding a rotary fastening tool. This rotary fastening tool is a rotary fastening tool with an automatic clutch device provided with at least a gear drum provided with an internal gear and a resilient engagement clutch means provided between the gear drum and the casing. When the tightening torque to the material to be fastened exceeds a predetermined torque, the clutch between the gear drum and the casing is released, and the gear drum rotates relative to the casing to reduce the reaction force. Can be planned.

Japanese Patent Publication No. 60-13798

  According to the rotary fastening tool disclosed in Patent Document 1, it is possible to reduce the reaction force when fastening a bolt or the like without applying a reaction force receiver. However, since the locking force by the clutch means is used to suppress the rotation of the gear drum, the tightening reaction force until the locking force is released cannot be reduced. Although there is no particular description in the literature, the drive motor of the rotary tightening tool is rotationally tightened with a continuous torque by a continuous current, and therefore, the torque reaction force from the seating to the completion of tightening becomes large. I know that.

  The present invention has been made in view of the above-described problems, and effectively reduces the reaction force at the time of tightening transmitted to an operator holding a rotary tightening tool over the entire tightening work process. An object of the present invention is to provide a rotary tightening tool that can be used.

  In order to achieve the above object, a rotary tightening tool according to the present invention includes a motor, a reduction gear comprising a planetary gear mechanism mounted on the rotation shaft of the motor, an output shaft mounted on the reduction gear, and a tip of the output shaft. And a control member that variably adjusts the rotational speed of the rotating shaft by a pulse signal, and the planetary gear mechanism is fixed to the rotating shaft. A sun gear, a plurality of planetary gears that revolve while rotating on the outer periphery thereof, and an outer ring gear that rotates on the outer periphery of the revolution orbit of the planetary gear, and the outer ring gear is relative to the motor. It is comprised so that it can rotate freely.

  A servo motor, a stepping motor, etc. can be applied to the motor constituting the rotary fastening tool of the present invention. A reduction gear made of a known planetary gear mechanism is mounted on the rotation shaft of the motor, and the tip of the output shaft protruding from the reduction gear is fixed by a socket for temporarily fixing a bolt, a screwdriver bit for temporarily fixing a screw, or the like. A member is mounted.

  The rotary tightening tool of the present invention is configured so that the outer ring gear constituting the speed reducer can rotate relative to the motor, and a great reaction force at the time of rotary tightening of the fastened material is generated from the outer ring gear to the motor. And it is not transmitted to the gripping part.

  The motor torque is amplified at a predetermined reduction ratio to become output torque, and a reaction force substantially corresponding to this output torque is returned to the speed reducer. At this time, the outer ring gear of the speed reducer is applied to the motor. Therefore, most of the reaction force is finally transmitted only to the outer ring gear, and inertia due to the reaction force acts on the outer ring gear. On the other hand, theoretically, only the motor torque is returned as a reaction force to the gripping portion directly gripped by the worker.

  In the rotary fastening tool of the present invention, in order to reduce the reaction force described above as much as possible, the rotation control of the motor is a control method based on a pulse signal. By applying the motor torque by the intermittent pulse signal as compared with the continuous torque, the reaction force (inertia generated by this reaction force) returning to the reduction gear can be significantly reduced. For example, in order to realize rotation by a pulse signal in an extremely short time of about 5 msec, it is preferable to apply a servo motor. This pulse signal control measures the output torque, measures the rotation speed or rotation speed of the motor with a rotary encoder, feeds back the measured value, and controls the PI so that the rotation speed of the motor converges to the target torque value. It can control by the method of transmitting by the method etc. and transmitting the pulse signal according to control to a motor. By applying such a control method, the material to be fastened can be tightened with high accuracy by design torque.

  According to the rotary tightening tool of the present invention, the rotational speed of the motor is controlled based on the pulse signal, and the outer ring gear of the speed reducer is configured to be rotatable relative to the motor. The reaction force returning to the reduction gear can be reduced as much as possible, and the reaction force felt by the worker can be adjusted to a small torque substantially corresponding to the motor torque.

  In another embodiment of the rotary tightening tool according to the present invention, an annular member is fixed to the motor, and the outer ring gear is surrounded by the annular member in a mechanically separated posture. It is characterized by that.

  For example, the motor described above is fixed to a gripping part that is directly gripped by an operator, and an annular member that houses a reduction gear is fixed to an end portion from which the rotating shaft of the motor projects. As for this annular member, at least an appropriate form in which the shape of the inner peripheral surface is an annular shape can be selected. The gripping portion and the annular member described above are preferably formed of a light material, and can be formed of a resin material such as plastic or a light metal material.

  The annular member and the outer ring gear constituting the planetary gear mechanism are mechanically separated from each other, and the reaction force at the time of rotational tightening of the material to be fastened is transmitted from the outer ring gear to the gripping part via the annular member. It is configured not to be. That is, it is possible to have a configuration in which both are separated by measures such as forming the inner diameter of the annular member slightly larger than the outer diameter of the outer ring gear. Note that the outer peripheral surface of the outer ring gear may be in sliding contact with the inner wall surface of the annular member, and the lubricant may be supplied to both sliding contact surfaces.

  According to the rotary fastening tool of the present invention, the rotational speed of the motor is controlled based on the pulse signal, and the outer ring gear of the speed reducer and the annular member fixed to the motor are mechanically separated. Due to the structure, the same effect as described above, that is, the reaction force returning to the reduction gear can be reduced as much as possible, and the reaction force felt by the worker is almost equivalent to the motor torque. Can be a small torque.

  According to another embodiment of the rotary fastening tool of the present invention, in the rotary fastening tool, the outer ring gear also serves as a speed reducer housing, and a weight is fixed to the outer periphery of the housing. The housing and the weight body are configured to rotate relative to the annular member by a reaction force acting when the material to be fastened is rotationally tightened.

  In the rotary tightening tool of the present invention, the outer ring gear also serves as the housing of the speed reducer, and a gear that meshes with the planetary gear mechanism is formed on the inner peripheral surface thereof. The weight is fixed. This weight, together with the housing, rotates relatively freely with respect to the motor and the gripping part by inertia generated by a reaction force returned when the material to be fastened is tightened. When the inertia is large, the weight corresponding to the inertia is required for both the weight body and the housing. However, in the present invention, the generated inertia can be reduced by controlling the rotation speed of the motor by pulse signal control. The weight required for the weight body and the housing may be small.

  Even if the inertia is reduced, the weight of the housing is light. Therefore, instead of increasing the weight of the housing, a weight body capable of absorbing the required (generated) inertia is added to the housing. By doing so, it is possible to appropriately adjust the weight of the weight body fixed to the housing in accordance with the design reaction force at the time of fastening the material to be fastened.

  In another embodiment of the rotary tightening tool according to the present invention, the outer ring gear also serves as a speed reducer housing, and a weight body is mounted on the outer periphery of the housing so as to rotate synchronously with the housing. A first threading is formed on a surface of the annular member facing the housing and the weight body, and the weight body is formed in a ring shape and is screwed into the first threading. The housing is rotated by a reaction force acting when the material to be fastened is rotationally tightened, and the weight body is guided by the first threading while rotating synchronously with the housing. The motor is configured to advance and retreat in the axial direction of the rotation shaft of the motor.

  The rotary tightening tool according to the present invention is configured so that the weight body can rotate synchronously with the housing and can move in parallel with the housing, and when the housing receives a reaction force, On the other hand, the housing rotates freely, and the weight body rotates in synchronization with the rotation of the housing and translates while being guided by the annular member.

  As the weight body performs rotational motion and translational motion, the generated inertia (required inertia) can be converted into both kinetic energies, so that the weight of the weight body is larger than when the weight body only performs rotational motion. Can be further reduced.

  For example, a rod member extending in the direction of the output shaft is attached to the outer periphery of the housing, and an annular shape is attached to the rod member. There is a form in which the hole of the perforated weight body is loosely fitted and the weight body can move forward and backward along the rod member.

  The threading (second threading) of the outer circumferential surface of the (annular) weight body is screwed with the threading (first threading) formed on the inner circumferential surface of the annular member, and the weight body is rotated by receiving inertia. When doing so, rotation and translation are performed while being guided by the first threading. Here, it is preferable to provide a configuration that can provide a lubricant for smoother translational movement between the two threads.

  According to the rotary tightening tool of the present invention, since the required inertia can be converted into the rotational motion and the translational motion of the weight body, the weight required for the weight body can be reduced as much as possible. The weight of the entire attached tool can be reduced.

  Furthermore, in another embodiment of the rotary fastening tool according to the present invention, a bearing mechanism is interposed between the annular member and the housing.

  By interposing a plurality of bearings between the ring-shaped annular member and the housing, smooth rotation of the housing (and the weight body) and pulsation during rotation can be prevented. In addition, since there is no need for maintenance such as appropriately providing a lubricant, it is possible to provide a rotary fastening tool with low total cost including maintenance.

  As can be understood from the above description, according to the rotary fastening tool of the present invention, the reaction force at the time of fastening the material to be fastened can be reduced by the motor rotation based on the pulse signal, and most of this reaction force is the outer ring gear. Since it acts on the weight body, only a small torque reaction force corresponding to the motor torque acts on the worker holding the tool. Therefore, excellent operability can be provided, and the mental load on the worker can be extremely reduced.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of an embodiment of the rotary fastening tool of the present invention, and FIG. 2 is a control block diagram of the rotary fastening tool of FIG. FIG. 3 is a dynamic model diagram illustrating the inertia (moment of inertia) acting on the weight body. FIG. 4 is a cross-sectional view of another embodiment of the rotary fastening tool of the present invention.

  FIG. 1 shows an embodiment of a rotary fastening tool. The rotary tightening tool 10 includes a servo motor 1 and a speed reducer 2 including a planetary gear mechanism fixedly attached to a rotating shaft 11 of the servo motor 1, to which a servo motor 1 and a grip portion 6 that is directly gripped by an operator are fixed. An output shaft 51 that is axially attached to the carrier 23 of the speed reducer 2 and is provided coaxially with the rotary shaft 11, a fixing member 52 that is detachably attached to the output shaft 51, and is fixed to the servo motor 1, and is decelerated. It is mainly composed of an annular member 4 provided so as to surround the machine 2.

  The planetary gear mechanism that constitutes the speed reducer 2 includes a central sun gear 21 and, for example, three or five planetary gears 22, 22,... That mesh with meshing teeth provided around the sun gear 21. An outer ring gear 24 having an outer diameter of the revolution orbit of the gears 22, 22,. It is configured. In the illustrated embodiment, the outer ring gear 24 also serves as the housing of the speed reducer 2, and an annular flange 24 a is fixed to the outer wall surface of the outer ring gear 24. The motor rotation of the servo motor 1 is decelerated by the speed reducer 2 according to a predetermined reduction ratio, the torque is increased, and the fastening material a is rotationally tightened via the output shaft 51 and the fixing member 52.

  A rod member 24b parallel to the rotary shaft 11 is fixed to the annular flange 24a, and an annular perforated weight body 3 with a predetermined weight is provided to the rod member 24b. It is attached to the flange 24a while being penetrated. The weight of the weight body 3 is set to a weight that can absorb the reaction force generated when the material to be fastened a is fastened by rotation and transmitted to the outer ring gear 24 and the weight body 3.

  Here, an annular member 4 fixed to the servo motor 1 and surrounding the outer ring gear 24 (flange 24a), and a bearing mechanism including a plurality of bearings 7, 7,... In the circumferential direction between the flange 24a. Is interposed, and the annular member 4 and the outer ring gear 24 (and the weight body 3) are completely separated from each other. With this configuration, it is possible to avoid that the torque reaction force at the time of rotational tightening of the material to be fastened a directly acts on the servo motor 1 and the grip portion 6, and most of the torque reaction force is free to the servo motor 1. Is transmitted to the outer ring gear 24 and the weight body 3 that can rotate relative to each other. Here, the theoretical value of the torque reaction force transmitted to the worker is only the motor torque.

  FIG. 2 shows a control block diagram of the rotary fastening tool 10. A rotary encoder 81 is attached to the servo motor 1 so that the rotation angle (or rotation speed) of the motor can be measured. The measurement data (signal) is sent to the control unit 82 (X direction). On the other hand, the output shaft 51 is provided with a detection unit 85 that senses the torque value and the rotation speed of the output shaft 51, and the measured analog signal is sent to the calculation unit 83 via the A / D conversion unit 84. (Z direction). The calculation unit 83 is preset / built-in with a target torque value and its allowable range. Further, the control unit 82 connected to the calculation unit 83 has a built-in PI control unit for accommodating signals sequentially sent from the rotary encoder 81 within a target torque value or a set range around the target torque. The PI control unit is operated by the CPU so that the torque of the output shaft falls within the target torque range while comparing the measurement signal sent from the rotary encoder 81 with the torque value and rotation speed of the output shaft. The pulse signal at predetermined time intervals is fed back to the servo motor 1 (Y direction).

  The control unit 82 incorporates a servo amplifier that controls the rotation of the servo motor 1, a resolver that controls the rotation angle of the servo motor 1, an I / F circuit, and the like. The A / D converter 84 and the like are provided outside the rotary tightening tool in the figure, but may be housed in the gripper 6, and such a form is more preferable. This is because the control means is accommodated in the rotary fastening tool, which leads to improvement in operability and transportability.

  The rotational speed of the servo motor 1 is feedback-controlled so that the torque value of the output shaft converges to the target torque (or its peripheral range), and the rotational speed of the servo motor 1 is controlled by an appropriate pulse signal. The reaction force generated when the fastening material is rotationally tightened can be suppressed as much as possible, and the fastened material can be rotationally tightened with a desired tightening torque with high accuracy.

Next, the inertia (moment of inertia) acting on (required) the weight body will be described based on the dynamic model of FIG. FIG. 3 schematically shows the servo motor 1, the speed reducer 2, the weight body 3, the rotating shaft 11, the output shaft 51, and the material to be fastened a. In the figure, TM is motor torque, and ηR is The reduction ratio, TR indicates the torque of the weight body, and TS indicates the tightening torque of the material to be fastened. Here, the equation of motion of the weight body is expressed by Equation 1.
[Equation 1]
TR = IR · ω '
Here, IR is the inertia generated (required) in the weight body, and ω ′ is the angular acceleration of the weight body.

On the other hand, Formula 2 can be derived from the relationship of TR = TS−TM and TS = ηR · TM between the torques.
[Equation 2]
TR = TS (1-1 / ηR)

From Equations 1 and 2, the inertia generated (required) in the weight body can be expressed by Equation 3.
[Equation 3]
IR = 1 / ω ′ · TS (1-1 / ηR)

  As is apparent from Equation 3, the inertia generated (required) in the weight body can be reduced by sufficiently increasing the angular acceleration ω ′ of the weight body. When the inertia is reduced, the weight of the weight body can be reduced, and the weight of the entire rotary tightening tool is reduced.

  To sufficiently increase the angular acceleration ω ′ of the weight body, it can be realized by transmitting an intermittent pulse signal to the servo motor as described above, and by making the time step of the pulse shorter. Thus, it becomes possible to obtain a larger angular acceleration ω ′.

  FIG. 4 shows another embodiment of the rotary fastening tool. In this rotary tightening tool 10A, a thread 4a1 is formed on the inner wall surface of an annular member 4a fixed to the servomotor 1, and a thread 3a1 is also formed on the outer peripheral surface of the annular weight 3a. Both threading 4a1 and 3a1 are screwed together. Further, the weight body 3a is separated from the flange 24a, and can be rotated synchronously with the flange 24a (X direction) by being connected to the flange 24a via the rod member 24b. On the other hand, translational movement is relatively possible (Y direction). This translational movement is performed while the weight body 3a is guided to the annular member 4a by screwing of the thread cuts 4a1 and 3a1.

  According to the rotary tightening tool 10A, the reaction force (inertia) acting on the weight body 3a is converted into the rotational motion and the translational motion of the weight body 3a, so that the reaction force is applied to the weight body 3a as light as possible. It can be absorbed. That is, the weight body 3a that is lighter than the weight body 3 applied in the rotary fastening tool 10 can be applied, which leads to a further reduction in the weight of the entire tool.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

Sectional drawing of one Embodiment of the rotary fastening tool of this invention. The control block diagram of the rotary fastening tool of FIG. FIG. 6 is a dynamic model diagram illustrating inertia (moment of inertia) acting on a weight body. Sectional drawing of other embodiment of the rotary fastening tool of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Servo motor, 11 ... Rotary shaft, 2 ... Reduction gear (planetary gear mechanism), 21 ... Sun gear, 22 ... Planetary gear, 23 ... Carrier, 24 ... Outer ring gear (also housing), 3, 3a ... Weight body, 3a1: thread cutting 4, 4a: annular member, 4a1: thread cutting, 51 ... output shaft, 52 ... fixing member, 6 ... gripping part, 7 ... bearing, 81 ... rotary encoder, 82 ... control unit, 83 ... arithmetic unit, 84 ... Conversion unit, 85 ... Detection unit, 10, 10A ... Rotary fastening tool, a ... Fastened material

Claims (5)

  A motor, a speed reducer comprising a planetary gear mechanism mounted on a rotating shaft of the motor, an output shaft mounted on the speed reducer, a fixing member attached to a tip of the output shaft and fixing a material to be fastened, and the rotation Control means for variably adjusting the rotation speed of the shaft by a pulse signal, and the planetary gear mechanism includes a sun gear fixed to the rotation shaft and a plurality of planets that revolve while rotating on the outer periphery thereof. A rotary tightening tool comprising a gear and an outer ring gear that rotates on the outer periphery of the revolution orbit of the planetary gear, wherein the outer ring gear is configured to be rotatable relative to the motor. In the rotary fastening tool according to claim 1,
An annular member is fixed to the motor, and the outer ring gear is surrounded by the annular member in a mechanically separated posture.   The outer ring gear also serves as a speed reducer housing, and a weight body is fixed to the outer periphery of the housing, and the housing and the outer ring gear are caused by a reaction force acting when the fastened material is rotationally tightened. The rotary fastening tool according to claim 1 or 2, wherein the weight body is configured to rotate relative to the annular member. The outer ring gear also serves as a reduction gear housing, and a weight body is mounted on the outer periphery of the housing so as to rotate synchronously with the housing.
A first threading is formed on a surface of the annular member facing the housing and the weight body, and the weight body is formed in a ring shape and is secondly engaged with the first threading. The housing is rotated by a reaction force acting when the material to be fastened is rotationally tightened, and the weight body is guided by the first threading while rotating synchronously with the housing. The rotary fastening tool according to claim 1 or 2, wherein the rotary fastening tool is configured to advance and retract in the axial direction of the rotary shaft.   The rotary fastening tool according to claim 3 or 4, wherein a bearing mechanism is interposed between the annular member and the housing.

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