JP4454674B2 - Screw tightening device - Google Patents

Description

  The present invention relates to a screw tightening device using a motor as a drive source.

Conventional screw tightening devices include an angle type and a pistol type. A reduction gear is connected to the output side of the motor drive, a clutch is connected to the output side of the reduction gear, and a tool is connected to the output side of the clutch. The thing which provided the socket is known (for example, refer patent document 1). After tightening the screws, a torque wrench is used to reach the required tightening torque.
Japanese Patent Laid-Open No. 06-079637

  However, in the conventional screw tightening device, since the clutch is provided on the output side of the reducer, it is necessary to operate the clutch with a high output torque after decelerating. There is a problem that the whole apparatus becomes large and the operability is not good. Further, when the required tightening torque is increased, there is a problem that the reaction force increases and one-handed work becomes difficult.

  The present invention has been made in view of such problems of the prior art, and the object of the present invention is to reduce the size of the clutch as well as to reduce the weight and weight of the entire device and to improve the operability. The present invention intends to provide a screw tightening device.

In order to solve the above-mentioned problems, the invention according to claim 1 is directed to a motor as a drive source, a clutch connected to the output side of the motor, a reduction gear connected to the output side of the clutch, and a tool on the output side of the reduction gear. A screw tightening device provided with a socket , wherein the clutch has a retainer plate and a retainer opposed to each other with a clutch steel ball interposed therebetween, and the steel ball protrudes about half from the surface of the retainer facing the retainer plate. A concave portion is formed on one surface of the retainer plate facing the concave portion, and a cam having a flat portion on which the steel ball rides and an inclined portion into which the steel ball is fitted is formed, and the clutch has a tightening torque. A displacement switch for detecting that a desired value has been reached is provided, and this displacement switch is connected to a switch lever connected to the retainer. The switch lever is urged to the on side of the displacement switch by a spring damper, and further, the steel ball is fitted to the inclined portion at the connecting portion between the retainer and the switch lever. This is a screw fastening device in which a gap for preventing propagation of the movement of the retainer is formed.

According to a second aspect of the present invention, in the screw tightening device according to the first aspect, the retainer plate is connected to a drive shaft of a motor, and the reducer is connected to the reducer via the retainer plate, the retainer, and the steel ball. In addition to a retainer rod for transmitting power, the retainer rod is biased by a spring disposed on the outer periphery of the retainer rod.

The invention according to claim 3 is the screw tightening device according to claim 1 or 2, wherein the angle of the inclined portion is 10 ° to 30 °.

The invention according to claim 4 is the screw tightening device according to any one of claims 1, 2, or 3, wherein pulsed power is intermittently supplied to the motor at a cycle of 0.1 msec, Rotate the motor intermittently.

According to the first aspect of the present invention, since the clutch is provided not on the output side of the speed reducer but on the input side of the speed reducer, the clutch can be reduced in size, so that the apparatus main body held by the operator can be reduced in size and weight. Can be planned. Further, the screw tightening operation is facilitated even in a narrow place due to the reduction in size and weight of the apparatus main body held by the operator. Further, the clutch has a retainer plate and a retainer which are opposed to each other with a clutch steel ball interposed therebetween, and a concave portion is formed on the surface of the retainer facing the retainer plate so that the steel ball is protruded by about half. One surface of the retainer plate facing the recess is formed with a cam having a flat portion on which the steel ball rides and an inclined portion into which the steel ball is fitted, and the clutch detects the tightening torque reaching a desired value. The displacement switch is turned on and off by a switch lever connected to the retainer, the switch lever is urged to the on side of the displacement switch by a spring damper, and the connecting portion between the retainer and the switch lever is connected to the switch lever. In a state where the steel ball is fitted in the inclined portion It provided clearance for preventing the movement of a main retainer propagation. This gap prevents unnecessary movement of the retainer from being transmitted to the switch lever.

According to the invention of claim 2, in the screw tightening device, the retainer plate is connected to a drive shaft of a motor, and transmits power to the speed reducer via the retainer plate, the retainer, and the steel ball. Since the retainer rod is provided, and the retainer is urged by a spring disposed on the outer periphery of the retainer rod, the structure in the axial direction is simplified and the size can be reduced. In addition, with this structure, the power of the DC motor is transmitted to the reducer via the retainer plate, steel ball, and retainer, so when the specified torque is exceeded, the steel ball rides on the flat surface, and the DC motor Since the displacement switch connected to the retainer is operated, the DC motor is also turned off and the transmission of power can be reliably interrupted.

According to the third aspect of the invention, the angle of the inclined portion provided on one surface of the retainer plate is set to 10 ° to 30 °, so that the steel ball can easily run on the flat portion even with a low torque.

According to the fourth aspect of the present invention, the pulsed power is intermittently supplied to the motor at a cycle of 0.1 msec, and the motor is intermittently rotated, so that the gear portion and the joint portion of the speed reducer are backed. An impact effect utilizing rush is born, and when torque is increased, the reaction force can be reduced by repeatedly rotating and stopping before the tightening reaction force is transmitted to the operator's arm.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is a schematic side view of a screw tightening device according to the present invention, FIG. 2 is also a schematic top view, FIG. 3 is an explanatory diagram of a clutch, FIG. 4 is an explanatory diagram of a retainer plate, and FIG. It is operation | movement explanatory drawing.

  As shown in FIGS. 1 and 2, a screw tightening device according to the present invention includes a pistol-type device main body 1, a controller (not shown) that controls a direct current (DC) motor 3 constituting the device main body 1, and It consists of a lithium ion battery (not shown) as a power source and a cable 2 for connecting the apparatus main body 1 and the controller. The controller and the battery can be attached to a belt wound around the operator's waist or can be incorporated into the apparatus main body 1.

  The apparatus main body 1 includes a DC motor 3 as a driving source, a mechanical clutch 5 that transmits the torque of the DC motor 3 to the speed reducer 4, and a planetary gear that reduces the rotational speed of the clutch 5. A tool socket 6 for tightening a screw engaged by torque output from the speed reducer 4, a gripping part (grip part) 7 for an operator to grip with one hand, a lever 7a provided on the gripping part 7, and the like. Yes. The DC motor 3 may be brushless or with a brush. Further, as shown in FIG. 5, the clutch 5 is provided with a displacement switch 8 for detecting the operation state of the clutch 5.

  The DC motor 3 is intermittently supplied with pulsed power (current) by a controller, and intermittent control is performed to rotate intermittently. By such intermittent control, an impact effect can be produced and torque can be increased by utilizing the backlash of the gear part and joint part of the speed reducer 4. In addition, if the cycle of intermittent time (on / off time) is shortened (for example, 0.1 msec) and the rotation and stop are repeated before the tightening reaction force is transmitted to the operator's arm, the reaction force can be reduced. I can plan.

  As shown in FIG. 3, the clutch 5 includes a clutch rod 11 to which the output shaft of the DC motor 3 is connected, a substantially disc-shaped retainer plate 12, three spherical steel balls 13, a substantially disc-shaped retainer 14, and a coil shape. Spring 15, spring holder 16, adjustment nut 17 and the like. On one surface of the retainer plate 12, as shown in FIG. 4A, a cam (inclined portion 18a, flat portion 18b, and inclined portion 18c) 18 is equally divided into three in the circumferential direction in the vicinity of the edge portion. . As for inclination | tilt angle (theta) of inclination part 18a, 18c, 10 degrees-30 degrees are desirable.

  In addition, a recess 14 a is formed on one surface of the retainer 14 so as to store the steel ball 13 in a state in which approximately half of the steel ball 13 protrudes at a portion facing the cam 18 formed on the retainer plate 12. The steel ball 13 is sandwiched between a cam 18 formed on the retainer plate 12 and a groove 14 a formed on the retainer 14.

  As shown in FIG. 4B, the steel ball 13 is positioned between the inclined portion 18 a and the inclined portion 18 c before the tightening torque exceeds the elastic force of the spring 15. When the force is exceeded, as shown in FIG. 4 (c), it rides on the flat portion 18b of the cam 18. And even if the DC motor 3 is driven, the steel ball 13 is repeatedly passed over the flat portion 18b of the cam 18, thereby blocking the rotation of the retainer plate 12 by the DC motor 3 from being transmitted to the speed reducer 4. Then, the rotation of the tool socket 6 stops.

  As shown in FIG. 5, the displacement switch 8 is an on / off switch that detects the movement of the retainer 14 that changes depending on the position of the steel ball 13. The displacement switch 8 is attached to a base member 21 fixed to the frame body 20 of the clutch 5. The movement of the retainer 14 is a switch in which one end 22a is clamped by the edge portion 14b of the retainer 14, the center portion 22b is slidably inserted into the base member 21, and the other end 22c is in contact with the displacement switch 8. This is transmitted to the displacement switch 8 by a lever 22 and a spring damper 23 that is mounted between the other end 22 c of the switch lever 22 and the base member 21. Reference numeral 8a denotes a push button that protrudes when the displacement switch 8 is in the OFF state.

  As shown in FIG. 5A, when the steel ball 13 is located between the inclined portion 18a and the inclined portion 18c of the cam 18 formed on the retainer plate 12, one end of the retainer 14 and the switch lever 22 is provided. A predetermined gap G is provided between 22a. Further, the other end 22c of the switch lever 22 presses the displacement switch 8 by the spring damper 23, so that the displacement switch 8 is reliably turned on. When the displacement switch 8 is on, the DC motor 3 can be driven. Since the predetermined gap G is provided between the retainer 14 and the one end 22 a of the switch lever 22, unnecessary movement of the retainer 14 is not transmitted to the switch lever 22.

  On the other hand, as shown in FIG. 5B, when the steel ball 13 rides on the flat portion 18 b of the cam 18 formed on the retainer plate 12, the retainer 14 moves in a direction in which the spring 15 is compressed. Then, the retainer 14 presses one end 22 a of the switch lever 22, so that the switch lever 22 slides with respect to the base member 21, and the other end 22 c of the switch lever 22 compresses the spring damper 23 to move the displacement switch 8. Turn off. When the displacement switch 8 is turned off, the DC motor 3 stops driving.

  The operation of the screw tightening device according to the present invention configured as described above will be described. First, the operator holds the holding part 7 of the apparatus main body 1 with one hand and attaches the screw to the tool socket 6. Next, the tip of the screw mounted on the tool socket 6 is positioned in the screw hole to be tightened, and a switch (not shown) provided on the grip portion 7 is pushed with a finger. Then, the DC motor 3 starts to be driven, and the torque and rotation speed generated by the DC motor 3 are transmitted to the screw mounted on the tool socket 6 via the clutch 5 and the speed reducer 4.

  At this time, since the DC motor 3 is intermittently controlled by the controller, an impact effect is created and torque can be increased by utilizing the backlash of the gear portion or joint portion of the speed reducer 4. Further, by setting an intermittent time (on / off time) such as 0.1 msec, rotation and stop are repeated before the tightening reaction force is transmitted to the operator's arm, and the reaction force can be reduced. .

  Then, when the screw is screwed into the screw hole by the rotation of the tool socket 6 and reaches a desired tightening torque, as shown in FIG. 5 (a), the position between the inclined portion 18a and the inclined portion 18c of the cam 18 is reached. As shown in FIG. 5B, the steel ball 13 that has been moved rides on the flat portion 18 b of the cam 18 and moves in a direction in which the retainer 14 compresses the spring 15. At this time, as shown in FIGS. 4B and 4C, the inclined portions 18a and 18c are provided with an inclination angle θ of about 10 °, for example. You can get on.

  When the steel ball 13 rides on the flat portion 18b, the clutch 5 interrupts the rotation by the DC motor 3 to stop the rotation of the tool socket 6, and the retainer 14 presses the one end 22a of the switch lever 22 to switch the switch. The other end 22c of the lever 22 compresses the spring damper 23 to turn off the displacement switch 8. At this time, since the flat portion 18b of the cam 18 on which the steel ball 13 rolls has a predetermined length, it is possible to provide a pressing time for reliably turning off the displacement switch 8.

  When the displacement switch 8 is turned off, the DC motor 3 stops driving. Then, the screw is screwed into the screw hole with a desired tightening torque, and the screw tightening operation for one screw is completed.

  FIG. 6 is a diagram showing an example of the computer setting screen of the intermittent control controller. In the screen, S1 represents the rotation speed, A1 to A3 represent current (torque), and T1 to T11 represent waveform time. In this example, a window part for setting the rotation speed S1, currents (torques) A1 to A3 and waveform times T1 to T11 is provided in the lower part of the screen, and there is a button on the right side of each window part. By clicking this button, the setting conditions can be increased or decreased. A graph in the upper half of the screen shows the above setting conditions over time.

  When the Start button on the screen is clicked, a motor control command is stored in the input controller from the computer, and the motor is rotated while being controlled.

  According to the screw tightening device of the present invention, since the clutch 5 is directly connected to the output side of the DC motor 3, the output of the DC motor 3 can be kept lower than in the prior art. Can be miniaturized. Therefore, the apparatus main body 1 becomes smaller and lighter than the conventional one. For example, the size and weight of the apparatus main body 1 when a tightening torque of 30 N · m is required are as follows.

  The length (L) × width (W) × height (H) shown in FIG. 1 and FIG. 2 is changed from the conventional 500 mm × 70 mm × 104 mm to 260 mm × 50 mm × 150 mm. About 50% decrease from the size. In addition, the weight of the apparatus main body 1 has been reduced from 2.4 kg to 1.5 kg, which is approximately 40% less than the conventional weight. In this case, the size of the clutch 5 is such that the diameter D shown in FIG. 3A is 33 mm from the conventional 116 mm, which is approximately 80% less than the conventional size, and the weight of the clutch 5 is also changed from 1200 g to 200 g. About 70% less than the conventional weight.

  In the embodiment of the present invention, the fact that the tightening torque has reached a desired value is determined by the operation state (change from the on state to the off state) of the displacement switch 8 provided in the clutch 5, but the DC motor 3 The driving time and the operation state of the displacement switch 8 can be used as the determination conditions. It can also be determined only by the driving time of the DC motor 3.

  According to the present invention, since the clutch is provided not on the output side of the speed reduction mechanism but on the input side of the speed reduction mechanism, the clutch can be reduced in size, so that the size and weight can be reduced, the operability is improved, and even in a narrow place. It is possible to provide a screw fastening device that facilitates screw fastening work.

Outline side view of screw tightening device according to the present invention Outline top view of screw tightening device according to the present invention It is explanatory drawing of a clutch, (a) is sectional drawing, (b) is an exploded view. Fig. 4 is an explanatory view of a retainer plate, (a) is a plan view of the retainer plate, (b) is a developed sectional view showing a relationship (clutch inactive state) of the retainer plate, the steel ball, and the retainer, (c) is the retainer plate and steel Cross-sectional development view showing the relationship between the ball and the retainer (clutch operating state) FIG. 4 is an explanatory diagram of the operation of the displacement switch, where (a) is an on state and (b) is an off state Diagram showing an example of the computer setting screen of the intermittent control controller

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Apparatus main body, 3 ... DC motor (motor), 4 ... Reduction gear, 5 ... Clutch, 6 ... Tool socket, 7 ... Holding part, 7a ... Lever, 8 ... Displacement switch, 11 ... Clutch rod, 12 ... Retainer plate , 13 ... steel balls, 14 ... retainers, 15 ... springs, 18 ... cams, 18a, 18c ... inclined portions, 18b ... flat portions, 22 ... switch levers, 23 ... spring dampers, θ ... inclination angles.

Claims (4)

A screw tightening device having a motor as a drive source, a clutch connected to the output side of the motor, a reduction gear connected to the output side of the clutch, and a tool socket provided on the output side of the reduction gear, wherein the clutch Has a retainer plate and a retainer that are opposed to each other with a clutch steel ball interposed therebetween, and a concave portion is formed on the surface of the retainer facing the retainer plate so that the steel ball is protruded by about half, and this retainer plate is opposed to the retainer plate. One surface of the retainer plate is formed with a cam having a flat portion on which the steel ball rides and an inclined portion into which the steel ball is fitted, and the clutch includes a displacement switch for detecting that the tightening torque has reached a desired value. The displacement switch is turned on and off by a switch lever connected to the retainer, and the switch lever is And a gap for preventing propagation of unnecessary movement of the retainer when the steel ball is fitted in the inclined portion at the connecting portion between the retainer and the switch lever. A screw fastening device characterized by being formed . 2. The screw tightening device according to claim 1, wherein the retainer plate is connected to a drive shaft of a motor, and includes a retainer rod that transmits power to the speed reducer via the retainer plate, the retainer, and the steel ball. In addition, a screw tightening device comprising a retainer biased by a spring disposed on the outer periphery of the retainer rod. The screw fastening apparatus according to claim 1 or 2 , wherein an angle of the inclined portion is 10 ° to 30 °. 4. The screw tightening device according to claim 1 , wherein pulsed electric power is intermittently supplied to the motor at a cycle of 0.1 msec to rotate the motor intermittently. A screw fastening device characterized by that.

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