JP2010125565A - Machine for temporarily fastening screw part, and method for temporarily fastening screw part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a machine for temporarily fastening a screw part that temporarily fastens the screw part quickly and precisely to a prescribed position and also performs the quality inspection of female screw machining in a screw-in stage. <P>SOLUTION: In the method for temporarily fastening the screw part to the prescribed position in which a screw S is engaged with the tip of a driver bit 11 that rotates accompanied by the rotation of a rotational drive source 13 and is screwed to a female screw T, the screw S is once screwed in to the lowermost end of the female screw T and unscrewed by a predefined rotational angle so that the screw S is temporarily fastened at the prescribed position. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a screw component temporary tightening machine and a screw component temporary tightening method that temporarily tighten a screw component at a predetermined position and also have an inspection function for female thread machining.

  A general purpose of temporary fastening is to first temporarily tighten a screw with an electric motor and manually perform final fastening after various inspection processes by an operator. Therefore, it is desirable to temporarily tighten the screw at a position close to the screw tightening completion position.

  As a means for achieving the object, there is a temporary fastening machine shown in Patent Document 1 (Japanese Patent No. 2953727). The temporary fastening machine includes an electric driver, a moving means of the electric driver, a position detector that detects a moving position of the driver bit of the electric driver, a signal from the position detector, and the electric driver and And a control device for controlling the moving means. This control device rotates the drive motor of the electric driver at a low speed when the screw is captured and at a high speed after the screw tightening is started, and when the screw reaches a predetermined position before the seating is completed, the voltage applied to the drive motor is zero. After that, the braking force is activated by applying a voltage of reverse polarity. That is, based on the signal from the position detector, when the driver bit reaches a predetermined position from this reference point, a brake is applied to the driver bit rotating in the tightening direction at a high speed, and the driver bit is suddenly stopped. The screw component is to be temporarily tightened at a predetermined position.

Japanese Patent No. 2953727

  However, the temporary fastening machine has a problem that the internal reference point does not match the actual reference point due to the time lag of the signal from the position detector, and the screw cannot be temporarily fixed at a predetermined position. Was. Further, in view of the shift of the stop position due to the inertia generated when the electric driver and the moving means are stopped, the screwing speed has to be limited, and there is a limit to the work efficiency.

  The present invention has been created in view of the above problems, and provides a screw component temporary fastening machine that temporarily fastens a screw component at a desired position at high speed and accurately, and also performs a quality inspection of a female screw processing at a screwing stage. The purpose is to do.

  The screw part temporary fastening machine of the present invention was created in view of the above problems, and has a driver bit that can be engaged with the head of the screw part and a rotation drive source that can freely operate the rotation angle thereof. A tool unit, a lifting unit that lifts and lowers the tool unit, and a control unit that controls the tool unit so as to return a predetermined rotation angle screw after screw parts are screwed to the lowest end of the female screw formed on the workpiece. And

  Further, the control unit can detect the load current value of the rotational drive source, and is configured to determine that the internal thread formation is defective when a torque increase occurs outside the preset rotation angle range in the screwing stage. It is characterized by that.

  The screw part temporary fastening machine according to claim 1 or 2, further comprising a jig for holding the workpiece so as to close a lower end of the through-formed female screw.

  The screw component temporary tightening method of the present invention has been created in view of the above-described problems. A screw component that engages with the tip of a driver bit that rotates as the rotation drive source rotates is screwed into a female screw to obtain a predetermined screw thread. In the method of temporarily tightening to the position, the screw part is once screwed to the lowest end of the female screw, and then screwed back by a predetermined rotation angle and temporarily tightened to a predetermined position.

  In addition, the load current value of the rotational drive source is detected in the screwing stage, and it is determined that the female thread formation is defective when the torque increase occurs outside the range of the preset rotation angle.

  The present invention is configured to determine the temporary tightening position of the screw with reference to the lowest end of the female screw. Therefore, the reference is always constant, and there is no time lag as in the case of using a signal from a conventional sensor as a reference, that is, there is no deviation of the reference, so that a screw part at a predetermined position can be temporarily tightened. . In addition, once the screw is screwed to the lowest end and the screw is turned back to the specified rotational angle, the movement distance becomes longer than before, but there is no need to consider the influence of the inertia of the tool unit or the lifting unit at the screwing stage. Screwing can be performed, resulting in an increase in work efficiency.

  In addition, with the load current value detection function, it is possible to detect that the screw part has reached the lowest end of the female screw by increasing the torque, and the torque will be increased outside the range of the rotation angle set according to the depth of the female screw. When this occurs, it is possible to determine that the internal thread formation is defective.

  Furthermore, by holding the workpiece with a jig that closes the bottom of the female screw, even a female screw formed through can be temporarily tightened with reference to the lowest end of the female screw.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 1 denotes a screw part temporary fastening machine (hereinafter simply referred to as a temporary fastening machine), and a headless screw S (hereinafter simply referred to as a screw part) that is an example of a screw part is attached to a female screw T formed on a workpiece W. S.) is temporarily tightened, and it is inspected whether the internal thread T is accurately tapped. The temporary fastening machine 1 includes a tool unit 10, an elevating unit 20 that is attached to the column 2 to raise and lower the tool unit 10, a turning unit 30 that is placed on the base 3 and holds a workpiece, and these units 10 , 20, and 30.

  As shown in FIG. 2, the tool unit 10 includes a driver bit 11 at the tip, and the driver bit 11 is integrated with the rotation of the drive shaft 13 a of the AC servomotor 13 via the transmission shaft 12. Installed to rotate. This AC servo motor 13 has a built-in rotary encoder and can freely control the rotation angle of the drive shaft 13a. The rotation angle of the driver bit 11 is acquired and transmitted to the control unit 40. It is configured as follows. Further, the tool unit 10 includes an outer sleeve 14 and an inner sleeve 15 attached so as to be able to be inserted through the outer sleeve 14. When the tool unit 10 is on the upper side, the inner sleeve 15 is urged by a spring 16 wound around the transmission shaft 12 and protrudes from the outer sleeve 14, and the driver bit 11 is accommodated in the inner sleeve 15. . On the other hand, when the tool unit 10 is lowered and the tip of the inner sleeve 15 comes into contact with the workpiece W, the inner sleeve 15 is pressed against the workpiece W and counters the bias of the spring 16 wound around the transmission shaft 12. Thus, the inner sleeve 15 is slid into the outer sleeve 14, and the slid inner sleeve 15 is configured to be detected by the proximity sensor 17 attached to the inner surface of the outer sleeve 14. As the inner sleeve 15 slides, the driver bit 11 protrudes from the tip of the inner sleeve 15, and the screw S sucked and held at the tip is screwed into the female screw T.

  As shown in FIG. 2, the elevating unit 20 elevates along the slide shaft 22 as the air cylinder 21 as a drive source for elevating the tool unit 10, the slide shaft 22, and the air cylinder 21 is driven. And a lifting member 23 to which the tool unit 10 is attached. The air cylinder 21 is provided with a cylinder rod 24 that can be moved in the up-and-down direction by sucking and discharging air, and a tool member 10 is attached to the tip of the cylinder rod 24 to raise and lower the tool unit 10. Further, a restricting member 25 is disposed on and below the movement locus of the cylinder rod 24. The restricting member 25 functions as a lower limit position of the cylinder rod 24 that moves up and down, and the cylinder rod 24 is lowered. And the descent of the tool unit 10 is restricted. Further, the restriction member 25 is configured such that its height can be adjusted, and the moving stroke of the cylinder rod 24 can be changed.

  As shown in FIGS. 1 and 3, the swivel unit 30 is attached to a slide table 31, a rotary table 32 attached to an attachment plate 31 a erected on the slide table 31, and the rotary table 32. It is comprised from the jig | tool 33 which hold | maintains. The swivel unit 30 is attached to a rodless cylinder 32 that slides the slide base 31 in the horizontal direction. When the operator attaches the workpiece to the jig 33, the swivel unit 30 is indicated by a two-dot chain line in FIG. Is located. While the sensor 37 senses this, the elevating unit 20 is controlled not to lower the tool unit 10. When the attachment of the workpiece W is completed and an operation button (not shown) of the control unit 40 is pressed, the turning unit 30 slides below the tool unit 10 and the temporary fastening operation is started.

  The workpiece W has a flange shape having a flange part, a pipe part W2, and a hole W3 extending in the axial direction. As shown in FIG. 4, the work part W is provided at three locations at equal intervals in the circumferential direction of the pipe part W2. An internal thread T is formed. The female screw T penetrates from the peripheral surface of the pipe portion W2 to the inner peripheral surface of the hole W3. The screw component temporary fastening machine 1 according to the present invention temporarily tightens the screw S at two locations among the three female screws. It is.

  As shown in FIGS. 4 and 5, the jig 33 has a protrusion 33 a that is inserted into the hole W <b> 3 of the workpiece W, and the protrusion 33 a is a plane orthogonal to the height direction of the female screw T. 33b. The flat surface 33b is located at the lowermost end of the female screw T, that is, is configured to be the bottom of the female screw T. Note that a plurality of the flat surfaces 33b may be formed on the protrusions 33a in accordance with the number of temporary fastening locations.

  As shown in FIG. 4, positioning bolts 34a and 34b are attached to the left and right locations above the side surface of the mounting plate 31a. The rotary table 32 is provided with a nut 35a that engages with the positioning bolt 34a and a nut 35b that engages with the positioning bolt 34b. With this configuration, when the rotary table 32 is rotated around the protrusion 33a of the jig 33, the workpiece W and the jig 33 are also rotated together. Then, the nut 35b and the positioning bolt 35a are engaged, and the female screw T is turned to a position where the screw S can be screwed. Further, a pin 36 attached to the rotary table 32 is inserted into the female screw T to which the screw S is not temporarily tightened, and is configured to prevent the workpiece W from being displaced.

  The control unit 40, upon receiving a work start command, an air cylinder drive unit 41 that drives the air cylinder 21, a motor drive unit 42 that drives the AC servo motor 13, a setting unit 43 that sets screw tightening information, A load current value detection unit 44 for detecting the load current value of the AC servo motor 13, a quality determination unit 45 for determining the quality of the internal thread formation based on the load current value and the value set in the screw tightening information, and an AC servo A rotation angle detection unit 46 that detects the rotation angle of the drive shaft 13a of the motor 13, a sensor detection unit 47 that detects a signal from the proximity sensor 17, and a ROM 48 that stores operation programs for the tool unit 10 and the lifting unit 20; The ROM 48 is housed and a control unit 49 that issues commands in response to various signals.

  In the ROM 48, as shown in FIG. 5, after the screw S is once screwed to the lowest end of the female screw T, the screw S is screwed back at a predetermined rotation angle and temporarily tightened at a predetermined position. 10 and an operation program for controlling the lifting unit 20 are stored.

  The setting unit 43 has a numeric keypad (not shown) for inputting screw tightening information. The screw tightening information includes a torque-up detection current value and a rotation angle of the drive shaft 13a at the time of torque-up detection. There are a torque-up detection angle upper limit value, a torque-up detection lower limit value, and a reverse rotation angle value as upper and lower limit values.

  Hereinafter, operation | movement of the screw component temporary fastening machine 1 of this invention is demonstrated along FIG. First, when a work start command is input from the control unit 40 (S01), the elevating unit 20 descends integrally with the tool unit 10 (S02). Then, the tip of the inner sleeve 15 of the tool unit 10 comes into contact with the upper end of the female screw, and when further lowered, the inner sleeve 15 of the tool unit 10 is pressed and inserted into the outer sleeve 14. Along with this, the driver bit 11 protrudes from the tip of the inner sleeve 15, and the screw S sucked and held at the tip comes into contact with the female screw. Here, when the proximity sensor 17 senses the insertion of the inner sleeve 15 into the outer sleeve 14 (S03), a forward drive start command is issued to the AC servo motor 13 (S04), and the screw S starts to be screwed. . In this screwing stage, when the load current value of the AC servomotor 13 exceeds the torque-up detection current value (torque-up) (S05), the rotation angle of the AC servomotor 13 when the torque is increased becomes the torque-up detection angle. It is determined whether it is within the upper limit value or the lower limit value (S06). When this torque-up occurs within the set rotation angle range (S06: YES), that is, the tip of the screw S comes into contact with the flat surface 33b of the jig 33, which is the lowest end of the female screw T, and torque-up occurs. When this is done, a reverse drive command is issued to the AC servomotor 13 and a lift command is issued to the lift unit 20 (S07). At this time, the AC servomotor 13 is reversely driven at a preset reverse rotation angle value so that the screw S is temporarily tightened at a predetermined position. When the reverse rotation angle of the AC servomotor 13 reaches the reverse rotation angle value (S08), the driving of the AC servomotor 13 is stopped (S09). Finally, the elevating unit 20 is raised to the highest point (S10), and the temporary fastening is finished. On the other hand, when the torque increase occurs outside the set range (S06: NO), that is, when it is impossible to smoothly screw in due to the formation failure of the internal thread T, it is determined that the internal thread formation is defective (S11), and the process jumps to S09. .

  The temporary fastening machine 1 according to the present invention is configured so that a predetermined rotational angle screw S is unscrewed from the lowest end of the female screw T and temporarily tightened. Here, the depth of the female thread T is always constant, and according to the present invention in which temporary tightening is performed with the lowermost end as a reference, there is no time lag or the like when using a signal from a conventional sensor as a reference, that is, the reference Since no deviation or the like occurs, the screw S at a predetermined position can be temporarily tightened. In addition, although the movement distance is longer than before by screwing to the lowest end and screwing back to a predetermined rotation angle, there is no need to consider the influence of the inertia of the tool unit 10 or the lifting unit 20 at the screwing stage. Screwing can be performed at a high speed, resulting in an increase in work efficiency.

  In addition, when the screw S is screwed from the uppermost end to the lowermost end of the female screw T, torque-up is detected over the entire thread of the female screw T, and torque-up detection set according to the depth of the female screw T is detected. When the torque increase occurs outside the range between the angle upper limit value and the torque increase detection lower limit value, it is possible to determine that the internal thread formation is defective. Thereby, the temporary fastening machine 1 which has a screw component temporary fastening function and a female screw formation quality inspection function can be provided.

  Furthermore, by holding the workpiece W with a jig 33 having a flat surface 33b that closes the bottom of the female screw T, and arranging the flat surface 33b at the lowermost end of the female screw T, even if the female screw T is formed through, Temporary tightening can be performed with this plane as the bottom of the female screw, that is, with reference to torque increase. Note that when the screw S is not formed through, that is, when the screw S is temporarily tightened to a female screw having a bottom (bottomed female screw), the jig 33 is not necessary, and the bottomed portion becomes a reference for torque increase.

  In the temporary fastening machine 1 described above, the torque increase that occurs when the driver bit 11 reaches the lowermost end of the female screw T is used as a reference. Instead, the tip of the cylinder rod 24 of the air cylinder 21 is a restriction member. You may use the time of contact with 25 as the lowest end. In this case, since the height of the regulating member 25 is adjustable as described above, the cylinder rod 25 is adjusted in accordance with the depth of the female screw T when the tip of the screw S reaches the lowest end of the female screw T. Adjust the height of to determine the lowest point. In this way, even if the jig 33 has a workpiece shape that cannot block the bottom of the through female screw T, by positioning the restricting member 25 in accordance with the depth of the female screw T, the restricting member 25 is positioned. Fulfills the function of the bottom of the female screw T, and can be temporarily tightened without being limited to the shape of the workpiece or the location of the female screw.

It is a block diagram of the present invention. It is a principal part expanded sectional view of a tool unit and a raising / lowering unit. It is a front view which shows the principal part of a turning unit. It is a partially cutaway sectional view showing a main part of a turning unit. It is a figure explaining the temporary fastening operation | movement of this invention. It is a flowchart which shows operation | movement of this invention.

Explanation of symbols

1 Screw parts temporary tightening machine 2 Prop 3 Base

10 Tool Unit 11 Driver Bit 12 Transmission Shaft 13 AC Servo Motor 13a Drive Shaft 14 Outer Sleeve 15 Inner Sleeve 16 Spring 17 Proximity Sensor

20 Lifting Unit 21 Air Cylinder 22 Slide Shaft 23 Lifting Member 24 Cylinder Rod 25 Restricting Member

30 Rotating unit 31 Slide base 31a Mounting plate 32 Rodless cylinder 33 Jig 33a Projection 33b Plane 34a, 34b Positioning bolt 35a, 35b Nut 36 Pin 37 Sensor

40 control unit 41 air cylinder drive unit 42 motor drive unit 43 setting unit 44 load current value detection unit 45 pass / fail judgment unit 46 rotation angle detection unit 47 sensor detection unit 48 ROM
49 Control unit

Claims (5)

A tool unit having a driver bit that can be engaged with the head of the screw component, and a rotation drive source that can freely operate the rotation angle thereof;
A lifting unit for lifting and lowering the tool unit;
A screw part temporary fastening machine comprising: a control unit that controls a tool unit so as to return a predetermined rotational angle screw after screw parts are screwed to the lowest end of a female screw formed on a workpiece.   The control unit can detect the load current value of the rotational drive source, and is configured to determine that the internal thread formation is defective when a torque increase occurs outside the preset rotation angle range in the screwing stage. The screw part temporary fastening machine according to claim 1 characterized by things.   The screw part temporary fastening machine according to claim 1 or 2, further comprising a jig for holding the workpiece so as to close a lower end of the through-formed female screw.   In a method in which a screw component that engages with the tip of a driver bit that rotates with the rotation of a rotation drive source is screwed into a female screw and temporarily tightened into a predetermined position, the screw component is once screwed to the lowest end of the female screw. A screw part temporary tightening method comprising: screwing back a predetermined rotation angle screw and temporarily tightening to a predetermined position.   5. The screw component according to claim 4, wherein a load current value of the rotary drive source is detected in the screwing stage, and it is determined that a female screw is not formed correctly when a torque increase occurs outside a preset rotation angle range. Temporary tightening method.

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