JP2000094241A - Inspection device for thread fastening dimension - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the simple structure device for assuring the acceptance of a thread and for inspecting thread fastening dimension by integrating a sensor for measuring the thread fastening dimension with a thread fastening mechanism. SOLUTION: This equipment for inspecting thread fastening dimension is formed of a displacement sensor 10 provided at a body unit 13 side integrated with a rotary prime motor 22 for driving a thread fastening bit 24; a detecting dog 11 provided at an attachment 14 side expandably installed on the body unit 13; a memory means for a faced gap between the displacement sensor 10 and the detecting dog 11 and the faced gap at the time of accepting a thread; an acceptance comparison determining means for determining success in accepting the thread when the memorized value is the appropriate value; and a comparing means for the memorized value relative to the faced gap at the time of completing the thread fastening. This configuration allows measurement is good accuracy of thread fastening dimension without being effected by a variation in the height of a thread head and confirmation of the acceptance of the thread.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw tightening mechanism used in an automatic assembling apparatus and the like, in which a target screw is reliably delivered from its supply device, and whether or not the screw is securely tightened is automatically determined. The present invention relates to an improvement of a screw tightening dimension inspection device for performing an inspection and alerting the user if there is any abnormality.

[0002]

2. Description of the Related Art (1) Description of the Structure of the Prior Art FIGS. 6 (a) and 6 (b) show the structure of a conventional screw tightening dimension inspection apparatus. In FIG. The member surface on which the screw 2 is tightened by the device, 1a is a member to be screwed into the member surface 1 by the screw 2, 3 is an elevating mechanism such as an air cylinder for raising and lowering the inspection unit 4, and 5 is the inspection unit 4. The reference pins 6 are slidably mounted on the reference pins 5 and springs 7 are provided.
The measuring pins 10 are held between the end faces 8 and 9 by the reference numeral 10, the displacement sensor 10 is mounted on the end face 8, and 11 is a detection dog which forms an opposing gap with the displacement sensor 10.

(2) Description of the operation and operation of the prior art Next, the operation of the conventional device will be described. FIG. 6A is a view showing a state in which the inspection unit 4 is raised by the lifting mechanism 3, and the gap between the displacement sensor 10 and the detection dog 11 in this state is A. Here, as shown in FIG. 6B, when the elevating mechanism 3 is driven to lower the inspection unit 4, the measuring pin 6 first hits the head of the screw 2, and then the reference pin 5 hits the tightened member 1a. . During this time, the spring 7 is compressed and the gap between the displacement sensor 10 and the detection dog 11 decreases to B. The value obtained by subtracting the opposing gap B from the opposing gap A is the dimension from the top surface of the head of the screw 2 to the surface of the member 1a to be tightened. If this matches the height of the head of the screw 2, the tightening has been completed in dimension. Will be. However, if the screw is not properly engaged or the pilot hole is poorly tapped, the head of the screw 2 is not seated on the surface of the member 1a to be tightened, and the subtraction value of AB is larger than an appropriate value. As a result, a screw tightening failure is detected.

[0004]

(1) Description of the Problems of the Prior Art Since the conventional screw tightening dimension inspection apparatus is configured as described above, if the size of the screw is changed, the proper height of the head of the screw is adjusted. In addition to the need to change the setting, even if the screws have the same size, there is a problem that if the height of the head of the screws varies, accurate dimension determination cannot be performed. Also,
Dimension measurement is a separate step from screw tightening, which has the disadvantage of complicating the mechanical system. JP-A-4-1158
Although the "screw tightening device" disclosed in No. 35 solves this, the receipt of the screw has not been confirmed,
There is the disadvantage of making incorrect storage. Also, JP-A-7-22
The "screw tightening device" disclosed in Japanese Patent No. 3130 confirms the engagement between the screw tightening bit and the head of the screw immediately before tightening the screw. Was required.

(2) Description of the Object of the Invention The present invention has been made to solve the above-mentioned problems, and a dimensional inspection apparatus is incorporated in a screw tightening mechanism to simplify the system and It is another object of the present invention to provide a screw tightening dimension inspection apparatus which is not affected by a change or variation in the height of a screw head. It is another object of the present invention to provide a screw tightening dimension inspecting apparatus which can check whether a screw is supplied to the screw tightening apparatus correctly by utilizing the fact that the dimension inspecting apparatus is incorporated in the screw tightening mechanism. The purpose is.

[0006]

According to a first aspect of the present invention, there is provided an apparatus for inspecting a screw tightening dimension, comprising: a rotary motor; a body unit integrated with a stator of the rotary motor; A screw-tightening bit connected to the output shaft of the prime mover and the other end of which is fitted to the head of the screw to be tightened; an attachment which is attached to the body unit in a manner to extend and retract in parallel with the screw-tightening bit; And a displacement sensor for measuring a relative movement distance between the body unit and the attachment, which is measured by the displacement sensor when the tip of the screw bit is fitted to the head of the screw to be tightened when the screw is taken out from the screw supply unit. Storage means for storing the relative movement distance between the screw and the body unit as the height of the screw head, and the screw head stored in the storage means If the height of the screw is not a predetermined value set in advance, it is determined that the screw is not properly transferred. At the time of completion of screw tightening, the relative movement distance between the attachment and the body unit measured by the displacement sensor is determined. Comparing means for comparing the height of the head of the screw from the surface of the screw-fastened member with the height of the head of the screw stored in the storage means based on the output of the comparing means; Means for determining whether screw tightening is good or not.

According to a second aspect of the present invention, the height of the head of the screw stored in the storage means is measured as the height from the surface of the screw supply member, and is not within a predetermined range. Sometimes we consider it a poor screw delivery,
The delivery processing is performed again assuming that the stored contents are not appropriate.

In the screw tightening dimension inspecting apparatus according to the third aspect of the present invention, the screw tightening quality determining means includes the screw head height from the screw tightened member surface measured from the height of the screw head stored in the storage means and measured. Judgment of screw tightening quality is made based on the tolerance with the height of the part.

According to a fourth aspect of the present invention, the attachment is a pipe member surrounding the screw tightening bit, and the screw is tightened by lowering the air pressure inside the pipe member. Is to be adsorbed.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 (1) Detailed Description of Configuration in First Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG.
1 is a diagram showing an overall configuration of a screw tightening dimension inspection device according to the present embodiment. In the drawing, reference numeral 12 denotes a stator incorporating a rotary motor described later, reference numeral 13 denotes a body unit integrated with the stator 12, and reference numeral 14 denotes a body mounted on the tip of the body unit 13, and an inner peripheral surface of the body unit 13 described later. Attachment 15 which is slidably extended and contracted by a spring, and a plate 15 fixed to the body unit 13
An elevating device such as an air cylinder for elevating and lowering the body unit 13 through 6, a feeding device 17 for transferring the entire body unit 13 and the stator 12 including the elevating device 15 left and right, and the feeding device 17 is not shown. It is driven left and right by an air cylinder or the like.

A detection dog 11 is attached to the attachment 14, and a displacement sensor 10 is attached to the body unit 13. Reference numeral 18 denotes a feeder block which is moved left and right by an air cylinder 19 or the like. After the screws 2 are mounted on the feeder block 18, the feeder block 18 is supplied from a dotted line position (left) to a solid line position (right). You. Reference numeral 20 denotes a comparator which performs a comparison control described later in response to an output signal of the displacement sensor 10, reference numeral 21 denotes a sequence controller which performs lifting / lowering and left / right operations of the body unit 13 and the like, and reference numeral 1 denotes a member to which the screw 2 is tightened. The surface 1a is a member to be tightened. The comparator 20 constitutes each comparing means, and the sequence controller 21 constitutes a storage means, a reception acceptability judging means, a screw tightening acceptability judging means and the like.

FIG. 2 is a sectional view for explaining the detailed structure of the body unit 13 shown in FIG. 1. In FIG. 2, reference numeral 22 denotes a rotary motor such as a DC motor fixed inside the stator 12, and reference numeral 23 denotes a stator. A planetary gear type reduction gear built in the motor 12 and driven by the rotary motor 22; a planetary gear type reduction gear 24 is provided in the body unit 13 integrated with the stator 12, and It is a screw tightening bit detachably fixed to the output shaft 26, and its tip is passed through the inside of the attachment 14.

Reference numeral 27 denotes a disk connected to the third shaft of the planetary gear type speed reducer 23, and reference numeral 28 denotes a disk with the planetary gear type speed reducer 23 through a clutch panel 29 and a hard sphere 30 which constitute a torque limiting device together with the planetary gear type speed reducer 23. A spring for pressing the hard sphere 30, 31
Is screwed onto the outer periphery of the body unit 13 and the spring 28
Torque adjusting nut for adjusting the pressing force of the disk 27
A limit switch for detecting that the clutch panel 29 has been lowered when the projection 32 rides on the rigid ball 30; a cylinder 34 pressed and fixed to the outer periphery of the lower end of the adjustment nut 31 by a ring nut 35; , The attachment 14 is slidably mounted in a cylinder 34, a spring receiving member pressed downward by a spring 37, 38 is connected to a vacuum pump (not shown), and the other end is fixed to the cylinder 34 by a base 39. Air tube,
Numeral 40 is a low-pressure space formed inside the cylinder 34 when the air pressure in the air tube 38 is reduced. The screw 2 supplied from the feeder block 18 to the tip of the attachment 14 by this low pressure is used as the screw tightening bit 24. Is held by suction at the cutting edge. 41 is a bracket for fixing the displacement sensor 10 to the cylinder 34, 42 is the attachment 14
The displacement sensor 10 and the detection dog 11 usually face each other with a gap G interposed therebetween. Reference numeral 43 denotes a connector for supplying power to the DC motor 22, which is a rotary motor, and for extracting a signal from the limit switch 33 to the outside. The connector 43 is provided above the stator 12.

Next, FIG. 3A is a partial cross-sectional view when the screw tightening mechanism is at the upper left origin position, and FIG. 3B is a partial cross-sectional view when the screw tightening mechanism is at the lower left screw supply position. In the state shown in FIG. 3A, the spring receiving member 36 is pressed by the spring 37 and is lowered to a position regulated by the projection 44 of the spring receiving member 36.
Attachment 14 integral with 6 is a screw tightening bit 24
At a position lower than the tip of. At this time, the displacement sensor 1
The facing gap between 0 and the detection dog 11 is G. FIG.
In the state (b), the tip of the attachment 14 comes in contact with the upper surface of the feeder block 18, and the attachment 14 retreats upward due to the contraction of the spring 37 which receives the drag from the upper surface. With the retreat, the detection dog 11 approaches the displacement sensor 10 arranged to face the body unit 13, so that the facing gap is reduced to A.

FIG. 4A is a partial cross-sectional view when the screw tightening mechanism is at the position immediately before the start of screw tightening at the lower right position by attracting the screw 2 to the tip of the screw tightening bit 24, and FIG. Partial sectional view when the tightening mechanism is at the lower right screw tightening completed position,
FIG. 4C is a partial cross-sectional view when the screw tightening mechanism is at the lower right position of screw tightening and screw tightening is incomplete.

In FIG. 4A, the facing gap between the displacement sensor 10 and the detection dog 11 has the same value G as in FIG. 3A. Further, in the state of FIG. 4B, the facing gap between the displacement sensor 10 and the detection dog 11 has the same value A as in FIG. 3B, but in the state of FIG. The use bit 24 is not sufficiently lowered, and the gap B is larger than the normal gap A.

(2) Detailed Description of Operation and Operation of the Embodiment The operation of the sequence controller 21 of the embodiment configured as described above will be described in accordance with the flowchart for explaining the operation shown in FIG. explain. In FIG. 5, in an initial step 50, a series of electrical operations of the apparatus are started by pressing a start button (not shown), and a screw supply step 51 is started.
When entering, the air cylinder 19 shown in FIG.
Screw the feeder block 18 with the screws 1
Move to the right so that it is located at the tip of 4.

Next, in the unit lowering step 52, the lifting device 15 shown in FIG. 1 is driven to lower the entire screw tightening mechanism in order to fit the tip of the screw tightening bit 14 into the cross groove of the head of the screw 2. . When the entire screw tightening mechanism is lowered to a position where the cross groove of the screw 2 is fitted to the tip of the screw tightening bit 14, the learning gap storage step 53 is entered, and the displacement sensor 10 in the state of FIG. And detection dog 11
Is stored in the storage means (not shown) of the sequence controller 21. The stored opposing gap is compared with the normal dimension set in the dimension setting step 56 according to the size of the screw 2 in the receiving comparison step 54. As a result of the comparison, if it is out of the normal size, the size comparison step 55
And the stored opposing gap is larger than the normal size,
Compare if smaller.

If it is determined that the screw is large, it is determined that the engagement between the head of the screw 2 and the cutting edge of the screw tightening bit 24 is poor, and the lifting device 15 of FIG. To raise. Then, in order to engage the head of the screw 2 with the cutting edge of the screw tightening bit 24, a jogging step 58 is started, and the rotary motor 22 in FIG. After the inching step 58, the process returns to the unit lowering step 52 to lower the entire screw tightening mechanism.

If the comparison result is determined to be "small" in the size comparison step 55, whether the screw 2 is too small,
It is determined that the screw supply from the feeder block 18 has been interrupted, and an alarm output indicating that the screw supply has been cut out is generated in an alarm step 59. The occurrence of this alarm output causes the unit ascending step 60
To raise the entire screw tightening mechanism. Then, the feeder block 18 is returned to the left row in the feeder left row step 61. The restored abnormality of the feeder block 18 is manually recovered in the abnormality clearing step 62, and the series of operations is completed in the completion step 63.

As is apparent from the above operation, since the height of the head of the screw 2 is measured in the screw receiving process, it is determined whether or not this value is an appropriate value. It is confirmed whether proper reception has been performed and proper storage has been performed. Further, there is also a secondary effect that it is possible to determine whether there is a missing screw or whether there is any abnormality in engagement between the head of the screw 2 and the cutting edge of the screw tightening bit.

In the receiving comparison step 54, when the receiving of the screw 2 is normal, the low pressure space 40 in FIG. 2 is set to a low pressure in the screw suction step 64, and the screw 2 is sucked to the cutting edge of the screw tightening bit 24. After the screw 2 is attracted, in the next receiving completion step 65, the entire screw tightening mechanism is raised, and then the feeder block 18 is returned to the left and the next screw 2 is pulled out. Then, the process proceeds to the unit rightward step 66, in which the feed device 17 is driven to move the entire screw tightening mechanism rightward, and the tips of the screws 2 sucked into the screw holes of the member to be tightened 1a are adjusted.

When the alignment between the tip of the screw 2 and the screw hole is completed, in a unit lowering step 67, the entire screw tightening mechanism is lowered. Next, in a screw tightening step 68, the rotary motor 22 of FIG. 2 is driven while the entire screw tightening mechanism is lowered, and the member 1a to be tightened is screwed to the member 1 and automatically stopped. These steps 67 and 68 constitute a screw tightening step.

In FIG. 2, when the rotary motor 22 is driven, the disk 27 rotates and the projection 32 hits the hard sphere 30 and stops, and in this state, the output torque of the speed reducer 23 is generated. When the screw tightening is completed, the screw tightening bit 24 stops, the reaction torque to the output shaft 26 increases, and the protrusion 32 of the disk 27 rides on the hard sphere 30.

As a result, the clutch panel 29 is lowered, the limit switch 33 is operated, and the sequence control is performed.
The rotation motor 22 stops under the control of the roller 21. Attachment 14 and screw tightening bit 24 in this state
Is as shown in FIG. 4 (b) or FIG. 4 (c).

After the completion of the screw tightening step, a gap measuring step 69 is entered to measure the opposing gap between the displacement sensor 10 and the detection dog 11 in the state shown in FIG. 4B or 4C. When the gap measuring step 69 is completed, the suction of the screw 2 from the tip of the screw bit 24 is released in the suction releasing step 70.

Next, in order to judge the quality of the screw tightening, the facing gap measured in the gap measuring step 69 is compared with the facing gap A stored in the storage means in the learning gap storing step 53, and the difference is reserved. In a pass / fail determination step 71, it is determined whether or not the value is within a range of an allowable error (tolerance) set in the step 72. When the judgment result is good, the whole screw tightening mechanism is raised in the unit raising step 73. Further, the entire screw tightening mechanism is moved leftward from the unit leftward moving step 74. As a result, the entire screw tightening mechanism returns to the origin position at the upper left and shifts to the operation completion step 63.

However, if the judgment result of the pass / fail comparison step 71 indicates that the screw 2 is defective or the tap is not set properly, an alarm is output in an alarm output step 75, and the entire screw tightening mechanism is output in a unit raising step 76. Is raised, and the entire screw tightening mechanism is moved leftward in the unit leftward moving step 77. Then, an operation completion step 6 is performed through a manual abnormality release step 78.
Move to 3.

As described above, according to the present embodiment, the tightening torque of the screw 2 is set to an appropriate value by the torque limiting mechanism using the planetary gear type reduction gear 23 and the clutch panel 28 provided on the output shaft of the rotary motor 22. Therefore, if there is a poor tap in the screw hole or a poor engagement of the male screw / female screw, the screw tightening may be completed in a state where the head of the screw 2 is not completely seated on the tightening surface.

In this case, the tightening dimension of the screw is measured to check whether this is equal to the target value.
Although this serves as a supplementary function for determining whether or not the true screw tightening is completed, since the above-mentioned target value uses a stored value learned at the time of receiving the screw 2, the screw 2
In general, the tightening dimension of the screw 2 can be accurately measured in units of 10 μm without being affected by variations in the height of the head.

By using the attachment 14 as a suction pipe for the screw 2, a normal contact surface can be secured even with the tightened member 1 a which is not so large as compared with the head of the screw 2. Things.

Further, a standard head height is set according to the screw size, and the acceptability of the screw 2 can be determined by comparing the learned screw size at the screw receiving stage with the target set screw size. For example, when it is determined that the head of the screw 2 is too high, the cutting edge of the screw tightening bit 40 is
Can be assumed not to be fitted to the head of the head.

Further, when it is determined that the head of the screw 2 is too low, it can be assumed that the supply of the screw 2 from the feeder block 18 is interrupted.

Further, the head height of the screw 2 learned at the time of receiving the screw 2 from the feeder block 18 is stored in the storage means. By performing the comparison, it is possible to obtain an accurate screw tightening determination result that is not affected by variations.

(3) Description of another embodiment, description of an example of diverting to another application. In the above embodiment, a DC motor is used as the rotary motor, and a torque limiting mechanism using a clutch panel that can adjust a riding force on a third ball of the planetary gear type speed reducer is used. Instead, an air-type motor is used, and air supplied to the motor is used.
A system in which torque is limited by pressure may be used. Further, in the above-described embodiment, the entire screw tightening mechanism is moved by the lifting device 15 or the left and right feeders 17, but instead of this, various deformation mechanisms such as moving and raising and lowering the member to be screwed are used. Can be.

[0036]

According to the first aspect of the present invention, a rotary prime mover,
A body unit integral with a stator of the rotary motor, a screw tightening bit in the body unit having one end connected to the output shaft of the rotary motor and the other end fitted to a head of a screw to be tightened; Attachment attached to the body unit so as to be extendable and contractible in parallel with the screw tightening bit, displacement sensor for measuring the relative movement distance between the attachment and the body unit, and screw for removing the screw from the screw supply unit Storage means for storing the relative movement distance between the attachment and the body unit measured by the displacement sensor when the tip of the tightening bit is fitted to the head of the screw to be tightened, as the height of the head of the screw,
If the height of the head of the screw stored in the storage unit is not a predetermined value set in advance, the reception quality determination unit that determines that the screw is not properly delivered, and the screw measurement is completed by the displacement sensor when the screw tightening is completed. Comparing means for comparing the height of the screw head from the surface of the screwed member based on the relative movement distance between the attachment and the body unit with the height of the screw head stored in the storage means; The screw tightening quality judgment unit is provided according to the output of the screw tightening, and the screw tightening quality judgment means is provided, so that the system is simplified and the screw tightening dimension inspection device is not affected by the change of the screw head height or the variation. There is an effect that can be provided.

In addition, utilizing the fact that the dimensional inspection device is incorporated in the screw tightening mechanism, it is also possible to confirm whether the screw has been correctly supplied to the screw tightening device.

According to the second aspect of the present invention, the height of the head of the screw stored in the storage means is measured as the height from the surface of the screw supply member. By performing the delivery process again assuming that the stored contents are not appropriate, it is possible to determine whether or not there is a normal screw transfer, whether there is a missing screw, or an abnormality in the engagement between the screw head and the cutting edge of the screw bit. There is.

According to the third aspect of the present invention, the screw tightening quality determination means determines the height of the screw head stored in the storage means and the measured height of the screw head from the surface of the screwed member. By judging the quality of screw tightening from the tolerance, there is an effect that accurate tightening dimension measurement can be performed in consideration of the screw tightening torque.

According to the fourth aspect of the present invention, the attachment is a pipe member surrounding the screw tightening bit. By lowering the air pressure inside the pipe member, the screw is attracted to the tip of the screw tightening bit. In addition, even if the tightened member is not so large as compared with the screw head, there is an effect that a normal contact surface can be secured.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of a screw tightening dimension inspection device according to an embodiment of the present invention.

FIG. 2 is a sectional view showing details of a screw fastening mechanism shown in FIG. 1;

3 is a partial cross-sectional view of the screw tightening mechanism shown in FIG. 2 at a screw receiving position.

4 is a partial cross-sectional view of the screw tightening mechanism shown in FIG. 2 at a screw tightening position.

FIG. 5 is a flowchart for explaining the operation of the present invention.

FIG. 6 is a diagram showing a configuration of a conventional screw tightening dimension inspection device.

[Explanation of symbols]

2 screw, 10 displacement sensor, 11 detection dog, 1
2 statuser, 13 body unit, 14 attachment, 21 sequence controller, 22
Rotary motor, 24 screw tightening bits, 29 clutch panel (torque limiting function), 53 learning gap storage step (storage means), 54 reception, comparison step (reception comparison judgment means), 71 pass / fail judgment step (comparison means).

Claims (4)

[Claims] 1. A rotary motor, a body unit integral with a stator of the rotary motor, and a head of a screw in the body unit, one end of which is connected to an output shaft of the rotary motor and the other end of which is a screw to be tightened. A screw tightening bit that fits into the body, an attachment attached to the body unit so as to be extendable and retractable in parallel with the screw tightening bit, and a displacement sensor that measures a relative movement distance between the attachment and the body unit. When removing the screw from the screw supply unit, the relative movement distance between the attachment and the body unit measured by the displacement sensor when the tip of the screw bit is fitted to the head of the screw to be tightened is determined by the head of the screw. Storage means for storing the height of the part, and the height of the screw head stored in the storage means must be a predetermined value set in advance. Means for judging whether or not the screw is not properly delivered; a screw head from the surface of the screw-fastened member based on a relative movement distance between the attachment and the body unit measured by the displacement sensor at the time of completion of screw tightening. Comparing means for comparing the height of the screw with the height of the head of the screw stored in the storage means, and determining whether screw tightening is good or bad according to the output of the comparing means. A screw tightening dimension inspection device characterized by the following. 2. The height of the head of the screw stored in the storage means is measured as the height from the surface of the screw supply member. If the measured value is not within a predetermined range, it is regarded as a screw transfer failure and stored. 2. The screw tightening dimension inspection device according to claim 1, wherein the delivery process is performed again with the content being inappropriate. 3. The screw tightening quality determining means determines the screw tightening quality based on a tolerance between the height of the screw head stored in the storage means and the measured height of the screw head from the surface of the member to be screwed. The screw tightening dimension inspection device according to claim 1, wherein 4. The screw member according to claim 1, wherein the attachment is a pipe member surrounding the screw bit, and the screw is attracted to the tip of the screw bit by lowering the air pressure inside the pipe member. The screw tightening dimension inspection device described.