JP3235263B2 - Screw fastening device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel screw fastening device. In detail, even if there is a deviation between the screw and the tip of the screw tightening bit due to variation in the shape of the screw head or the position of the screw hole on the work side, the tip of the screw tightening bit can follow the screw. In the screw tightening device described above, even if the screw tightening bit swings while the tip of the screw tightening bit attempts to follow the screw, the screw tightening bit comes into contact with the bit housing supporting the screw tightening and disturbance occurs in torque detection of the screw tightening bit. It is an object of the present invention to provide a new screw tightening device that does not have any problem.

[0002]

2. Description of the Related Art In a conventional screw tightening device, a screw tightening bit is often supported by a rough supporting method such that the screw tightening bit does not fall out of the bit housing.

[0003] Further, because of this, the screw tightening bit can rotate to some extent with respect to the bit housing, and the tip of the screw tightening bit can follow the variation in the position of the screw head and the like. .

[0004]

However, for example, when the screw tightening bit is rotated by a torque driver having a torque detecting function to control the screw tightening torque, the screw tightening is particularly performed by suction using a negative pressure. When the tip of the bit is engaged with the head of the screw, there is a problem that disturbance occurs with respect to the above-described torque detection and accurate torque detection cannot be performed.

[0005] That is, in order to perform suction by the negative pressure of the screw,
The space up to the tip of the screw tightening bit is surrounded by the bit housing, and the space surrounded by the bit housing is subjected to negative pressure so that the screw is attracted to the tip of the bit housing and the screw tightening bit is engaged with the screw head. I have to.

In this case, when the screw tightening bit tilts with respect to the bit housing so that the tip of the screw tightening bit follows the position of the head of the screw, a part of the screw tightening bit comes into contact with the inner surface of the bit housing. However, this causes a disturbance in the detection of the tightening torque of the screw tightening bit, so that accurate detection of the tightening torque cannot be performed, and it is determined that the tightening is completed even though the screw is not completely tightened. This causes inconveniences such as insufficient tightening.

In order to avoid the above-mentioned contact between the screw tightening bit and the inner surface of the bit housing, the screw tightening bit may be supported on the bit housing in a state where the axial relation between them is substantially fixed.

[0008] By doing so, the screw tightening bit does not touch the bit housing, so that it is possible to avoid occurrence of disturbance in detecting the tightening torque of the screw tightening bit, and to accurately detect the tightening torque. I can do it.

However, since the axis of the screw tightening bit cannot be tilted with respect to the bit housing, when the screw position is shifted from a predetermined position, the tip of the screw tightening bit follows the shift. Can not do,
A situation occurs in which the screw cannot be tightened.

[0010]

According to the present invention, there is provided a screw tightening apparatus comprising:
In order to solve the above-mentioned problem, a screw tightening bit having a tip engaged with a head of a screw, a bit housing rotatably supporting the screw tightening bit and a shaft housing supporting each other in a substantially fixed state are provided. A bracket supported by a support, and a driver supported by the bracket, the output shaft being removably connected to the screw tightening bit with a margin between the screw tightening bit and the bracket. Is formed with a mounting surface serving as a reference surface, the bit housing is formed with a supported surface mounted on the mounting surface of the bracket, and supported by an elastic member interposed between the bit housing and the bracket. The surface is elastically brought into contact with the mounting surface.

[0011]

Therefore, in the screw tightening device of the present invention, the screw tightening bit is supported by the bit housing so as to be rotatable and the axial relationship therebetween is substantially fixed. There is no disturbance in touch torque detection.

Further, the bit housing is supported by the bracket by a resilient member elastically abutting the supported surface of the bit housing to the mounting surface of the bracket, so that the elastic member may be deformed as necessary. As a result, the bit housing can be tilted with respect to the bracket together with the screw tightening bit, whereby the tip of the screw tightening bit can follow the variation in the position of the screw.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the screw tightening device of the present invention will be described below with reference to the illustrated embodiments.

Reference numeral 1 denotes a bracket, which is supported by a support member described later.

The bracket 1 comprises a substantially annular main part 2 and a substantially annular support ring 3.

A circular groove 5 is formed on the lower surface of the main part 2 so as to surround the center hole 4.

The center hole 6 of the support ring 3 is formed to have a larger diameter than the center hole 4 of the main part 2, and a lower edge of the support ring 3 is formed with a receiving edge 7 projecting toward the center. The upper surface of 7 is a mounting surface 7a.

Then, the support ring 3 is fixed to the lower surface of the main part 2 in a state where the axes of the center holes 4 and 6 are aligned with each other, whereby the bracket 1 is formed.

Reference numeral 8 denotes a bit housing, which comprises a main part and a sheath part slidably supported in the main part in the axial direction.

Reference numeral 9 denotes a main portion of the bit housing 8, which is formed in a substantially cylindrical shape as a whole.

An outwardly projecting flange 10 is integrally provided at an upper end portion of the main portion 9, and a lower surface 10a of the flange 10 is a supported surface.

A circular groove 11 is formed on the upper end surface of the bit housing 8 including the flange 10.

The groove 11 is provided in the groove 5 of the bracket 1.
Is formed at a position opposed to.

The thickness of the flange 10, that is, the dimension in the vertical direction, is formed to be slightly smaller than the distance between the lower surface of the main part 2 of the bracket 1 and the mounting surface 7a.

The center hole of the main part 9 has an upper half 12 and a lower half 13
The lower half 13 has a smaller diameter than the upper half 12.

An annular rib 14 slightly protruding toward the center is provided between the upper half portion 12 and the lower half portion 13.

Then, the flange 10 of the main part 9 is located in an annular space formed between the lower surface of the main part 2 of the bracket 1 and the support ring 3, whereby the main part 9 of the bit housing 8 is formed. The bracket 1 is supported in a suspended manner.

As described above, since the thickness of the flange 10 is formed to be slightly smaller than the distance between the lower surface of the main part 2 of the bracket 1 and the mounting surface 7a,
The main part 9 of the bit housing 8 can be slightly tilted with respect to the bracket 1.

Numeral 15 denotes a ring-shaped rebound seal, which is formed of a rubber material and is compressed between the groove 5 of the bracket 1 and the groove 11 of the main part 9 of the bit housing 8 so that the respective grooves 5, 11 are compressed. Are fitted and supported.

As a result, the space between the main portion 9 of the bit housing 8 and the bracket 1 is sealed, and the elastic force of the repulsion seal 15 causes the main portion 9 of the bit housing 8 to move downward. Energized and its supported surface 1
0a is properly brought into contact with the mounting surface 7a of the bracket 1,
That posture is maintained correctly.

Reference numeral 16 denotes a sheath, which has a cylindrical shape as a whole and is supported by the lower half 13 of the main part 9 so as to be slidable in the axial direction.

The sheath 16 is a part 1 which forms approximately one third of the upper part.
Reference numeral 7 denotes a supporting portion, and the supporting portion 17 is formed to have a diameter slightly larger than that of the remaining portion, and a step portion 18 facing downward is formed at a lower end outside the supporting portion.

Further, the inner surface of the upper end portion of the support portion 17 is cut out in an annular shape, and the inner diameter is formed to be larger than that of the remaining portion. Is formed.

The outer surface of the lower end portion of the sheath 16 is thinly cut annularly to form a head mounting portion 20 having a reduced outer shape.

Reference numeral 21 denotes a suction head, which has a short cylindrical shape, and has an upper half portion 22 as a support portion and a lower half portion 23 as a suction portion.

A rib 24 protrudes from the inner surface of the upper end of the suction portion 23, and the lower surface of the rib 24 is formed as a conical surface following the shape of the head of the screw to be tightened by the main screw tightening device.

Reference numeral 25 denotes a synthetic resin stopper pin press-fitted so as to penetrate the side wall of the support portion 22 of the suction head 21.

Thus, the support portion 22 is externally fitted to the head mounting portion 20 of the sheath 16 and the stopper pin 25 is
The suction head 21 is mounted on the head mounting portion 20 of the sheath 16 by being press-fitted into the side wall of the housing 16.

Reference numeral 26 denotes a ring-shaped spring support, in the center of which is formed an insertion hole 27, and a rib 28 projecting downward from the edge of the insertion hole 27 is formed.

Such a spring support 26 is provided in the lower half 1 of the main part 9.
3 is inserted at the upper end.

Numeral 29 denotes a cylindrical bush whose inner diameter is substantially the same as the outer diameter of the sheath 16 and whose outer diameter is formed to be substantially the same as the inner diameter of the lower half 13 of the main part 9. I have.

The bush 29 is formed with a guide notch 30 extending from the lower end to the middle in the vertical direction.

The bush 29 includes the lower half 1 of the main part 9.
3 is screwed into the side wall of the main part 9 and screwed through the main part 9 so as to penetrate the main part 9.
Fixed to

The sheath 16 is slidably positioned so as to fit inside the bush 29 whose support 17 is fixed to the main part 9, and in this state, a closing plate 32 is provided at the lower end of the main part 9. Fixed.

The closing plate 32 has an annular shape and has a central hole 33.
Is formed substantially the same as the outer diameter of the portion of the sheath 16 immediately below the support 17.

Therefore, when the closing plate 32 is fixed to the lower end of the main portion 9, the step 18 of the supporting portion 17 of the sheath 16 abuts on the upper peripheral portion of the center hole 33 of the closing plate 32, This prevents the sheath portion 16 from falling down from the main portion 9.

Numeral 34 denotes a non-rotating pin erected on the outer surface of the lower end portion of the support portion 17 of the sheath portion 16.
Is slidably positioned in the guide notch 30, whereby the sheath 16 is detented with respect to the main part 9.

Reference numeral 35 denotes a compression coil spring, one end of which is located at the upper end of the support portion 17 of the sheath 16, one end of which is in contact with the step 19, and the other end of which is fitted on the rib 28 of the spring support 26. In this state, the spring abuts against the lower surface of the spring receiver 26 and is compressed between the spring receiver 26 and the step 19.

As a result, a downward moving force is applied to the sheath portion 16.

Reference numeral 36 denotes a screw tightening bit, which connects the connecting portion 37 at the upper end, the supporting portion 38 following the connecting portion 37, the operating portion 39 at the lower end, and connects between the supporting portion 38 and the operating portion 39. And an intermediate portion 40 formed integrally therewith.

The connecting portion 37 has the largest diameter.
The diameter decreases in the order of the support portion 38, the intermediate portion 40, and the action portion 39.

The connecting portion 37 is formed with a connecting recess 41 having an opening on the upper surface and having a non-circular cross section, for example, a square.

Reference numeral 42 denotes a ball bearing externally fitted to the upper end of the support portion 38. A stop ring 43 is attached to the support portion 38 directly below the ball bearing 42, whereby the screw tightening bit 36 of the ball bearing 42 is provided. The position with respect to is specified.

Reference numeral 44 denotes a ball bearing, which is located at the lower end of the main portion 9 of the bit housing 8 so as to be fitted inside.

Reference numeral 45 denotes a cylindrical collar, which is fitted inside the main part 9 so as to be located above the ball bearing 44.

Then, the screw tightening bit 36 is inserted from above the main part 9 into the bit housing 8 in this state.

As a result, most of the intermediate portion 40 of the screw tightening bit 36 except for the upper end portion and the working portion 39 are inserted into the sheath portion 16, and the lower end portion of the support portion 38 is fitted in the ball bearing 44. The outer periphery of the ball bearing 42 supported by the support portion 38 abuts on the upper end of the collar 45.

Thus, the screw tightening bit 36 is rotatably supported by the bit housing 8, particularly the main part 9, with the height with respect to the bit housing 8 being defined.

In this state, the lower end of the action portion 39 of the screw tightening bit 36 is located slightly above the rib 24 of the suction head 21.

Reference numeral 46 denotes a cylindrical collar, which is fitted inside the main portion 9 of the bit housing 8 so as to be located directly above the ball bearing 42, and furthermore, contacts the main portion 9 with the upper end of the collar 46. A retaining ring 47 is attached to the main body 9 to prevent the ball bearings 42, 44 and the collars 45, 46 from coming off from the main part 9, so that the screwing bit 36 is prevented from coming off with respect to the main part 9. You.

Reference numeral 48 denotes a position sensor for detecting a relative position of the sheath 16 with respect to the main part 9, which comprises a photo interrupter 49 fixed to the main part 9 and a dog 50 fixed to the sheath 16.

Reference numeral 51 denotes a suction port formed at a substantially intermediate position of the sheath 16 through the side wall thereof, and is connected to an air suction device via a hose (not shown).

When the air suction device is driven, the air inside the sheath 16 is sucked, and a negative pressure is generated at the lower end thereof. Therefore, the suction head 2 attached to the lower end is sucked.
1, a negative pressure is generated in the suction portion 23, and the screw 52
Is adsorbed by the adsorption section 23 of the adsorption head 21.

The upper end of the sheath 16 is connected to the upper half 12 of the main part 9.
However, a repulsion seal 15 is interposed between the upper end of the main part 9 and the bracket 1 to keep the airtight between them, and a driver described later is attached to the upper end opening of the bracket 1. As a result, the inside of the sheath 16 is kept airtight except for its lower end.

Reference numeral 53 denotes a support portion, for example, an arm of an orthogonal robot.

A reference plate 54 is fixed to the support 53 in a direction extending in the up-down direction.

Reference numeral 55 denotes a linear slide which is long in the vertical direction, and is fixed to the reference plate 54.

Reference numeral 56 denotes an air cylinder, and its rod 5
7 is fixed to the upper end of the reference plate 54 in a direction protruding downward.

Reference numeral 58 denotes a base plate, on which two linear bearings 59, 59 are fixed vertically apart from each other. The linear bearings 59, 59 are slidably mounted on the linear slide 55. By being engaged, the base plate 58 is supported slidably in the vertical direction with respect to the reference plate 54.

The upper end of the base plate 58 is connected to the lower end of the rod 57 of the air cylinder 56.

Accordingly, the base plate 58 is
Is moved up and down by the drive of

Reference numeral 60 denotes a tension coil spring for reducing the load, the upper end of which is connected to the reference plate 54,
The lower end is connected to the base plate 58.

Reference numeral 61 denotes a torque driver, for example,
This is a torque driver with torque detection function manufactured by GSE, USA.

The torque driver 61 is mounted on the base plate 5.
8, the lower end 61 a is fitted into the center hole 4 of the main part 2 of the bracket 1 from above, and the output shaft 62 protruding from the lower end is connected to the connection recess 41 of the screw tightening bit 36.
, Whereby the screw tightening bit 36 can be rotated by the torque driver 61.

The cross section of the connection recess 41 of the screw tightening bit 36 is formed in a non-circular shape, for example, a square, whereas the output shaft 62 of the torque driver 61 has a cross section of the cross section of the connection recess 41. It is formed in a similar shape slightly smaller than the surface shape, for example, a square.

Therefore, there is a slight clearance between the two, and the bit housing 8 holding the screw bit 36 can be rotated with respect to the bracket 1.

The screw tightening operation of the screw tightening device will be described below.

The action portion 39 of the screw tightening bit 36 is positioned with respect to the screw 52 supplied by a predetermined feeder, and the air cylinder 56 is driven to lower the base plate 58.

In this case, the supporting force of the air cylinder 56 does not work so that the screw tightening bit 36 descends in accordance with the increase in the amount of screwing of the screw 52.

Accordingly, considerable weight including the screw tightening bit 36, the bit housing 8, the torque driver 61, and the base plate 58 is applied to the screw 52 and a work (not shown) to which the screw 52 is tightened. Therefore, in the above screw tightening device, a tension coil spring 60 is stretched between the base plate 58 and the reference plate 54, thereby reducing the load applied to the screw 52 and the like.
A so-called floating structure is adopted in which the screw tightening bit 36 follows the screwing in accordance with the screwing.

When the suction portion 23 of the suction head 21 comes to a position where the suction portion 23 comes into contact with the head 52a of the screw 52, even if there is a slight deviation between the position of the suction portion 23 and the head 52a of the screw 52, The bit housing 8, in which the supported surface 10 a is placed on the placement surface 7 a and maintains a vertical position, is rotated so that the suction portion 23 follows the head 52 a of the screw 52 due to the deformation of the repulsion seal 15. Move.

Even if the bit housing 8 is rotated in this way, the screw tightening bit 36 is supported by the main portion 9 of the bit housing 8 by the two ball bearings 42 and 44. The shaft of the tightening bit 36 is not displaced, and therefore, there is no possibility that the screw tightening bit 36 touches the sheath 16 or the like of the bit housing 8 and the torque detected by the torque driver 61 is deviated.

Although the screw tightening bit is supported in a state where the axial relation between the screw tightening bit and the bit housing is substantially fixed,
Instead of being supported by two ball bearings spaced apart in the axial direction, for example, it may be supported by a single bearing metal having a long axial length.

When the air suction device (not shown) is driven to suck the air in the sheath 16, a negative pressure is generated in the suction portion 23 of the suction head 21, and the head 5 of the screw 52 is moved.
2a is adsorbed in the adsorption section 23.

Then, the inner surface of the upper end of the suction portion 23 is
The head 52a is formed in a conical surface following the shape of the head 52a, so that the posture of the screw 52 sucked by the head 23a is properly maintained.

Immediately after the screw 52 is sucked by the suction portion 23, the inside of the bit housing 8 becomes negative pressure, the compression coil spring 35 is further compressed, and the sheath 16 moves upward.

Then, when the screw tightening bit 36 is rotated, the operating portion 39 at the tip of the screw tightening bit 36 is automatically engaged with the head 52 a of the screw 52.

Then, the screw tightening device holding the screw 52 is moved to a predetermined position, and the torque driver 61 is driven, so that the action portion 39 is engaged with the head 52a of the screw 52. Bit 36 is rotated,
The screw 52 is tightened.

Then, the completion of the tightening of the screw 52 is detected by the torque detection by the torque driver 61 and the relative position between the main part 9 and the sheath part 16 in the bit housing 8 by the position sensor 48. Is detected, the suction of air by the air suction device is released, and the screw tightening device is moved to a position where the next screw 52 is picked up.

As the tightening of the screw 52 progresses, the sheath 16
Slightly descends with respect to the main part 9.

Therefore, when the position sensor 48 detects that the height of the sheath 16 is relatively high even though the torque detected by the torque driver 61 indicates that the screw 52 has been completely tightened, Assuming that the screw 52 is in a state of being lifted from a predetermined tightening completion position, it is determined that the operation is defective.

Incidentally, the suction head 21 is a part where the screw is repeatedly sucked frequently and is considerably worn out. However, the suction head 21 is fitted to the head mounting portion 20 of the sheath 16 of the bit housing 8 and Since the suction head 21 is held by the retaining pin 25, the worn suction head 21 can be easily replaced.

When an impact is applied to the tip of the screw tightening bit 36, the shock is applied to the ball bearings 42, 44 supporting the screw tightening bit 36 with respect to the main part 9 of the bit housing, especially the screw tightening bit 36. To the ball bearing 42, which is fixed to the motor, and does not reach the expensive torque driver 61.

Therefore, even if the ball bearing 42 is broken by the above-mentioned impact, the ball bearing 42 can be easily replaced without causing any trouble.

When the screw does not need to be picked up by air suction, the sheath 16 and its related structures and members are not required.

[0096] And even in such a case, it is clear that it has many of the advantages of the screw tightening device described above.

When the screw is not sucked by air, the tip of the screw tightening bit is magnetized,
The screw may be picked up by magnetic attraction.

[0098]

As is apparent from the above description, the screw tightening apparatus of the present invention comprises a screw tightening bit having a tip engaged with a head of a screw, and a screw tightening bit rotatably and mutually rotatable. A bit housing that supports the shaft relationship in a substantially fixed state, a bracket supported by the support, and an output shaft that is supported by the bracket and has a margin between the screw shaft and the screw tightening bit. A detachable driver, wherein the bracket has a mounting surface serving as a reference surface, and the bit housing has a supported surface mounted on the mounting surface of the bracket. An elastic member is interposed between the bracket and the bracket, and the supported surface is elastically brought into contact with the mounting surface.

Therefore, in the screw tightening device of the present invention,
Since the screw tightening bit is rotatably supported by the bit housing in a state in which the axial relation between the screw tightening bit is substantially fixed, the screw tightening bit does not touch the bit housing, so that there is no disturbance in detecting the tightening torque.

Further, the bit housing is supported by the bracket by a resilient member abutting the supported surface of the bit housing against the mounting surface of the bracket, so that the elastic member may be deformed as necessary. As a result, the bit housing can be tilted with respect to the bracket together with the screw tightening bit, whereby the tip of the screw tightening bit can follow the variation in the position of the screw.

Incidentally, the specific shapes and structures of the respective parts shown in the above-described embodiments are only examples of the embodiment for carrying out the present invention, and the technical scope of the present invention is thereby reduced. It should not be interpreted restrictively.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an example of an embodiment of a screw tightening device of the present invention and showing an enlarged main part.

FIG. 2 is a side view showing a whole with a part cut away.

FIG. 3 is a view taken in the direction of the arrow III in FIG. 1;

FIG. 4 is a sectional view taken along the line IV-IV in FIG. 1;

FIG. 5 is an enlarged longitudinal sectional view of a main part showing a state where a screw is sucked.

FIG. 6 is an enlarged longitudinal sectional view of a main part showing a state in which the tip of the screw tightening bit is engaged with the head of the screw.

FIG. 7 is an enlarged longitudinal sectional view of a main part showing a state immediately after the tightening of the screw is completed.

[Explanation of symbols]

 Reference Signs List 1 bracket 7a mounting surface 8 bit housing 9 main part 10a supported surface 15 elastic member 16 sheath 35 resilient biasing means 36 screw tightening bit 52 screw 52a screw head 58 support 61 driver 62 output shaft

────────────────────────────────────────────────── ─── Continued on the front page (72) Mitsuko Sato, Inventor Sony Corporation, 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo (56) References JP-A-62-282833 (JP, A) 4-60623 (JP, U) Japanese Utility Model Application 53-130599 (JP, U) Japanese Utility Model Application Hei 2-90019 (JP, U) Japanese Utility Model Application Utility Model 61-181621 (JP, U) (58) Fields surveyed (Int. Cl. ⁷ , DB name) B23P 19/06

Claims (3)

(57) [Claims] 1. A screw tightening bit having a tip engaged with a head of a screw, a bit housing rotatably supporting the screw tightening bit and having a substantially fixed axial relationship with each other, and a support body. A supported bracket, a driver supported by the bracket and having an output shaft connected to the screw tightening bit and having a margin between each other so as to be detachably connected to each other. A mounting surface is formed, and a supported surface to be mounted on the mounting surface of the bracket is formed in the bit housing, and the supported surface is mounted with an elastic member interposed between the bit housing and the bracket. A screw tightening device characterized by being elastically contacted with a surface. 2. A bit housing comprising a main portion rotatably supporting a screw tightening bit, and a sheath surrounding a distal end portion of the screw tightening bit, wherein the sheath slides in the axial direction with respect to the main portion. The screw tightening device according to claim 1, further comprising: a resilient biasing means that is movable and that resiliently biases the sheath in a direction away from the main portion between the main portion and the sheath. apparatus. 3. A space inside the bit housing is connected to a negative pressure generator, and the screw is engaged with the tip of the screw tightening bit by a negative pressure generated by driving the negative pressure generator. The screw fastening device according to claim 1 or 2, wherein a space between the screw and the bracket is sealed by the elastic member.