JP2023110745A - Screw fastening machine - Google Patents

Abstract

To provide a screw fastening machine capable of fastening a plurality of kinds of screws without tool exchange.SOLUTION: A screw fastening machine 10 includes a driver bit 38 which is configured so as to be capable of rotation by receiving a drive of a rotating drive source 34 and a box bit 39 which is configured so as to be capable of rotation integrally with the driver bit 38 and so as to be relatively movable in an axial direction with respect to the driver bit 38. Thereby, both of a screw N1 having a drive hole and a screw N2 having a drive part can be fastened without tool exchange. Further, the box bit 39 is suspended and supported by the driver bit 38 and is preferably provided with a fitting hole 391 having such a depth that a lower end of the driver bit 38 can be contained.SELECTED DRAWING: Figure 2

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw tightening machine for fastening screws to a work.

Conventionally, as shown in Patent Documents 1 and 2, a screwdriver equipped with a box bit or a driver bit as a fastening tool to be fitted with a screw is known. The fastening tools of these screw tightening machines are connected to a rotary drive source, and are configured to be capable of fastening a screw to a work with a predetermined torque.

JP-A-09-174351 Japanese Unexamined Patent Publication No. 10-328946

However, conventional screwdrivers can only be equipped with either a box bit or a driver bit, so when tightening screws with different head shapes, it is necessary to replace the fastening tool or prepare another screwdriver. There were problems such as

SUMMARY OF THE INVENTION The present invention was made in view of the above problems, and an object of the present invention is to provide a single screw tightening machine capable of tightening a plurality of screws. In order to achieve this object, the present invention provides a driver bit that is rotatable by being driven by a rotary drive source, and a driver bit that is rotatable integrally with the driver bit and relatively movable in the axial direction with respect to the driver bit. It comprises a structured box bit. It is preferable that the box bit is suspended from the driver bit and has a fitting hole with a predetermined depth that can accommodate the lower end of the driver bit. Moreover, it is preferable that a screw guide containing the driver bit and the box bit is provided, and an intake means is connected to the screw guide. Further, the outer diameter of the box bit is substantially the same as the inner diameter of the screw guide, and the bottom surface of the fitting hole is formed with an intake path penetrating to the end surface on the intake means side. preferably. Further, it is preferable that a tapered surface whose diameter gradually decreases toward the drive hole is formed on the end surface of the box bit on the intake means side. Furthermore, it is preferable to have a lifting means for lifting the screw guide toward the rotational drive source.

According to the screwdriver of the present invention, since it has both the driver bit and the box bit that can rotate integrally with the driver bit and can relatively move in the axial direction, the drive hole is formed in the head. It is possible to fasten both screws and screws with a drive in the head profile. As a result, it is possible to reduce the replacement work of the screwdriver and improve the work efficiency. Since the lower end of the driver bit is enclosed in the box bit and the screw is in surface contact with the box bit, there is an advantage that the sucked and held screw is less likely to tilt. In addition, since the driver bit and the box bit are contained in the screw guide, and the screw guide can attract and hold any head-shaped screw that can be attracted and held, it is possible to tighten a larger number of screws. There are also advantages. Furthermore, since the outer diameter of the box bit is substantially the same as the inner diameter of the screw guide, there is an advantage that even a screw with a diameter smaller than that of the screw guide can be sucked and held. In addition, since the box bit has a tapered surface, it is possible to prevent the friction between the box bit and the screw guide from increasing due to dust sucked in when the screw is attracted, and as a result, it is possible to prevent the occurrence of tightening failure. There are advantages. Furthermore, the provision of the lifting means has the advantage of enabling tightening in a narrow space.

BRIEF DESCRIPTION OF THE DRAWINGS It is a partial cross-sectional side view which shows the structure of the screwdriver based on this invention. (a) is an enlarged partial cross-sectional side view of the main part showing the peripheral structure of the driver bit in a standby state, and (b) is the peripheral structure of the driver bit in a state in which the driver bit has moved relative to the box bit in the axial direction. 1 is an enlarged partial cross-sectional side view of a main part showing the . (a) is a cross-sectional view taken along line AA of FIG. 2, (b) is a cross-sectional view along line BB of FIG. 2, and (c) is a bottom view of (a) of FIG. BRIEF DESCRIPTION OF THE DRAWINGS It is operation|movement explanatory drawing of the screw fastening machine based on this invention, (a) is a principal part enlarged partial notch cross-sectional side view which shows the state which adsorbed-held the 1st screw, (b) is a 1st screw. 2 is an enlarged partial cutaway cross-sectional side view of a main part showing a state in which the is fastened to the work W. FIG. FIG. 2 is an operation explanatory view of the screw tightening machine according to the present invention, where (a) is an enlarged, partially cutaway cross-sectional side view of the main part showing a state in which the second screw is held by suction, and (b) is the second screw; 2 is an enlarged partial cutaway cross-sectional side view of a main part showing a state in which the is fastened to the work W. FIG. FIG. 3 is an operation explanatory diagram of the screw tightening machine according to the present invention, in which (a) is an enlarged, partially cutaway cross-sectional side view of the main part showing the state in which the third screw is held by suction, and (b) is the fourth screw; is an enlarged, partially cutaway cross-sectional side view of a main part showing a state in which the is held by suction. Fig. 10 is a partially cutaway side view showing another embodiment of the screw tightening machine according to the present invention, where (a) is a partially cutaway side view showing a standby state, and (b) is a state in which the lifting means is driven; is a partially cutaway side view showing the .

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described based on the drawings. In FIG. 1, reference numeral 10 denotes a screw tightening machine that fastens a screw N1, which is an example of a fastening part, to a workpiece W (not shown). The screwdriver 10 is composed of a position control mechanism 20 which is driven by a horizontal articulated robot (not shown) for horizontal movement, and a driver unit 30 which is driven by the position control mechanism 20 to move up and down. there is

As shown in FIG. 1, the position control mechanism 20 has a vertically extending frame 21. A horizontally extending upper plate 22 and a lower plate 23 are integrally fixed to the upper and lower ends of the frame 21. As shown in FIG. ing. A guide rod 24 extending parallel to the frame 21 is provided between the upper plate 22 and the lower plate 23. A slidable driver table 25 is attached to the guide rod 24 so as to be able to move up and down. It is An AC servo motor 26 (hereinafter referred to as a lifting motor 26), which is an example of a lifting drive source, is mounted on the upper plate 22, and a ball screw 27 is integrated with the output shaft of the lifting motor 26. is rotatably connected to the The ball screw 27 is provided between the upper plate 22 and the lower plate 23, and the driver base 25 is attached to the ball screw 27 via a drive nut (not shown) that moves up and down as the ball screw 27 rotates. Concatenated. The driver unit 30 is connected to the driver base 25 . Therefore, the driver base 25 and the driver unit 30 connected thereto are lifted and lowered by the rotational driving of the lift motor 26 .

The driver unit 30 has a connection plate 31 fixed to the driver base 25 , and a hollow cylindrical housing 311 is fixed to the lower surface of the connection plate 31 . A guide holder 32 is suspended from the housing 311 so as to be relatively movable in the vertical direction. A substantially hollow cylindrical screw guide 33 is fixed to the lower end of the guide holder 32 . A hose joint 321 having one end connected to the screw guide 33 is attached to the guide holder 32, and the other end of the hose joint 321 is connected to a suction means such as an external vacuum generating device. not shown) are connected. Therefore, when the intake means is driven, the inside of the screw guide 33 becomes negative pressure, and the screw N1 can be held by suction at the lower end opening of the screw guide 33 . The guide holder 32 is always urged downward by a guide spring 322 enclosed inside the housing 311. When the guide spring 322 is flexed, the guide holder 32 and the screw guide 33 move toward the housing. 311 can move axially relative to it.

A motor base 312 is placed on the connecting plate 31, and above the motor base 312 is an AC servo motor 34 (hereinafter referred to as a fastening motor), which is an example of a rotational drive source for fastening the screw N1. 34) is installed. The fastening motor 34 is fixed to the motor base 312 with its output shaft directed downward, and the output shaft of the fastening motor 34 has a connection joint that rotatably penetrates the motor base 312 and the driver base 25 . A bit shaft 37 is connected via 35 .

The connection joint 35 is formed with a bottomed hole 351 into which the bit shaft 37 is inserted, and the bottomed hole 351 is formed with an elongated hole 352 extending in the axial direction of the bit shaft 37 at right angles thereto. It is A connecting pin 361 configured to move up and down along the elongated hole 352 is inserted. Support. As a result, the bit shaft 37 can rotate integrally with the output shaft of the fastening motor 34 and can move relative to the fastening motor 34 in the axial direction of the bit shaft 37 . A cushion spring 362, which is an example of a biasing member, is enclosed in the bottomed hole 351, and the cushion spring 362 always biases the bit shaft 37 downward. The dimension of the elongated hole 352 is set within a range in which the cushion spring 362 can always bias the bit shaft 37 and the cushion spring 362 is not crushed when the bit shaft 37 rises relative to the connection joint 35. there is

The bit shaft 37 is a cylindrical member configured to be rotatable within the screw guide 33 and relatively movable in the axial direction, and a driver bit 38 is connected to its lower end. As shown in FIG. 2A, the driver bit 38 is a rod-shaped member inserted through the screw guide 33 so as to be rotatable and relatively movable in the axial direction. , a hanging portion 382 that is continuous with the lower end of the engaging portion 381 and has an area larger than that of the engaging portion 381 in a plan view, and a fitting portion 383 that is continuous with the lower surface of the hanging portion 382 and has a hexagonal prism shape. and As shown in FIG. 3(a), the engaging portion 381 is formed in an arc shape at the corner thereof so as to be slidable on the inner surface of the screw guide 33. As shown in FIG. Therefore, it is possible to prevent the bit shaft 37 and the driver bit 38 from swinging within the screw guide 33, and a gap through which air can pass is formed between the engaging portion 381 and the inner surface of the screw guide 33. The lower end of 33 can hold the screw N1 by suction.

Further, the driver bit 38 has a box bit 39 which is rotatably configured integrally with the driver bit 38 and supported by suspension. The box bit 39 has a diameter substantially equal to the hole diameter of the screw guide 33 as shown in FIG. A fitting hole 391 is formed in the lower surface of the box bit 39 so that the head of a screw N2, which will be described later, can be fitted. An engaging hole 392 having the same shape as that of the box bit 39 penetrates to the upper surface. The box bit 39 configured as described above has the engaging portion 381 of the driver bit 38 inserted into the engaging hole 392 thereof, and is suspended while the bottom surface of the engaging hole 391 is in contact with the suspension portion 382. , can rotate integrally with the driver bit 38, and can move relative to each other in the axial direction as shown in FIG. 2(b). The fitting hole 391 is formed deeper than the axial dimension of the hanging part 382 and the fitting part 383 of the driver bit 38, and the hanging part 382 and the fitting part 382 are always in the fitting hole 391. 383 can be accommodated. Further, the fitting hole 391 is formed with a plurality of ventilation holes 393 penetrating to the upper surface of the box bit 39 . Further, the box bit 39 is always biased by a biasing spring 384 attached to the driver bit 38 . Moreover, as shown in FIG. 2, the upper surface of the box bit 39 is formed with a tapered surface 394 whose diameter gradually decreases downward.

The fitting hole 391 has an arcuate fitting recess 3911 centered on the axis of the box bit 39 as shown in FIG. It has a substantially petal shape in which six fitting projections 3912 protruding inward are alternately formed in the circumferential direction. Furthermore, one end of the box bit 39 is formed with a lead-in surface 3913 as shown in . This lead-in surface 3913 is configured to incline while decreasing in diameter as it goes inward from the opening edge of the fitting hole 391 , and its maximum diameter part is the same diameter as the circular arc shape of the fitting recess 3911 . is set. Six ventilation holes 393 are formed at equal intervals in the circumferential direction for each fitting recess 3911 .

The screw N1 is a fastening part in which a head and a shaft are integrally formed, and the heads have different shapes. The screw N1 has a hexagonal driving hole (not shown) formed in the head thereof, and an enlarged diameter portion protruding in the outer peripheral direction is formed in the head bearing surface of the screw N1. This enlarged diameter portion has a diameter substantially equal to the hole diameter of the screw guide 33. As shown in FIG. designed to be held by suction.

Next, operation of the screw tightening machine 10 configured as described above will be described.
When the work W is transported to a predetermined screw tightening point by an external transport means (not shown), the controller outputs a drive signal to the screw tightening machine 10 . Upon receiving this drive signal, the screwdriver 10 drives the horizontal articulated robot to move the driver unit 30 onto an external supply device (not shown). After that, when the driver bit 38 reaches the axis of the screw N1 waiting on the supply device, the position control mechanism 20 is driven to lower the driver unit 30 toward the screw N1.

As described above, when the screw guide 33 of the driver unit 30 descending toward the screw N1 comes into contact with the bearing surface of the screw N3 or the parts supply device, the suction means is driven, and the screw N1 is moved as shown in FIG. Adsorb to hold. When the screw N1 is held by suction, the position control mechanism 20 and the horizontal articulated robot are driven to move the driver bit 38 and the screw N1 onto the axis of the pilot hole W1 formed in the work W. As shown in FIG. When the screw N1 reaches the axis of the pilot hole W1, the position control mechanism 20 is driven again to lower the driver unit 30 toward the pilot hole W1, and the fastening motor 34 is driven to drive the driver bit 38 and the box bit 39. to rotate.

In such a screw tightening process, when the screw N1 comes into contact with the work W, the screw N1 and the box bit 39 coming into contact with it stop descending. However, since the driver bit 38 receives the downward thrust of the position control mechanism 20 and descends while deflecting the biasing spring 384, the fitting portion of the driver bit 38 does not move as shown in FIG. 4(b). 383 protrudes from box bit 39 and fits into the drive hole of screw N1. After that, when the tightening motor 34 outputs a predetermined tightening torque, the screw tightening machine 10 ends the screw tightening process and returns to the initial position. In the screw tightening process, when the lower end of the screw guide 33 comes into contact with the workpiece W, the driver bit 38 moves relative to the screw guide 33 while the guide spring 322 is similarly deflected. N1 and driver bit 38 are fitted.

Further, when the above-described screw tightening process is completed, the suction means is stopped. As a result, impurities such as dust in the air sucked into the screw guide 33 fall onto the box bit 39 . At this time, since the tapered surface 394 is formed on the upper surface of the box bit 39 , impurities falling on the box bit 39 fall along the tapered surface 394 to the bottom side, that is, to the inside in the radial direction. and the screw guide 33. This prevents an increase in friction generated between the box bit 39 and the screw guide 33, which causes torque loss and prevents proper tightening torque from being transmitted to the screw N1. As a result, screw tightening failures and the like are less likely to occur.

Next, the case of fastening the second screw N2 will be described. The screw N2 is a fastening component having a hexagonal prism-shaped driving portion on its head, and an enlarged diameter portion protruding in the outer peripheral direction is formed on the bearing surface of the head. The enlarged diameter portion of the screw N2 is configured to have substantially the same diameter as the hole diameter of the screw guide 33, and as shown in FIG. It is designed to be held by adsorption at

The screw N2 sucked and held as described above is fastened to a predetermined workpiece W as shown in FIG. 5B by rotating the box bit 39 in the screw tightening process as described above. In the screw tightening process, the box bit 39 retreats until the lower end of the driver bit 38 abuts on the upper surface of the head of the screw N2, and the screw N2 receives screw tightening thrust from the driver bit 38. By providing the driver bit 38 and the box bit 39 configured to be rotatable integrally with the driver bit 38 and relatively movable in the axial direction, the screw fastener 10 has a drive hole (not shown) in the head. It is possible to tighten both the screw N1 on which the screw is formed and the screw N2 on which the driving part is formed on the outer shape of the head. As a result, there is no need to change bits when tightening different screws, improving work efficiency.

Next, the case of fastening the third screw N3 will be described. The screw N3 is a fastening component having a drive hole (not shown) formed in the head portion of which the same shape as that of the screw N1 is formed. The enlarged diameter portion of the screw N3 is configured to have a smaller diameter than the hole diameter of the screw guide 33, and the upper edge of the head portion is formed on the lower surface of the box bit 39 as shown in FIG. 6(a). It is sucked and held in a state of contact with the drawn-in surface 3913 . At this time, the outer diameter of the box bit 39 is configured to be substantially the same diameter as the hole diameter of the screw guide 33, and the air that can pass through the minute gap between the outer peripheral surface of the box bit 39 and the inner peripheral surface of the screw guide 33 is provided. and most of the sucked air passes through the fitting hole 391 of the box bit 39. Therefore, even if there is a gap between the screw N3 and the screw guide 33, the screw N3 is almost the same as the screw N1. It is sucked and held in the screw guide 33 by the suction force.

Next, the case of fastening the fourth screw N4 will be described. The screw N4 is also a fastening component having a hexagonal driving hole (not shown) formed in its head, and an enlarged diameter portion protruding in the outer peripheral direction is formed on the bearing surface of the head. The screw N4 has an enlarged diameter portion larger in diameter than the hole diameter of the screw guide 33. As shown in FIG. It is designed to be held by adsorption at

The screws N3 and N4 sucked and held as described above are fitted with the fitting portion 383 of the driver bit 38 protruding from the box bit 39 and the driving hole formed in the head portion thereof, similar to the screw N1. is clamped to the work W of In this way, the screw guide 33 containing the driver bit 38 and the box bit 39 is provided, and the screw is sucked into the screw guide 33. If the screw can be sucked and held by the screw guide 33, it can be sucked, held, and tightened. It becomes possible. As a result, it becomes possible to tighten a larger number of screws, further improving work efficiency.

Further, as a second embodiment, a lifting means 40 for lifting the guide holder 32 may be provided. As shown in FIG. 7A, the lifting means 40 includes a lifting cylinder 41, which is an example of a lifting drive source, and a lifting plate connected to the driving portion of the lifting cylinder 41 and in contact with the lower surface of the guide holder 32. 42, in which a U-shaped groove 43 configured to avoid the screw guide 33 is formed. When the lifting means 40 constructed as described above is driven, the guide holder 32 and the screw guide 33 lifted by the lifting plate 42 are lifted with respect to the driver bit 38 and the box bit 39 as shown in FIG. 7(b). Therefore, the box bit 39 protrudes from the lower end of the screw guide 33 . As a result, the screw guide 33 does not come into contact with the workpiece W in the screw tightening process. As a result, the outer diameter of the tip of the driver unit 30 becomes small, so that it can be tightened in a relatively narrow place, and the repulsive force of the guide spring 322 that urges the screw guide 33 downward is not applied to the workpiece W. , the downward thrust acting on the workpiece W is reduced.

The screw tightening machine 10 according to the present invention is not limited to the one described above, and various modifications can be made without departing from the spirit of the invention. For example, the shape of the fitting portion 383 of the driver bit 38 and the shape of the fitting hole 391 of the box bit 39 are preferably changed according to the head shape of the screw to be used. There is no problem. Also, the cross-sectional shapes of the engaging portion 381 and the engaging hole 392 are not limited to the substantially quadrangular prism shape, and other shapes may be used without any problem. Furthermore, the present screw tightening machine 10 may be used as a temporary tightening machine that temporarily tightens screws at high speed and low torque, and in particular, it may be applied to the upstream process of a retightening machine that tightens screws at low speed and high torque. no problem.

REFERENCE SIGNS LIST 10: Screwdriver 33: Screw guide 38: Driver bit 39: Box bit 391: Fitting hole 393: Intake path 394: Tapered surface 40: Lifting means

Claims (6)

and a box bit configured to be rotatable integrally with the driver bit and relatively movable in the axial direction with respect to the driver bit. screwdriver. 2. The screwdriver according to claim 1, wherein the box bit is suspended from the driver bit and has a fitting hole of a predetermined depth capable of enclosing the lower end of the driver bit. A screw guide containing the driver bit and the box bit is provided,
3. The screwdriver according to claim 1, wherein the screw guide is connected to suction means. The box bit has an outer diameter substantially equal to the inner diameter of the screw guide,
4. The screwdriver according to claim 3, wherein a bottom surface of said fitting hole is formed with an intake path penetrating to an end surface on the side of said intake means. 5. The screwdriver according to claim 3, wherein the end face of the box bit on the suction means side is formed with a tapered face whose diameter gradually decreases toward the drive hole side. . 6. The screw tightening machine according to claim 3, further comprising lifting means for lifting the screw guide toward the rotary drive source.

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