Multiple spindle screw fastening machine

Abstract

To provide a multiple spindle screw fastening machine capable of determining screw floating even when a space between driver bits is narrow.SOLUTION: A multiple spindle screw fastening machine 10 includes a plurality of screw fastening tools 30 in each of which a motor 31 and a driver bit 33 receiving drive of the motor 31 to rotate are connected via universal joints 321, 322. A dog 36 movable so as to be integral with the driver bit is attached to the driver bit 33 and a sensor 39 capable of detecting the dog 36 is disposed on the moving route of the dog 36. The dog 36 is constituted so that a detection target part 363 detected by the sensor 39 projects in the radially outer side from a relief part 361 facing the dog 36 of the other screw fastening tool 30, and the shaft direction cross section of the driver bit 33 is formed in a non-circular shape.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a multi-axis screw fastener that simultaneously fastens a plurality of screws. [Background technology]

[0002] Conventionally, a multi-axis screw tightening machine that tightens multiple screws simultaneously is known, as shown in Patent Document 1. This multi-axis screw tightening machine has multiple screw tightening tools, each of which includes a driver bit that can be engaged with a screw, a screw guide that can move upward relative to the driver bit, and a motor that rotates and drives the driver bit. These screw tightening tools are mounted on a tool table, and are configured to be able to be raised and lowered simultaneously in response to the elevation and lowering of the tool table. In addition, the multi-axis screw tightening machine is provided with a universal joint or the like between the motor and the driver bit, and the shaft joint is inclined at a predetermined angle, so that the driver bit can be separated from the axis of the motor. This makes it possible to bring the driver bit closer to the workpiece, making it possible to tighten multiple screws simultaneously even in a workpiece with a narrow pitch.

[0003] In addition, the driver bit of a conventional multi-axis screw tightening machine is equipped with a dog that can be raised and lowered integrally with the driver bit, and a sensor that can detect the dog is provided on the path of movement of the dog.When tightening is complete, the sensor detects the position of the dog to determine whether the screw is floating. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Utility Model Application Publication No. 54-085500 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the dog of a conventional multi-axis screw tightening machine is configured in a disk shape that is sufficiently larger than the driver bit so that it can be detected by the optical sensor, and rotates together with the driver bit. Therefore, if the distance between adjacent fastening positions is smaller than the diameter of the dog, there are problems such as the dogs coming into contact with each other, making it impossible to attach the dog to the driver bit, and making it impossible to judge the screw float.

[0006] Therefore, an object of the present invention is to provide a multi-axis screw tightening machine that can determine screw float even when it is based on the distance between fastening points. [Means for solving the problem]

[0007] The present invention has been created in view of the above problems, and is a multi-axis screw tightening machine having a plurality of screw tightening tools, each of which has a motor and a driver bit that rotates when driven by the motor, connected via a universal joint, and a dog that can move integrally with the driver bit is attached to the driver bit, and a sensor that can detect the dog is arranged on the movement path of the dog, the dog has a detection part that is detected by the sensor protruding radially outward from a relief part that faces the dog of another screw tightening tool, and the axial cross section of the driver bit is configured to be non-circular. Also, it is preferable that a sliding part that allows rotation is provided between the dog and the driver bit. It is also preferable that the dog has a fitting recess formed therein, into which a guide rod extending in a direction parallel to the driver bit can be fitted. It is also preferable that the sensor is a non-contact sensor. Effect of the Invention

[0008] According to the multi-axis screw fastener of the present invention, the dogs are configured in a non-circular shape, and by opposing the recesses of the dogs, screws can be fastened simultaneously even at fastening points that are closer together than with circular dogs, and screw float can also be determined. In addition, since a rotary sliding member is provided between the dog and the driver bit, there is an advantage that the rotation of the driver bit is not hindered. In addition, since the guide rod can be fitted into the fitting recess formed in the dog to prevent rotation, there is also the advantage that the dogs do not come into contact with each other. In addition, since the sensor is an optical sensor, there is an advantage that the screw floating can be determined with high accuracy. [Brief description of the drawings]

[0009] [Figure 1] 1 is a side view showing the structure of a multi-axis screw fastener according to the present invention. FIG. [Diagram 2] 1 is an enlarged, partially cutaway, cross-sectional side view of a main portion showing the structure of a multi-shaft screw fastener according to the present invention. [Diagram 3] 2A is a cross-sectional view taken along line AA in the figure, FIG. 2B is a cross-sectional view taken along line AA of another embodiment having three screw tightening tools, and FIG. 2B is a cross-sectional view taken along line AA of another embodiment having four screw tightening tools. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1, reference numeral 10 denotes a multi-axis screw fastening machine that simultaneously fastens a plurality of screws S into a workpiece (not shown). This multi-axis screw fastening machine 10 includes a lifting unit 20, two screw fastening tools 30, 30 that are lifted and lowered in response to the operation of this lifting unit 20, and a control unit (not shown) that controls the lifting drive source and the drive of the screw fastening tool 30.

[0011] The lifting unit 20 has a base member 21 that is fixed upright as shown in Fig. 2. Two sliding rods 22, 22 extending parallel to the upright direction of the base member 21 are provided in parallel, and a tool table 23 is attached to the sliding rods 22, 22 via bushes that slide along the respective sliding rods so that the tool table 23 can be raised and lowered. A lifting cylinder 24 with a piston rod that drives the lifting cylinder 24 is attached to the base member 21 in parallel to the upright direction, and the tool table 23 is connected to the piston rod of the lifting cylinder 24. This allows the tool table 23 to reciprocate along the sliding rods 22, 22 by a predetermined stroke of the lifting cylinder 24.

[0012] The two screw tightening tools 30, 30 are supported symmetrically by the tool base 23, and the screw tightening tools 30, 30 are configured in the same manner. For this reason, only the configuration of one screw tightening tool 30 will be described below. The screw tightening tool 30 has an AC servo motor 31 (hereinafter referred to as motor 31) fixed on the tool base 23. The output shaft of the motor 31 is configured to protrude downward from the tool base 23, and a driver bit 33 is connected to the output shaft of the motor 31 via universal joints 321, 322 that can transmit the rotational driving force in an inclined direction. By being connected by the universal joints 321, 322, the driver bit 33 can rotate by receiving the rotational driving force of the motor 31 even if it is located on the opposite screw tightening tool 30 side from the output shaft of the motor 31. In addition, the driver bit 33 has a fitting portion at its lower end that fits with the screw S, and is constantly biased downward by a compression spring 34 (hereinafter referred to as the bit cushion 34) provided between the universal joints 321, 322, so as to have a predetermined thrust.

[0013] 2, a dog 36 is rotatably attached to the upper end of the driver bit 33 via a sliding part 35 that allows rotation, such as a ball bearing, and a hollow cylindrical screw guide 37 is suspended therefrom, containing the driver bit 33 rotatably and axially relatively movable. The screw guide 37 is constantly biased downward by a second compression spring 38 (hereinafter referred to as a guide cushion 38) provided between the screw guide 37 and the dog 36. A suction means (not shown), such as a vacuum pump, is connected to the screw guide 37, and the screw S is configured to be attracted and held at its lower end opening.

[0014] On the other hand, an optical sensor 39 capable of detecting the dog 36 is disposed on the screw guide 37. The optical sensor 39 is integrally provided with a light-emitting section that outputs detection light and a light-receiving section that receives the detection light, and is configured to detect the relative positional relationship between the screw guide 37, the tool base 23, and the driver bit 33 by the dog 36 entering between them and blocking the detection light. The dog 36 and the optical sensor 39 are installed at a height where the dog 36 can block the detection light when the lower end of the screw guide 37 abuts against the workpiece and the screw S fitted to the tip of the driver bit 33 is seated on the workpiece, and the multi-shaft screw tightening machine 10 judges whether the screw S has been normally fastened based on whether the detection light of the optical sensor 39 is blocked or not when the motor 31 outputs a predetermined tightening torque. 3(a), the dog 36 has a non-circular shape in a plan view, including a recess 361 formed in a D-cut shape on the opposing screw tightening tool 30 side, and a fitting recess 362 formed to allow the guide rod 26, which will be described later, to fit therein. The dog 36 also has a detection target 363 capable of blocking the detection light of the optical sensor 39, and the detection target 363 is configured to protrude from the recess 361 radially outward of the driver bit 33.

[0015] Further, a chuck table 25 is fixed to the base member 21 below the universal joints 321, 322, and a guide rod 26 extending parallel to the screw guide 37 is fixed to the upper surface of the chuck table 25. The upper end of the guide rod 26 is configured to be located above the dog 36 and configured to always fit into the fitting recess 362 of the dog 36. As a result, the dog 36 is fixed to the guide rod 26 without rotating, while being freely slidable in the axial direction.

[0016] A chuck unit 40 is suspended and supported by the chuck table 25. This chuck unit 40, like the chuck unit 40 disclosed in JP-A-9-174349, includes a screw supply hose 41 continuing to an external screw supply device, and a pair of chuck jaws 42 capable of holding the screw S that has passed through the screw supply hose 41 on an extension of the screw guide 37 and the driver bit 33. The chuck jaws 42 are configured to swing when pressed from above by the screw guide 37 or the driver bit 33, and to be able to retreat from an extension of the screw guide 37 and the screw tightening tool 30.

[0017] The control section is connected to the motor 31, the lift cylinder 24, and the optical sensor 39, and is configured to be able to control the driving based on various input signals.

[0018] Next, the operation of the multi-axis screw driver 10 constructed as above will be described. First, the control unit operates the lift cylinder 24 to lower the tool table 23 and the screw tightening tools 30, 30, and sends a rotation command to the motor 31 to rotate and drive the motor 31 at a predetermined rotation speed and tightening torque. As a result, the screw guide 37 and the driver bit 33 come into contact with the workpiece or the screw S. At this time, the guide cushion 38 and the bit cushion 34 bend and absorb the impact at the time of contact, preventing damage to the workpiece and the screw S, etc. In addition, since the driver bit 33 is configured to be movable relative to the motor 31, the tool table 23 can be lowered to a predetermined height at which the bit cushion 34 is sufficiently bent, and the driver bit 33 engages with the screw S in a state in which a thrust is constantly applied, even though the height at the time of temporary tightening differs slightly for each screw S. At this time, the driver bit 33 receives a rotation torque from the motor 31, so the screw S is tightened with a predetermined tightening torque. At this time, the tool table 23 is connected to the sliding rod 22, so the tool table 23 is prevented from tilting with respect to the base member 21. This prevents the tool base 23 from tilting, preventing a decrease in the thrust applied to the screw S by the driver bit 33, and improving the screw tightening accuracy. After that, when the output torque of the motor 31 reaches a preset tightening torque, the control unit stops the rotational drive of the motor 31. When the motor 31 stops, the control unit checks whether the optical sensor 39 detects the dog 36. At this time, if the optical sensor 39 detects the dog 36, it determines that the driver bit 33 has descended to the desired height and the seating surface of the screw S is in contact with the workpiece, that is, the screw S is properly tightened and seated. On the other hand, if the optical sensor 39 does not detect the dog 36, it determines that the screw float has occurred, and notifies an external device or the like of an error.

[0019] In the multi-shaft screw fastener 10 as described above, the recesses 361 are formed at the opposing locations of the dogs 36, so that it is possible to bring the driver bits 33 closer together than in the conventional multi-shaft screw fastener 10. Furthermore, since the dog 36 is attached to the driver bit 33 via a sliding part and the dog 36 is prevented from rotating by the guide rod 26, the dog 36 does not rotate together with the driver bit 33 during fastening. Due to these structures, it is possible to determine the floating of the screw even when the driver bits 33 are close to each other.

[0020] The multi-shaft screw driver 10 according to the present invention is not limited to the above, and various modifications are possible without departing from the spirit of the invention. For example, the multi-shaft screw driver 10 in the above embodiment is configured to have only two screw tightening tools 30, and therefore has only one recess 361 as shown in Fig. 3(a), but is not limited to this, and there is no problem even if it has multiple recesses 361 in cases where three or more screw tightening tools 30 are provided as shown in Fig. 3(b) and (c).

[0021] Furthermore, the multi-axis screw fastener 10 of this embodiment is equipped with the chuck unit 40 capable of temporarily holding the screw S, but is not limited thereto, and the same effect can be obtained even with a multi-axis screw fastener 10 that simultaneously tightens a plurality of screws S temporarily set in a workpiece. Furthermore, the optical sensor 39 is an example of a non-contact sensor that detects the dog 36, and there is no problem with using other non-contact sensors such as a proximity sensor as long as they are capable of detecting the detected portion 363. [Explanation of symbols]

[0022] 10... Shaft screw tightening machine 20 … Lifting unit 21 ... Base material 22 ... Sliding rod 23 ... Tool stand 24 … Lifting cylinder 25 … Chuck stand 26 ... Guide rod 30 … Screw tightening tool 31 ... Motor 321... Universal joint (upper side) 322… Universal joint (lower side) 33 ... Driver bit 36 ... Dog 39 ... Optical sensor S: Screw

Claims

1. The screw tightening tool includes a motor and a driver bit that is rotated by the drive of the motor and is connected via a universal joint, A multi-shaft screw tightening machine in which a dog that can move integrally with the driver bit is attached to the driver bit and a sensor that can detect the dog is disposed on a movement path of the dog, A multi-axis screw fastening machine characterized in that the dog has a detection portion detected by the sensor protruding radially outward from a recess facing the dog of another screw fastening tool, and the axial cross section of the driver bit is configured to be non-circular in shape.

2. 2. The multi-axis screw driver according to claim 1, wherein a sliding part that allows rotation is provided between the dog and the driver bit.

3. 3. The multi-axis screw driver according to claim 2, wherein the dog has a fitting recess formed therein, into which a guide rod extending in a direction parallel to the driver bit can be fitted.

4. 2. The multi-axis screw fastener according to claim 1, wherein the sensor is a non-contact sensor.

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