JP3376486B2 - Screw tightening system for assembly line - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw tightening system to be installed and used in a parts assembly line, and more specifically,
As long as there is at least a screw bit insertion space for the work to be screwed into the screwdriver head or screw head, it is suitable to install on the parts assembly line and automatically tighten the screw. It concerns the improvement of the system.

[0002]

2. Description of the Related Art Generally, in a screw tightening system used in an assembly line, it is the most important to move a supplied screw to a screw tightening place in a correct posture and securely fix and hold the parts to each other. , Means are adopted on the assumption that there is sufficient space in the screw tightening part. As a typical means, a system is known in which a screw held by chucking means is tightened with a driver bit.

In this screw tightening system, the driver bit is rotated and lowered with respect to the screw supplied by the screw supply unit, and the screw is rotated when the tip end thereof is fitted in the groove of the head of the screw. At the same time as stopping, the head of the screw is held by the chucking means that is lowered together with the driver bit and the chuck pawls are closed by the vacuum means.

Then, after the chucking means and the driver bit are lifted together while holding the screw, the parts (workpiece) in which the screw holes are set in the coupled state are stopped by intermittently moving in synchronization with this. Just above the screw tightening position,
Move the screw in the correct posture and lower the chucking means and driver bit together again, and when the screw tip of the work comes into contact with the screw tip, release the screw and simultaneously rotate the driver bit with torque. The operation is performed in a cycle that ends at the screw tightening stage where the screw is tightened and returns to the first screw holding stage for tightening the screw of the next workpiece that moves intermittently.

[0005]

Since the above-mentioned known screw tightening system adopts means for holding the screw head by expanding and contracting the chuck claws, it does not hinder the lifting and expanding and contracting of the chuck claws as the screw tightening position. Space is needed.
Therefore, in a work assembly line in which a screw can be tightened in a portion where such a space can be secured, there is no problem in installing and using a known screw tightening system. However, in many cases, it is necessary to tighten the screws in a narrow part where a space that does not prevent the chuck jaws from moving up and down and expansion / contraction cannot be secured.
As a screw tightening system in the assembly line for small parts such as home electric appliances, there are many cases where it cannot be installed and used, and in such a case, it must be entrusted to the operator's manual work, which reduces the work efficiency. This is a cause of increasing the assembly cost.

According to the present invention, as long as there is an insertion opening into which at least a large-diameter portion of the driver bit or the head portion of the screw is inserted, as the screw insertion space of the work to be screwed, regardless of the size of the insertion opening. It is widely installed in a parts assembly line and is most suitable for automatic and reliable screw tightening. Moreover, the system configuration is simple and the system cost is low, and the product cost is reduced by the efficiency of line assembly. An object of the present invention is to provide a screw tightening system for an assembly line that can be used.

[0007]

In the assembly line screw tightening system according to the present invention, a screw S made of a magnetic material housed in a container is sucked onto the tip of a driver bit 31 which is a constituent part of a driver unit 3 described later. At the holding position, the screw floats to lift slightly upward vertically with air pressure.
With the unit 2, the screw S made of a magnetic material is attached to the bottom.
A screw holding slider block 13 provided with a vent hole 15
The screw supply unit 1 configured to supply the screw S in the normal position with the head of the screw S facing upward, and the screw S supplied in the normal position are held and moved to the screw tightening position of the work W to move the screw. Driver unit 3 for tightening
And a work supply unit 5 that supplies the work W to the screw tightening position in association with the movement of the driver unit 3, and the driver unit 3 is a driver made of a permanent magnet or a material magnetized by excitation control. By the cooperation of the rotation of the bit 31 and the attraction force and the pressing force by the magnetic force,
The tip of the driver bit 31 is fitted into the groove of the head of the screw S supplied from the screw supply unit 1 and floated so that the screw axis is vertical, and the screw S supplied from the screw supply unit 1 is inserted. Hold the screw S held,
The driver unit driving means 4 is moved up to a screw tightening position of the work W which is a screw tightening work area and coincides with a screw tightening position of the work W immediately below the driver bit 31.
In the screw tightening work area, torque rotation and lifting movement for screw tightening are given to the driver bit 31, and ascending and descending together with the driver bit 31 secures a descending stroke required for screw tightening. It is configured to include a tightening confirmation sensor 6 and a work holder 7 that holds down the bite of the work as the driver bit rises.

[0008]

In the construction of the screw tightening system for the assembly line according to the present invention described above, the screw housed in the container is held at the tip of the driver bit which is a constituent part of the driver unit, and then the work is carried out. The basic system for screw-fastening the workpieces supplied in the set state by the torque rotation transmitted to the driver bit and the up-and-down movement in the vertical axis direction while moving to the screw tightening position of It is a screw tightening system.

However, in the present invention, there is provided means for holding the screw S slightly levitated vertically upward by air pressure at the tip of the bit of the driver bit 31 made of a permanent magnet or a material magnetized by excitation control. Since the driver bit is held in cooperation with the rotation of the driver bit and the attraction force and the pressing force by the magnetic force, the bit tip corresponding to this is fitted in the groove of the head of the screw S supplied from the screw supply unit 1 and floated. In addition to being rounded, the bit tip and the groove bottom are in close contact by pressing with the bit tip without forming a gap between them, and the posture of holding the screw at the tip of the bit is secured in a normal posture with the screw axis being vertical. Moreover, the empty supply is eliminated by reliable holding.

Therefore, unlike the conventional case, it is not necessary to take a normal posture by chucking immediately before fitting the tip of the bit into the groove of the head of the screw S. Therefore, as a screw insertion space of the work W to be screwed, the chuck is used. Even if there is no wide insertion hole that allows the maximum diameter part to enter, at least the driver bit 3
It suffices if there is an insertion opening into which the large diameter portion of either 1 or the head of the screw S is inserted, so that regardless of the size of the insertion opening, it can be widely installed in the parts assembly line and automatically tightened with screws. Become.

Further, as described above, the fitting of the groove of the head of the screw S and the tip of the bit in the normal posture is performed by the floating of the screw S, the rotation of the driver bit 31, and the attraction and pressing by the magnetic force . Since it is performed without difficulty, it can be ensured by setting a relatively rough lifting stroke at the screw holding stage.Therefore, with high accuracy and precision, taking into consideration damage to members due to collision etc. as in the past. It is not necessary to set a different lifting stroke, the configuration is simple, the system cost can be reduced, and the driver bit 3
Since it is possible to avoid damage to the tip of the bit and damage to the work W due to the collision of No. 1, it is possible to suppress the reduction of the defective rate of the work W and to reduce the product cost by improving the efficiency of line assembly. Can be provided.

Further, as described in claim 2, the supplied screw S is held as a means of the screw levitation unit 2 which slightly lifts the screw S supplied from the screw supply unit 1 vertically upward by air pressure. By using a configuration that uses a part of the holding part and the air supply pipe that is integrally connected to the pipe, the airtightness of the connection is maintained, air leakage does not occur, and the pressure setting for screw levitation up to the required height is set. Easy and no pressure fluctuation. Therefore, the screw is securely held by the tip of the bit, the holding failure is drastically reduced, and the operation efficiency of the screw fastening system can be improved.

Further, as described in claim 3, the screw S of the driver bit 31 is used as a means of the screw levitation unit 2 for slightly levitation the screw S supplied from the screw supply unit 1 vertically upward by air pressure. Even in the case where the air is supplied from the air supply port opened at a fixed position immediately below the position where the tip is sucked and held, through the ventilation hole 15 of the screw holding hole 14 for holding the screw S, the airtightness is higher than that of the means of claim 2. Although a little inferior in the above, this can be solved by using a seal member.
Since the same effect as in the case of the configuration can be obtained, and since the air piping part is in a fixed position, flexibility is not required for the piping member, and as a piping structure of a system that is smart and cohesive by piping with a hard pipe member. Durability can be secured.

According to a fourth aspect of the present invention, the work supply unit 5 is provided with a plurality of holders for setting the parts to be screwed and fixed to the edge of the table which is intermittently rotated about the vertical axis. By fixing the parts and setting the parts in the holder one after another by the operator, not only can the screw tightening work be performed efficiently by simple and easy work and monitoring, but also the parts can be mounted from the same side. When it is necessary to tighten the screws, the work supply unit 5 can be shared, and the other units can be arranged so as to be set and controlled so as to move to the respective screw tightening positions. Can be improved. Of course, when tightening a plurality of the same screws S on the same work W, the intermittent movement of the work supply unit 5 and the movement stroke of the driver bit 31 should be adjusted to the screw S.
It goes without saying that the repetitive motion corresponding to the number of lines is set and controlled as one cycle.

Further, as described in claim 5, the tightening confirmation sensor 6 for ascending and descending together with the driver bit 31 to secure the descending stroke necessary for tightening the screw of the driver bit 31 and the bite of the work as the driver bit 31 rises. By providing the work retainer 7 for holding the attachment, it is possible to prevent the halfway end tightening of the screw S from occurring and to securely tighten the screw, and also to prevent the work W from being lifted together with the driver bit 31 after the tightening. it can.

The magnetic force when a permanent magnet is used as the driver bit 31 is such that the screw S is magnetized to a strength such that the screw S does not fall off from the driver bit 31 due to mechanical vibration or the like. If a permanent magnet is integrated with the tip of the bit to achieve material economy of the entire driver bit, and if the tip of the bit is replaceable, it may be changed depending on the magnetic strength of the screw or into the groove of the tip of the bit. It is possible to deal with the case where the fitting is hindered due to wear or the like.

If the driver bit 31 made of a magnetic material is controlled so as to be electrically excited and demagnetized,
A constant magnetic force can be secured at all times to secure the adsorption of the screw S, and in addition, a commercially available driver bit 31 made of a magnetic material can be used.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The drawings show an embodiment of a screw tightening system for an assembly line, which is most suitable for fixing a bracket B to a motor M, which is a component of a cassette deck, with two screws S of the same size (see FIG. 5). 1 is a front view of the system, FIG. 2 is a schematic plan view, FIG. 3 is a schematic view of the structure of a screw supply unit including a screw supply unit 1 and a screw levitation unit 2, and FIG. FIG. 5 is a perspective view of an air supply to the screw holding hole 14, and FIG. 5 is a perspective view of a motor, which is a component of a cassette deck, and a bracket which is screwed to the motor.

The screw fastening system for assembly line illustrated above may Toka screw supply unit 1 and the screw floating unit 2
A screw supply unit consisting of a screw unit, a screw capturing and moving unit including a driver unit 3 and driver unit driving means 4 for driving the driver unit 3, and a work supply unit 5.
Is moved to a predetermined position by the magnetic attachment by the driver bit 31 of the driver unit 3 and the driver unit driving means 4, and one screw S is fastened to a predetermined position of the work W,
The other screw S is connected so as to repeat a series of operations for tightening by the same operation as a cycle, and the configuration of each unit and means will be described below together with the operation.

First, the screw supply unit 1 constituting the screw supply unit is no different from the supply means which is usually used, that is, a large number of screws are provided in a semitransparent container 11 which has a supply port and is visible. A screw S made of a magnetic material is sequentially slid into the inclined passage 12 to support a neck portion of the head of the screw S formed on a screw holding slider block 13 which is reciprocally driven by an air cylinder in a predetermined stroke in a horizontal direction. The screw shaft portion is supplied to one screw holding hole 14.

The screw levitation unit 2 which constitutes a screw supply portion is provided with an air supply port 16 at the bottom of the screw holding hole 14 of the screw holding slider block 13 by penetrating the ventilation hole 15 to the lower surface and providing a pressure air supply source. 21 (compressor,
A flexible pipe 22 is provided to supply air to the air supply port 16 via a control valve 23 that controls the injection timing of air from a cylinder or the like), and the air pressure is supported by the screw holding hole 14. Screw the normal position screw S 3-5
mm The pressure is such that it floats and is set according to the weight of the screw, airtightness, and the like.

In the driver unit 3 which constitutes the screw capturing / moving portion, the guide member 33 through which the nut 32 to which the spiral shaft 42 of the beam-like member 41 is screwed and the guide shaft 43 pass is inserted.
With respect to the base bracket 35 fixed to the front surface of the horizontal movement slider 34 protruding from the back surface, and the base bracket 35 for imparting the torque rotation motion for screw tightening and the bit lifting motion to the driver bit 31. An air cylinder 36 controlled by an air regulator, a driver driving air motor 37, a driver chuck 38 provided on an output shaft of the air motor 37, and a driver bit 31 made of a permanent magnet held by the chuck 38. There is.

The base bracket 35 of the driver unit 3 is sandwiched by a screw suction space at the tip of the bit of the driver bit 31, and the presence or absence of the screw S is checked by a photo sensor (not shown) to notify the operator. Means for notifying rotation of the driver bit 31, an arm for supporting a bearing, for example, a bearing, a bearing made of resin or oil-impregnated metal having excellent wear resistance, and a descending stroke required for screw tightening. It is provided with a tightening confirmation sensor 6 to be secured and a work retainer 7 that holds down the biting of the work W as the driver bit 31 rises.

The tightening confirmation sensor 6 prevents the screw bit with respect to the work W from changing and the rotational load increases, and prevents the driver bit 31 from reversely rotating and ascending in a state where the driver bit 31 is not fully lowered. The lower end of the driver bit 31 is lowered together with the bit 31, and the tip is brought into contact with the work W or the member surface integral with the work W to be pushed in, and the position where the proximity switch is operated is the lower position where the screw tightening of the driver bit 31 is completed. The work clamp 7 has a knock type rod-like structure, and the work retainer 7 is provided with a work W as the driver bit 31 rises.
Driver bit 31 for holding down the bite of
The work W is lowered to a position corresponding to the holding position height of the work W to elastically press the work W, and is mounted on the base bracket 35 so as to rise slightly later than the rise of the driver bit 31. .

Further, the driver unit driving means 4 constituting the screw capturing / moving portion transmits the forward / reverse rotational driving force to the beam-shaped member 41 fixed to the two columns 44 so that the vertical position can be freely set under the control of the control motor. The spiral shaft 42 rotating via the drive shaft 45 and the guide shaft 4 for smooth horizontal sliding
3 are vertically installed, and the base bracket 3
The screw shaft 42 is screwed into the nut 32 provided in the guide member 5, the guide shaft 43 is passed through the guide member 33, and is coupled to the driver unit 3 from a position where the screw S from the screw supply unit 1 is sucked. It is configured to reciprocate horizontal strokes of different lengths up to the screw tightening position of the work supply unit 5 described below.

In the work supply unit 5, the motor M, which is a component of the cassette deck, and the bracket B for fixing the motor M, which is a component of the cassette deck, are provided in the edge portions of the table 51 which is intermittently rotated about the vertical axis, respectively. A plurality of holders 52 to be set are fixed so that they are aligned with the screw insertion holes, and an operator sequentially sets the motor M and the bracket B (see FIG. 5) on the holder 52.

As for the relationship between the constituent parts of the assembly line screw tightening system described above, the screw S supplied from the screw supply unit 1 is replaced with the screw levitation unit as described in the respective constituent description parts. The screw bit S is sucked and held by the driver bit 31 in a normal posture in which the groove of the head of the screw S and the bit tip are fitted by the cooperation of the rotation of 2 and the driver bit 31 and the attraction and pressing by the magnetic force, and sucks this. After moving the driver bit 31 up to just above the screw tightening position of the work W while keeping it, the driver bit 31 is lowered while applying the torque rotation drive, and screw tightening is performed on the supplied work W with a constant rotational force. The series of operations to be performed are linked and linked under a control setting that is repeated corresponding to two screw fixing portions of the same work W.

In the above embodiment, driver bit 3
Although the case where 1 is a permanent magnet has been described, a magnetizable member is used as the driver bit 31, and this is excited.
If the control is performed by penetrating the electromagnetic coil for degaussing, it becomes possible to use the driver bit 31 made of a commercially available magnetic member, and also to secure a constant magnetic force to secure the adsorption of the screw S. Needless to say, it is possible to provide a screw tightening system for an assembly line which has a very low defective rate.

Further, as the work supply unit 5, the work W is set in the holder 52 provided at the edge of the table 51 which is intermittently rotated about the vertical axis, but the work is controlled by the holder controlled by the fluid cylinder. The set work W may be projected and retracted directly under the driver bit 31, or an endless conveyor may be used, and a support controlled by a fluid cylinder may be projected and retracted under the holder when screwing. .

[Brief description of drawings]

FIG. 1 is a schematic front view showing an embodiment of a screw tightening system for an assembly line according to the present invention.

FIG. 2 is a schematic diagram of the same plane configuration.

FIG. 3 is a schematic configuration diagram of a screw supply unit including a screw supply unit 1 and a screw levitation unit 2.

FIG. 4 is an explanatory diagram of air supply to the screw holding holes 14 of the screw holding slider block 13.

FIG. 5 is a perspective view of a motor that is a component of a cassette deck and a bracket that is fixed to the motor by screws.

[Explanation of symbols]

1 screw supply unit 11 Semi-transparent container S screw 12 inclined passage 13 Screw holding slider block 14 Screw holding hole 15 vents 16 Air supply port 2 Screw levitation unit 21 Pressure air supply source 22 Flexible tube 23 Control valve 3 driver unit 31 driver bits 32 nuts 33 Guide member 34 Horizontal movement slider 35 base bracket 36 Air cylinder 37 Air motor for driver drive 38 Driver chuck 4 Driver unit driving means 41 Beam member 42 spiral axis 43 Guide shaft 44 props 45 drive shaft 5 Work supply unit 51 tables 52 holder 6 Tightening confirmation sensor 7 Work clamp W work M motor B bracket

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B23P 19/06

Claims (5)

(57) [Claims] 1. A screw S made of a magnetic material is vented to the bottom.
Screw retaining of the screw retaining slider block 13 provided with the hole 15
The screw supply unit 1 adapted to supply the holding hole 14 in a normal posture with the head of the screw S facing upward, and the screw S supplied from the screw supply unit 1 are attached to the tip of the driver bit 31 of the driver unit 3 described later. At the position where it is sucked and held, the screw holding hole 15 is pressed by air pressure.
A screw floating unit 2 to slightly floated to the support has been vertically upwards, made of a material which is adapted to magnetize the permanent magnets or excitation control, the floated thread S head driver bit 31
In cooperation with the suction and pressing by the rotary magnetic force applied, the driver bit 31 holding the screw S with the bit tip is fitted into the groove of the head in normal posture screws axis is vertical, the The driver unit driving means 4 moves the screw to the screw tightening position of the work W which is the screw tightening work region, and the screw tightening position of the work W immediately below the driver bit 31 coincides with the screw tightening position. A screwdriver unit 3 adapted to impart a torque rotation motion for screw tightening and a bit ascending / descending motion to the screw 31, and a work W screwed by an intermittent motion synchronized with the ascending / descending motion of the driver bit 31 in the screw tightening work area. A work supply unit 5 for sequentially moving the work W so that the screwing position of is located directly below the driver bit 31; The assembly line screw tightening system is characterized by 2. The means of the screw levitation unit 2 for slightly floating the screw S supplied from the screw supply unit 1 vertically upward by air pressure is integrated with a part of a holding portion for holding the supplied screw S. The screw tightening system for an assembly line according to claim 1, which is configured to be performed by an air supply pipe connected to the. 3. A means of a screw levitation unit 2 for slightly floating the screw S supplied from the screw supply unit 1 vertically upward by air pressure, sucks and holds the screw S on the front end of the driver bit 31. 2. The screw tightening system for an assembly line according to claim 1, wherein the air supply port 16 has a pipe opening at a fixed position immediately below the position where the screw holding hole 14 is provided, and the screw hole 14 has a ventilation hole 15 . 4. The work supply unit 5 fixes a plurality of holders for setting parts to be screwed and fixed to an edge portion of a table which is intermittently rotated around a vertical axis, and the holder is held by an operator. 2. The screw tightening system for an assembly line according to claim 1, wherein the parts are sequentially set to each other. 5. The tightening confirmation sensor 6 and the driver bit 31 which ascend / descend together with the driver bit 31 to secure a descending stroke required for tightening the screw of the driver bit 31.
The screw tightening system for an assembly line according to claim 1, further comprising a work retainer (7) for restraining the biting of the work as the work rises.