JPS6322951B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a screw supply device particularly suitable for supplying minute size screws or small screws with long legs and long head diameter (hereinafter referred to as L/D).

[Conventional technology]

An automatic screw tightening machine or a screw tightening robot generally requires a device that automatically feeds screws to a screw catching position located below the screw tightening bit.
As a device for this purpose, there has conventionally been a screw feeding device as shown in FIG. Reference numeral 1 shown in FIG. 7a is a so-called swinging hopper type feeding device, in which a hopper 2 scoops up a screw and feeds the screw into an inclined chute 3a consisting of parallel flat plates facing each other with an interval slightly wider than the screw diameter. However, the screws are guided under the screw tightening bit 4 by gravity while adjoining each other. On the other hand, reference numeral 5 shown in FIG. 7b is a so-called vibrating type feeding device, in which the screw advances along a helical track 7 provided inside the bowl 6 by the vibration action of a vibrator 8, and furthermore, the screw is advanced by the vibration action of a vibrator 8. It is guided through a chute 3b having the same construction as the type feeding device 1 to a position where the screw bit 4 is captured. However, in both devices, the screws are fed into the groove-shaped chute 3a, 3b, and the screws are allowed to adjoin and come in contact with each other, resulting in a problem as shown in FIG. 8. That is, as shown in FIGS. 8a and 8b, while the screws S ₁ and S ₂ are being fed while contacting each other, engagement occurs between the screw heads of each other or between the screw heads and the washer parts, and the screws are fed. Defects occur. This tendency is particularly noticeable in the case of an inclined chute or in the case of a so-called sems screw as shown in FIG. 8b. Furthermore, when the L/D (foot length to head diameter ratio) is less than 1, the screw is inserted into the groove of the opposing flat plate that constitutes the chute 3.
S ₃ itself falls, making it impossible to insert and feed the screw like screw S ₄ in the normal feeding position.

[Problem that the invention seeks to solve]

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a screw supply device particularly suitable for supplying screws of minute size or having a small foot length/head diameter ratio.

The present invention has been made to achieve the above object, and provides a screw feeding device that sequentially feeds screws to a screw catching position of a screw tightening bit.
The present invention provides a screw feeding device comprising the following components.

(1) A feeding tape that is a loop-shaped flexible thin strip with through-holes slightly larger than the diameter of the thread to be supplied formed at a predetermined pitch on the surface of the strip; (2) The feeding tape is wound around and fed. A notch with a width smaller than the width of the tape and a depth larger than the length under the head of the screw is formed on the circumferential surface, and the screw catching position is located on the pitch line of the through hole near the contact area with the feed side feeding tape. (3) a second pulley on which the feed tape is wound, and which forms a pair with the first pulley and on which the feed tape is wound; (4) a second pulley provided on the second pulley side, (5) a pulley rotation means connected to either the first pulley or the second pulley; (6) a screw feeder for inserting a screw into the through hole of the side feed tape; (7) A feed detection sensor that detects the pitch of the through hole and transmits the detection signal to the pulley rotating means; Determines whether there is a screw inserted into the hole,
a screw detection sensor that transmits the discrimination signal to the pulley rotation means; (8) a base portion on which the first pulley, the second pulley, the screw input and supply means, the pulley rotation means, the feed detection sensor, and the screw detection sensor are mounted, respectively; , and (9) a base moving means that engages with the base portion and moves the base portion to a range where the screw tightening bit can be lowered from the screw catching position to the screw tightening position.

[Effect]

By dropping the screws to be supplied into a feeding tape with through holes made in a flexible thin strip at a predetermined pitch, and feeding the feed tape in pitches to feed the screws into the predetermined positions, micro-sized screws or L/D To feed even a small screw to a predetermined position without causing the screw to become jammed or fall during feeding.

〔Example〕

FIG. 1 is a perspective view of an embodiment of the present invention. A feeding tape 11 in which through-holes slightly larger than the diameter of the screws S are bored at a predetermined pitch in a loop-shaped flexible thin strip is first attached.
It is wound around the pulley 12 and the second pulley 13, and a pulley rotating means 14 is provided on either of the pulleys.
On the second pulley side there is a screw feeding means 15 for feeding and dropping screws into the through hole of the feed tape 11, and on the first pulley side there is a screw feeding means 15 for feeding and dropping screws into the through hole of the feed tape ₁₁ .
A screw detection sensor 16 for detecting the presence of the feed tape 11 is provided, and a feed detection sensor 17 for detecting the pitch of the through hole in the feed tape 11 is provided along the return side of the feed tape 11. The above elements are attached to the base 18, and a base moving means 19 is attached to the base 18 for retracting the base 18 so that the screw tightening bit 4 can be lowered to the screw tightening position _P2 . Here, the screw supply means 15 rotates and feeds the screw from above to the feeding tape 1 near the second pulley 13.
1, the pulley rotation means 14 is driven, and the feed tape 11 is fed in pitches according to the signal from the feed detection sensor 17. At this time, the presence or absence of a screw at the screw capture position _P1 is checked by the screw detection sensor 16, and if there is no screw, the feed tape 11 continues to advance until the screw is present, ensuring that the screw is at the screw capture position _P1 . is positioned. After that, the screw tightening bit 4 descends once, captures the screw, and then rises, and the base part 1
8 is retracted by the action of the base moving means 19, the screw tightening bit 4 is lowered again, and the screw tightening operation becomes possible.

By the way, although various methods can be applied to the screw inputting and supplying means 15 shown in FIG. 1, in this embodiment, a so-called drum type supplying means is used. That is, when the drum body 15a rotates due to the action of a drum rotation mechanism (not shown), the blade-like blade 15b attached along the inner circumferential surface of the drum body 15a is inserted into the drum body 15a in advance. Scoop up the screw of
A screw is dropped into the through hole of the feed tape 11 wrapped around the pulley 13. Such a drum body 15
The rotation operation a may be carried out continuously, or it may be stopped once after the feed tape 11 has been fed, and the rotation may be started again after the feeding tape 11 has been fed one pitch.

The screws inserted into the through holes of the feed tape 11 in this way are transferred from the second pulley 13 to the first pulley 1.
They are arranged in a suspended state on the feed tape 11 leading to the feed tape 2, that is, the feed side feed tape 11. Here, the through-holes of the feed tape 11 are slightly larger than the diameter of the screws to be supplied, and have pitch intervals such that screws are not adjacent to each other, and the pitch intervals are equal intervals for the function of the feed detection sensor 17, which will be described later. It's summery. Therefore, when the first pulley is driven by the rotatably mounted pulley rotating means 14, the screw is fed along the feed side feeding tape 11 to the screw catching position _P1 .

Next, the means for positioning the screw at the screw catching position will be explained. FIG. 2 is a sectional view of the first pulley 12 and the surrounding area, and FIG. 2b is a cross-sectional view taken along the line B--B in FIG.
B cross section is shown. The first pulley 12 is rotated so that the top of the circumference of the first pulley 12 is at the screw catching position _P1 .
In addition to setting the relative position of the screw tightening bit 4, it is possible to detect the through-hole pitch interval of the feed tape 11 along the feed tape 11 from the first pulley 12 to the second pulley 13, that is, along the return side feed tape. A feed detection sensor 17 is provided, and the feed detection sensor 17 is located at a location where the through hole of the return side feed tape is detected when the through hole of the feed side feed tape is located at the screw catching position _P1 . It will be done. On the other hand, a notch is formed in the circumferential surface of the first pulley 12, the width of which is narrower than that of the feed tape 11 and which is deeper than the length under the neck of the screw. A screw detection sensor 16 is provided in or near this notch to detect the presence of a screw at the screw capture position _P1 .

The cutout portion of the first pulley 12 is provided to feed the screw to the screw catching position _P1 without interfering with the first pulley 12, and to provide the screw detection sensor 16 at a position where it can be detected. When the pulley rotating means 14 rotates the first pulley 12 shown in FIG. 2b via the shaft 20, the feeding tape 11 is fed.
When the screw suspended in the through hole of the feed side feeding tape approaches the screw catching position P ₁ and the feed detection sensor 17 detects the through hole of the return side feeding tape, a feed detection signal Q ₁ is sent to the pulley rotation means 14. do. At this time, since the through hole of the feed tape is always located at the screw catching position P ₁ , the screw detection sensor 16 similarly sends out the screw detection signal Q ₂ to the pulley rotating means 14 . Therefore, if the pulley rotating means 14 stops driving when both the feed detection signal Q ₁ and the screw detection signal Q ₂ are in the detection state, the screw is always present and positioned at the screw capturing position P ₁ .

FIG. 3 shows a control circuit existing within the pulley rotation means 14 that realizes the above-mentioned positioning operation. As shown in the figure, feed detection signal Q ₁ , screw detection signal Q ₂
(both have a positive logic detection state) are connected to an AND gate 101, and a drive signal _Q3 from an external control device (not shown) or the like is connected to an inverter gate 102. Also and gate 10
1 and the outputs of inverter gate 102 are input to inverted AND gate 103, respectively. Furthermore, the output of the inverted AND gate 103 is connected to the base of the transistor 104 and the resistor 10.
5, and the other end of the resistor 105 is connected to the positive electrode side of a power source 106. Further, the emitter of the transistor 104 is connected to the negative pole of the power source, the collector is connected to the coil of the relay 107, and the other end of this coil is connected to the positive pole of the power source 106.
The A contact terminal and B contact terminal of the relay are connected to the positive and negative poles of the power supply, respectively, and the common terminal is connected to the motor 1.
The negative pole of the motor 108 is connected to the negative pole of the power supply 106. Here, when the output of the inverted AND gate 103 is ON, a bias current is applied to the base of the transistor 104 through the resistor 105, making the transistor 104 conductive, and as a result, the relay 107 is turned ON, and the motor 10
8 rotates. Inverted and Gate 10
When the output of No. 3 is OFF, the relay 107 is also OFF, and at this time, the positive and negative electrodes of the motor 108 are short-circuited and the brake is applied. In addition,
The motor 108 serves as a drive source for the pulley rotating means 14. Here, the motor 108 rotates when both inputs to the inverted gate 103 are OFF, that is, when the drive signal _Q3 is ON and neither the feed detection signal _Q1 nor the screw detection signal _Q2 is ON. However, when the feed detection sensor 17 detects that the screw is not being fed at a predetermined pitch and the screw is present at the screw capture position _P1 , the pulley rotating means 14 stops, and even if the screw is fed in a pitch, the pulley rotation means 14 will not penetrate. If no screw is inserted into the hole, the feeding tape continues to advance until the through hole in which the screw is present reaches the screw catching position and then stops.

When the screw is positioned at the screw capturing position as described above, the screw tightening bit 4 shown in FIGS. 1 and 2 descends, and when the screw is captured by suction or the like, it rises once again. Here, when the screw tightening bit 4 is raised, the base portion 18 in FIG. 1 is moved backward by the action of the base moving means 19, that is, in the same direction as the traveling direction of the return side feeding tape. The amount of movement thereof is at least larger than the radius of the first pulley 12, and it is sufficient to move within a range that does not interfere when the screw tightening bit 4 descends to the screw tightening position _P2 .
After that, when the screw tightening bit 4 descends to the screw tightening position to perform the screw tightening work and rises again, the base portion moves forward, that is, in the same direction as the feed side feeding tape.
It is something that will return.

However, by repeating the above operations, the screws are successively fed to the screw catching position _P1 , making it possible to perform continuous screw tightening work.

However, in the present invention, it is not necessary to insert screws from the screw inputting and supplying means 15 into all the through holes of the feeding tape 11. However, it is natural that the higher the probability of injection into the through hole, the more benefits such as shorter takt time will result. Therefore, it is effective to add a means to increase the probability of inserting a screw into the through hole of the feed tape 11 as shown in FIGS. 4 and 5. FIG. 4 shows that a swinging tray 21 is provided between the screw feeding and supplying means 15 and the feeding tape 11, a screw is once received in the swinging tray 21, and the swinging tray 21 is moved while giving a swinging motion to the screw. A screw is dropped into the through hole of the feed tape 11 from a notch provided on the lower surface.

FIGS. 4a and 4b are a plan view and a front view of a mechanism that provides a swinging motion to the swinging tray 21. FIG. In the figure, a disc 23 is connected to a motor 22, and a disc 23 is connected to a motor 22.
A pin 24 is fixed at a predetermined eccentric position from the center. On the other hand, the swinging arm 25 extending from the swinging tray 21 loosely fits into the pin 24 and engages with the fixed arm 26 via a connecting pin 27 in a mutually orthogonal groove. As a result, when the motor 22 rotates, the swinging arm 25, that is, the swinging tray, is moved between the swinging arm 25 and the fixed arm 2.
Since the rotational movement is regulated by the action of the connecting pin 27 that is loosely fitted into each groove portion of 6, the swinging movement is performed in the direction of the arrow shown in the figure. Therefore,
The swinging tray 21 receives the screws from the screw inputting and supplying means 15 while making a swinging motion, and drops the screws downward through the notch to the feeding tape 11 side. The amount can be concentrated, increasing the probability of input.
In addition, if a flexible sweeper blade 28 is provided on the lower surface of the swinging tray 21 with a slight clearance from the screw head after loading, it is possible to remove screws that are left on the feed tape 11 due to loading errors. more effective.

FIG. 5 is an explanatory diagram of a means for increasing the probability of screw insertion into the through-hole of the feed tape 11, which uses an excitation means. In the figure, a vibrator is provided in contact with the feed tape 11 in the vicinity of the screw insertion part on the feed side of the feed tape 11, and applies horizontal vibration that corresponds to the longitudinal direction of the feed tape 11. As a result, even if the screw remains on the feed tape 11, the screw will easily enter the through hole due to the excitation force, so the screw will be inserted into the through hole of the feed tape 11. The probability increases. Note that such a vibrating means also has the effect of eliminating screws that remain on the feeding tape 11 due to insertion errors.

FIG. 6 is an explanatory diagram showing a state in which the shape of the through hole of the feeding tape has been improved in order to further improve the reliability of the screw feeding device according to the present invention. FIG. 6a shows a normal through hole, in which the screw S is caught by the screw tightening bit 4 at the screw catching position and pulled upward. At this time, if the thickness of the feed tape 11 is thin, or more precisely, if it is smaller than the thread pitch of the screw S, the side surface of the through hole of the feed tape 11 will enter the trough of the screw thread, and the screw S will be ejected. There may be cases where things don't go smoothly. Normally, the thread shape of the screw S is tapered, so this problem hardly occurs, but depending on the thread shape, dimensions, and thickness of the feeding tape, it may not be possible to completely prevent ejection errors. Therefore, as shown in FIG. 6b, the through hole of the feed tape 11 is made into a cylindrical shape having a height longer than the thread pitch, and the lower end of the cylindrical portion 30 is made into a shape with a slight bend outward. This can be completely resolved. Note that the above-mentioned cylindrical portion 30 and bent portion 31 can be easily formed by burring processing and curling processing, respectively, and if they are shaped like this, it will be easier to insert the screw feeding tape into the through hole. Useful.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the following remarkable effects can be achieved.

(1) Due to the structure, the screws to be fed are not adjacent to each other from the screw input position to the screw capture position, so even with so-called sems screws and flat head screws, the phenomenon of jamming during feeding can be completely eliminated. Supply reliability is extremely high.

(2) It is possible to reliably supply even minute screws or screws with particularly small L/D (leg length to head diameter ratio).

(3) As long as the screw diameters are the same, the screw feeding device according to the present invention can be used as is without modification, regardless of the shape of the screw head. Also, even if the screw diameter changes, it can be handled simply by changing the feeding tape.

(4) The structure of the device itself is simple and lightweight, so it can be easily mounted on a robot.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention, FIGS. 2 a and b are sectional views of essential parts of the embodiment of the present invention, FIG. 3 is a control circuit diagram of the embodiment of the present invention, and FIGS. 4 a and b 5 and 6 are explanatory diagrams of the embodiment of the present invention, and FIGS. 7 a and b are examples of conventional screw feeding devices, respectively. FIGS. 8a, 8b, and 8c are explanatory diagrams illustrating problems with the conventional screw feeding device. 11...Feeding tape, 12...First pulley, 1
3...Second pulley, 14...Pulley rotating means, 1
5... Screw input and supply means, 16... Screw detection sensor, 17... Feed detection sensor, 18... Base portion, 19... Base moving means, 21... Rocking tray, 29... Vibrator. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Scope of Claims] 1. A screw supply device that sequentially supplies screws to a screw catching position of a screw tightening bit, which includes: (a) a loop-shaped flexible thin strip having a diameter smaller than the diameter of the screw to be supplied on the surface of the strip; A feed tape with slightly larger through holes formed at a predetermined pitch; (c) a first pulley formed on the surface and provided so that a screw catching position is located on the pitch line of the through hole near the contact portion with the feed side feeding tape; a second pulley on which the feed tape is stretched; (d) a screw insertion supply means provided on the second pulley side for inserting a screw into a through hole of the feed tape; (e) the first pulley or the second pulley. (f) A feed detection sensor that detects the pitch of the feed tape through hole on the return side of the feed tape and transmits the detection signal to the pulley rotation means; (g) a screw detection sensor provided in the notch of the first pulley or in the vicinity of the first pulley, which determines the presence or absence of a screw inserted into the feed tape through hole at the screw capturing position, and transmits the determination signal to the pulley rotation means; , (h) a base part on which the first pulley, the second pulley, a screw input and supply means, a pulley rotation means, a feed detection sensor, and a screw detection sensor are mounted, respectively; A screw feeding device comprising: a base moving means for moving a base part to a range where a tightening bit can be lowered from a screw catching position to a screw tightening position. 2. The through-hole of the feeding tape is formed by forming a cylindrical part on the back surface of the feeding tape by burring, which is longer than the thread pitch length of the screw to be supplied, and further bending the tip of the cylindrical part sharply outward by curling. A screw feeding device according to claim 1, characterized in that: 3. The screw feeding device according to claim 1, further comprising a vibrator placed on the base portion and applying horizontal vibration to the feeding tape. 4. A swinging tray that receives screws from the screw inputting and supplying means and has a notched hole through which the screws can pass, and that swings horizontally to drop and input the screws into the through holes of the feeding tape. The screw feeding device according to claim 1, characterized in that it is provided between the input feeding means and the feeding tape.