JPS6213146B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to an automatic screw tightening method, and more particularly to a method for ensuring screw tightening by an automatic screw driver.

(Background technology) An automatic screw tightening machine is a machine that automates screw tightening. In automatic screw tightening machines, it is important to hold the screw at the tip of the driver and to correctly guide the screw tip into the screw hole. FIG. 1 shows a typical screw holding method in a conventional automatic screw tightening machine. In FIG. 1, 1 is the tip of a driver, 2 is a guide pipe, and 3 is a screw. screw 3
The spring washer 4 and the washer 5 are attached to the neck of the screw in steps to prevent them from falling off.
The screws 3 are supplied by a parts feeder (automatic supply machine). In order to set this as shown in FIG. 1, a method is used in which the inside of the guide pipe 2 is placed in a vacuum state and the screw is suctioned. With this method, it is difficult to maintain the correct posture of the screw, which has a small and complicated shape, and the screw often tilts as shown in Figure 2, making it impossible to guide the screw tip into the screw hole. There were many cases where mistakes were made in closing.

(Disclosure of the Invention) An object of the present invention is to provide an automatic screw tightening method that solves the above problems.

The automatic screw tightening method according to the present invention consists of the following steps. First, process the tips of all the screws to be used into funnel shapes. Set such a screw on one side of the screw hole so that the center axes of the screw and the screw hole coincide, and fit the tip of the screwdriver correctly into the screw head slot. At the same time, a support rod with a sharp point and greater rigidity and thinner than the diameter of the screw hole is inserted from the other side of the screw hole, passes through the screw hole, and the point tightly fits in the center of the funnel-shaped recess at the tip of the screw. let In this way, the screw is supported with appropriate clamping pressure in the axial direction by the driver and the support rod. After confirming that the support rod is securely supported, the driver is moved forward in the direction of the screw hole while maintaining this state, and the support rod is retreated at the same speed.
When the screw tip is fitted into the entrance of the screw hole in the correct position, the support rod is removed, and the screw is rotated using a screwdriver and tightened into the screw hole.

By the automatic screw tightening method with the above configuration,
Because the screw is held in the correct position, the screw does not tilt, and the screw tip is accurately guided into the screw hole.
Screw tightening errors in automatic screw tightening machines are prevented.

(Best Mode for Carrying Out the Invention) Examples of the present invention will be described below with reference to the drawings. FIG. 3 shows the basic configuration of the automatic screw tightening method of the present invention. All the screws to which this method is applied are processed so that their screw tips have funnel-shaped recesses 3A. The head of the screw 3 is set at the tip of the driver 1. On the other hand, a support rod 7 is made to protrude from below the screw hole 6 by passing through it. The support rod 7 has a pointed head 7A, and the pointed head 7A can be brought into close contact with the deepest center of the funnel-shaped recess 3A of the screw 3. In this way, as shown in FIG. 3, the screw 3 is held in the axial direction by the driver 1 and the support rod 7. In this state, if the driver 1 and the support rod 7 are moved downward at the same speed,
Funnel-shaped recess 3A at the screw tip and tip 7A of the support rod 7
The screw tip 3A is surely guided to the entrance of the screw hole 6 by descending while remaining in close contact with each other without coming off.
Once the threads of the screw 3 and the screw hole 6 are engaged, even if the support rod 7 is removed, the screw can be tightened only by rotating the driver 1 as usual.

FIG. 4 shows an embodiment of the present invention. A spring washer 4 and a washer 5 as described above are attached to the screw 3 so that they cannot be removed. The driver 1 is rotatably mounted in the inner cavity of the guide pipe 2. The driver 1 and the guide pipe 2 can move up, down, left and right as a unit. The screws 3 supplied by the parts feeder are drawn to the tip of the guide pipe 2 by a vacuum suction method or the like and set in the position shown in FIG. The subsequent procedure is the same as that described in FIG. 3 above, except that a guide tube is added.

FIG. 5 shows another embodiment. In this figure, 8 indicates the tip of the chuck. Check 8
opens and closes to the left and right using a shaft (not shown) as a fulcrum.
Figure 5 shows it in its closed position.

Initially, the chuck 8 is closed, the screw 3 is not supplied, the driver 1 and the guide tube 2
The process starts with the support rod 7 not being lowered and the support rod 7 not being raised. The space inside the closed chuck 8 is funnel-shaped. The size of the outlet 9 of the funnel-shaped space is slightly larger than the shaft diameter of the screw 3. The upper part 10 of the funnel is provided with a shelf 11 on which a washer 5 is engaged at a depth appropriate to the length of the screw 3. When the washer 5 is seated on this shelf 11, the tip of the screw 3 is dimensioned to be exactly located at the outlet 9 of the funnel.
Further, a tapered guide hole 12 gradually widens downward from the exit 9 of the funnel. This guide hole 12
is provided so that the point of the support rod 7 can be easily guided to the tip of the screw 3.

Now, with the chuck 8 in the closed state as described above, the screw 3 is fed into the chuck 8 from the parts feeder (not shown), and the washer 5
is seated on the shelf 11 and stands still with the screw 3 hanging thereon (that is, the position shown in FIG. 5). Next, the driver 1 and the guide pipe 2 move down in conjunction with each other, the lower end of the guide pipe 2 comes into contact with the washer 5, and the tip of the driver 1 is fitted into the head slot of the screw 3. Next, the support rod 7 is pushed up from below the screw hole 6, and its tip is inserted into the funnel-shaped recess at the tip of the screw 3 through the guide hole 12 of the chuck 8 and is tightly fitted. After confirming that the screw 3 is clamped from above and below by the driver 1 and the support rod 7, the chuck 8 is opened and the state shown in FIG. 4 is reached. From this state, the driver 1, guide pipe 2 and support rod 7
When the screws descend at the same speed, the tip of the screw 3 is accurately guided into the screw hole 6. If chuck 8 is used in this manner, there is no need for vacuum suction, further improving reliability.

In the above embodiment, in order to confirm that the screw 3 is securely clamped from above and below by the driver 1, the guide pipe 2, and the support rod 7, for example, a screw is inserted between the guide pipe 2 and the support rod 7. This can be easily carried out by forming an electric circuit through 3 and detecting the connection/disconnection state of the circuit. However, in the embodiment shown in FIG. 5, it is necessary that at least the portions of the chuck 8 in contact with the screw 3, driver 1, guide pipe 2, and washer 5 be insulated.

FIG. 6 is an explanatory diagram of the tightening situation after the screw 3 is fitted into the screw hole 6. The guide pipe 2 is coupled to the driver body 100 via a spring 13. With this structure, as the screw 3 advances due to the pressing rotation of the driver 1, the guide pipe 2 moves relatively upward against the elasticity of the spring 13.
When the screw tightening is finished and the driver main body 100 is pulled up, the guide pipe 2 is returned to its original position by the spring 13.

In the embodiments described above, the holding of the screw, the accurate positioning of the holding device and the support rod, the timing of interlocking between the supporting devices on both sides of the screw, etc. can be controlled by conventional techniques.

Note that the upper and lower sides of the explanatory diagrams of the above embodiments are not limited to the vertical direction.

[Brief explanation of the drawing]

FIGS. 1 and 2 are explanatory diagrams of the prior art, FIG. 3 is an explanatory diagram showing the basic configuration of the present invention, FIGS. 4 and 5 are explanatory diagrams showing different embodiments, and FIG.
The figure is an explanatory diagram showing a screw tightening state. 1...driver, 3...screw, 6...screw hole,
7...Support rod.

Claims (1)

[Claims] 1. Set a screw with a funnel-shaped recess at the tip so that its center axis coincides with one side of the screw hole, and while correctly applying the tip of the screwdriver to the screw head, insert the screw on the other side of the screw hole. A support rod having a pointed tip and thinner than the screw hole is passed through the hole, the pointed end is brought into close contact with the center of the funnel-shaped recess of the screw, and the screw is axially moved by the driver and the support rod. Guide the screw into the screw hole while holding it by applying appropriate clamping pressure, fit the screw tip into the entrance of the screw hole in the correct posture, and then remove the support rod and rotate the screwdriver to tighten the screw. An automatic screw tightening method characterized by tightening.