JPS6135771Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a plastic fastener called a so-called screw rivet.

By receiving a male threaded bolt or screw, the elastic leg is expanded, and an article such as two panels is inserted between the expanded portion of the elastic leg and the opposing flange. Screw rivets are commonly used plastic fasteners. The fastener 1 shown in Figures 1A and B is
This is the most common conventional example of this type.

First, this fastener 1 will be explained. The female member has a flange 2 and elastic legs 3 that hang down from the flange and have free ends. An insertion hole 6 for a bolt or screw 5 having a handle is passed through in the axial direction. The elastic legs 3 are arranged around the screw insertion hole 6, and are provided in an appropriate number, such as a pair facing each other at 180 degrees or a total of four at every 90 degrees. It is a diameter-reduced portion 7 that narrows the diameter.

For example, when fixing two panels P ₁ and P ₂ in an overlapping manner, insert the elastic legs 3 of the female member in the axial direction into the mounting holes H that are aligned and drilled in both panels P ₁ and P ₂ . Place the flange on the surface of one panel _P1 , insert the shaft rod with the male screw thread 4 of the screw 2 into the insertion hole 6 of the screwdriver from the flange side, and push it in (No. 1A).
figure).

As a result, the reduced diameter portion 7, which had narrowed the diameter of the insertion hole, is pushed radially outward due to the interruption of the screw shaft, and eventually the portion toward the tip of the elastic leg 3 expands, and this expanded portion The outer surface of the panel P ₁ , is pressed into engagement with the edge of the mounting hole H, and between the flange 2 and the
Clamp P ₂ from above and below to secure it (Figure 1B).

After the fixation is completed in this way, the screw 5 must be held in such a way that it will not slip out, and the reason why a screw is used in the first place is that it can be removed when necessary, unlike a normal screw. Since it is intended that the screw can be operated by twisting, this type of fastener has a protuberance inward of the insertion hole 6 so that it functions both to hold the screw and to remove the screw by twisting. An engaging protrusion 8 corresponding to a female thread that engages with the male thread 4 of the screw 5 is essential.

From the above-mentioned function, it is clear that it is desirable that the engagement protrusion 8 has a height sufficient to dig deeply into the valley between the male screw threads 4. However, conventional fasteners such as those shown in Figures 1A and 1B have not been able to meet this demand.

This is because the engagement protrusion 8 protrudes from the inner wall of the insertion hole 6 or the inner surface of the elastic leg so as to narrow the diameter of the insertion hole, so the male screw thread 4 of the screw will rub against this protrusion 8 during the initial push-in operation of the screw 5. However, if the height of the engagement protrusion is made high enough, a large insertion force will be required when pushing the screw in, resulting in a decrease in work efficiency. Due to excessive pushing, the male screw thread 4 of the screw scrapes this engagement protrusion 8,
This is because there is no point in choosing a high height. On the other hand, if the screw 5 is made of plastic, the male thread 4 may be shaved off or crushed, but in this case, of course, this will become an obstacle to the subsequent removal work. .

This proposal was made in view of the above, and in order to ensure the screw engagement between the engaging protrusion and the male thread of the screw, it is possible to eliminate the "grabbing" between the two, especially when inserting the screw, and prevent damage. The main purpose is to provide this type of fuasuna with improvements that can prevent
It is essentially an improvement over Skrill.

Embodiments of the present invention will be described below with reference to the accompanying drawings, and the same reference numerals will be used for components that are basically the same as those of the conventional example shown in FIGS. 1A and 1B.

2 and 3 show a first embodiment of the present invention. The female member into which the screw 5 is inserted may have a conventional structure. That is, there are a suitable number of elastic legs 3 hanging down from the flange 2, which narrow the diameter of the screw insertion hole 6 that passes through the inside in the axial direction at the diameter-reduced portion 7, and the wall surface around the insertion hole 6. It is only necessary that an engaging protrusion 8 corresponding to a female screw thread that engages with the male screw thread 4 is provided. The position of this engaging protrusion 8 is relatively close to the flange, etc.
It's good that it's a sturdy part that doesn't expand too much.

The screw 5 is made of plastic and includes a head 10 and a shaft 11 hanging from the head 10.
As before, male screw threads 4 are cut on the outer periphery of the shaft rod 11. However, this male thread 4
When the screw is inserted into the female member in the axial direction, it is sufficient that it engages with the female screw thread of the other party or the engagement protrusion 8, so in this embodiment, the screw is inserted all the way to the tip of the shaft rod 11. It is not as long as it should be, and is only halfway up the length.

The first characteristic of this case is that the shaft rod 11 is hollow 12 at least in the part where the male thread 4 is provided.In other words, the male thread 4 is thin. It is formed on the outer circumferential surface of the portion 13 having a ring-shaped cross section. Therefore, this male threaded portion is flexible in the radial direction.

In addition, the shaft rod portion 14 further forward than the male screw thread 4
Rather, it is preferable that it is solid and strong, and its diameter is fixed to the diameter of the valley of the male thread. The reason why it is better to do this will be explained in the following explanation of the screw insertion process. Furthermore, as a second feature of the present invention, an auxiliary pin 15 that is integrated with the screw 5 is also provided, which will also be described later.

To explain the case where two panels P ₁ and P ₂ are sandwiched and fixed as an article, first, as shown in Figure 3A, the mounting holes H are aligned and drilled in both panels P ₁ and P ₂ .
Insert the elastic legs 3 of the female member and place the flange 2 on the surface of one panel _P1 . Then, the shaft rod 11 of the screw 5 is inserted into the screw insertion hole 6 from the opening on the flange 2 side. At this time, if the outer diameter of the shaft rod portion 14 at the tip of the male screw thread 4 is less than the root diameter of the screw thread, this tip portion 14
protrudes from the peripheral wall of the screw insertion hole 6 of the female member and engages with the male thread. You can pass through it without destroying it.

Eventually, when the male screw thread advances to the engagement protrusion 8, each thread of the male thread progresses to the engagement protrusion in order from the tip until the screw 5 is finally pushed in. However, in this case, since the interior of the part 13 where the male thread 4 is provided is hollow 12, one part of the male thread 4 must be overcome, as also shown in Figure 3A. When each one passes over the engagement protrusion 8, this thin portion 13 bends radially inward, allowing the male screw thread to escape inward.

Therefore, there is no need to forcibly scrape and rub the engagement protrusion 8 which later functions as a female screw thread as in the conventional case, and a low pushing force as indicated by the arrow _F1 of the screw 5 is sufficient.

In this way, if the pushing is continued while utilizing the inward deflection of each thread of the male screw thread, the tip portion 14 of the shaft rod 11 will move in the direction of diameter reduction of the elastic leg 3. It cuts inward and expands the elastic legs 3 outward.

In the final state shown in FIG. 3B, the article or the two panels P ₁ and P ₂ are clamped between the outer surface of the expanded portion of the elastic leg 3 and the lower surface of the flange 2.
Then, the engagement protrusion 8 becomes wedged between the nearest male screw threads, and since both of them are not in a damaged state, the function to reliably prevent the screw 5 from coming off is achieved. In addition, in this state, a normal smooth screw engagement relationship of a male screw and a female screw is established between the male screw thread 4 and the engagement protrusion 8 which are engaged or screwed together. When you want to remove the screw 5 and remove the fastener itself from the article,
When twisting the screw 5 in the extraction direction, smooth and efficient work can be expected without any unreasonable feeling of catching, and the screw 5 can be reused later by the same pushing procedure as described above.

In this embodiment, since the portion of the screw shaft 11 that is forcibly cut into the elastic leg diameter reduction portion 7 is solid and strong, the diameter reduction of the elastic leg is strengthened. Even if the legs 3 are designed to have stronger elasticity to increase the article clamping force, this resistance force can be overcome and the diameter of the legs 3 can be sufficiently expanded.

However, if the elastic leg expansion portion 14 of the screw shaft 11 is not required to be so sturdy due to design, the hollow portion 1 may be formed over the entire length of the shaft portion.
2 may be arranged, and the male thread 4 may also extend over the entire length.

However, on the other hand, after it is attached to an article as shown in Figure 3B, there is also a request to increase the screw retaining force by losing the flexibility of the thin wall portion 13 of the shaft where the male thread 4 is provided. It will be done.

Therefore, in this proposal, after the installation is completed, the flexible part 13 that invades the hollow part 12 and stands in the way, and supports the flexible part 13 where the male screw thread 4 is provided from the back, or rather actively presses it radially outward. Male thread 4
An auxiliary pin 15 is used to improve the biting of the engaging protrusion 8.

In order to insert this pin 15 (or rather, it is necessary to cut out the hollow part 12), the hollow part 12 opens into the head 10 of the screw 5, and from this opening the arrow mark is inserted. The shaft portion 1 of the auxiliary pin 15 inserted into the hollow portion 12 as shown by F ₂
If the diameter of 6 is equal to or slightly larger than the diameter of the hollow portion 12 over the entire length, force is required for insertion. A raised portion 17 is provided at a corresponding position so as to forcefully press only the rear of the crest, and the other shaft portions are made small in diameter so that they can fit easily into the hollow portion 12.

From Figure 3B to Figure 3C, this pin 15
As mentioned above, in the state shown in Figure 3C, when the screw has been inserted into the hollow part 12, the thin part 13 around the hollow part pressed from the back by the raised part 17 is The male screw thread 4 is securely engaged with the engagement protrusion 8.

Further, in this case, the auxiliary pin 15 has a head 18, while the head 10 of the screw is formed with a receiving recess 19 in which it is accommodated, so that in the final state shown in Figure 3C, both are just fitted. As a result, the auxiliary pin head 18 becomes integrated with the screw head 10.

Generally, when twisting the screw 5 to remove it, it is convenient to twist the screw head using a tool such as a screwdriver. Therefore, in the present invention, a tool engaging portion 20 such as a cross groove is provided on the auxiliary pin head 18, which can be regarded as a part of the screw head, and when a tool is engaged with this and twisted, the auxiliary pin 15 In order to prevent the screw from spinning idly, the auxiliary pin head is provided with a radially outward protrusion 21, and the screw head is provided with a radial groove 22 to accommodate it. It is designed to transmit torque. However, of course, other measures to prevent spindle rotation can be taken at will, and the point is that the screw head 1
It is sufficient that the screw 5 and the auxiliary pin head 18 have an engaging portion that engages with each other to prevent idle rotation, and that the screw 5 and the auxiliary pin 15 are dynamically integrated in the direction of rotation. . However, if there is a protrusion 21 as an engaging part on the side of the auxiliary pin 15 as in the illustrated embodiment, the auxiliary pin 15 can also be pulled out in the axial direction from the removed screw 5 by hooking the tool on the protrusion. When reusing the product later, the steps shown in figures 3A to 3C described above can be repeated as they are, and the workability during reuse is improved.

As detailed above, according to the present invention, when inserting the screw, the male screw thread can easily pass through the engagement protrusion, so damage to both can be avoided, and the screw insertion force is low. On the other hand, the design allows for a sufficient height for the two screws to be screwed together, so the retention force of the screw is strong, and when necessary, the work of unscrewing the screw can be done without any strange crushing. This work is smooth and easy since the work involves removing the screws that have not been properly engaged, and the screws that have been removed can be reused, that is, they can be treated in the same way as new screws. be able to.

[Brief explanation of the drawing]

Figures 1A and 1B are longitudinal sectional views of a typical example of a conventional screw rivet type fastener at each installation process;
FIG. 2 is a partially fragmented perspective view of the fastener according to the first embodiment of the present invention, and FIGS. 3A, B, and C are longitudinal sectional views of each working process in the example of use of the fastener shown in the second figure. In the figure, 1 is the fastener as a whole, 2 is the flange, 3 is the elastic leg, 4 is the male thread, 5 is the screw,
6 is a screw insertion hole, 8 is a female screw thread or engaging protrusion, 10 is a screw head, 11 is a screw shaft,
12 is an internal hollow part, 13 is a thin part around the internal hollow part, 15 is an auxiliary pin, 16 is its shaft, and 17 is a raised part.

Claims (1)

[Scope of Claim for Utility Model Registration] By inserting the shaft of a screw having a shaft with a male thread on the outer periphery into a screw insertion hole opened in the flange, the elastic legs hanging from the flange are expanded. A plastic fastener is provided with an engaging protrusion corresponding to a female thread that engages with the male screw thread around the screw insertion hole, the screw being made of plastic and having a screw thread attached to the shaft rod. The inside of the part where the male screw thread is provided is hollow and opens into the screw head, and the part where the male thread thread is provided is flexible, while the screw head is provided with flexibility. There is an auxiliary pin having a shaft portion that loses the flexibility of the portion where the male thread is provided by being inserted into the internal hollow portion of the shaft rod, and the head of the auxiliary pin and the screw head are connected to each other. for,
Engagement portions that engage with each other to prevent idle rotation so that when the auxiliary pin shaft portion is inserted into the internal hollow portion of the screw shaft rod, the auxiliary pin and the screw are dynamically integrated in the direction of rotation. Huasuna is characterized by: