JPH0353044Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a self-threading screw, such as a self-drilling screw or a tapping screw, which is provided with a head made of synthetic resin.

[Prior Art] Conventionally, a self-drilling screw has been known that self-drills and threads a workpiece without a prepared hole through a drill portion provided at its tip. In addition, for the prepared hole pre-formed in the workpiece,
Tapping screws that self-thread while tapping are known.

These self-threading screws are particularly useful in the construction field when attaching an attachment such as a panel to an adherend, since there is no need to form a female thread in advance on either the adherend or the attachment, and it can be machined on site. It is widely used because it enables the simple operation of screwing screws into objects.

However, in order to perform the above-mentioned functions, these self-threading screws are made entirely of strong hardened metal, and after being attached to the workpiece,
There is a drawback that the screw head rusts and spoils the aesthetic appearance. In addition, when attaching an attachment such as a colorful panel to an adherend, the screw head exposed on the surface of the attachment exhibits a simple metallic color that does not match the color tone of the panel, etc. There are drawbacks that detract from the aesthetic appearance.

For this reason, in recent years, screws have been proposed in which a self-screwing metal screw body is provided with a head made of synthetic resin.

[The problem that the idea aims to solve]

The above-mentioned known self-threading screw provided with a head made of synthetic resin has a claw-like engagement piece formed in the head of the metal screw body, which is embedded and integrated into the head made of synthetic resin. A synthetic resin head is injection molded with a joint piece inserted into a mold, and a polygonal socket trench engaging portion is formed on the outer periphery of the synthetic resin head.

However, in this known self-threading screw, although the synthetic resin head is molded from nylon or other resin material with relatively excellent physical properties,
When actually screwing the screw into the workpiece, the polygonal engaging part of the synthetic resin head cannot withstand the rotational torque of the socket trench, and the polygonal engaging part is crushed. There is a risk that the engaging portion of the socket trench and the engaging portion of the socket trench may become loose with each other. That is, since an extremely large rotational torque is required to screw a self-threading screw into a workpiece, the socket trench is usually rotated by a power tool such as an electric tool or an air tool. As a result, an extremely large load acts on the engaging portion of the synthetic resin head.

Therefore, the above-mentioned slipping phenomenon may occur not only after the self-threading screw has completely screwed into the workpiece, but also when the self-threading screw is in the middle of screwing into the workpiece. There is a possibility that this may occur depending on the situation. If the screw turns idly while it is being screwed in, there is a problem that it will no longer be possible to reverse the screw and unscrew it.

[Means to solve the problem]

The present invention provides a self-threading screw that can solve the above-mentioned problems, and its means include a metal screw body equipped with a shank that self-threads into the workpiece. A small head is embedded and integrated into a head made of synthetic resin, an annular seat is integrally formed at the bottom of the head made of synthetic resin, and a seal receiving part is formed on the lower surface of the seat. An annular packing is arranged along the packing receiving part: The synthetic resin head and the small head of the screw body both form a socket trench engaging part whose outer periphery is polygonal. The head made of synthetic resin is molded from a short fiber reinforced resin that can be removed from the small head by breaking it with a striking tool, and A guide sleeve is formed integrally with the inner circumferential portion of the packing, the outer diameter of which is gradually reduced, and the tip of the guide sleeve is positioned between the packing receiving portion and the lower surface of the packing.

〔Example〕

An embodiment of the present invention will be described in detail below based on the drawings.

In Figures 1 and 2, self-threading screw 1
In this example, a head 3 made of synthetic resin is provided on a metal screw body 2 that self-threads into the workpiece.

The screw body 2 has a drill portion 5 at the tip of the shank portion 4, and a small head 7 formed in series from a flange-shaped seat 6 at the base end of the shank portion 4. A thread 8 is formed on the outer periphery.

The head 3 made of synthetic resin is made of a resin material reinforced by mixing nylon or other strong synthetic resin with short fibers such as glass fiber or carbon fiber, and the head 3 is made of a resin material reinforced by mixing short fibers such as glass fiber or carbon fiber. The base end of the shank portion 4 including the small head 7 is inserted into a mold and then injection molded. Therefore, this synthetic resin head 3 covers the small head 7 of the screw main body 2, and further has a seat 9 that covers the seat 6 of the screw main body 2 integrally formed in a series.

The synthetic resin head 3 and the small head 7 of the screw body 2 each form socket trench engaging portions 3a and 7a whose outer peripheries are polygonal. In the illustrated example, the socket trench engaging portion 3a of the synthetic resin head 3 is formed in a hexagonal shape, and the socket trench engaging portion 7a of the small head 7 is shaped like a hexagon.
It is formed into a substantially similar hexagon that is smaller than a. Further, the small head 7 has a driver engagement groove 7b such as a minus groove or a plus groove formed at the top.

According to the self-threading screw based on this embodiment, when attaching an attachment such as a panel to an adherend, there is no need to form a pilot hole or female thread in advance in either the adherend or the workpiece of the attachment. , the screw 1 is forcibly screwed into these workpieces on site. That is, the self-threading screw 1 is stood up with the tip drill part 5 in contact with the workpiece, and the synthetic resin head 3 of the screw 1 is engaged with a socket trench attached to a power tool or an air tool and rotated. If so, the drill part 5 drills a hole from the attachment to the adherend, and the shank part 4, which continues to enter, penetrates the thread 8.
The attachment is screwed forward while tapping the hole, and the attached screw 1 is used to secure the attachment to the adherend. During this screwing, the synthetic resin head 3 is made of short fiber-reinforced resin and has excellent crush resistance and abrasion resistance as described above, so that the engaging portion 3a is firmly engaged with the socket trench. However, there is less risk of idle rotation due to crushing, unlike in the conventional case.

By the way, in the unlikely event that the engaging portion 3a of the synthetic resin head 3 is crushed in the middle of screwing and causes idle rotation with respect to the socket trench, the synthetic resin head 3 should be hit with a hammer or the like. The small head 7 is exposed by breaking it with a tool and removing the broken synthetic resin head 3. Then, by engaging a small-sized socket trench with the socket trench engaging portion 7a formed in the small head 7 of the exposed metal screw main body 2, and reversing the wrench, the screw in the mid-screwing state is removed. 1 can be returned and extracted from the workpiece. Incidentally, if the operator does not have a small-sized socket trench, he or she may simply engage the screwdriver in the driver engagement groove 7b of the small head 7 and reverse the operation.

Further, in the illustrated embodiment, the small head 7 of the screw main body 2 forms a neck 10 between the seat 6 and the shank 4, and the synthetic resin head 3 is inserted into the neck 10 from the lower surface of the seat 9. A guide sleeve 11 covering the outer periphery of the guide sleeve 11 is integrally formed.

On the other hand, a packing receiving part 9a is formed on the lower surface of the seat 9 of the synthetic resin head 3, and a packing 12 is attached along the packing receiving part 9a. This packing 12 is integrally molded from an elastic material such as rubber or elastomer, and includes an annular thick-walled portion 13 located on the lower surface of the seat 9 of the synthetic resin head 3 and an inner peripheral portion of the thick-walled portion 13. An annular thin wall portion 14 extending in a rib shape is provided. That is, the cross-sectional shape of the packing 12 is
The thin wall portion 14 has a vertically symmetrical shape with respect to the center line of the wall thickness. Therefore, if the screw body 2 is inserted into the packing 12 through the elastic deformation of the thin-walled portion 14, the packing 12 will be attached to the lower surface of the seat 9 of the synthetic resin head 3, and in this state, the thin-walled portion 14 will be attached to the neck. 1
Since the packing 12 contacts the lower surface of the thread 8 and engages with the screw thread 8, the packing 12 does not move toward the tip of the screw body 2 and does not fall off. At this time, if the inner diameter of the thin part 14 is made slightly smaller than the outer diameter of the shank part 4 (the root diameter of the thread 8), the thin part 14 will elastically hold the shank part 4 and prevent the packing 12 from moving loosely. It can be prevented. By the way, when attaching the gasket 12, since the outer periphery of the shank portion 4 of the screw body 2 is threaded with the thread 8, it is engaged with the thread 8 and attached to the lower surface of the seat 9 as described above. The attached packing 12 is not always set concentrically with the guide sleeve 11. For this reason, the guide sleeve 11 has a tapered surface whose outer peripheral surface reaches downward and has a small diameter, so that when the self-threading screw 1 is screwed into a workpiece as described later, the inside of the packing 12 Care is taken so that the guide sleeve 11 smoothly enters the peripheral portion (inner peripheral portion of the thick wall portion 13).

Further, the tip of the guide sleeve 11 is positioned between the seal receiving portion 9a and the lower surface of the seal 12 (in the case of the illustrated example, the lower surface of the thick part 13), and constitutes a stopper at the screwing end position, which will be described later. are doing.

According to this embodiment, when the screw 1 is completely screwed into the workpiece, the packing 12 is compressed and brought into close contact with the surface of the workpiece (the attachment on the surface side).
The surface of the workpiece and the packing receiving portion 9a of the synthetic resin head 3 are sealed watertightly. Therefore, when the self-threading screw 1 of the present invention is used to attach an attachment to an adherend outdoors, rainwater etc. will not enter between the hole of the workpiece and the shank portion 4 of the screw.
Watertight treatment is performed simultaneously with the completion of screwing in the screw 1.

By the way, as mentioned above, a self-threading screw is screwed into a workpiece while being subjected to a powerful rotational torque by a power tool such as an electric tool or an air tool, so it cannot be stopped at a predetermined screwing end position. It is difficult to do so, and the vehicle is usually stopped at an over-approach position that exceeds a predetermined position. In other words,
If only a seal is provided on the underside of the seat 9 of the synthetic resin head 3, the seal will be excessively larger than the design value between the seal receiving part 9a of the seat 9 and the surface of the workpiece at the screwing end position. It is compressed and deformed so as to protrude outside of the seat 9. However, when the packing is excessively compressed in this way, it causes early deterioration of the packing and reduces the watertight effect.

In this regard, according to the above embodiment, when the self-threading screw 1 approaches the screwing end position and the packing 12 is compressed to some extent, the guide sleeve 1
After the impact of the tip of the screw 1 is alleviated through the thin-walled portion 14, the screw-in end position is defined in a state where the thin-walled portion 14 is compressed until it reaches the compression limit, and no further excessive force of the screw 1 is set. Prevents screwing. Therefore, due to the stopper function of the tip of the guide sleeve 11, the thick part 1 of the packing 12 is
3 is compressed by a predetermined design value between the packing receiving portion 9a and the surface of the workpiece, and is not compressed any more. For this reason, the packing 12 (thick wall portion 13) is
A suitable watertight seal is formed between the packing receiving part 9a and the surface of the workpiece while maintaining appropriate elasticity.

The invention is not limited to the illustrated embodiment. For example, the packing 12 does not need to have both the thick part 13 and the thin part 14 integrally formed, and it is sufficient that the packing 12 has at least the thick part 13. Therefore,
Feel free to use a seal such as an O-ring. Further, since the stopper function can be performed by the tip of the guide sleeve 11,
The neck 10 integrated with the shank 4 of the screw 1 as described above does not necessarily have to be provided.

[Effect of idea]

As a result of the above-described configuration, the present invention has the following effects.

(1) In self-threading screws such as self-drilling screws and tapping screws, the synthetic resin head 3 provided on the metal screw body 2 is molded from short fiber reinforced resin, so it has excellent crush resistance and It has excellent abrasion resistance, and when the engaging part 3a of the head 3 is engaged with a socket trench and rotated while the screw body 2 is self-threaded into the workpiece, the engaging part 3a can be easily moved as in the conventional case. There is little risk of crushing and causing idle rotation.

(2) A socket trench engaging portion 7a having a polygonal outer periphery is formed in the small head 7 of the screw body 2 embedded in the synthetic resin head 3, and the synthetic resin head 3 is used as an impact tool. Since it is molded from short fiber reinforced resin that can be removed from the small head 7 by breaking it with When the socket trench is crushed and idles, the synthetic resin head 3 is broken and the small head 7 is removed.
By removing the small head 7 from the inside, the small head 7 is exposed, and by engaging a small socket trench with the socket trench engaging portion 7a of the small head 7 and reversing the screw 1, the screw 1 is removed in the middle of screwing.
can be returned and extracted from the workpiece.

(3) Guide sleeve 1 extending from the seal receiving portion 9a of the synthetic resin head 3 to the inner circumference of the seal 12
1 is integrally formed, and the outer diameter of the guide sleeve 11 is formed in a tapered shape that gradually becomes smaller toward the shank portion 4. Therefore, the packing 12 that is compressed when the screw 1 is screwed in is formed on the tapered surface. Since the packing 12 is properly centered along the packing receiving portion 9a and can be compressed while aligning the packing 12 along the packing receiving portion 9a,
No deviated compression of 2 or compression in an overturned state will occur.

(4) Since the tip of the guide sleeve 11 is positioned between the packing receiving portion 9a and the lower surface of the packing 12, the tip of the guide sleeve 11 opposes the workpiece (adherent) when screwing the screw 1. This constitutes a stopper that prevents excessive screw-in, compresses the packing 12 by a predetermined thickness, and prevents further compression, making it possible to extend the life of the packing and improve the watertight effect.

[Brief explanation of the drawing]

Figure 1 is a front view showing one embodiment of the present invention, Figure 2 is a front view showing one embodiment of the present invention;
The figure is a longitudinal sectional view of the main part. 2...Metal screw body, 3...Synthetic resin head, 3a...Socket trench engagement part, 7...Small head, 7a...Socket trench engagement part, 9...
Seat, 9a...Putskin receiving part, 11...Guide sleeve, 12...Putskin.

Claims (1)

[Claims for Utility Model Registration] A small head 7 of a metal screw body 2 having a shank portion 4 that self-threads into a workpiece is embedded and integrated into a synthetic resin head 3, and the synthetic Resin head 3
An annular seat 9 is integrally formed in the lower part of the seat 9, a packing receiving part 9a is formed on the lower surface of the seat 9, and an annular packing 12 made of an elastic material is inserted into the packing receiving part 9.
In the case where the head 3 made of synthetic resin and the small head 7 of the screw main body 2 both form socket trench engaging parts 3a and 7a whose outer peripheries are polygonal. Composition: The head 3 made of synthetic resin is molded from a short fiber reinforced resin that can be removed from the small head 7 by breaking it with a striking tool, and is inserted into the shank part 4 from the packing receiving part 9a. A guide sleeve 11 is integrally formed to extend around the inner periphery of the packing 12 while gradually decreasing the outer diameter toward the packing, and the tip of the guide sleeve 11 is positioned between the packing receiving portion 9a and the lower surface of the packing 12. A self-threading screw comprising;