JPS62220709A - Heat-section stepped countersunk head screw and oval countersunk screw - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a countersunk machine screw and a round countersunk machine screw whose head has a stepped bottom.

To describe the field of industrial application for which the present invention is intended, in recent years, advanced technology has developed across various fields, and as symbolized by the words "light, thin, short and small," resource saving,
With the ever-increasing demand for precision, the field of machine screws now requires dense machine screws, which were previously difficult to produce.

Specifically, in the field of countersunk machine screws and round countersunk machine screws (hereinafter referred to as countersunk machine screws), short countersunk machine screws whose length or nominal length is equal to or less than the nominal length recommended by Japanese Industrial Standards for countersunk machine screws are It has become increasingly necessary in industry.

With conventional technology, when manufacturing countersunk screws with a short nominal length, when rolling the threaded part of a countersunk screw, the head surface is tapered and the neck is rounded, so it is short. The head of a countersunk eagle has a large ratio of the head to the threaded part! Since σ( is heavy, when the blank is fed into the flat rolling die,
The head tends to tilt and the blank is not stable.If the blank is inserted at an angle, the screws in the threaded part will become slanted and there is a problem that it will not become a product.Because the blank has a radius, it tends to float on the flat rolling die. In many cases, the incomplete threaded portion became long.

Therefore, the problem with conventional countersunk machine screws is that short countersunk machine screws with a nominal length less than the nominal length recommended by this industrial standard have a high incidence of defective products and are subject to technical difficulties in manufacturing. However, there are only a limited number of manufacturers of small screws, and it is very difficult to sort out some defective screws. Short countersunk machine screws are much more expensive.

In addition, since the threaded portion is extremely short compared to the incompletely threaded portion including the rounded portions of the head and neck, there are few effective threads, and there is a problem in the force with which the screw is tightened.

In addition, when tightening thin objects, due to the rounded part of the neck and incomplete screw threads, the tightening force of thin objects is weak and play may occur, and the head of the screw may stick out from the object when tightened. However, assembly has the drawback of producing defective products.

The present invention solves many of these problems.

To explain the present invention in detail, for a countersunk machine screw whose nominal length is less than the nominal length recommended by the Japanese Industrial Standards, the base of the head is equal to one screw thread. It is a flat head machine screw with a stepped head that has been rounded up, flattened into a stepped shape, and the threaded portion has been threaded.

To further explain the configuration in detail with reference to the drawings, Fig. 3,
As shown in Figure 4, the 1″ 1 rounded part of a conventional countersunk screw (
1) becomes unreliable in structure, the length of the rounded part (+) and the incompletely threaded part (2) becomes large, and a countersunk machine screw with a short nominal length has fewer threads.

In the present invention, the base of the head is rounded up to the length of one thread, flattened with steps, and the number of threads is increased.

To give an example and explain it in scale, the conventional countersunk screw designation 2.5X3 (Δl) 2.5X4 (
Bl) When applied to 2.5X5 (CI), the number of effective threads in the threaded part is small due to its short length, and the force required to tighten the screw is less than the number of threads, so it is originally small, but especially 2.5X3. When it is extremely short like (AI), there is one or one and a half RF effective threads, and there is concern about the +-J force for tightening.

In the case of <2.5X3(Δ) as shown in FIGS. 1 and 2, the present invention has two or two and a half effective threads, and the shorter the thread,
Compared to conventional countersunk screws, the force ratio for tightening is greater.

In addition, as mentioned above, with conventional countersunk machine screws, the lower surface of the head is tapered, the neck radius (1) is large, the ratio of the head is large compared to the threaded part, and the head is heavy. As a result, the head of the rolling die tends to tilt when riding on the flat rolling die, resulting in poor thread cutting.As shown in Figures 1 and 2, the present invention
Since the bottom of the head is flat, it is stable when mounted on a flat rolling die and can prevent thread cutting defects.As shown in Figure 5, the bottom of the head is shaped Since it is flat, stability is good.

When using flat head machine screws, when tightening precision thin objects, the rounded part (1) and incomplete thread part (2) of conventional flat head machine screws are attached to the upper side of the female thread part of the object as shown in Figure 6. If the upper surface of the head gets stuck and the upper surface of the head floats on a flat surface, or there is play in the assembly, and if you try to prevent this, the upper surface of the head is more likely to sink below the flat surface.

In the present invention, as shown in Fig. 7, hollow parts are formed on the two sides of the female thread part of the assembly, so that the upper surface of the head is flush with the flat surface, allowing for a clean finish.

In addition, as a result of repeated torsional tightening tests to determine whether or not there is a risk of the neck of the head snapping due to rounding up and stepping the base of the head, the top machine screw in Figure 5 and the neck have the same structure, and it is safe. has been confirmed.

Effect of the invention.

B. In the case of thread rolling, flat rolling dies are used, which eliminates skewing due to the tilt of the head, provides good stability, and prevents the generation of defective products.Therefore, disposal of good products due to contamination of defective products. Efficiency was significantly improved without having to do anything.

It is now possible to stably manufacture flat head machine screws with extremely short thread lengths, which were technically and physically difficult to manufacture in the past.

C. Tightening with short countersunk screws can increase the insufficient force.

2. Eliminates the jamming caused by the rounded part at the bottom of the head of conventional countersunk machine screws and the incompletely threaded part, and prevents looseness of objects when tightening thin materials, and prevents the head from rising or sinking, resulting in a clean finish.

As a result of the above, things that were previously expensive became
It can now be produced cheaply.

Is it something that could not be manufactured using normal technology as shown in 1-?
The effects of this technology are very obvious, such as expanding the scope of production, eliminating large losses of good products due to defective products, and so on.

[Brief explanation of drawings]

Figure 1 is a side view Figure 2 is a side view Figure 3 is a side view of the conventional product. Figure 4 is a side view of the conventional product. Figure 5 is a side view of the top screw. Figure 6 is a partially sectional side view showing the embodiment. Figure 7 is a partially sectional side view showing the embodiment.

Claims (1)

[Claims] For countersunk machine screws and round countersunk machine screws whose length is less than the nominal length recommended by Japanese Industrial Standards for the nominal length of countersunk machine screws and round countersunk machine screws, the base of the head is Countersunk head machine screws with a stepped head and round countersunk machine screws with one length rounded up and made flat with a step, and the threaded part cut.