JPH0258016B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for processing slotted screws. More specifically, the present invention relates to a method of processing a slotted screw having a self-locking function by providing a slot in the thread.

[Prior Art] Threaded members such as bolts or nuts may loosen after being tightened due to vibrations or other causes. In order to prevent this loosening, a locking member such as a spring washer is also used. If a locking member such as a spring washer is used, tightening work is inconvenient. Also, spring washers alone cannot sufficiently prevent loosening. For this reason, self-locking screw members have been developed and put into practical use, in which the entire threaded portion is coated with a rubber or plastic wear patch to increase resistance to loosening.

However, this type of threaded member with a friction patch is expensive because it requires an extra process to manufacture, and it is difficult to obtain a reliable contact surface between the thread and the friction patch during tightening. It's not easy. Furthermore, the friction patch has a limited anti-loosening effect due to its material strength, and cannot provide sufficient reliability.

On the other hand, Japanese Patent Publication No. 47-39387 describes a bolt in which an elastically deformable rib is provided on the threaded surface of the bolt, and the rib is elastically deformed and locked when the bolt is tightened. However, in this type, the elastic deformation portion, that is, the rib portion is small, so the force in the ballistic direction for locking is weak. Furthermore, since the ribs are locally provided on a portion of the threaded surface, permanent plastic deformation occurs and the locking effect decreases with repeated use. Furthermore, since the load due to the elastic deformation of the ribs is localized, there is a risk that the ribs may bite into the threaded surface of the other party and damage the threaded surface.

In view of these conventional problems, the present applicant has developed a cell lock screw member that provides elasticity to all threads and prevents them from loosening by providing slits cut in the central direction, that is, radial direction, from the tops of all threads. (Japanese Unexamined Patent Application Publication No. 1983-65252, Japanese Patent Publication No. 1983-19492)
Publication No.). Since the screw surfaces of this screw are in contact with each other over the entire surface like normal screws, the probability of local contact is low, and all screw threads have slits, so they can be used as described above. There are no problems.

[Problem to be solved by the invention] However, it is extremely difficult to industrially process the slit for this slotted screw because the width of the slit is very narrow and deep compared to the width of the slit. It was hot. For example, when machining a slit by cutting, it is necessary to use a grooved cutting tool with an extremely thin blade width. In fact, using this method to make a slit in a screw thread is economically and technically impossible to produce industrially, considering the wear of the cutting tool and the machining time.

In addition, in order to perform slit processing by rolling,
Because the slit width is extremely narrow and the depth of the groove is deep considering the ratio of the slit width, it is impossible to ensure the strength of the slit formed in the rolling die, that is, the protrusion opposite to the slit, so it is virtually impossible to roll. It was not possible to process it by Even if this mold could be manufactured, it would not be mechanically strong enough to withstand long-term use. In the end, there was no practical slit processing method. This invention was invented based on these technical backgrounds, and achieves the following objects.

An object of the present invention is to provide an industrially effective method for processing slotted screws.

[Means and actions for solving the problem] The following means are taken to solve the problem.

A method for processing a screw with a slotted slot in which a slit is formed in the radial direction on the screw thread, the method includes forming a small screw 1 which is an intermediate product with a pitch of 1/2 of the pitch of the thread of the screw, The threads of a forming means having twice the pitch of the threads are engaged with the space 4 defined by the side wall 3 of the small screw 1, and the small screw 1 is plastically deformed by the forming means. This is a method of processing a slotted screw in which the space 4 of the thread of the small screw 1 is transformed into the slit by deforming it as a part of the thread.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is the first screw to be machined, and is a schematic diagram showing the shape of the thread with a small pitch. FIG. 2 is a schematic diagram showing the shape of a large pitch screw thread that will be machined later. FIG. 3 is a diagram showing a schematic diagram of the finally machined screw thread. First, in this processing method, as shown in Fig. 1, a small screw 1 having a thread of pitch p is made. This screw thread is
It has the shape of a normal screw, and has side walls 3 and a space 4 surrounded by the side walls 3 and having a triangular cross section. Pitch p is 1/2 of the pitch of the screw to be machined.

This process is performed using any of the flat dies, planetary dies, round dies, and rolling attachments commonly used for thread rolling. Next, the machined small screw 1 is machined using a die having 2p, which is twice the pitch. If you do not process this process and use only this die, you will get a normal 2p pitch large screw 2, as shown in Figure 2.
can be produced.

Pitch p and pitch 2p are pitches that are multiples of integers, so when a small screw 1 with pitch p is processed using a die with twice the pitch, pitch 2p will be formed in every other space 4 of small screw 1. The threads of the die are positioned for insertion and engage. This positioning can be done without using any special positioning means, since the pitch is an integer multiple, simply use a small screw.
easily meshes with a die of twice the pitch. A space 4 formed by the side walls 3 of the threads of adjacent small screws 1 becomes a slit 4 after rolling. The thread of the die with twice the pitch meshes with the space 4 of the pitch p of the small screw 1, causing the small screw 1 to be plastically deformed into a part of the large thread 2. Therefore, as shown in FIG. 3, the screw has a slit 4 formed in the thread. This shaping is also carried out by rolling in the same manner as described above.

The slit 4 is processed by the above method.
When tightening, the side wall of the mating screw will open the slit 4.
is deformed in the direction of contraction, and its repulsive force pushes back the side wall of the mating screw thread, thereby significantly improving the loosening prevention effect against vibration.

[Effects of the Invention] As detailed above, the slotted screw processing method of the present invention basically allows slotting to be formed in only two steps. Since the two steps are almost the same as the conventional rolling method, manufacturing is extremely simple. Furthermore, since the metal fibers are manufactured by plastic deformation and are continuous without being cut, they have excellent mechanical strength. Moreover, it is industrially extremely effective because it can be produced at low cost.

[Brief explanation of drawings]

Figure 1 is a schematic diagram showing the shape of a small thread that is machined first, Figure 2 is a diagram that shows the shape of a large thread that is machined later, and Figure 3 is a diagram that shows the shape of a large thread that is machined on top of a small thread. 2 is a schematic diagram showing the shape of a screw thread processed by 1...small screw, 2...large screw, 3...
The side wall of the small screw thread, 4...the space that makes up the slit.

Claims (1)

[Claims] 1. A method for processing a slotted screw in which a slit is formed in the radial direction on the screw thread, the method comprising: manufacturing a small screw 1 which is an intermediate product with a pitch of 1/2 the pitch of the thread of the screw; The screw thread of the molding means having twice the pitch of the thread of the small screw 1 is engaged with the space 4 surrounded and partitioned by the side wall 3 of the small screw 1, and the molding means The slotted part is characterized in that the space 4 of the thread of the small screw 1 is transformed into the slit and processed by plastically deforming the small screw 1 and deforming it as a part of the thread. How to process screws.