JPH03234331A - Drill screw manufacturing method and rolling die - 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 (Field of Industrial Application) The present invention relates to a method for manufacturing a drill screw and a rolling die used for manufacturing the same.

(Prior Art) Generally, a drill screw consists of a head and a leg, a tapping thread is formed in the leg, and a drill part is formed at the tip of the leg. This drill screw is a screw that is fastened by drilling a pre-screw hole in a mating member with a drill portion at the tip, and a tapping thread is screwed into the pre-prepared hole.

Conventionally, methods for producing drill screws have been broadly classified into two methods as described below. First, one method is to forge a screw material 13 with a head 11 and a leg 12 integrally formed from a cut wire, as shown in Fig. 4 (a > (b) and (c)). Drill part 1 at the tip of leg 12 of 13
4 is cut, and then a tapping screw thread 17 is formed between the head 11 and the drill part 14 by rolling.

A pair of rolling dies 20A used for this rolling process,
20B has a thread rolling surface 21 having a predetermined width as shown in FIG. 5, and a flank surface 22 that does not come into contact with the drill portion 14 is integrally provided below the thread rolling surface 21.

The second method, as shown in FIGS. 6(a), (b), (C>), involves forging a screw material 13 with a head 11 and a leg 12 integrally formed from a cut wire, and 13
A drill part 14 is formed at the tip of the leg part 12 by heading, and then a tapping thread 17 is formed between the head 11 and the drill part 14, and at the same time, the chip 15 protruding from the drill part 14 is removed. This is the manufacturing method.

A pair of rolling dies 30A used for this rolling process,
30B has a thread rolling surface 31 having a predetermined width as shown in FIG. 7, and a chip removing section 32 whose dimension is such that it does not come into contact with the outer diameter of the drill section 14 is integrally provided below the thread rolling surface 31. It is configured.

[Problems to be Solved by the Invention] However, in the above-mentioned manufacturing method in which the drill part is machined by cutting force, it is inevitable that burrs occur during cutting, and in the manufacturing method in which the drill part is formed by heading, , it is unavoidable that debris remains in the area where the chip has been removed.

If debris remains on the drill part, the outer diameter of the drill part may become larger, causing variations in the outer diameter. For this reason, when a drill screw is used, the machinability of the drill part is reduced, and the diameter of the hole prepared for the screw varies, making it impossible to perform stable fastening. The present invention was invented with the aim of solving these problems.

(Means for Solving the Problem) A first invention to achieve this object relates to a method for manufacturing a drill screw, in which a screw material having a head and a leg is subjected to heading processing from a cut wire, and the leg is A method for manufacturing a screw in which a drilled portion is cut or forged at the tip and a threaded portion is rolled between the bottom of the head and the neck and the drilled portion. This is a method for manufacturing a drill screw, in which rolling is performed using a die and a pair of block tools that finish the outer diameter of the drill portion to a predetermined size.

A second invention relates to a rolling die used for manufacturing the drill screw, including a flat die provided with a rolling surface formed with a plurality of processing teeth for rolling a tapping thread, and a flat die provided with a rolling surface parallel to the rolling surface. This is a rolling die for a drill screw constructed by combining the block tool with a block tool having a flat surface and a dimension thicker than at least the length of the drill part.

(Function) The head 11 and the leg 12 are integrally forged on the cut wire by a cold heading machine, and the screw material 13 is then drilled at the tip of the leg 12 by a special press or the like. Headed. Next, the thread material 16 is sent to a thread rolling machine, and the head 11 is formed by a pair of flat dies FA, 1B.
A predetermined tapping thread 17 is formed between the drill portion 14 and the drill portion 14 . At the same time, a pair of block tools 4A and 4B
The chip 15 protruding to the outside of the drill part 14 can be removed by this, and the flat surface 5 can be used to remove or modify the burrs on the outer periphery of the drill part 14, and the outer diameter of the drill part 14 can be finished to desired dimensions. .

[Example〕 An embodiment of the present invention will be described below.

The manufacturing method of this drill screw is shown in Fig. 1 (a), (b), (C) (
As shown in d), first, a head 11 is forged on a cut wire 10 using a cold heading machine to produce a thread material 13.

Next, a drill shape is machined at the tip of the leg portion 12 of the screw material 13. The drill portion 14 is processed by forging using a mold using a special press or the like. (Alternatively, a cutting process using a milling machine or the like may be used.) Thereafter, a thread rolling machine is used to form a tapping thread 17 between the bottom of the head 11 of the screw material 16 and the drill part 14. This rolling process is performed in the second step. As shown in the figure, a pair of flat dies 1A and IB for machining a predetermined tapping thread 17, and the drill portion 14
A pair of block tools 4 for finishing the outer diameter of
Rolling is performed using A and 4B.

As shown in FIG. 3, the aforementioned rolling tool includes a flat die FA having a rolling surface 3 on which a plurality of machining teeth 2 are formed for machining a predetermined tapping thread 17, and a flat die FA that is parallel to the rolling surface 3. This rolling die is a combination of a four-method block tool 4A that has a flat surface 5 and is thicker than at least the length of the trill portion 14.

These rolling dies are made to face each other, and a pair of flat dies 1A
, IB and a pair of block tools 4A, 4B are attached to a thread rolling machine so as to be movable and adjustable in opposing directions, respectively. (Fig. 2) As mentioned above, the head 11 and the leg 12 are integrally forged on the cut wire 10 by a cold heading machine, and the thread material 13 is then pressed into the leg 12 by a special press or the like. The drill part 14 is headed at the tip of the screw.Next, the thread material 16 is sent to a thread rolling machine, and a predetermined tapping is made between the head 11 and the drill part 14 by a pair of flat dies 1A and IB. The thread 17 is rolled. At the same time, the chip 15 protruding outside the drill part 14 is removed using a pair of block tools 4A and 4B.
In addition, the flat surfaces 5 of the block tools 4A and 4B can remove or correct burrs on the outer periphery of the drill part 14 and finish the outer diameter of the drill part 14 to desired dimensions.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, in the thread rolling process, a pair of dies for rolling a predetermined tapping thread and a pair of block tools for finishing the outer diameter of a drill portion to a predetermined dimension are provided. In order to perform rolling processing using
It is possible to easily adjust and set the outer diameter dimension of the drill part and perform rolling processing, and no burr remains on the outer periphery of the drill part. Therefore, the outer diameter of the drill part is stabilized, machinability is improved, and the quality of the self-tapping screw is significantly improved. This reduces the variation in the pilot hole diameter when using screws, making it possible to perform extremely stable screw fastening.

Furthermore, it is possible to change the diameter of the pilot hole relative to the thread diameter, that is, the engagement rate of the thread, and it is also possible to change the holding force and axial force, making it possible, for example, to manufacture the optimal drill screw depending on the mating material. Many effects can be obtained.

[Brief explanation of drawings]

Figure 1 (a > (b), c, and d) is a front view showing the processing order of a trill screw, Figure 2 is a sectional view of the main part of rolling process, Figure 3 is a perspective view of a rolling die, Figure 4 (a > (b) and (c) is a front view showing the processing order of conventional trill screws, Figure 5 is a sectional view of the main part of the rolling process in Figure 4, and Figure 6 (a > (b) )(
c) is a front view showing the processing order of another conventional drill screw, and FIG. 7 is a sectional view of the main part of the rolling process in FIG. 6. 1A: Flat die 2: Machining tooth 4A: Block tool 5: Flat surface 10: Cutting wire 12: Leg portion 14 Nitrile portion 16: Screw material D Outer diameter of nitrile portion 1B: Flat die 3: Rolling surface 4B: Block tool 11: Head 13: Screw material 15: Tip 17: Tapping thread

Claims (1)

[Scope of Claims] 1] Forging a screw material having a head and a leg from a cut wire, cutting or forging a drill part at the tip of the leg, and forming a screw material between the bottom of the head neck and the drill part. A method for manufacturing a screw in which a threaded portion is rolled in the leg portion, using a pair of flat dies for rolling a tapping thread on the leg portion and a pair of block tools for finishing the outer diameter of the drilled portion to a predetermined dimension. A method for manufacturing a drill screw, which is characterized by rolling the drill screw. 2] Combination of a flat die provided with a rolling surface with a plurality of machining teeth for rolling tapping threads, and a block tool having a flat surface parallel to the rolling surface and thicker than at least the length of the drill part. A rolling die for a drill screw, characterized in that it is configured by: