JPS624357Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a metal cold forging device, and more particularly to a die assembly for upsetting an extension bolt thread rolling portion used in a multi-stage extension bolt forming machine.

As is well known, an extension bolt is a bolt whose diameter is reduced from the threaded bottom diameter so that the central shaft portion to which tension is applied can be easily extended. Conventionally, as shown in Figure 1, the method for manufacturing stretch bolts is to form the material using a multi-stage forming machine, to make the shaft of the stretch bolt have the lower thread diameter d ₀ of the thread rolling part, and to form a thread into the threaded part. After rolling (step a in Figure 1), the shaft part is reduced to a diameter d ₁ by machining or swaging (step b in Figure 1), or the R groove is rolled (step 1). A method is known in which the effective diameter of the shaft portion is reduced by step c in the figure.

In addition, as shown in Figure 2, after forming the material with a multi-stage forming machine and drawing the shaft part to the required diameter d ₁ (step a in Figure 2), another machine is used to thread-roll the material. Perform upsetting of the part to make the lower screw diameter d ₀ (b in Fig. 2).
It is also known to carry out thread rolling (step c in FIG. 2) using a separate machine.

However, in any of these methods, it is impossible to carry out all of the above steps with one machine, and therefore many processes using different machines are required, resulting in problems in terms of workability, productivity, and cost. I was at a disadvantage.

The purpose of this invention is to carry out the first step of cutting the rod-shaped material, the second step of upsetting the bolt head and narrowing the shaft to the required final diameter d ₁ , and the second step of forming the head and, if necessary, the flange. 3 steps, a 4th step of upsetting the stretched bolt thread rolled portion to a lower thread diameter d ₀ larger than the above diameter d ₁ , and a 5th step of rolling a screw in the thread rolled portion.
To provide a die assembly for upsetting a bolt thread rolling part suitable for carrying out the fourth step described above, in order to consistently carry out cold multi-stage forming of an elongated bolt consisting of the steps in one multi-stage forming machine. That's true.

The above object is achieved by the die assembly for upsetting thread rolling parts of the present invention, which comprises (a) a die housing having a through cavity extending in the longitudinal direction; It has an end surface that supports the head of the intermediate elongated bolt product in the third step and, if necessary, the lower surface of the flange, and has a substantially cylindrical inner hole with a diameter substantially equal to the diameter of the neck. a first die member; (c) an intermediate slide that is longitudinally slidably mounted in the cavity adjacent to the first die member and has a conical inner bore that diverges toward the first die member; (iv) a substantially cylindrical inner hole having an outer circumferential surface that matches the conical inner hole of the intermediate slide ring and having a diameter substantially equal to the shaft diameter d ₁ ; intermediate dies slidably mounted within the bore, the intermediate dies being capable of being separated from one another when sliding along the conical bore towards the first die member and converging together when sliding in the opposite direction; (e) a means for urging the intermediate die toward the first die member; and (f) a means for adjoining the intermediate slide ring and slidable in the longitudinal direction within the cavity. (g) means for urging the third die member toward _the intermediate slide ring; The gist of the system is to be equipped with the following.

In one embodiment of the present invention, the inner bore of the third member may be provided with an undercut having a diameter slightly larger than the threaded diameter d ₀ . In this way, since the thread rolling portion is strained when the product is ejected, the shaft diameter of the thread rolling portion can be made uniform.

In another embodiment, the outer peripheral surface of each segment of the intermediate die is provided with at least one longitudinally extending groove, and the intermediate slide ring is provided with a guide pin that engages the groove, and each segment of the intermediate die is provided with a guide pin that engages the groove. As the segments slide along the intermediate slide ring and separate from each other, each segment can be guided so that they can expand with uniform spacing from each other.

Moreover, the first and third die members can each be composed of a die and a die holder.

Additionally, the cavity of the die housing can be cylindrical. The cavity preferably has a multi-stepped cylindrical shape, and the first die member, the intermediate slide ring, and the third die means abut each shoulder formed between each cylindrical cavity to restrict their movement. be able to do so.

If the die assembly of the present invention is used, it is possible to integrally form an elongated bolt with the same multi-stage forming machine, so there is no need to change the machine and process as in the conventional method. Therefore, productivity and workability are improved. Additionally, machine investment and installation space can be reduced. Furthermore, the material yield is higher than when cutting is performed. Furthermore, manufacturing costs can be reduced for these reasons.

Hereinafter, embodiments of the present invention will be described with reference to the drawings from FIG. 3 onwards.

FIG. 3 is a longitudinal cross-sectional view of an embodiment of the die assembly for extension bolt thread rolling and upsetting of the present invention. In this embodiment, the die housing 10 has four stages with inner diameters increasing sequentially from the top to the bottom. It has a stepped through hole consisting of cylindrical inner holes 12, 14, 16, and 18. In this embodiment, these bores are cylindrical, but they may also be polygonal or other shapes. A first die member is fitted into the inner holes 12 and 14 so as to be slidable in the longitudinal direction. This first die member consists of a first die holder 20 and a first die 22 firmly and replaceably fixed to the first die holder 20, the first die having a cylindrical inner hole having a diameter equal to the diameter of the neck of the stretch bolt to be manufactured. It has 24. An intermediate slide ring 26 is fitted into the inner hole 16 of the die housing so as to be slidable in the longitudinal direction. This intermediate slide ring 2
6 has a frusto-conical inner bore 28 that tapers toward the first die member. This conical inner hole 2
Inside 8 is an intermediate die 30 having a shape that matches the inside 28.
is stored. This intermediate die 30 has a cylindrical bore 32 with a radius of curvature that approximately corresponds to the final diameter of the shank of the expansion bolt to be manufactured. As shown in FIG. 4, this intermediate die 30 is constructed as a split mold, and in the illustrated embodiment is divided into four die segments 34. A tapered groove 36 is formed in the outer circumference of each die segment 34 in the longitudinal direction. On the other hand, the intermediate slide ring 26 is provided with a hole in the radial direction, and a guide pin 38 is inserted into the hole.
is inserted so that it can be withdrawn freely (Figure 3). Each guide pin engages a respective groove 36 in the die segment. Therefore, when the four die segments slide and expand along the conical surface 28 of the intermediate slide ring 26, the die segments expand in the radial direction while maintaining uniform spacing from each other as shown in FIG. It can expand. Each die segment 3
4, a blind hole is provided on the lower surface, into which a coil spring 40 is inserted. The lower end of each coil spring 40 is seated on the upper surface of the third die member. This third die member is the die housing 1
The third die holder 2 is fitted into the inner hole 18 of 0 so as to be slidable in the longitudinal direction, and this third die holder 4
It consists of a pair of third dies 44 and 46 that are firmly fixed to the die 2 in a replaceable manner. The third dies 44, 46 have a generally cylindrical bore 48 with a diameter equal to the underthread diameter of the thread roll of the stretch bolt to be produced. Preferably, as shown in FIG. 5, the inner hole 48 is provided with an undercut 5 having a diameter _d2 larger than the threaded diameter _d0 .
0 is provided, and when the product is ejected, the material on the outer periphery of the thread rolling part is strained to stabilize the shaft diameter of the thread rolling part. The third die holder 42 has an inner hole 4
A through hole is provided on the extension of 8 so that a knockout pin of a multi-stage molding machine can be inserted into and removed from the hole. Further, a recess 52 is provided on the lower surface of the third die holder 42, and a coil spring 4 is provided therein.
A coil spring 54 having a spring constant greater than zero is inserted.

Next, the operation of the die assembly of the present invention will be explained with reference to FIG. Multi-stage molding machine (not shown)
An elongated bolt is cut from a rod-shaped material in the first step, the head is upset in the second step and the shaft is narrowed to the required final diameter d ₁ , and the head and, if necessary, a flange are formed in the third step. The intermediate product 56 is charged into the die assembly. When the punch 58 connected to the ram of the multi-stage molding machine descends, the lower surface of the head of the intermediate product 56 (or the lower surface of the flange if necessary) comes into contact with the upper end surface of the first die 22. While supported, the neck is held in a precise fit within the bore 24 of the first die. punch 58
As it descends further, the pressing force is transmitted to the first die 22 and first die holder 20 through the head or underside of the flange of the intermediate product, and further to each segment 34 of the intermediate die 30. For this reason, each die segment 34 descends along the slope 28 of the intermediate slide ring 26 while compressing the spring 40 and being guided by the guide pin 38, and comes together to converge. As a result, the bore 32 of each die segment 34 forms a cylindrical bore with a diameter equal to the final diameter d ₁ of the elongated bolt shank to tighten and retain the shank. In this state, all intermediate die segments have completely entered the intermediate slide ring, and their upper and lower end surfaces are aligned, respectively. Therefore, if the punch 58 is further lowered, the first die members 20, 22, the intermediate slide ring 26, the die segment 34, and the third
The die members 42, 44, and 46 are lowered together and are elastically supported by the coil spring 54.
Next, while the knockout pin 60 of the multistage molding machine remains fixed, the first, second, and third dies are further stroked together, so that the neck of the intermediate product 56 is held by the first die 22 and the shaft is Since they are tightened by the intermediate die segments 34 and cannot expand in diameter, only the thread rolled portion is plastically deformed and the diameter d ₂
It will be taken up to the point of Next, when the punch 58 is retreated to remove the pressing force applied to the head, the third die holder and the intermediate slide ring return upward due to the action of the coil spring 54 and abut against the shoulder of the die housing inner hole. leading to. Each die segment 34 is then moved by the guide engaging the groove 36 while pushing the first die holder upwardly until the first die holder abuts the corresponding shoulder in the die housing bore under the action of the coil spring 40. Guided by the pin, it slides along the conical surface of the intermediate slide ring and expands, releasing the shank of the extension bolt. Next, when the knock-out pin further strokes upward, the thread-rolled portion of the bolt is pressed by the throat formed by the undercut of the third die and is adjusted to the lower thread diameter d ₀ . The product is extracted from the die assembly. This intermediate product is thread-rolled in the next process of a multi-stage forming machine to become a finished product.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the conventional stretch bolt manufacturing method.
Fig. 2 is an explanatory diagram of another conventional method, Fig. 3 is a longitudinal sectional view of the die assembly of the present invention, Fig. 4 is a sectional view taken in the direction of the third die, and Fig. 5 is an enlarged view of the third die. 6 is a cross-sectional view of a die assembly during upsetting of an extension bolt thread rolling section. 10...Die housing, 12, 14, 16,
18... Inner hole of die housing, 20, 22...
First die member, 20...first die holder, 22
...First die, 24...Inner hole of first die, 26...
... Intermediate slide ring, 28 ... Conical inner hole of intermediate slide ring, 30 ... Intermediate die, 32 ...
Inner hole of intermediate die, 34... intermediate die segment,
36... Groove of intermediate die segment, 38... Guide pin, 40, 54... Coil spring, 4
2, 44, 46...Third die member, 42...Third
Die holder, 44, 46...Third die, 48...
... Inner hole of third die, 50 ... Undercut of third die, 56 ... Intermediate product of stretch bolt, 58 ...
...Punch, 60...Knock out pin.

Claims (1)

[Scope of claim for utility model registration] 1. The first step of cutting the rod-shaped material, and the second step of upsetting the head of the extension bolt and narrowing the shaft portion to the required diameter d ₁ .
a third step of forming the head and, if necessary, a flange; a fourth step of upsetting the thread-rolled portion of the stretch bolt to a lower thread diameter d ₀ larger than the above-mentioned diameter d ₁ ; A die for upsetting an elongated bolt thread rolling part used to carry out the fourth step in an elongated bolt multi-stage forming machine for carrying out cold multi-stage continuous forming of an elongated bolt consisting of a fifth step of rolling a thread. An assembly comprising: (a) a die housing having a through cavity extending in the longitudinal direction; and (b) a head of the intermediate product of the elongated bolt in the third step, which is slidably installed in the cavity in the longitudinal direction; and, if necessary, a first die member having an end surface supporting the lower surface of the flange and having a substantially cylindrical inner hole having a diameter substantially equal to the diameter of the neck; an intermediate slide ring that is slidably mounted in the longitudinal direction and has a conical inner hole that extends toward the first die member in a diverging manner; and (d) has an outer circumferential surface that matches the conical inner hole of the intermediate slide ring. and an intermediate die having a substantially cylindrical inner hole having a diameter substantially equal to the shaft diameter d ₁ and slidably mounted in the conical inner hole of the intermediate slide ring, (e) the intermediate die is attached in the direction of the first die member; (f) a third member which is slidably installed in the cavity adjacent to the intermediate slide ring and has a substantially cylindrical inner hole having a diameter substantially equal to the threaded diameter d ₀ ; A die assembly for upsetting an extension bolt thread rolling section, comprising: a die member; (g) means for biasing the third die member in the direction of the intermediate slide ring. 2. Request for registration of a utility model characterized in that the inner hole of the third die member is provided with an undercut having a diameter slightly larger than the lower thread diameter d ₀ , so that the thread rolling portion can be strained when the product is ejected. A die assembly for upsetting an extension bolt thread rolling part as described in item 1. 3. Utility model registration claim 1, characterized in that the outer peripheral surface of the split intermediate die is provided with a groove extending in the longitudinal direction, and the intermediate slide ring is provided with a guide pin that engages with the groove. Diameter assembly for upsetting the rolled part of the extension bolt thread as described. 4. The die assembly for upsetting an extension bolt thread rolled part according to claim 1, wherein the first and third die members each include a die and a die holder. 5. The die assembly for upsetting an extension bolt thread rolled part according to claim 1, wherein the cavity of the die housing is cylindrical. 6. The cavity of the die housing has a multi-stage cylindrical shape, and the first die member, the intermediate slide ring, and the third die member can respectively abut against each shoulder of the multi-stage cylindrical cavity. A die assembly for upsetting an elongated bolt rolled part as set forth in claim 1 of the utility model registration claim.