JPH08243675A - Manufacture of pin with groove and pin with groove for connecting chain - Google Patents

Abstract

PURPOSE: To manufacture a pin having a peripheral groove at one end by means of a roll-forming with high productivity at low cost, in a manufacturing method for the pin with groove and the pin with groove to be manufactured with this method. CONSTITUTION: A roll-forming die having projections becoming gradually higher toward the outlet side from the inlet side of a mandrel forming the peripheral groove 2 and a cutting edge becoming gradually higher toward the outlet side from the inlet side of the material cutting off the excess length part of the end surface in the material adjoined to this projection, is used. The material 6 having the length at a little shorter than the necessary product length is passed through the roll-forming die, and only the peripheral edge parts of a bulging part 8 and a projecting part 9 developed the end surface of the material by forming the peripheral groove 2 is cut off with the cutting edge. The pin with groove manufactured in this method has the cut-off surface with the roll- forming die on the outer peripheral part of the end surface at the side arranging the peripheral groove and a remained recessed part 5 after cutting off at the center part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a grooved pin of a connecting link used for connecting both ends of a chain to form a loop (endless shape) and a grooved pin to be manufactured by the method. It's about pins.

[0002]

2. Description of the Related Art The chain connecting portion is provided with a connecting link 22 having a grooved pin 21 as shown in FIG. 6 so that the length of the chain can be adjusted when the chain is extended. The grooved pin 21 is a round rod-shaped pin provided with a circumferential groove 2 into which a clip ring 23 is fitted at one end as shown in FIG.
A clip ring 23 is fitted in the circumferential groove 2 to connect the connecting link 2
2 through one of the link plates 24 and then through the sleeve 26 at the end of the chain 25 to be connected,
The chain 25, 25 is connected by inserting the other link plate 24 and then caulking the tip of the pin 21 (the end where the circumferential groove 2 is not provided).

When adjusting the lengths of the chains connected to each other, the clip ring 23 is removed, the grooved pin 21 is pulled out, and an appropriate number of chain links are added or cut off, and then the chain ends are again attached. This is performed by inserting the grooved pin 21 and connecting with a connecting link, and fitting a clip ring into the circumferential groove 2.

The grooved pin 21 is manufactured by cutting a long round steel into a required size and then cutting the peripheral groove 2 with an automatic lathe. The grooved pin 21 is, of course, required to have high dimensional accuracy in its diameter and groove shape, but is also required to have a length within a predetermined tolerance.
If the pin is too long, the amount of protrusion from the link plate increases, which interferes with other adjacent members such as chains and sprockets to hinder smooth rotation and generate noise.

In the conventional manufacturing method, the grooved pin 2 is used.
The length of 1 is, when cutting the material before turning from round steel,
The accuracy was obtained by cutting with a dimension within a predetermined tolerance.

[0006]

The process of cutting a circumferential groove with an automatic lathe is very time-consuming and less productive than the process of cutting a material from round steel. Rolling is known as a highly productive method of forming a screw or a circumferential groove on a pin or a round bar. However, it is impossible to form the circumferential groove on the end portion of the pin by rolling and to keep the axial length of the pin within the same tolerance as the cutting or cutting. This is because when the peripheral groove 2 is formed by rolling at the end portion of the material 6, the material at the peripheral portion of the groove is extruded to the end surface of the pin, particularly the peripheral portion thereof, as shown in FIG. This is because it becomes impossible to control the protrusion height (M) due to (L) or the chamfering work. By rolling the circumferential groove 2 and then reworking the end face, it is possible to keep this length within a predetermined tolerance, but this increases the number of steps, which is an adverse effect.

Therefore, the inventor of the present application provides a cutting blade on a die for rolling the circumferential groove 2 to roll the circumferential groove 2 and, at the same time, to form the bulging portion 8 or the projecting portion 9 of the pin end surface caused by the rolling. Tried to remove. However, cutting off the end face by rolling is far more difficult than forming the circumferential groove 2 and the like.

[0008] Since cutting by rolling is a process close to push-cutting, a large force is applied to a sharp cutting edge, and the cutting edge is immediately worn. If the mold is made of a hard material in order to avoid this wear, the mold becomes very expensive, and if the material dances in the mold or there is a partially hard part, the cutting edge is immediately chipped. When the cutting edge is worn or chipped, the uncut protrusion 2 shown in FIG. 8D is formed at the center of the end surface of the pin.
7 occurs, and the length of the pin cannot be set within a predetermined dimensional tolerance. When a worn or chipped mold is to be replaced, the cost is higher than the cutting because the mold is expensive.

The present invention was found in various attempts to solve the above-mentioned conflicting problems, and as a result, all of the above problems are solved by a very simple method. However, the grooved pin for chain connection can be manufactured by rolling at high productivity and at low cost.

[0010]

The method for manufacturing a grooved pin according to the present invention is provided with ridges 14 and 15 which gradually increase from the inlet side of the material for forming the circumferential groove 2 toward the outlet side thereof. A cutting blade 1 for cutting off an extra length portion of an end face of a material adjacent to a ridge and gradually increasing from an inlet side of the material toward an outlet side thereof
Using the rolling dies 11, 12 having 8 and the material 6 cut into a length slightly shorter than the required product length is passed through the rolling dies, and the bulging portion 8 formed on the end surface of the material by forming the circumferential groove 2
It is characterized in that only the peripheral edge of the projection 9 is cut off by the cutting blade 18.

The chain connecting grooved pin of the present invention is a chain connecting grooved pin having a peripheral groove 2 at one end, and the peripheral groove 2 is formed by rolling and is adjacent to the peripheral groove 2. The end surface 3 of the pin is characterized in that the outer peripheral portion thereof is a cut surface formed by a rolling blade, and the uncut concave portion 5 remains in the center of the end surface.

[0012]

The length R of the material 6 passed through the rolling dies 11, 12 is slightly shorter than the length S of the product, and the dimensional difference Δ
x = S−R is a dimensional difference smaller than the maximum height W to T on the outer peripheral side of the bulging portion 8 or the protruding portion 9 formed on the end surface of the material due to the molding of the circumferential groove 2. When this material 6 is passed through the rolling dies 11 and 12 having the above-described structure, the circumferential grooves 2 are first formed by the ridges 14 and 15, and the bulging portion 8 or the bulging portion 9 generated by the bulging portion 8 or 9 exceeds the dimensional difference Δx. A portion having no protrusion or a protrusion height is cut off by the cutting blade 18. The axial position of the material when it is cut off is precisely defined by the fit between the rolling ridges 14, 15 and the circumferential groove 2 of the material molded by it, and thus the length dimension of the pin produced. S is
Depending on the precision of the rolling die, it can fit within the required dimensional tolerances.

Although the bulging portion 8 or the protruding portion 9 is cut off by a process close to push-cutting, since the dimensional relationship is such that the uncut portion 5 is left in the center of the end face and the recessed portion 5 remains, the material escapes toward the center portion during push-cutting. Since the force acting on the cutting edge 18 is reduced, the cutting edge 18 is less likely to be worn or chipped,
The durability of the rolling die increases.

Further, even when the cutting edge is chipped, when the end of the cutting blade is chipped, the bulging portion 8 or the protruding portion 9 to be cut before the material reaches the chipped portion is cut off. If there is a chip and the part is missing, the cutting edge 1 behind it
Since the portion left uncut by 8 is cut off, the cutting action and the accuracy of the length dimension of the molded product will not be hindered by only a part of the cutting edge. As a result, the life of the rolling die, especially the cutting edge 18 is extended several times, together with the decrease in the rate of occurrence of wear and chipping of the cutting edge, which is much cheaper and much higher than conventional cutting. The grooved pin 1 can be manufactured in a machining cycle.

The grooved pin manufacturing method of the present invention is suitable for manufacturing a grooved pin for chain connection in terms of its processing accuracy and high productivity, and the chain connection according to claim 2 above. The grooved pin for use can be manufactured with the desired dimensional accuracy by the method of the present invention at low cost and efficiently.

[0016]

1 is a perspective view of a grooved pin for connecting a chain according to the present invention. The grooved pin 1 has a peripheral groove 2 for mounting a clip ring at the right end of the figure. The end surface 3 on the groove side is a cut surface whose peripheral portion is cut by a cutting blade of a rolling die described later, a tapered surface 4 is formed on the outer edge portion thereof, and a recess 5 is formed at the center of the end surface 3. ing.
The length S of the grooved pin 1 is within a predetermined tolerance.

FIG. 2 shows an embodiment of the manufacturing method of the present invention. Material 6 is obtained by cutting round steel into a length R slightly shorter than the length S of the grooved pin 1 as a product (FIG. 2).
(A)). The material 6 is passed through a rolling device described later to form the circumferential groove 2. At the time of forming the groove, the peripheral edge portion 7 of the material 6 is pushed out in the axial direction to form a ring-shaped bulging portion 8 having a height W (FIG. 2B). Since the central part of the end face of the material is hardly deformed, it becomes the recess 5 surrounded by the bulging part 8. Further, the peripheral edge portion 7 and the bulging portion 8 of the material are applied to the inclined surface of the rolling die to form the tapered surface 4. Swelling portion 8 during chamfering work
Deforms into a conical protrusion 9 of height T having a recess 5 in the center (FIG. 2 (c)). After cutting the top of the conical protrusion 9 at the position of the chain line in FIG. 2 (c), quenching and centerless grinding are performed to manufacture the grooved pin of FIG.
The position of the chain line is a position defined by the length S of the product, which is the length R of the material plus the dimensional difference Δx (Δx = S−R).

3 to 5 show the essential parts of the rolling device. The rolling die is composed of a fixed die 11 and a movable die 12, and the material 6 is inserted between the two in the vertical direction. Since the fixed mold and the movable mold have symmetrical shapes, only the movable mold will be described below.

A flat surface 13 for holding the material 6 is provided on the front side surface of the movable mold 12, and a triangular pyramidal guide ridge 14 is provided from the rear edge thereof at a distance A (FIG. 5). (A)), the prismatic shaped projecting ridge 15 forming the circumferential groove 2 is provided in a distance B from the guide ridge (FIG. 5B). A loose recess 16 is provided below the molding ridge in the center of the mold (FIG. 5C), and a chamfered inclined surface 17 is formed from the rear surface of the recess by a distance (C + D) ( FIG. 5 (d)). The cutting edge 18 is provided at a distance D from the middle of the inclined surface (after passing the distance C). The cutting blade 18 cuts the top of the conical protrusion 9 deformed by the chamfering work to manufacture a pin (FIG. 5 (e)).

In the present invention, considering that the end face 3 swells in the axial direction in the rolling process, the length of the material is adjusted so that the length (S) of the grooved pin falls within a predetermined tolerance. R is shorter than the product length S by Δx. Therefore, when inserting the material 6 into the rolling die with the material supply device, the lower surface of the pin is
It is necessary to set the position higher by x.

[0021]

According to the manufacturing method of the present invention, the peripheral groove is formed by rolling, and only the peripheral edge of the bulge or protrusion formed on the end surface of the material by the forming of the peripheral groove is cut by the rolling die. Since it is cut off, the life of the rolling die can be extended, and the grooved pin for chain connection with high processing accuracy can be efficiently manufactured. Further, the grooved pin of the present invention has a shape suitable for manufacturing a pin having a desired dimensional accuracy by rolling, and can be manufactured inexpensively and efficiently by rolling.

[Brief description of drawings]

FIG. 1 is a perspective view of a grooved pin according to the present invention.

FIG. 2 is a schematic diagram showing a manufacturing method of the present invention.

FIG. 3 is a perspective view of a rolling die.

FIG. 4 is a plan view of a movable mold.

5 is a partial cross-sectional view of FIG.

FIG. 6 is a perspective view of a chain connecting portion.

FIG. 7 is an exploded perspective view of a connecting link.

FIG. 8 is a schematic diagram showing a conventional rolling method.

[Explanation of symbols]

 2 Circumferential groove 3 End surface 5 Recess 6 Material 8 Bulging part 9 Projection part 11 Fixed mold 12 Movable mold 14 Guide ridge 15 Molding ridge 18 Cutting edge

Claims (2)

[Claims] 1. A ridge (14, 15) gradually increasing from the inlet side of the material for forming the circumferential groove (2) toward the outlet side, and a margin of the end surface of the material adjacent to this ridge. Cutting edge that gradually increases from the inlet side to the outlet side of the material for cutting the long part
Using a rolling die (11, 12) having (18) and a material (6) cut into a length slightly shorter than the required product length, pass the material through the rolling die, and form the groove (2) to form the material. Only the peripheral edge of the bulging part (8) or the protruding part (9) generated on the end face is cut by the cutting blade (18).
A method for producing a pin having a circumferential groove at its end, which is characterized in that the pin is cut off with. 2. A grooved pin for chain connection having a circumferential groove (2) at one end, wherein the circumferential groove (2) is formed by rolling, and the end surface (3) of the pin adjacent to the circumferential groove (2) is formed. ) Is a grooved pin for chain connection, characterized in that the outer peripheral portion thereof is a cut surface by a rolling blade, and an uncut concave portion (5) remains in the center of the end face.