JP4751967B1 - Screw point manufacturing method - Google Patents

Abstract

The present invention provides a screw point manufacturing method that can be efficiently manufactured and cost reduction.
In a manufacturing method of a screw point 10 composed of four screws such as a twisted quadrangular pyramid, a parting line 20 corresponds to an outline in a plan view of the screw point 10 to be formed. A ridge line 22 that hits the ridge line of each ridge that appears discontinuously and a valley line 24 that crosses the ridge in each valley's valleys are alternately and continuously arranged in a zigzag-shaped party. Using the upper die 16 and the lower die 18 set in the grinding line 20, the heated material is hot forged to form a screw.
[Selection] Figure 2

Description

  The present invention relates to a method for producing screw points.

A so-called Swedish sounding test (JIS A 1221) is generally widely used to investigate soil quality and soil strength.
In the Swedish sounding test, a screw point is attached to the tip of the rod and the rod is penetrated into the ground while applying a load and rotation to the rod. The stratum structure of the land is determined from the load at the required penetration position and the number of rotations of the rod. Is determined.
The screw point has a four-threaded shape in which a rod-like body having a length of 20 cm and a substantially quadrangular pyramid is twisted once, and its specific shape and dimensions are defined in the JIS standard.
Conventionally, generally, a screw point is manufactured by cutting a round bar (patent document 1).

JP 2006-263868 A

As described above, the screw point penetrates into the ground while being applied with a load and rotation, and thus wears due to contact with earth and sand or gravel at the time of penetration. Therefore, it is necessary to exchange frequently, and the cheaper thing is calculated | required from the cost side.
However, as described above, when the screw point is manufactured by cutting, since it has a complicated shape, there is a problem that it cannot be efficiently manufactured, is expensive, and cannot be provided at low cost. In addition, although it is conceivable to manufacture the screw point by casting, there is a problem that a nest can easily enter the product in the case of casting, and the required strength cannot be obtained.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a screw point manufacturing method that can be efficiently manufactured and cost can be reduced.

In order to achieve the above object, the present invention comprises the following arrangement.
That is, the screw point manufacturing method according to the present invention is a screw point manufacturing method comprising four screws such as a twisted quadrangular pyramid, and the parting line is in plan view of the screw point to be formed. The ridge line corresponding to the contour line corresponding to the ridge line of each ridge that appears discontinuously and the valley line that crosses the ridge in each valley's valley are alternately and continuously zigzag in the vertical direction. Using the upper die and the lower die set in a parting line having a shape, the heated material is hot forged to form a screw.

Further, the upper mold and the lower mold have a parting surface that is uneven in the vertical direction along the parting line, and in the forging process, the material flows out as burrs between the parting surfaces, and the burrs are removed. Including the step of:
In addition, it includes a finishing step of finish grinding the trace from which the burr has been removed.
Further, the method includes a threading step of forming a screw as an attachment portion to the rod.

According to the present invention, by setting the parting line to a required uneven parting line, it can be divided into two split molds, and a screw point having a complicated shape having a portion that becomes an undercut in a plan view. By forging, it can be easily produced and mass-produced, and the cost can be reduced.
Moreover, since it forms by forging, the screw point excellent in quality can be provided.

It is a top view of a screw point. It is explanatory drawing which shows the burr | flash mark at the time of forging. It is explanatory drawing which shows the parting line of the unevenness | corrugation of an upper mold | type and a lower mold | type. It is a description top view of a lower mold | type.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a plan view of the screw point 10.
The screw point 10 is composed of four screws that twist a square pyramid, and has a screw portion 12 and a male screw portion 14 that is an attachment portion to a predetermined rod (not shown).
In the present embodiment, as shown in FIG. 3, the screw point 10 is manufactured by hot forging using two forging dies, that is, an upper die 16 and a lower die 18 that are divided vertically.

As described above, the screw point 10 has a four-threaded shape like a twisted quadrangular pyramid. Therefore, a plan view, an undercut portion is generated, and a simple flat parting line split mold is used. It cannot be manufactured.
Since it has a four-screw shape, it can be a flat parting line split mold if four split molds from four directions are used. Manufacturing would be virtually impossible. In addition, the mold cost will rise.

Therefore, in the present embodiment, by setting the parting lines of the upper die 16 and the lower die 18 as follows, the screw point 10 can be manufactured by forging with only two split dies.
FIG. 2 is an explanatory view showing the burr mark remaining on the forged product, and the parting line is understood from this burr mark.

In other words, in the present embodiment, the parting line 20 corresponds to the ridgeline of the peak portion of each strip that appears discontinuously corresponding to the outline (the outline shown in FIG. 1) in plan view of the screw point 10 to be formed. The upper mold 16 and the lower mold 16 are set in a parting line 20 that is formed in a zigzag shape in the up and down direction, in which the peak line 22 and the valley line 24 that crosses the valley in the valleys of each strip are alternately and continuously arranged. A mold 18 is used.
Since the threading of the male screw portion 14 is performed after the forging process, the portion corresponding to the male screw portion 14 is formed in a simple rod-like body at the time of forging. Therefore, the parting line (rod-like body line) 26 in this portion is formed. Becomes a flat line.

  3 is a front view of the mold, and it will be understood that the parting lines are zigzag in the vertical direction. In FIG. 3, 22a, 24a, and 26a are parties on the front edge of the mold. 22b, 24b, and 26b are parting lines 20b at the inner edge of the mold. It goes without saying that the parting lines 20a and 20b are formed in a recess 28 (FIG. 4) having a required inner surface shape corresponding to a rod-like part for forming the screw part 12 and the male screw part 14. Yes.

FIG. 4 is a plan view of the lower mold 18. As shown in FIG. 4, on both sides of the recess 28, a parting surface 30 that is concave and convex in the vertical direction is formed along the parting line 20. The upper die 16 is also formed with a parting surface (not shown) that is concave and convex with respect to the parting surface 30 of the lower die 18.
The space between the parting surface 30 of the lower die 18 and the parting surface of the upper die 16 is set so that a space having a required thickness is formed when the complete die is closed. Flesh flows out into the space as burrs. In this way, during forging, the material is sufficiently distributed in the concave portions 30 of the lower mold 18 and the upper mold 16, and the screw point 10 having an accurate shape can be manufactured.

The lower mold 18 and the upper mold 16 are formed as described above.
Therefore, the lower die 18 and the upper die 16 are set in a forging machine (not shown), and a heated round bar-like material is disposed between the lower die 18 and the upper die 16 by a conventional method, and forging is performed. By stamping with a machine, it is possible to obtain a raw product of the screw point 10 in which burrs are generated along the parting line.
The punching using the lower die 18 and the upper die 16 was performed twice as rough punching and finish punching, whereby a raw product could be obtained. Alternatively, if necessary, a dedicated crushing mold, a roughing mold, and a finishing mold may be prepared, and the raw product may be formed by multiple stages of stamping.

Next, deburring is performed.
A dedicated die and punch are prepared for deburring (not shown).
The dies and punches are also concavo-convex surfaces along the parting lines of the lower die 18 and the upper die 16, and are dies and punches each having a die opening slightly larger than the outline of the screw point 10 and a pressing surface. Form. Using this die and punch, the blank product is punched. Thereby, it is possible to obtain a trimmed product with some burr remaining along the parting line.
The burrs remaining on the trimmed product are removed by finishing using a grindstone.

Further, the male threaded portion 14 is formed by threading the rod-shaped portion corresponding to the male threaded portion.
And if necessary, quenching and tempering are performed to complete the screw point 10.
Furthermore, it is good also as a finished product by forming finish plating films, such as nickel plating.

According to the present embodiment, by setting the parting line to the required uneven parting line, it can be divided into two split molds, and a screw having a complicated shape having a portion that is undercut in plan view The points can be forged easily and mass-produced, and the cost can be reduced.
Moreover, since it forms by forging, the screw point excellent in quality can be provided.

DESCRIPTION OF SYMBOLS 10 Screw point 12 Screw part 14 Male thread part 16 Upper mold | type 18 Lower mold | type 20 Parting line 22 Mountain part line 24 Valley part line 26 Rod-shaped body line 28 Parting surface 30 Recessed part

Claims (4)

In the manufacturing method of the screw point which consists of four screws which twisted a square pyramid,
A parting line corresponding to an outline in plan view of a screw point to be formed, a peak line corresponding to a ridge line of each peak appearing discontinuously, and a trough that crosses the trough in each trough It is characterized by forming a screw by hot forging the heated material using an upper die and a lower die set in a parting line that forms a zigzag shape in the vertical direction. Screw point manufacturing method.   The upper mold and the lower mold have a parting surface that is uneven in the vertical direction along the parting line, and a material is discharged as burrs between the parting surfaces in a forging process, and the burr is removed. The screw point manufacturing method according to claim 1, comprising:   The screw point manufacturing method according to claim 2, further comprising a finishing step of finish grinding the trace from which the burr has been removed.   The screw point manufacturing method according to any one of claims 1 to 3, further comprising a threading step of forming a screw as an attachment portion to the rod.

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