JPH0880585A - Method and mold for producing rubber crawler - Google Patents

Abstract

PURPOSE: To enhance the durability of a rubber crawler by reducing the effect of the thermal expansion strain applied to rubber at the time of the production of the rubber crawler. CONSTITUTION: In a method for producing a rubber crawler by arranging unvulcanized rubber constituting the rubber crawler, a steel cord band and, if necessary, a core metal in the cavities of upper and lower molds having cavities forming the inner and outer shapes of the rubber crawler to heat them under pressure, on the cavity sides of the mating surfaces of the upper and lower molds, chamfering processing is applied to at least one of the mating surfaces and the elongation strain due to thermal expansion of the rubber in the cavities is averaged. The lower mold 1, the upper mold 2, the cavities (a), (b), the chamfered parts P, the angle θ of inclination of the chamfered parts P and the length L of the chamfered part are shown.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a rubber crawler and a mold thereof, and reduces the influence of thermal expansion strain applied to the rubber during the manufacture of the rubber crawler to improve the durability of the rubber crawler. It is a thing.

[0002]

2. Description of the Related Art A rubber crawler is usually formed as an endless belt, and a method is adopted in which both ends are revulcanized to form an endless belt. Then, a mold divided into two parts that forms the inner and outer shapes of the rubber crawler is used. Usually, the mold on the side that forms the inner surface of the rubber crawler is the lower side, and the unvulcanized rubber, the steel cord band, and the outer peripheral surface that form the inner peripheral side surface in the cavity of this lower mold. The unvulcanized rubber forming the above is sequentially laminated with a cored bar, a woven fabric, etc., which are embedded in the rubber, and the upper mold is closed and heated under pressure.

FIG. 4 is a cross-sectional view showing an example of this prior art, showing the materials constituting the upper and lower molds 11 and 12 and the rubber crawler. That is, lower mold 11
The unvulcanized rubber A, the core metal B, the steel cord band C, and the unvulcanized rubber D, which form the outer peripheral side surface of the rubber crawler, are successively superposed in the cavity a of the rubber crawler. The unvulcanized rubber is vulcanized by closing these in the upper mold 12 and heating under pressure to form a rubber crawler.

[0004]

However, in the rubber crawler thus obtained, rubber deterioration such as cracks occurs along the mating surfaces of the upper and lower molds, which causes the rubber crawler. It was also supposed to reduce the durability of LA.

The present invention provides a manufacturing method for preventing deterioration of rubber such as cracking of rubber which occurs on the mating surfaces of the upper and lower molds and a mold used for the manufacturing method.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above objects, and the first of the invention is to provide an upper and lower mold having a cavity for forming the inner and outer shapes of a rubber crawler. In the method of manufacturing a rubber crawler in which an unvulcanized rubber, a steel cord band, and in some cases a cored bar, which constitute a rubber crawler, are placed in a cavity and heated under pressure, the mating surfaces of the upper and lower molds are On the cavity side,
At least one side thereof is chamfered to average elongation strain due to thermal expansion of rubber in the cavity.

The second is an upper and lower mold having a structure in which a cavity forming the inner and outer shapes of the rubber crawler is divided at an edge portion of the rubber crawler, and the cavity side of the upper and lower molds is located on the cavity side. According to a rubber crawler manufacturing mold characterized by chamfering on at least one of the mating surfaces,
The chamfered angle is 30 to 60 degrees, and the chamfered length is 1 to 10 mm.

[0008]

According to the first aspect of the present invention, at the time of vulcanization of unvulcanized rubber in the cavity, the cavity side of the mating surfaces of the upper and lower molds is chamfered, preferably on both sides thereof. -It uses a field.

[0009] aforementioned 4 prior Gomukuro - is a field, the vertical mode - - vertical mode La cavity side 11 mating surface of the shield 11, 12 _0, 12 ₀ sites are substantially right angle formed . However, when the unvulcanized rubber filled in the cavity is heated under pressure, the thermal expansion of the rubber causes a flow with a large force toward this mating surface. part end, i.e. 11 _0, 12 ₀
The elongation strain is concentrated on the rubber due to the heat applied from the part.

The rubber crawler thus obtained is
Rubber deterioration is progressing facing the mating surface of the mold,
For this reason, it is often seen that the rubber is cracked or broken, and this is because the extension strain due to the thermal expansion of the rubber due to the joint portion of the mold, that is, the acute angle portion, is caused during the pressure heat molding. Concentration is believed to be the cause.

The present invention has been devised in order to avoid the concentration of elongation strain of rubber during heating under pressure.
Chamfering is performed on the cavity side of the mating surface of the joints to prevent the concentration of extension strain and prevent deterioration such as rubber cracks. In this chamfering, it is preferable to chamfer both the upper and lower molds. Further, the inclination angle of the chamfered portion with respect to the cavity depends on the type of unvulcanized rubber used, but it is preferable that chamfering is performed with an inclination angle of about 30 to 60 degrees. Is about 1 to 10 mm. Both are done to reduce the effect of heat concentration on rubber.

[0012]

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a cross-sectional view of a rubber cradle manufacturing mold according to a second embodiment of the present invention. That is, it is composed of a lower mold 1 having a cavity a forming the inner surface of the rubber crawler and an upper mold 2 having a cavity b forming the outer surface thereof. In this example, the lower mold 1 is formed. The cavity a
Is approximately half the thickness T of the rubber crawler, and the recesses 3 for accommodating the protrusions of the cored bar, which will be described later, are formed in the longitudinal direction at a constant pitch, while the upper mold 2 is provided with the rubber crawler.
A depth of about half the thickness T of the la and a recess 4 for forming a rubber lug are formed. Then, the upper and lower molds are aligned, and the cavity a on this mating surface is
The corner on the b side is chamfered (P) to a length L of 5 mm with an inclination Θ of about 45 degrees.

As a result, it is possible to avoid the concentrated supply of the elongation strain due to the thermal expansion, particularly to the corner portions of the mating surfaces, with respect to the rubber filled in the cavities a and b. .

Now, referring to the first invention, as shown in FIG. 2, in the cavity a of the lower mold 1 shown in FIG. Two vulcanized rubbers A are placed, and then the protrusions of the cored bar B are aligned and aligned so as to match the recesses 3 of the cavity a, and the steel cord band C is divided into right and left wings of the cored bar B. , And the unvulcanized rubber D forming the outer peripheral side of the rubber crawler is placed thereon, and then the upper mold 2 is closed as shown in FIG. The steel cord band C is formed by arranging a plurality of steel cords and superposing unvulcanized rubber sheets on both sides thereof to form a band.

Then, for example, under a condition of a pressure of 150 kg / cm ² , 170 ° C. and 70 minutes, pressure is applied to heat the rubber rubber.
Got la In the obtained rubber crawler, the upper and lower moulds
The rubber does not deteriorate on the contact surface of the rudder.

[0016]

The present invention has the above-mentioned constitution, and the rubber crawler obtained by the present invention is excellent in durability without rubber deterioration at the mating surfaces of the upper and lower molds. .

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a rubber crawler manufacturing mold of a second invention.

FIG. 2 is a first diagram showing a first method for producing a rubber crawler of the first invention.
It is a state diagram at the time of step.

FIG. 3 is a second drawing of the method for producing the rubber crawler of the first invention.
It is a state diagram at the time of step.

FIG. 4 is a sectional view showing an example of this conventional technique.

[Explanation of symbols]

 1 ... Lower mold, 2 ... Upper mold, 3 ... Recess for accommodating protrusion of core metal, 4 ... Recess for forming rubber lug, a ... Forming inner surface of rubber crawler Cavity, b ... Cavity forming outer surface of rubber crawler, A ... Unvulcanized rubber constituting inner circumference side of rubber crawler, B ... Core bar, C ... Steel cord band, D ... Unvulcanized rubber that forms the outer circumference of the rubber crawler, P ... Chamfer, Θ ... Chamfer inclination angle, L ... Chamfer length.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location B29K 105: 24

Claims (4)

[Claims] 1. An unvulcanized rubber, a steel cord band, which constitutes a rubber crawler in the upper and lower mold cavities having cavities for forming inner and outer shapes of the rubber crawler,
Depending on the case, in a method of manufacturing a rubber crawler in which a core metal or the like is placed and heated under pressure, at least one side of the cavity side of the upper and lower mold mating surfaces is chamfered to heat the rubber in the cavity. A method for producing a rubber crawler characterized by averaging elongation strain due to expansion. 2. An upper and lower mold having a structure in which a cavity forming the inner and outer shapes of the rubber crawler is divided at an edge portion of the rubber crawler, and at least a mating surface on the cavity side of the upper and lower mold. A mold for manufacturing a rubber crawler, which is chamfered on one side. 3. The mold for producing a rubber crawler according to claim 2, wherein the chamfering angle is 30 to 60 degrees. 4. The mold for producing a rubber crawler according to claim 2, wherein the chamfered length is 1 to 10 mm.