JP4110322B2 - Weldless mold, cylindrical rubber elastic body manufactured thereby, and rubber roller manufactured using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to, for example, a weldless mold used for manufacturing a cylindrical rubber elastic body of a rubber roller such as a pinch roller in a VCR (video cassette recorder), and a cylindrical rubber elastic body without a weld line manufactured thereby. In addition, the present invention relates to a rubber roller such as a pinch roller manufactured using the same.
[0002]
The present invention is applied to a rubber roller such as a pinch roller mounted on a VCR (video cassette recorder) such as a video deck, 8 mm, digital video cassette recorder (DVC).
[0003]
[Prior art]
Conventionally, for example, a pinch roller for a VCR is a cylindrical rubber elastic body vulcanized by a molding die having a so-called multi-point gate, that is, a molding die usually having 8 to 12 injection gates for rubber raw materials. A resin-made or metal-made boss is fitted in the center hole, and a shaft is attached in a plug-in shape through a bearing mounted in the boss.
[0004]
[Problems to be solved by the invention]
However, in the above conventional VCR pinch roller, a so-called weld line is formed on the outer peripheral surface of the cylindrical rubber elastic body during vulcanization molding. As a result, the outer peripheral surface becomes uneven, and the VCR When the tape is played back, noise (harmonics) is generated, which causes a problem of deterioration in sound quality (increase in wow / flutter value).
[0005]
The object of the present invention is to solve the above-mentioned problems of the prior art, and is used for producing a cylindrical rubber elastic body in a VCR pinch roller or the like, and does not cause a so-called weld line (fusion line) during vulcanization molding. Weldless mold, and cylindrical rubber elastic body with a uniform outer peripheral surface manufactured thereby, and when the tape is reproduced by VCR and excellent in running stability of the tape, An object of the present invention is to provide a rubber roller such as a pinch roller that can suppress deterioration of sound quality (increase in wow and flutter value) without generating noise (harmonic).
[0006]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 of the present invention is a molding die used for manufacturing a cylindrical rubber elastic body for a rubber roller, comprising: a lower mold having a center pin; An intermediate mold having a circular cavity with a horizontal section that is placed on the center pin and inserted into the center pin; a gate hole that is placed on the middle mold and communicates with the cavity; and an upper portion of the gate hole and a rubber raw material containing recess that opens upward. And a gate mold at the lower end of the gate-type gate hole, the gate mold being placed on the gate mold and having a raw material pushing core portion inserted from above into the rubber raw material containing recess. It has a reverse funnel shape, and the upper end of the center pin is inserted into the gate portion from below, and is inserted between the inner peripheral surface of the gate portion and the outer peripheral surface of the upper end portion of the center pin. It is characterized in that the rubber raw material supply port of the annular leading to the cavity is formed.
[0007]
The invention according to claim 2 of the present invention is the weldless mold according to claim 1, wherein the top surface of the center pin has a gently curved cross section inclined downward from the center toward the outer periphery. The annular rubber raw material supply port between the inner peripheral surface of the gate portion of the gate mold after molding and the outer peripheral surface of the upper end portion of the center pin is 0.1 to 2.0 mm, preferably 0.2 to 0.4 mm. It is characterized by having a width of.
[0008]
Here, the width of the annular rubber raw material supply port between the inner peripheral surface of the gate part of the gate mold and the outer peripheral surface of the upper end of the center pin is in the range of 0.1 to 2.0 mm. This is because the molding of the well-dress molding mold does not hinder the flow of the rubber raw material composition and facilitates the removal treatment of the cured product in the gate after crosslinking.
[0009]
According to a third aspect of the present invention, in the weldless mold according to the first aspect, the center pin is fitted with a metal boss to be attached to the peripheral surface of the center hole of the cylindrical rubber elastic body. The upper end of the center pin holding the metal boss is inserted into the gate part at the lower end of the gate-type gate hole from below, and the metal held by the inner peripheral surface of the gate part and the center pin. An annular rubber material supply port leading to the cavity is formed between the outer peripheral surface of the upper end portion of the boss and the boss.
[0010]
The invention according to claim 4 of the present invention is the weldless mold according to claim 3, wherein the top surface of the center pin has a gently curved cross section inclined downward from the center to the outer periphery, The width of the annular rubber material supply port between the inner peripheral surface of the gate part of the gate mold after mold assembly and the outer peripheral surface of the upper end of the metal boss is 0.1 to 2.0 mm, preferably 0.2 to 0.4 mm. It is characterized by being made to have.
[0011]
The invention according to claim 5 of the present invention is the well-dressing mold according to any one of claims 1 to 4 above, on the outer periphery of the upper and lower ends of the cavity of the middle mold, on the upper and lower sides. Deburred annular recesses with a substantially semicircular cross section are provided, and open downward and upward in the part facing the outer periphery of the upper end of the cavity of the gate mold and the part facing the outer periphery of the lower end of the cavity of the lower mold, respectively. An annular recess for deburring having a substantially semicircular cross-section is provided, and when rubber raw material is pressed into the cavity after assembling the mold, part of the raw material is separated from the upper and lower ends of the cavity from the middle mold, the gate molds, and the middle mold. It passes through the gap between the lower molds and flows into the deburring annular cavities each having a substantially circular cross section, and in the upper and lower cavities with respect to the cylindrical rubber elastic body having no weld line cured in the cavity. It is characterized by being adapted to be brought removed by phased deburring annular rubber molded product Kuikiri.
[0012]
The invention according to claim 6 of the present invention is the weldless mold according to any one of claims 1 to 4, wherein a plurality of cavities are provided in the middle mold at a predetermined interval, and The mold is provided with the same number of center pins that are inserted into the center of these cavities, and the gate mold is provided with a gate hole that leads to each cavity and a rubber material containing recess that opens to the upper end of the gate hole and opens upward. It is characterized by being.
[0013]
The invention according to claim 7 of the present invention is a molding die used for manufacturing a cylindrical rubber elastic body for a rubber roller, and includes a lower mold having a center pin, a lower mold placed on the lower mold, and the center pin inserted. A middle mold having a cavity with a circular cross section, a gate hole placed on the middle mold and leading to the cavity, and a gate mold having a rubber material containing recess that opens to the upper end of the gate hole and opens upward; and on the gate mold And a lower protrusion having a gate hole lower end opening at the center of the cavity corresponding portion of the gate mold. The lower end surface of the gate-type downward projecting portion and the upper end surface of the center pin are opposed to each other in a close proximity, and a gap between the two leads to the cavity. It is characterized by being made the charge supply port.
[0014]
The invention according to claim 8 of the present invention is the weldless mold according to claim 7, wherein the gap between the lower end surface of the downward projecting portion of the gate mold and the upper end surface of the center pin after assembling. The rubber raw material supply port is formed with a width of 0.1 to 2.0 mm, preferably 0.2 to 0.4 mm.
[0015]
Here, the width of the rubber raw material supply port formed by the gap between the lower end surface of the downward projecting portion of the gate mold after the assembling and the upper end surface of the center pin is in the range of 0.1 to 2.0 mm. This is because the molding of the weldless mold does not hinder the flow of the rubber raw material composition and facilitates the removal treatment of the cured product in the gate after crosslinking.
[0016]
The invention according to claim 9 of the present invention is the weldless mold according to claim 7, wherein the burrs having a substantially semicircular cross section opened upward and downward on the outer periphery of both upper and lower ends of the cavity of the middle mold. Deburring with a substantially semicircular cross-section that is provided with an annular recess for removal and opens downward and upward in the portion facing the outer periphery of the upper end of the cavity of the gate mold and the portion facing the outer periphery of the lower end of the cavity of the lower mold, respectively. An annular recess is provided, and when rubber raw material is pressed into the cavity after assembling, part of the raw material passes through the gap between the middle mold and the gate mold and between the middle mold and the lower mold from the upper and lower ends of the cavity. The deburring ring is hardened in the upper and lower voids against the cylindrical rubber elastic body having no weld line and cured in the cavity. It is characterized in that the molded product is adapted to be brought removed by Kuikiri.
[0017]
According to a tenth aspect of the present invention, in the weldless mold according to the seventh aspect, a plurality of cavities are provided in the middle mold at a required interval, and the lower mold is provided at the center of these cavities. The same number of center pins to be inserted are provided, and the gate mold is provided with a lower protrusion that forms a rubber raw material supply port that leads to the cavity facing the upper end surface of the center pin in the cavity, and each of the lower protrusions. A gate hole that penetrates and communicates with the cavity through the rubber material supply port, and a rubber material accommodation recess that is continuous with the upper end of the gate hole and that opens upward are provided.
[0018]
The invention according to claim 11 of the present invention is a molding die used for manufacturing a cylindrical rubber elastic body for a rubber roller, and comprises a lower die and a middle die placed on the lower die and having a horizontal section circular cavity. And an upper die that is placed on the middle die and has a downward pin-like convex portion that is inserted into the center of the cavity, and after the combination of the lower die and the middle die, a rubber raw material is introduced into the cavity, The upper mold is fitted over the middle mold, and the downward pin-like convex part is inserted into the center of the raw material containing cavity, so that the rubber raw material in the cavity can be molded into a cylindrical shape. It is a feature.
[0019]
The invention according to claim 12 of the present invention is the well-dressing mold according to claim 11, wherein the upper surface of the middle mold is provided with a recessed portion that opens upward and has a tapered inner peripheral surface. A convex part having a tapered outer peripheral surface is provided on the lower surface of the mold, and after the mold is assembled, the concave part of the middle mold and the convex part of the upper mold are fitted in a liquid-tight manner. It is a feature.
[0020]
A thirteenth aspect of the present invention is the weldless mold according to the eleventh aspect, wherein the burrs having a substantially semicircular cross section opened upward and downward on the outer circumferences of the upper and lower ends of the cavity of the middle mold. Deburring with a substantially semicircular cross-section, which is provided with an annular recess for removal, and opens downward and upward in a portion facing the outer periphery of the upper end of the cavity of the upper die and a portion facing the outer periphery of the lower end of the cavity of the lower die, respectively. An annular recess is provided, and when rubber raw material is pressed into the cavity after assembling, a part of the raw material passes through the gap between the middle mold and the upper mold and between the middle mold and the lower mold from the upper and lower ends of the cavity. The deburring annular rubber component cured in the upper and lower voids against the cylindrical rubber elastic body having no weld line and cured in the cavity. Object is characterized in that it is adapted to be brought removed by Kuikiri.
[0021]
According to a fourteenth aspect of the present invention, there is provided the weldless mold according to the eleventh aspect, wherein a plurality of cavities are provided in the middle mold at a required interval, and the upper mold is provided at the center of these cavities. The same number of downward pin-shaped convex portions to be inserted is provided.
[0022]
A fifteenth aspect of the present invention is a cylindrical rubber elastic body for a rubber roller having no weld line, which is manufactured using the weldless mold according to any one of the first to fourteenth aspects. .
[0023]
The invention according to claim 16 of the present invention is a cylindrical rubber elasticity having no weld line manufactured using the weldless mold according to any one of claims 1, 2, 5 to 14. A rubber roller is characterized in that a resin or metal boss is fitted in a center hole of the body so as to be fitted, and a shaft is fitted in an insertion manner through a bearing mounted in the boss.
[0024]
According to a seventeenth aspect of the present invention, there is provided a metal boss provided in a central hole of a cylindrical rubber elastic body having no weld line, which is manufactured using the weldless mold according to the third or fourth aspect. A rubber roller is characterized in that a bearing is mounted inside and a shaft is inserted through the bearing.
[0025]
The invention according to claim 18 of the present invention is the rubber roller according to claim 16 or 17, which is used for a pinch roller of a VCR (video cassette recorder).
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
[0027]
1 to 4 show a first embodiment of the present invention. First, in FIG. 1, a weldless mold according to the present invention is used for manufacturing a cylindrical rubber elastic body for a pinch roller in a VCR (video cassette recorder).
[0028]
The weldless mold according to the present invention includes a lower mold (1) having a center pin (5), and a horizontal section circular cavity (6) placed on the lower mold (1) and into which the center pin (5) is inserted. ), And a rubber hole for containing rubber material, which is placed on the middle mold (2) and communicates with the cavity (6), and is connected to the upper end of the gate hole (7) and opens upward. A gate mold (3) having (9), and an upper mold having a raw material pushing core part (10) placed on the gate mold (3) and inserted from above into the rubber raw material containing recess (9) ( 4) with.
[0029]
The gate hole (7) of the gate type (3) has a gate section (7a) at the lower end having a vertical cross-section inverted funnel shape, and when all the types are combined, the gate type (3) The upper end of the center pin (5) of the lower mold (1) is inserted into the insertion part (7a) from the bottom, and the gate part (7a) and the outer peripheral surface of the upper end of the center pin are inserted into the part (7a). An annular rubber raw material supply port (8) leading to the cavity (6) is formed therebetween.
[0030]
In addition, the top surface (5a) of the center pin (5) has a gently curved cross section that slopes downward from the center to the outer periphery, and the gate hole (7) of the gate mold (3) after assembling The annular rubber material supply port (8) between the inner peripheral surface of the lower end gate portion (7a) and the center pin (5) upper peripheral portion is 0.1 to 2.0 mm, preferably 0.2 to 0 mm. It has a width of 4 mm.
[0031]
On the outer periphery of the upper and lower ends of the cavity (6) of the middle mold (2), there are provided deburring annular recesses (11), (14) having a substantially semicircular cross section opened upward and downward, respectively. Deburring with a semi-circular cross section that opens downward and upward in the part facing the outer periphery of the upper end of the cavity of the gate mold (3) and the part facing the outer periphery of the cavity (6) of the lower mold (1), respectively. An annular recess (12) (15) is provided, and when the rubber raw material is pressed into the cavity (6) after assembling the mold, a part of the raw material is transferred from the upper and lower ends of the cavity (6) to the middle mold (2 ) And the gate mold (3), and through the gap between the middle mold (2) and the lower mold (1) so as to flow into the deburring annular space (13) (16) having a substantially circular cross section. Has been made.
[0032]
As shown in FIG. 2, when the cylindrical rubber elastic body (20) having no weld line cured in the cavity (6) is removed, the rubber molded product (21) cured in the gate portion (7). Is removed, and the annular rubber moldings (22) and (22) for deburring cured in the upper and lower spaces (13) and (16) are removed by so-called biting, and the cylindrical rubber of the present invention shown in FIG. An elastic body (20) is manufactured.
[0033]
Further, as shown in FIG. 4, the middle mold (2) is provided with a large number of cavities (6) at required intervals. Although not shown, the lower die (1) is also provided with the same number of center pins (5) to be inserted into the center of the cavities (6), and the gate die (3) is provided in each cavity (6). There are provided a gate hole (7) that communicates with the upper end of the gate hole (7) and a rubber raw material containing recess (9) that opens upward. It is designed to be manufactured with good productivity by individual.
[0034]
In addition, in FIG. 1, the lower die (1) is provided with a plurality of guide pins (17) in a predetermined arrangement, and these guide pins (17) are located at corresponding positions of the middle die (2) when assembling. The guide hole (18) and the bush (19) provided, and the bush (19) embedded in the corresponding part of the gate mold (3) are respectively inserted.
[0035]
FIG. 5 shows a second embodiment of the present invention. Here, the difference from the first embodiment is that the center pin (5) of the lower mold (1) has a metal boss (23) to be attached to the peripheral surface of the center hole of the cylindrical rubber elastic body. The upper end of the center pin (5) holding the metal boss (23) is inserted from below into the gate (7a) at the lower end of the gate hole (7) of the gate type (3). Between the inner peripheral surface of the gate portion (7a) and the outer peripheral surface of the upper end portion of the metal boss (23) held by the center pin (5). 24) is formed.
[0036]
The top surface (5a) of the center pin (5) has a gently curved cross section inclined downward from the center to the outer periphery, and the gate portion (7a) of the gate die (3) after assembling The annular rubber material supply port (24) between the inner peripheral surface and the outer peripheral surface of the upper end of the metal boss (23) has a width of 0.1 to 2.0 mm, preferably 0.2 to 0.4 mm. It has been made. The metal boss (23) is made of a metal such as aluminum or brass. When assembling the mold, it is desirable to apply an adhesive with rubber to the outer peripheral surface of the metal boss (23) in advance.
[0037]
Since the other points of the second embodiment are the same as those of the first embodiment, the same components are denoted by the same reference numerals in the drawings.
[0038]
FIG. 6 shows a third embodiment of the present invention. Here, the difference from the case of the first embodiment lies in the shape of the center pin (5) of the lower die (1) and the shape of the gate die (3). That is, in the second embodiment, the center pin (5) of the lower mold (1) is slightly lower than the height of the cavity (6) of the middle mold (2), while the gate mold ( The lower protrusion (26) having the opening at the lower end of the gate hole is provided at the center of the cavity-corresponding portion of 3), and the lower end surface of the lower protrusion (26) of the gate mold (3) Are opposed to each other in the proximity state. The rubber raw material supply port (28) through which the gap between the lower end surface of the downward projecting portion (26) of the gate die (3) and the upper end surface of the center pin (5) after the die assembly leads to the cavity (6) It has been. The rubber raw material supply port (28) has a vertical width of 0.2 to 0.4 mm.
[0039]
Further, in the third embodiment, the gate hole (27) of the gate type (3) is connected to the rubber raw material containing recess (9) opened upward, and tapers into the tapered upper hole that tapers downward. (27a) and a thin lower hole portion (27b) that continues to the lower end of the gate die (3) and penetrates the central portion of the downward projecting portion (26) of the gate mold (3). Note that the gate hole (27) may be configured only by the tapered upper hole portion (27a), omitting the thin lower hole portion (27b).
[0040]
Since the other points of the third embodiment are the same as those of the first embodiment, the same components are denoted by the same reference numerals in the drawings.
[0041]
FIG. 7 shows a fourth embodiment of the present invention. Here, the difference from the case of the first embodiment is that the weldless mold is composed of a lower mold (1), a middle mold (2), and an upper mold (4), and has a gate mold (3). And a downward pin-like convex portion (45) to be inserted into the central portion of the cavity (6) is provided on the upper die (4) side.
[0042]
A concave portion (30) that opens upward and has a tapered inner peripheral surface (31) is provided on the upper surface of the middle die (2), and a tapered outer peripheral surface (41) is provided on the lower surface of the upper die (4). A core (40) having an inner die (40) is provided so that the recessed portion (30) of the middle die (2) and the core (40) of the upper die (4) can be liquid-tightly fitted after the die is assembled. .
[0043]
In this fourth embodiment, after combining the lower mold (1) and the middle mold (2), a required amount of rubber raw material is introduced into the cavity (6), and then the upper mold (4) is placed on the middle mold (2). ) Is inserted and the downward pin-shaped convex part (45) of the upper mold (4) is inserted into the central part of the raw material accommodating cavity (6) of the middle mold (2), so that the inside of the cavity (6) The rubber raw material is formed into a cylindrical shape, and a cylindrical rubber elastic body (20) for a pinch roller is formed by heat vulcanization.
[0044]
The outer periphery of the upper and lower ends of the cavity (6) of the middle mold (2) is provided with a deburring annular recess (11) (14) having a substantially semicircular cross section opened upward and downward, respectively. Deburring annular recess (42) having a substantially semicircular cross section opened downward and upward, respectively, at the portion facing the outer periphery of the cavity upper end of 4) and the portion facing the outer periphery of the lower end of the cavity of the lower mold (1). 15) is provided, and when the rubber raw material is pressed into the cavity (6) after assembling, a part of the raw material is placed between the middle die (2) and the upper die (4) from the upper and lower ends of the cavity (6). In addition, they pass through a gap between the middle mold (2) and the lower mold (1) and flow into the deburring annular cavities (43) and (16) each having a substantially circular cross section.
[0045]
Then, the cylindrical rubber elastic body (20) having no weld line cured in the cavity (6) is cured in the upper and lower voids (43) (16), and the annular rubber molded product for deburring (22) (22 ) (See FIG. 2) is removed by so-called biting when the cylindrical rubber elastic body (20) is removed.
[0046]
Since other points of the fourth embodiment are the same as those of the first embodiment, the same components are denoted by the same reference numerals in the drawings.
[0047]
In any case, the cylindrical rubber elastic body (20) for a rubber roller manufactured using the weldless mold according to the first to fourth embodiments of the present invention has a weld line (fused) on its outer peripheral surface. There are no streaks.
[0048]
Although not shown in the drawings, the resin is formed in the center hole of the cylindrical rubber elastic body (20) having no weld line manufactured using the weldless molds of the first, third and fourth embodiments. Alternatively, a metal boss is fitted in, and a shaft is fitted in via a resin bearing mounted in the boss to produce a rubber roller used for, for example, a VCR (video cassette recorder) pinch roller. Is.
[0049]
Although not shown, the inside of the metal boss provided in the center hole of the cylindrical rubber elastic body (20) having no weld line manufactured using the weldless mold of the second embodiment. A resin bearing is mounted on the shaft, and a shaft is inserted through the bearing so that a rubber roller used for, for example, a pinch roller of a VCR (video cassette recorder) is manufactured.
[0050]
Thus, according to the manufactured pinch roller according to the present invention, it is possible to suppress deterioration in sound quality (increase in wow and flutter value) without generating noise (harmonic) when the tape is reproduced by the VCR. Is.
[0051]
【Example】
Next, examples of the present invention will be described, but the present invention is not limited to these examples.
[0052]
Example 1
A cylindrical rubber elastic body for a pinch roller in a VCR (video cassette recorder) was manufactured using the weldless mold shown in FIG. 1 to FIG. 4 showing the first embodiment of the present invention.
[0053]
(Preparation of rubber raw material composition)
100 parts by weight of NBR (acrylonitrile butadiene rubber) (trade name / N250S, manufactured by JSR Corporation), 30 parts by weight of carbon black (trade name / Asahi 60 #, manufactured by Asahi Carbon Co., Ltd.), and zinc oxide (positive 3 parts by weight of Zinc Kagaku Co., Ltd., 1 part by weight of sulfur as a vulcanizing agent (trade name, Sulfax PS, manufactured by Tsurumi Chemical Co., Ltd.) and a vulcanizing agent accelerator (Ouchi Shinsei Chemical Industry) A rubber raw material composition for molding was prepared by blending 1 part by weight of a trade name, Noxeller TT, manufactured by Co., Ltd.
[0054]
And the said rubber composition was manufactured the cylindrical rubber elastic body for pinch rollers using the well-dress molding die by this invention shown in FIG.
[0055]
The weldless mold according to the present invention includes a lower mold (1) having a center pin (5) having an outer diameter of 8 mm, a middle mold (2) having a cavity (6) having a height of 18 mm and an outer diameter of 15 mm, and a cavity ( 6) A gate die (3) having a rubber material containing recess (9) connected to the gate hole (7) and the upper end of the gate hole (7), and an upper die (4) having a material pushing core portion (10). And has.
[0056]
Here, in order to give the strength of the mold, the material of the lower mold (1) and the center pin (5) was SK hardened material (SKH). Pre-hardened steel (precipitation hardening) was used for the material of the middle mold (2), and untreated material (iron S50C) was used for the materials of the other gate mold (3) and upper mold (4).
[0057]
The ring rubber raw material supply port (8) between the inner peripheral surface of the gate portion (7) at the lower end and the outer peripheral surface of the center pin (5) upper end portion It had a width of 0.3 mm.
[0058]
After assembling the mold, the rubber raw material composition is placed in the rubber raw material containing recessed part (9) of the gate mold (3), and the raw material pushing core part of the upper mold (4) is placed in the rubber raw material containing recessed part (9). When (10) is press-fitted from above, the rubber raw material composition is formed between the inner peripheral surface of the gate section (7a) and the upper end of the center pin. The annular rubber raw material supply port (8) consisting of a gap between them was quickly flown into the cavity (6) of the middle mold (2) by a so-called single point gate.
[0059]
Next, the rubber raw material composition in the mold is vulcanized and molded at 160 ° C. for 10 minutes to produce a cylindrical rubber elastic body (20) for a pinch roller having an outer diameter of 14 mm and a height of 18 mm. did. Thus, the cylindrical rubber elastic body (20) for a pinch roller manufactured using the weldless molding die of the present invention had no weld line (fusion line) on its outer peripheral surface.
[0060]
Next, an aluminum boss (not shown) is fitted into the center hole of the cylindrical rubber elastic body (20), and a resin bearing is mounted in the boss, and then a stainless steel shaft is inserted through the bearing. A pinch roller was manufactured by attaching the to the insert. Then, this pinch roller was mounted on a VCR (video cassette recorder) deck (Matsushita Electric Co., Ltd., trade name: NVH120), and the wow and flutter values were measured using a standard tape (JVC VHS wow flutter test tape). Here, a wow and flutter meter (Meguro Electric Manufacturing Co., Ltd., trade name: MK-668E) and an FFT analyzer (Ono Sokki Co., Ltd., trade name: CF910) were used.
[0061]
A standard tape was inserted into the VCR deck having a pinch roller without a weld line on the outer peripheral surface manufactured using the weldless molding die of the present invention, and reproduction was performed. I read the value of the flutter meter. Similarly, a standard tape was inserted into the VCR deck and played back, and after about 1 minute, the 9 Hz component value of the FFT analyzer was read and the results obtained are shown in the graph of FIG. It was. Here, the horizontal axis of the graph of FIG. 8 shows the component value (Hz) of the FFT analyzer, and the vertical axis shows the value displayed by converting the magnitude of noise (harmonic) into voltage (V).
[0062]
In the VCR deck, a standard tape is pressed against a rotationally driven capstan (not shown) by a pinch roller, and the tape is transferred. In this case, the rotation speed of the pinch roller is determined according to the VCR reproduction standard. The speed was set to 0.75 revolutions / second.
[0063]
Here, the wow and flutter value is an index indicating the stability of the tape running. This is because the standard tape receives a signal (f) of 3000 Hz, and the ratio of the deviation (Δf) of the signal output by the VCR to the signal (f) as a percentage. Is the wow and flutter value (W / F), and is expressed by the following equation.
[0064]
W / F = Δf / f × 100 (%)
Therefore, if the wow / flutter value (W / F) is large, the stability of the tape running is poor, and noise (harmonics) is generated when the tape is reproduced, so that the sound quality is deteriorated.
[0065]
The wow / flutter value is not caused solely by the pinch roller, but is also influenced by, for example, the rotation of the head. Therefore, it is the FFT analyzer that decomposes the wow and flutter values for each frequency. The 9 Hz component value can be read by the FFT analyzer.
[0066]
As for the 9 Hz component value, as described above, since the rotation speed of the pinch roller is 0.75 rotation / second, for example, a rubber raw material is injected into the cavity by a 12-point gate using a conventional molding die. In this case, from the relational expression of 0.75 × 12 = 9, the 9 Hz component value is attributed to the pinch roller.
[0067]
Comparative Example 1
For comparison, an aluminum boss to be attached to the peripheral surface of the central hole of the cylindrical rubber elastic body is previously attached to a molding die having a multi-point gate (12-point gate) by a conventional method, Using this molding die, a cylindrical rubber elastic body having an aluminum boss in the center hole was manufactured by vulcanization molding. Next, a resin bearing is mounted inside an aluminum boss equipped in the center hole of the cylindrical rubber elastic body, and a stainless steel shaft is inserted through the bearing to insert a pinch for a conventional VCR. A roller was produced.
[0068]
Comparative Example 2
For comparison, an aluminum boss is fitted into the center hole of a cylindrical rubber elastic body vulcanized by a conventional molding die having a multi-point gate (12-point gate) by a conventional method. After mounting a resin bearing inside, a stainless steel shaft was inserted through the bearing to produce a pinch roller for VCR.
[0069]
For the pinch rollers of Comparative Examples 1 and 2, wow and flutter values were measured in the same manner as in Example 1 above. The obtained results are shown in the graph of FIG.
[0070]
As is apparent from the results of FIG. 8, according to the conventional pinch roller of Comparative Example 1, the wow and flutter value (W / F) is as high as 0.10 to 0.14% as shown in FIG. 8a. Further, the running stability of the tape was poor, and the 9 Hz component value of the FFT analyzer was large, and noise (harmonic) was generated, and deterioration of sound quality could not be suppressed.
[0071]
Further, according to the pinch roller according to the conventional method of Comparative Example 2, as shown in FIG. 8B, the wow and flutter value (W / F) is the highest, 0.12 to 0.18%, and the running stability of the tape. In addition, the 9 Hz component value of the FFT analyzer is very large, and noise (harmonics) is considerably generated, so that deterioration of sound quality cannot be suppressed.
[0072]
On the other hand, according to the pinch roller using the cylindrical rubber elastic body (20) manufactured using the weldless mold according to the first embodiment of the present invention, as shown in FIG. (W / F) is as low as 0.08 to 0.12%, the running stability of the tape is very good, the 9Hz component value of the FFT analyzer is almost “0”, and noise (harmonic) It was possible to suppress the deterioration of sound quality with almost no occurrence.
[0073]
Example 2
A cylindrical rubber elastic body for a pinch roller in a VCR (video cassette recorder) was manufactured using the well-dress mold shown in FIG. 5 showing the second embodiment of the present invention. The weldless mold according to the second embodiment of the present invention has an aluminum boss (23) to be attached to the peripheral surface of the center hole of the cylindrical rubber elastic body on the center pin (5) of the lower mold (1). The upper end of the center pin (5) holding the aluminum boss (23) is inserted from the bottom into the gate (7a) at the lower end of the gate hole (7) of the gate type (3). Between the inner peripheral surface of the gate portion (7a) and the outer peripheral surface of the upper end portion of the aluminum boss (23) held by the center pin (5). 24) is formed.
[0074]
The top surface (5a) of the center pin (5) has a gently curved cross section inclined downward from the center to the outer periphery, and the gate portion (7a) of the gate die (3) after assembling The annular rubber material supply port (24) between the inner peripheral surface and the outer peripheral surface of the upper end of the aluminum boss (23) had a width of 0.3 mm. When assembling the mold, an adhesive with rubber is applied to the outer peripheral surface of the aluminum boss (23).
[0075]
After assembling, the same material as in Example 1 is put into the rubber raw material accommodation recess (9) of the gate die (3), and the raw material of the upper die (4) is placed in the rubber raw material accommodation recess (9). When the indented core part (10) is press-fitted from above, the rubber raw material composition becomes the gate hole (7) of the gate mold (3) and the inner peripheral surface of the reverse-foil-shaped gate part (7a) at the bottom and the aluminum boss. The aluminum boss (24) in the cavity (6) of the middle mold (2) is quickly flown through the annular rubber material supply port (24) formed by a gap between the center pin (23) and the upper end of the center pin. 23) was allowed to flow outside.
[0076]
Next, the rubber raw material composition in the mold is vulcanized and molded at 160 ° C. for 10 minutes to produce a cylindrical rubber elastic body (20) for a pinch roller having an outer diameter of 14 mm and a height of 18 mm. did. Thus, the cylindrical rubber elastic body (20) for the pinch roller having the aluminum boss (23) at the center portion manufactured using the weldless mold of the second embodiment of the present invention is formed on the outer peripheral surface thereof. There was no weld line.
[0077]
Next, a resin bearing is mounted inside the aluminum boss (23) provided in the center hole of the cylindrical rubber elastic body (20) without the weld line, and the stainless steel shaft is attached via this bearing. A pinch roller was manufactured by mounting it in an inset. For this pinch roller, the wow and flutter values were measured in the same manner as in Example 1 above.
[0078]
As a result, the pinch roller using the cylindrical rubber elastic body (20) for the pinch roller having the aluminum boss (23) at the center manufactured using the weldless mold according to the second embodiment of the present invention. As in the case of Example 1, the wow and flutter value (W / F) is as low as 0.08 to 0.12%, the running stability of the tape is very good, and the FFT analyzer The 9 Hz component value was almost “0”, and noise (harmonic) was hardly generated, and deterioration of sound quality could be suppressed.
[0079]
【The invention's effect】
As described above, the invention according to claim 1 of the present invention is a molding die used for manufacturing a cylindrical rubber elastic body for a rubber roller, and is placed on a lower die having a center pin and a lower die. And a middle mold having a circular cavity with a horizontal cross section into which the center pin is inserted, a gate hole placed on the middle mold and leading to the cavity, and a gate mold having a rubber raw material containing recess that opens to the upper end of the gate hole and opens upward An upper mold having a raw material pushing core part placed on the gate mold and inserted from above into the rubber raw material containing recess, and the gate part at the lower end of the gate type gate hole has a vertical cross-section inverted filter type The upper end of the center pin is inserted into the gate portion from below, and the cavity is formed between the inner peripheral surface of the gate portion and the outer peripheral surface of the upper end portion of the center pin. It is characterized in that Jill annular rubber material supply port is formed.
[0080]
Further, as described above, the invention according to claim 3 of the present invention is the metal to be attached to the peripheral surface of the center hole of the cylindrical rubber elastic body in the center pin in the weldless mold according to claim 1. The center boss holding the metal boss is inserted into the gate part at the lower end of the gate-type gate hole so that it is inserted from the bottom into the gate part of the gate type gate hole. An annular rubber raw material supply port leading to the cavity is formed between the outer peripheral surface of the upper end portion of the metal boss held by the metal boss.
[0081]
In addition, the invention according to claim 7 of the present invention is a molding die used for manufacturing a cylindrical rubber elastic body for a rubber roller as described above, and is mounted on a lower mold having a center pin and a lower mold. A middle mold having a circular cavity with a horizontal section that is placed and into which a center pin is inserted, a gate hole placed on the middle mold and leading to the cavity, and a gate having a rubber raw material containing recess that opens to the upper end of the gate hole and opens upward A mold and an upper mold that is placed on the gate mold and has a raw material pushing core portion that is inserted from above into the rubber raw material containing recess, and the gate hole has a lower end at the center of the cavity corresponding portion. A downward projecting portion having an opening is provided, and the lower end surface of the gate-type downward projecting portion and the upper end surface of the center pin are opposed to each other so that a gap between them is a key. And it is characterized in that it is made with the rubber raw material supply port leading to the Activity.
[0082]
Furthermore, the invention according to claim 11 of the present invention is a molding die used for manufacturing a cylindrical rubber elastic body for a rubber roller, as described above, and is placed on the lower mold, the lower mold and horizontally. An intermediate mold having a cavity with a circular cross section, and an upper mold having a downward pin-like convex portion that is placed on the middle mold and inserted into the center of the cavity. The rubber raw material is introduced into this, the upper mold is fitted over the middle mold, and the downward pin-shaped convex part is inserted into the central part of the raw material accommodating cavity, so that the rubber raw material in the cavity is formed into a cylindrical shape. It is characterized by being made like this.
[0083]
According to the weldless mold according to the present invention, in any of the above cases, it is possible to manufacture a cylindrical rubber elastic body having no weld line (fusion line) on the outer peripheral surface. When a tape is played back by a VCR equipped with a rubber roller such as a roller, it has excellent running stability of the tape and suppresses deterioration of sound quality (increase in wow and flutter values) without causing noise (harmonics). There is an effect that can be.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a weldless mold showing a first embodiment of the present invention.
FIG. 2 shows a cylindrical rubber elastic body without a weld line and a deburring annular rubber molding in which a rubber raw material is press-fitted into a cavity after assembling the weldless mold according to the first embodiment. It is an enlarged vertical sectional view showing an object.
FIG. 3 is a schematic perspective view of a cylindrical rubber elastic body manufactured by the weldless mold according to the first embodiment.
FIG. 4 is a schematic perspective view of a middle size used in the first embodiment of the present invention.
FIG. 5 is a longitudinal sectional view of a weldless mold showing a second embodiment of the present invention.
FIG. 6 is a longitudinal sectional view of a weldless mold showing a third embodiment of the present invention.
FIG. 7 is a longitudinal sectional view of a weldless mold showing a fourth embodiment of the present invention.
FIG. 8 shows the FFT analyzer at each wow and flutter value when a standard tape is reproduced by a VCR equipped with a pinch roller using a cylindrical rubber elastic body manufactured in Example 1 of the present invention and Comparative Examples 1 and 2. It is a graph which shows the relationship between a component value and the magnitude | size of noise (harmonic).
[Explanation of symbols]
(1): Lower mold
(2): Medium size
(3): Gate type
(4): Upper mold
(5): Center pin
(5a): Top surface with a loose curved cross section
(6): Cavity
(7): Gate Hall
(7a): Gate section with a vertical section inverted filter funnel
(8): An annular rubber material supply port
(9): Rubber material containing recess
(10): Raw material indentation core
(20): Cylindrical rubber elastic body for rubber roller
(23): Aluminum boss (metal boss)
(26): Projecting downward
(27): Gate Hall
(28): Rubber material supply port
(30): Recessed portion having a tapered inner peripheral surface
(40): Convex part having tapered outer peripheral surface
(45): Pin-shaped convex part

Claims (18)

A molding die used for manufacturing a cylindrical rubber elastic body for a rubber roller, comprising a lower mold having a center pin, an intermediate mold placed on the lower mold and having a horizontal section circular cavity into which the center pin is inserted, A gate mold placed on the middle mold and connected to the cavity, and a gate mold having a rubber raw material containing recessed part connected to the upper end of the gate hole and opened upward, and placed on the gate mold and above the rubber raw material containing recessed part And an upper die having a raw material pushing core portion inserted from the gate portion, the gate portion at the lower end of the gate type gate hole has a vertical cross-section inverted funnel shape, and the upper end portion of the center pin is in the gate portion. An annular rubber material supply port that leads to the cavity is formed between the inner peripheral surface of the gate portion and the outer peripheral surface of the upper end portion of the center pin. And wherein, wells dress molding die used for producing the rubber roller for cylindrical rubber elastic body. The top surface of the center pin has a gently curved cross section inclined downward from the center to the outer periphery, and between the inner peripheral surface of the gate portion of the gate mold and the outer peripheral surface of the upper end portion of the center pin after assembling. The weldless mold according to claim 1, wherein the annular rubber material supply port has a width of 0.1 to 2.0 mm. The center pin is fitted with a metal boss to be attached to the peripheral surface of the center hole of the cylindrical rubber elastic body, and the upper end of the center pin holding the metal boss in the gate part at the lower end of the gate type gate hole The annular rubber material supply port leading to the cavity is formed between the inner peripheral surface of the gate portion and the outer peripheral surface of the upper end portion of the metal boss held by the center pin. The weldless mold used for manufacturing the cylindrical rubber elastic body for a rubber roller according to claim 1. The top surface of the center pin has a gently curved cross section inclined downward from the center to the outer periphery, and between the inner peripheral surface of the gate part of the gate mold after assembling and the outer peripheral surface of the upper end part of the metal boss. The welded mold according to claim 3, wherein the annular rubber raw material supply port has a width of 0.1 to 2.0 mm. Deburring annular recesses with a semi-circular cross-section opening upward and downward are provided on the outer periphery of the upper and lower ends of the middle cavity, respectively, and the part facing the outer periphery of the upper edge of the gate mold and the lower edge of the lower cavity A part of the raw material when a rubber raw material is press-fitted into the cavity after assembling is provided with a substantially semicircular deburring annular recess that opens downward and upward at the part facing the outer periphery of the part. Flows from the upper and lower ends of the cavity through the gap between the middle mold and the gate mold and between the middle mold and the lower mold, respectively, into a deburring annular cavity having a substantially circular cross-section, and is welded in the cavity. An annular rubber molded product for deburring that is hardened in the upper and lower voids with respect to a cylindrical rubber elastic body without a line is configured to be removed by biting. Well dress molding die according to any one claim of ~ 4. A plurality of cavities are provided in the middle mold at a required interval, and the same number of center pins inserted into the center of these cavities are provided in the lower mold, and the gate hole leading to each cavity and the upper end of the gate hole are provided in the gate mold. The well-dressing mold according to any one of claims 1 to 4, further comprising a rubber raw material containing recess that is continuous and opens upward. A molding die used for manufacturing a cylindrical rubber elastic body for a rubber roller, comprising a lower mold having a center pin, an intermediate mold placed on the lower mold and having a horizontal section circular cavity into which the center pin is inserted, A gate mold placed on the middle mold and connected to the cavity, and a gate mold having a rubber raw material containing recessed part connected to the upper end of the gate hole and opened upward, and placed on the gate mold and above the rubber raw material containing recessed part And a lower protrusion having a gate hole lower end opening at a central portion of the corresponding part of the cavity of the gate mold, and a lower protrusion of the gate mold. The lower end surface of the center pin and the upper end surface of the center pin are opposed to each other so that the gap between them is a rubber material supply port that leads to the cavity. The symptom, well dress molding die used for producing the rubber roller for cylindrical rubber elastic body. The rubber raw material supply port composed of a gap between the lower end surface of the gate mold downward projecting portion and the upper end surface of the center pin after mold assembly has a width of 0.1 to 2.0 mm. The weldless mold according to claim 7, characterized in that it is characterized in that Deburring annular recesses with a semi-circular cross-section opening upward and downward are provided on the outer periphery of the upper and lower ends of the middle cavity, respectively, and the part facing the outer periphery of the upper edge of the gate mold and the lower edge of the lower cavity A part of the raw material when a rubber raw material is press-fitted into the cavity after assembling is provided with a substantially semicircular deburring annular recess that opens downward and upward at the part facing the outer periphery of the part. Flows from the upper and lower ends of the cavity through the gap between the middle mold and the gate mold and between the middle mold and the lower mold, respectively, into a deburring annular cavity having a substantially circular cross-section, and is welded in the cavity. An annular rubber molded product for deburring that is hardened in the upper and lower voids with respect to a cylindrical rubber elastic body without a line is configured to be removed by biting. Well dress molding die described. Multiple cavities are provided in the middle mold at the required intervals, and the same number of center pins that are inserted into the center of these cavities are provided in the lower mold, and the gate mold is in close proximity to the upper end surface of the center pin in the cavity. A lower protrusion that forms a rubber raw material supply port that communicates with the cavity facing the cavity, a gate hole that passes through each lower protrusion and communicates with the cavity via the rubber raw material supply port, and is open upward. The weldless mold according to claim 7, wherein the rubber raw material containing recess is provided. A molding die used for manufacturing a cylindrical rubber elastic body for a rubber roller, comprising a lower die, a middle die placed on the lower die and having a circular cavity having a horizontal section, and placed on the middle die and in the cavity And an upper die having a downward pin-like convex portion inserted into the center of the rubber, and after the combination of the lower die and the middle die, a rubber raw material is introduced into the cavity, and the upper die is fitted over the middle die A cylindrical rubber elastic body for a rubber roller, characterized in that the rubber raw material in the cavity is formed into a cylindrical shape by inserting a downward pin-shaped convex portion into the central portion in the raw material containing cavity. Weldless mold used for manufacturing of The upper surface of the middle mold is provided with a concave portion that opens upward and has a tapered inner peripheral surface, and the lower surface of the upper mold is provided with a convex portion having a tapered outer peripheral surface. The weldless mold according to claim 11, wherein the concave portion and the convex portion of the upper mold are fitted together in a liquid-tight manner. Deburring annular recesses with a semi-circular cross-section opening upward and downward are provided on the outer periphery of the upper and lower ends of the middle mold cavity, respectively, and the part facing the upper periphery of the upper mold cavity and the lower end of the lower mold cavity A part of the raw material when a rubber raw material is press-fitted into the cavity after assembling is provided with a substantially semicircular deburring annular recess that opens downward and upward at the part facing the outer periphery of the part. Flows from the upper and lower ends of the cavity through the gap between the middle mold and the upper mold and between the middle mold and the lower mold into the annular deburring cavity having a substantially circular cross section, and is welded in the cavity. 12. An annular rubber molded product for deburring that is hardened in the upper and lower spaces with respect to a cylindrical rubber elastic body having no line, is configured to be removed by biting. Well dress molding die. 12. The well according to claim 11, wherein a plurality of cavities are provided in the middle mold at a predetermined interval, and the same number of downward pin-shaped protrusions are provided in the central part of the cavities. Dress molding mold. A cylindrical rubber elastic body for a rubber roller having no weld line, produced using the weldless mold according to any one of claims 1 to 14. A resin or metal boss is formed in the center hole of a cylindrical rubber elastic body without a weld line manufactured using the weldless mold according to any one of claims 1, 2, 5 to 14. A rubber roller, wherein the shaft is attached in a fitting manner and a shaft is attached in an insertion manner via a bearing mounted in a boss. A bearing is mounted inside a metal boss provided in the center hole of a cylindrical rubber elastic body without a weld line manufactured using the weldless molding die according to claim 3 or 4. A rubber roller, characterized in that it is manufactured by inserting a shaft in an insertion shape. The rubber roller according to claim 16 or 17, which is used for a pinch roller of a VCR (video cassette recorder).

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