JPS6317034A - Manufacture of double timing belt - Google Patents

Abstract

PURPOSE:To reduce man-hours and shorten the forming time by a method wherein a preformed body under semi-cured state is formed and, after that, homogeneous, upper and lower toothed parts are formed by forming and curing each upper and lower pair of toothed part with press tools. CONSTITUTION:A green belt formed body 8 is made by wrapping green rubber-backed flexible canvas 4, low extension high strength tension material rope 5, green rubber sheet 6 and flexible canvas 7 in the order named round the outer peripheral surface of a cylindrical toothed mold. A preformed body 10, which is obtained by semi-curing the green belt formed body 8, is passed between and round two toothed pulleys 11, the shaft of each of which is adjustable. A lower platen 15 and an upper platen 14 are fitted to the toothed part 9 of the preformed body so as to form upper teeth 24 by curing the preformed body under the state being pinched by the upper platen 14 and the lower platen 15, both or which face opposite to each other. A belt formed body with double teeth or upper and lower teeth, which are partially formed, is obtained by removing respective press tools 14 and 15. Next, after the toothed pulleys 11 and rotated in the direction indicated with arrows, by repeating the similar process as mentioned above, the upper teeth 24 are formed without a break in order to make a broad cured endless timing belt. The desired double timing belt 26 is obtained by cutting said broad belt in predetermined widths.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for manufacturing a double timing belt, and more specifically, a method for manufacturing a double timing belt by shortening the molding time and uniformly molding the upper and lower tooth portions. Regarding.

(Prior art) Among the double timing belts that have peaks on both sides, the manufacturing method for polyurethane belts has already been established because they can be molded by casting, and the performance of the belts has also reached the desired level. There is.

However, rubber double timing belts, on the other hand, are made of rubber and are extremely difficult to cast into.Although various manufacturing methods have been proposed, no definitive method has yet been established. Not yet.

For example, as the manufacturing method and apparatus for these (a canvas, a tensile material, a rubber layer, and a canvas are sequentially laminated in an inner mold with a lli, a cylindrical grooved rubber matrix is inserted, and then the rubber layer is vulcanized). A method in which both teeth are formed by press-fitting into the grooves of the inner mold and the mother mold (see Japanese Patent Publication No. 46-22101), (2) a molded unvulcanized rubber sheet preformed in the grooved inner mold; A method of wrapping the tensile material in a helical shape, laminating the same patterned unvulcanized rubber sheets as above, wrapping a grooved matrix, and then vulcanizing it (Japanese Patent Laid-Open No. 49-135056
, (3) A device for laminating and press vulcanizing an unvulcanized band having a covered rubber crest on the back side of a toothed belt in which a tensile member is embedded and 3/4 of the vulcanized belt is vulcanized. (Unexamined Japanese Patent Publication No. 53
-71181 Publication), and (4) a mold in which a plurality of rod-shaped molds are set on the circumferential surface of an inner mold having teeth on the outer circumferential surface, and each rod-shaped mold is moved to the center of the inner mold. A device using
0-139, No. 875), and (5) After grinding the back surface of the vulcanized toothed belt molding, an unvulcanized rubber sheet and a woven fabric are laminated and a toothed mold is used to form the toothed belt. A method of forming the other belt ridge portion on the back side of the formed body (Japanese Patent Application Laid-open No. 118442/1983) has already been proposed.

(Problems to be Solved by the Invention) However, in the manufacturing method of fl) F21, the rubber matrix is easily deformed during belt molding, so it is easy to obtain a tooth profile different from the desired shape. , The lifespan of the matrix is short because it deforms under high temperature and high pressure, and the vulcanized molded product is in close contact with the matrix, so it takes a lot of effort to remove the molded product from the matrix. There is a drawback: in the device (3), 3/4 of the belt body of the internal teeth is vulcanized, so the vulcanized product is not homogeneous, and therefore the adhesive force between the internal teeth and external teeth is low. However, when the resulting belt is run, there is a drawback that peeling occurs between the internal teeth and the external teeth within a short period of time. and,
Furthermore, in the device (4) above, since the number of rod-shaped molds used corresponds to the number of external teeth of the belt, there is a problem that rubber enters between the rod-shaped molds, making it impossible to obtain an outer tooth profile of the desired size. be.

Furthermore, method (5) had the disadvantage of requiring a large number of molding steps.

As described above, in conventional manufacturing methods, the mother mold is easily deformed, the belt outer crest and inner teeth are easily molded to different degrees of vulcanization, and many bar-shaped molds are used, so it is difficult to create a belt with the desired dimensions. There were major problems in that a tooth profile could not be obtained and the adhesive strength between the belt outer crest and the inner teeth was lacking.

The present invention is intended to improve each of these drawbacks in response to the above-mentioned actual situation.In particular, it reduces the number of belt forming steps to enable short-time forming, and also maintains the upper and lower peaks of the belt in the same vulcanized state. The purpose is to provide a homogeneous double timing belt.

(Means for Solving the Problems) That is, the present invention is characterized by wrapping an elastic canvas along the outer peripheral surface of a cylindrical mold in which belt-like projections and grooves are alternately formed in the axial direction of the outer surface, A tensile material is wound in a spiral shape on top of that, an unvulcanized rubber sheet of a predetermined thickness is wrapped on top of that, and an elastic canvas is further wrapped on top of that, and the belt molded product thus obtained is made. A step of heating and pressurizing and extruding and filling the groove with a rubber sheet to obtain a preform having unvulcanized peaks; taking out the preform from the cylindrical mold and adjusting the distance between the centers The process of winding it around two adjustable toothed pulleys, in which concave grooves with ridges are alternately formed at predetermined intervals in the horizontal direction, and a top plate with pin insertion holes at both ends and dowel pins at both ends. A step of fitting the lower plate and the upper plate of each mold of a pair of press molds each consisting of a lower plate into the lower teeth of the preform wound around the toothed pulley, and fitting with the teeth. The upper and lower plates, which face the upper and lower surfaces of the lower and upper plates, respectively, are fitted with dowel pins and pin holes through multiple thickness adjustment plates, and the upper and lower plates are heated from above and below. A step of clamping and pressurizing the preformed body in a press to form and vulcanize the upper tooth portion; After vulcanization, a step of removing each press mold from the vulcanized molded body portion; and a step of removing the vulcanized molded body A process of moving the position of the part and repeating the above steps in order to form the next tooth part, and then repeating this process again to obtain a wide endless strip vulcanized double timing belt, and the obtained vulcanized double timing belt. This process consists of cutting the belt into a predetermined width in the longitudinal direction to form a plurality of double timing belts.

(Example) Hereinafter, specific aspects of the method for manufacturing a double timing belt according to the present invention will be described with reference to the accompanying drawings.

First, the first step in the method of the present invention is to form a cylindrical toothed mold in which band-like protrusions (tooth shapes) (1) groups and grooves (2) groups are alternately formed in the axial direction of the outer surface, as shown in FIG. A stretchable canvas (4) with unvulcanized rubber is wrapped around the outer circumferential surface in an endless manner, and then a low elongation material such as glass fiber, Kevlar (trade name: aromatic polyamide), polyester fiber, or steel wire is placed on top of this. A strong tensile rope (5) is spirally wound under a constant tension, and an unvulcanized rubber sheet (6) of a required constant thickness with a volume to form both teeth is wound on top of it, and further on top of this. A stretchable canvas (7) similar to that described above is wrapped around the belt to form an unvulcanized belt molded body (8).

The thus obtained unvulcanized belt molded body (8) is semi-vulcanized in the next molding process, but semi-vulcanization is usually
A cylindrical rubber sleeve (not shown) is fitted onto the outer circumferential surface of the unvulcanized belt molded body, and this is placed in a vulcanizing can, and 1~'
This is done by introducing l kg/cnl of steam into the can.

At this time, in the above molding process, the unvulcanized belt molded body (
8) is heated and pressurized so that the unvulcanized rubber sheet (6) plastically flows, and the rubber below the gap between the tensile ropes (5) wound in parallel in the circumferential direction on the mold (3) While stretching the elastic canvas (4), insert the concave groove (2) in the mold (3).
When the lower tooth portion (9) is formed and the vulcanizer is not completely vulcanized but approaches a semi-vulcanized state, the internal pressure and temperature of the vulcanizer are lowered and the vulcanizer is placed under conditions that prevent vulcanization from proceeding any further.

Incidentally, semi-vulcanization in the present invention refers to a state in which each physical property value reaches 1 to 5%, assuming that each physical property value such as tensile strength, modulus, and elongation at the time of optimum vulcanization is 100. In this case, as a guideline for optimal vulcanization, the tensile strength is at a point slightly past the maximum, the modulus is at a point slightly before the maximum, and the elongation is at a point slightly before the minimum, and these points are below the vulcanization curve. It will be judged.

Thereafter, the mold (3) is removed from the vulcanizer, and the preform α0) is removed from the mold (3). In this case, since the preform O0 is in a semi-vulcanized state, it is possible to scrape out the peak portion (9) without significantly deforming it.

The preform αω thus obtained is wound around two toothed pulleys (11) (11) whose shafts can be adjusted as shown in Fig. 3, and the process proceeds to the next molding and vulcanization process for the upper toothed part. do.

First, protrusions (12a) (12
Of a pair of press molds consisting of an upper plate (10) and a lower plate (G) as shown in Fig. 4, which can alternately form grooves (13a) and (13b), (+4) is fitted into the teeth (9) of the preform, and is held between an upper plate Q4) and a lower plate (2) facing each other and vulcanized.

As shown in Figures 4 and 5, the mold press has dowel pins (2) at diagonal positions at both ends of the lower plate (2), and pin insertion holes (1) are formed in the upper plate (2) at positions opposite to the pins. By inserting and fitting the knock pin (■) into the pin insertion hole tn, the upper and lower teeth of the belt are prevented from shifting and the upper and lower teeth of the belt are evenly arranged.
To adjust the belt thickness to form a uniform PLD (thickness adjustment 1 (18) (usually 2 to 3 times thick) and multiple thickness fine adjustment plates GE+) (usually 0.5 + n thickness) are inserted and fixed. There is.

After fitting the lower plate (0) and the upper plate ((9) to the teeth (9) of the preform as described above, the opposing upper plates of the above configuration) and the lower plate (0, Thickness adjustment Fj, (1
8) Dowel pin with G■ inserted (insert and fit the fence and pin insertion hole CI into each other, and then install a heating mechanism (not shown) such as steam or electric heater inside, and a cooling mechanism on both sides. Vulcanization is performed by applying pressure in the direction of the arrow using upper and lower heating presses f21) equipped with the following. This vulcanization is usually carried out by sandwiching a cooling plate 02 equipped with a cooling mechanism (2) on both upper and lower sides between the lower plate (ISll) at the upper part of the figure and the upper plate (6) at the lower part of the figure, as shown in Fig. 6. The molding widths are upper plate (15 mm) and lower plate 1 (15 mm), respectively.
) It is done by forming it into a wider width. By narrowing the width, excess rubber flows out to the side of the press die, making the belt thickness uniform. Note that the above-mentioned cooling 1C22& is not necessarily essential and may not be inserted.

Therefore, during vulcanization, the semi-vulcanized rubber layer exhibits a fluid state,
At the same time, while stretching the elastic canvas with unvulcanized rubber (4) (7), the concavity of the upper fiQ4)! (13b) and the concave groove (13b) of the lower plate (2) to form the upper teeth aO.

Here, the upper plate of the mold press (■
and the lower plate (as mentioned above, the dowel pin (■) forms symmetrical upper and lower peaks that are evenly arranged to fit and fix on the pin hole surface, and the thickness adjustment plate GO is inserted into the dowel pin 00) ( 1) to properly adjust the belt thickness and form a uniform PLD in the circumferential direction of the belt.Furthermore, the upper and lower heating presses (cooling mechanisms 2 installed on both sides of 221 and mold presses () 4) (15 ) sandwiched between the cooling plate a
t;n (cooling water is circulated inside as a cooling mechanism) to prevent the semi-vulcanized rubber layer from flowing into the unmolded area.

Thus the upper teeth c! After molding and vulcanization, each press mold (
+4) and ■ are removed from the vulcanized tooth profile forming body, resulting in a belt molded body with partially formed upper and lower double teeth.

Next, the toothed pulley (11) is rotated in the direction of the arrow in FIG. The laminated portion is clamped and pressed using a hot press (2D) to continuously form upper teeth C4 on the back surface of the belt to create a wide endless vulcanized double timing belt.

Then, the vulcanized double timing belt obtained as described above is subsequently cut into a predetermined width in the longitudinal direction, so that a constant amount of rubber is symmetrically applied to the upper and lower surfaces of the tensile member (5) as shown in FIG. It is possible to obtain a double timing belt (2) in which a peak portion (91t211) and a tooth valley portion (4) are formed, and a PLD is uniform in the circumferential direction of the belt and in the upper and lower directions.

In the method of the present invention, the pitches of the upper and lower teeth of the double timing belt may be the same or different.

Further, the shapes of the upper teeth and the lower teeth do not necessarily have to be the same, and in the case of the upper teeth in particular, they may be shaped teeth having not only a power transmission mechanism but also a mechanism for transporting articles.

(Effects of the Invention) As described above, the manufacturing method of the present invention produces a semi-vulcanized preform, and molds and vulcanizes the pair of upper and lower peaks using a press mold to form the upper and lower homogeneous teeth. In addition, since the conventional step of attaching the teeth by vulcanization to the back of the vulcanized preform is eliminated, the number of man-hours is reduced and the molding time can be shortened. I can do it.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an aspect of the forming process of a preform in the double timing belt manufacturing process of the present invention, and FIG.
The figure is a partial side view of the preform obtained in the process shown in Figure 1.
FIG. 3 is a side view showing an embodiment of the molding and vulcanization process for the double timing belt of the present invention, FIG. 4 is a perspective view of a mold press used in the above process, and FIG. 5 is a partially enlarged side view of FIG. 4. ,
FIG. 6 is a partial side view showing an aspect of the molding and vulcanization process of the double timing belt of the present invention, and FIG. 7 is a partial side view of the double timing belt obtained by the manufacturing method of the present invention. (3)... Cylindrical toothed mold (41 (7)... Stretchable canvas (5)... Tensile rope (6)... Unvulcanized rubber sheet fabric... Preformed body倶）・・・Upper board■・・・Lower board
0■...Dowel pin 071...Pin insertion hole θ■...Adjustment plate @...Unvulcanized rubber layer

Claims (1)

[Scope of Claims] 1. A method for manufacturing a double timing belt, characterized in that the following steps (a) to (d) are performed in that order. (a) A stretchable canvas is wrapped around the outer circumferential surface of a cylindrical mold in which band-like protrusions and grooves are alternately formed in the axial direction of the outer surface, a tensile material is wound in a spiral shape on top of the canvas, and a predetermined length is further wrapped on top of the elastic canvas. A preformed body in an unvulcanized state, which is obtained by wrapping a thick unvulcanized rubber sheet and an elastic canvas, heating and pressing the thus obtained belt molded body, and press-fitting the rubber sheet into the grooves. The process of obtaining (b) A step of taking out the preform from the cylindrical mold and wrapping it around two toothed pulleys whose center distance can be adjusted. (c) A step of molding and vulcanizing the upper and lower toothed portions by clamping and pressurizing the preform wound around the toothed pulley using a press mold consisting of a pair of upper and lower toothed molds. (d) Move the position of the vulcanized part that has finished vulcanization and repeat the step (c) above to form the next tooth part,
Thereafter, this process is repeated to obtain an endless vulcanized double timing belt.