GB2103991A - Degassing arrangement for vulcanizing machine - Google Patents

Abstract

A degassing arrangement for use in a vulcanizing machine including a bladder (8), an upper ring (3) and a lower ring for supporting the bladder (8) and a centre post (2) extending through the upper and lower rings. The arrangement comprises a degassing passage (01) formed in the upper ring (3) and which opens into the inside of the bladder (8) through, in one embodiment, a valve (11). A conduit (d) connects the degassing passage (01) to a passage (16) formed in a valve seat (15). A valve member (32) is movable axially to contact the valve seat (15) and has a pipe (31) extending from its upper end. The pipe (31) is connected to a suction pump and may be raised or lowered whereby the valve member (32) is brought out of or into contact with the valve seat (15). Gas is discharged through the degassing arrangement by the suction pump when the valve member (32) is brought into contact with the valve seat (15). <IMAGE>

Description

SPECIFICATION Degassing arrangement for vulcanizing machine The present invention generally relates to a process for vulcanization of elastomer products made, for example, of synthetic rubber, elastomeric plastics, etc., and more particularly, to a degassing or breathing arrangement for use in a vulcanizing machine of a pneumatic tire and the like.

Commonly, in the vulcanizing process for elastomer products such as a pneumatic tire for a motor vehicle or the like, there has been employed a vulcanizing machine provided with a degassing or breathing arrangement as shown in Fig. 1 (referred to as degassing arrangement hereinbelow), which has a central mechanism including an expandable bag-iike member or a bladder (referred to as a bladder hereinbelow), an upper ring and a lower ring for supporting said bladder, and a center post associated therewith.

More specifically, the conventional tire vulcanizing machine as shown in Fig. 1 includes, for example, a lower ring RI and an upper ring Ru mounted on a center post S extending through said lower ring RI for supporting a bladder C, and is so arranged that, through a feed pipe P1 and a discharge pipe P2 formed in a piston gland G, fluids or vulcanizing mediums such as hot water, steam, gas, cooling water, etc., are successively fed into or discharged from the interior of the tire T accommodated in a metal mold M via the bladder C for vulcanization and shaping of the tire T to be treated.

The known arrangement as described above, however, has such problems that, since the feed pipe P1 and the discharge pipe P2 are provided in the piston gland G, which is a core portion of the central mechanism, feeding of the medium such as hot water is undesirably delayed due to gas (for example, air, nitrogen gas, steam gas, etc.) remaining at an upper portion within the tire T during filling of hot water or cooling water thereinto, or irregular vulcanization tends to take place owing to insufficient cooling at portions of the tire T where the remaining gas is present.

Accordingly, it would be desirable to provide an improved degassing arrangement for use in a tire vulcanizing machine in which a degassing passage or gas vent is provided in the upper ring for quick and sufficient degassing so as to preliminarily prevent insufficient vulcanization through uniform heating and cooling, while, as compared, for example, with a degassing arrangement of a float system to be set in the bladder as previously proposed by the present inventors, most of parts involved may be installed outside the bladder for facilitation of assembly work.

It would also be desirable to provide a degassing arrangement of the above described type which is simple in construction and stable in functioning at high reliability, and can readily be incorporated into vulcanizing machines of this kind at low cost.

According to the present invention there is provided a degassing arrangement for use in an elastomer product vulcanizing machine including a bladder, the degassing arrangement comprising at least one degassing passage opening into the bladder, a valve seat member having a passage defined therein in fluid communication with the or each degassing passage, a pipe member adapted to be selectively raised or lowered and having a suction mechanism coupled to one end thereof, and a valve member mounted at the other end of the pipe member, the valve member having a passage defined therein in fluid communication with the pipe member and being arranged to contact the valve seat when the pipe member is lowered, whereby when the valve member is brought into contact with the valve seat a passageway is formed between the degassing passage and the pipe member so that gas within the bladder is discharged through degassing passage, by the action of said suction mechanism.

According to one preferred embodiment of the present invention, there is provided a degassing arrangement for use in an elastomer product vulcanizing machine including a bladder, an upper ring and a lower ring for supporting the bladder, and a center post associated with the upper and lower rings, in which the degassing arrangement comprises at least one degassing passage formed in the upper ring, a valve seat mounted on an upper end of the center post, with a passage of the valve seat and the degassing passage being connected for communication by a conduit tube, a pipe provided on a stop ring for guiding an upper mold of the vulcanizing machine so as to be selectively raised or lowered, a suction mechanism coupled to one end of the pipe member, and a valve mounted at the other end of the pipe member and capable of contacting the valve seat by urging force, whereby, during descent of the upper mold, the valve is brought into contact with the valve seat so as to discharge gas within the bladder through the degassing passage, by the action of the suction mechanism.

At least in preferred embodiments the present invention provides for substantial elimination of disadvantages inherent in the conventional arrangements.

The present invention is further described by way of example only with reference to the accompanying drawings, in which; Fig. 1 is a side sectional view of a degassing arrangement in a conventional tire vulcanizing machine (already referred to), Fig. 2 is a fragmentary side sectional view of an improved degassing arrangement in a tire vulcanizing machine according to one preferred embodiment of the present invention.

Fig. 3 is a side sectional view showing, on an enlarged scale, the construction of a special valve employed in the degassing arrangement of Fig. 2, and Fig. 4 is a schematic diagram explanatory of a suction mechanism employed in the arrangement of Fig. 2.

Before the description of the present invention proceeds, it is to be noted that like parts are designated by like reference numerals throughout several views of the accompanying drawings.

Referring now to the drawings, there is shown, in Fig. 2, an improved degassing arrangement for a vulcanizing machine of pneumatic tires, etc.

according to one preferred embodiment of the present invention which generally includes an upper ring 3 mounted by a clip member 9 on a center post 2, with a bladder 8 being pressed, at its peripheral edge, against the upper ring 3 by a bladder holder 10, a nipple 12 threaded into a bore 01 formed in the upper ring 3 so as to extend through the bladder holder 10 and said upper ring 3, and a special valve 11 (Fig. 3) threaded into the peripheral under surface of the upper ring 3 in a position corresponding to the lower end of the bore 01, with an inlet port 19 (Fig. 3) of said special valve 11 being directed in a direction towards the outer periphery of said upper ring 3, and thus, a degassing passage 13 is formed, through the bore 01, by the nipple 12 and the special valve 11.It is to be noted here that the special valve 11 may be dispensed with, depending on necessity as described later.

The degassing arrangement of Fig. 2 further includes a valve seat 1 5 of stainless steel, brass and the like having a packing 14 of fluororubber, Teflon (name used in trade and manufactured by Du Pont group) rubber, etc. at its bottom portion with a central opening, and threaded into a bore 02 formed at an upper end of the center post 2, a nipple 1 7 also threaded laterally into the upper end of said center post 2 for communication with said bore 02 and a passage 1 6 of the valve seat 15, and a conduit tube d connected between the nipple 1 7 at the side of the center post 2 and the nipple 1 2 for the upper ring 3.

As shown in Fig. 3, the special valve 11 has an inverted U-shaped passage 1 8 formed therein, and the inlet port 19 for a lower passage 1 8a thereof is arranged to be engageable with a degassing or vent hose 20 of flexible material, while a valve disc 21 is fitted into an upper passage 1 8b of the passage 1 8 through a degassing gap therearound, with a communicating hole 22 being formed in the bottom portion of the upper passage 1 8b for communication with the lower passage 18a.A compression spring 26 is accommodated in the upper passage 1 8b in a space between a sleeve screw 25 threaded into an outlet port of the upper passage 1 8b and the upper portion of the valve disc 21 for normally urging said valve disc 21 downwards to a closed position.

It should be noted here that the force required for opening and closing of the valve disc 21 is suitably set by adjusting the biasing force of the compression spring 26 through alterations of the threaded positions of the sleeve screw 25.

Since a spring force fs of the above compression spring 26 acts to close the communicating hole 22 with the valve disc 21, by overcoming a pressure Pl within the bladder 8, and also, to open said communicating hole 22, by yielding to a suction force PV arising from an ejector 38 to be described later (Fig. 4), it is preferable to set the relation between an inner diameter B of the upper passage 1 8b and an inner diameter A of the communication hole 22 as large as possible.

More specifically, the above relation may be represented by rrA2 fs > Pl 4 ,rB2 7rA2 fs+ PV < Pl 4 4 Accordingly, the larger the ratio B A A the smaller becomes the vacuum degree, and thus, the pressures Pl and PV are rendered to be unbalanced at a minimum vacuum degree as necessary, so as to raise the valve disc 21 for attraction of the medium.

Referring back to Figs. 2 to 4, in a known top ring 29 (Fig. 4) which guides an upper mold 27 through a platen (not shown) or the like, and is driven for vertical movement by a hydraulic cylinder (not shown), etc., a pipe 31 restricted, at its lower portion, by a vibration preventing guide 30 is movably supported for being raised or lowered as desired. To the lower end of said pipe 31, a valve member 32 which is arranged to contact the valve seat 1 5 of the center post 2 is secured, while loose bolts 34 fixed to a flange portion 36 of said guide 30 extend through a corresponding flange portion 33 of the valve member 32 for guiding said valve member 32 in the vertical direction, with a compression spring 35 being confined in the space between the flange portion 33 of the valve member 32 and the guide 30.

The compression spring 35 normally urges the valve member 32 downwardly together with the pipe 31 for retaining the valve member 32 in position by the loose bolts 34 at the lowered position, while, upon lowering of the top ring 29, the valve member 32 contacting the packing 14 of the valve seat 1 5 is pressed against said packing 14 as said valve member 32 is raised against the biasing force of the spring 35.

As shown in Fig. 4, the upper end of the pipe 31 as described above is connected through an opening 41 formed in the top ring 29, to a suction mechanism 42, which is further coupled to the water ejector 38 for supplying pressurized water (3 to 21 kg/cm2) through a change-over valve 39, while the ejector 38 is connected to the source of the pressurized water through a change-over valve 37.

It is to be noted here that a vacuum pump (not shown) may further be provided in addition to the water ejector, and that when the special valve 11 described earlier is adopted, it is necessary to employ such water ejector or vacuum pump line in the pipe line system.

If the degassing arrangement for the tire vulcanizing machine is constructed as described in the foregoing embodiment, it becomes possible to install the special valve 11 and the degassing hose 20 depending on necessity, during mounting of the bladder 8, and also, to mount the nipples 12 and 17, conduit tube d, valve seat 15, valve member 32, pipe 31, etc. outside the bladder 8 during mounting of the bladder assembly on the center post 2, and thus, work required for installation and assembling of these parts is markedly facilitated.

By the above arrangement, when the top ring 29 is lowered by the hydraulic cylinder (not shown), the pipe 31 and valve member 32 are also lowered together with the upper mold 27 which is brought into engagement with a lower mold (not shown), and the valve member 32 contacts the packing 14 of the valve seat 1 5, while rising upwards against the urging force of the compression spring 35 (in other words, it is so arranged that the tightening force by the vulcanizing machine is not transmitted to the side of the center post 2), and thus, air-tight joint is established thereat by the pressure contact of the valve member 32 with the packing 14 of the valve seat 1 5. In other words, when the upper and lower molds of the vulcanizing machine are open, the valve seat 1 5 and the valve member 32 do not establish the joint therebetween, while, upon closing of said upper and lower molds of the vulcanizing machine, the joint between said valve member 32 and the valve seat 1 5 is established.

It is to be noted here that the valve seat 1 5 and valve member 32 should be so constructed as to withstand high temperatures and high pressure.

Subsequently, during the degassing process in the bladder 8 (i.e. during change-over period from the gas filling process to the cooling water filling process), upon feeding of pressurized water into the ejector 38 with the change-over valves 37 and 39 opened, gas is rapidly and sufficiently extracted through the passage in the order of the degassing hose 20, special valve 11, nipple 12, conduit tube d, nipple 17, valve seat 15, valve member 32, pipe 31 and change-over valve 39, and thus, insufficient vulcanization is preliminarily prevented through uniform heating and cooling of the tire to be processed.

Since the special valve 11 functions to confine the vulcanizing medium such as steam, gas or the like within the bladder 8, there is no possibility that steam or gas leads through pipings outside the bladder 8.

It should be noted here that, if the changing over of the change-over valve 39 is properly effected, the special valve 11 needs not be ~particularly provided. In other words, when the special valve 11 is not employed, steam or gas is to be shut off by the change-over valve 39.

As is clear from the foregoing description, in the arrangement according to the present invention, since the degassing passage of the upper ring and the passage of the valve seat for the center post are connected to each other by the conduit tube, while the valve member capable of contacting the valve seat by the urging force of the spring is provided for the pipe to be guided by the top ring, not only the gas in the bladder can be quickly and sufficiently discharged through the degassing passage by the suction mechanism for the piping, but also the installation for the bladder for degassing may be effected mainly at the exterior of the bladder, and thus, work required for the assembly is appreciably facilitated.

Furthermore, if the special valve is employed for the degassing passage, possibility of leakage may be eliminated, since steam or gas is not passed through the pipings outside the bladder at all times, and thus, conditions required for installation of various parts may be alleviated to that extent.

Although the present invention has been fully described by way of example with reference to the accompanying drawings, it is to be noted here that various changes and modifications will be apparent to those skilled in the art. Therefore, unless otherwise such changes and modifications depart from the scope of the present invention, they should be constructed as included therein.

Claims (5)

Claims

1. A degassing arrangement for use in an elastomer product vulcanizing machine including a bladder, the degassing arrangement comprising at least one degassing passage opening into the bladder, a valve seat member having a passage defined therein in fluid communication with the or each degassing passage, a pipe member adapted to be selectively raised or lowered and having a suction mechanism coupled to one end thereof, and a valve member mounted at the other end of the pipe member, the valve member having a passage defined therein in fluid communication with the pipe member and being arranged to contact the valve seat when the pipe member is lowered, whereby when the valve member is brought into contact with the valve seat a passageway s formed between the degassing passage and the pipe member so that gas within the bladder is discharged through degassing passage, by the action of said suction mechanism.

2. A degassing arrangement as claimed in Claim 1 wherein the vulcanising machine includes an upper ring and a lower ring for supporting the bladder and a centre post extending through the rings, the degassing passage(s) being formed in the upper ring, the valve seat member being mounted on the upper end of the center post, and the passage defined in the seat member being connected by a tube to the or each degassing passage.

3. A degassing arrangement as claimed in Claim 1 or Claim 2 wherein the degassing passage is provided with a valve means which is adapted normally to be closed against pressure within the bladder and to be opened by a suction force applied by the suction mechanism.

4. A degasslng arrangement as claimed in any one of the preceding claims wherein the degassing passage or the valve means is provided with a flexible hose member at its entrance to the bladder.

5. A degassing arrangement substantially as hereinbefore described with reference to Figures 2, 3 and 4 of the accompanying drawings.