MXPA96005708A - Vulcanization mold of tires with ventilac capacity - Google Patents

Abstract

The present invention relates to a vulcanization mold for tire manufacture having mold walls with between 600 to 3000 ventilation holes. A valve is inserted in each of the ventilation holes. The valve is designed in such a way that the advancing surface of the unvulcanized part, inserted in the vulcanization mold for its volcanization, closes the valve and the valve opens when the vulcanized rim is removed after vulcanization.

Description

VULCANIZATION MOLD OF TIRES WITH VENTILATION CAPACITY Background of the Invention The present invention relates to a vulcanization mold for the manufacture of pneumatic tires for vehicles, with a plurality of perforations of ventilations in the range of 1000 to 3000 perforations. individual It is known that any tire vulcanization mold must be ventilated so that the tire not cured during blow-off from the inside can come into contact with the molding tools of the vulcanization mold. During this process, the outside of the green tire pushes the air radially outward. When this air can not be ventilated, it is compressed at a pressure just below the applied blowing pressure. Despite the fact that the application of pressure results in an increase in the capacity of air absorption within the rubber, the capacity of air absorption remains extremely low. The remaining air, which is neither ventilated nor dissolved in the rubber materials, forms cushions located between the internal contour of the vulcanization mold and the external contour of the green tire. The lack of contact in these places between the vulcanization mold and the green tire, not only results in the formation of a depression inside the green tire in these places, but also results in a reduction of the heating due to the great reduction of the coefficient of heat transmission of the air in relation to the metal of the vulcanization mold. This can result in a cure to insufficient sulfur from the rim and subsequent fracture of the material during the operation. Therefore, all tire manufacturers pay close attention to the ventilation of vulcanization molds. The drawings of the rims are, in general, highly detailed, comprising longitudinal and transverse notches, as well as a plurality of cuts, which are sometimes even meander cuts, which define different positive portions, such as blocks and reinforcements. of the drawings. As regards the pneumatic behavior, the plurality of projections of the vulcanization mold that defines the negative portions of the rim pattern, in general divide radially inward the volume to be dissipated in the numerous isolated chambers, where each requires the removal or ventilation of the volume of air, so that each one requires at least one ventilation channel. According to the oldest and still prevailing technology, a plurality of fine perforations are used which extend approximately perpendicular to the surface that must be formed to ventilate the vulcanization mold. The perforations are arranged in the molding tools, such that they form ventilation channels of the external components of the vulcanization mold. These perforations have a diameter of approximately 0.7 to 1.5 mm, depending on the required drilling depth and the size of the rim. A typical vulcanization mold for passenger car tires has approximately 1500 ventilation holes; A typical tire vulcanization for heavy duty has more than 2,500 ventilation holes. These perforations present a minimum resistance to the air flow that must be ventilated. However, the flow resistance is also minimal for viscose rubber so that, after the inflation pressure is generated until sufficient cross-curing prevents the rubber material from flowing, an amount of air flows into the ventilation holes. substantial rubber. In general, it is possible, by adjusting the vulcanization rate, to degenerate the course of the temperature with respect to time, the accelerator and sulfur dose, the diameter of the ventilation perforations and the rupture stability of the excess of vulcanized rubber in the shape of spikes in the drawings, to avoid breaking the excess of rubber knots the excess of rubber knots during when removing the rim from the mold. If the excess rubber is broken, the spike projections would be inside their respective ventilation hole and therefore prevent proper ventilation of the vulcanization mold during the vulcanization of another tire that should be vulcanized.

However, especially for tires in the higher price range, many customers do not like the look of spikes on the rim produced. Consequently, in many cases the spikes are eliminated before distributing the tires to the distributors. For this purpose, several techniques are known that are similar to a shaving process, a flattening process or grinding process. It is also known that the spikes are supercooled to produce clean cutting edges in the rim pattern. However, all these techniques require a considerable expense. Therefore, for a long time it was an objective to provide devices and / or methods that produce a spare tire of excess rubber according to the spike without requiring a post-vulcanization treatment period. In the prior art a plurality of suggestions are known to solve this objective. From US Pat. No. 3,377,662, it is known that a pin whose cross-section is essentially star-shaped can be inserted into each of the ventilation holes, where the external envelope of the star is slightly larger than the internal diameter of the star. the ventilation perforation, so that each bolt can be secured in its respective ventilation perforation by means of pressure adjustment. In this way, the ventilation perforation, which initially had a relatively large cross-sectional area, is divided into a plurality of small channels of smaller cross-sectional area. The sum of the cross-sectional areas of the resulting channels is approximately one-tenth of the cross-sectional area of the ventilation perforation thus adjusted, wherein the individual transverse areas of each individual channel is approximately one hundredth of the initial cross-sectional area . This solution is based on the knowledge that a drilling tool can not exceed a certain limit in terms of the proportion of the length of the tool with respect to the diameter to be drilled, because when this limit is exceeded, the drill could break. . Therefore, the diameter of the ventilation perforation can not be as small as desired. But the desired ventilation function of the cross section could be much smaller than what can be produced by a drilling tool. In this way, the excess gum-shaped rubber material could be of much smaller diameter. The basic idea of this patent is that perforations with a relatively large diameter, produced with conventional drilling tools, are subsequently reduced in their cross-sectional area by dividing it into a plurality of narrow channels. European patent 0 518 899 essentially suggests the same solution. European patent application 0 311 550 teaches that an essentially circular bolt should be inserted in a ventilation hole, which has an external diameter slightly smaller than the internal diameter of the ventilation hole on the side of the vulcanization mold which forms the tire. In an area located radially outward, a ventilation channel is provided with projections that secure the respective bolt by means of pressure adjustment. This patent application also deals with a retrofit solution for narrowing the channels of a large cross-sectional area, in this case by inserting a bolt. This application differs from the States patent As previously discussed, in the sense that the remaining flow cross section of the ventilation perforation is not divided into a plurality of small gaps arranged in a circular manner, but a narrow and continuous annular gap is formed. As the external profile according to the star of the inserts, according to the Patent of the United States 3,377,662 can be produced economically by drawing a wire with corresponding molds, the internal form of grooved drilling of cubes of the ventilation channels according to European application 0 311 550, require more expensive cutting operations. European patent application 0 591 745 suggests the use of a porous material in the vulcanization mold that comes into contact with the rim. The pores should have a pore size of less than 0.05. This porosity should be large enough to provide an air removal fast enough, but sufficiently reduced to prevent the penetration of the rubber into the pores, which would cause the pores to clog. However, experiments in this regard showed that after a small number of vulcanization cycles, many pores are clogged. However, it is impossible to clean these clogged pores. From the application of the European patent 0 440 040, it is known that the segments of the mold can be divided into partial segments on the planes connecting the places that ventilation is required. Again, this is based on a principle that the ventilation channels must be narrower so that the resulting flow resistance allows only very superficial penetration of gum into the channels. In contrast to the solutions of the prior art, discussed above, this solution allows the ventilation gaps to be cleaned by dismantling the respective mold segments in their partial segments. However, these molds, due to the large number of contact surfaces that, for the drawing designs of modern rims, can no longer be flat, but must be curved corresponding to the course of the transverse notches of the finished rim, which could be very expensive From the German application 39 14 649 a special arrangement of these ventilation gaps is known, indicated with reference to number 18 of this publication, which are arranged directly on the bottom of the ribs (see column 2, line 43). European patent application 0 451 832 also teaches an arrangement of ventilation gaps with a fine division in the form of a crossword of the segments of the mold. The German patent application (claim 6), the Japanese application 76 91 423, the Japanese application 51 119776, and, the United States patent 4,691 431 as well as the United States patent 4,708,609, are all based on the same concept. It was also repeatedly suggested to generate a vacuum, inside the tire vulcanization mold before shaping the rim pattern. For this purpose, a substantially smaller number of ventilation channels would suffice; for a satisfactory time of evacuation of the mold, even a single ventilation channel could be sufficient. The rims produced in these molds are essentially free of excess rubber projections, and there is no need to clean the mold. However, it has the disadvantage with respect to the size and the numerous dividing planes of the molds of the vulcanization molds of rim because a vacuum below 0.1 bar can be achieved only with high costs. However, with a vacuum of 0.1 bar, there remains a residual amount of air that exceeds the solution's absorption capacity of the rubber for air. Thus, ventilation channels can not be omitted completely. In the United States Patents 4,573,894, 4,597,929, 4881,881, and 5,283,022 similar suggestions are proposed, as well as in German patent 22 10099 and European patent application 0 458 154. European patent application 0 414 630, is also related to a solution of this type, and also teaches to perform the opposite, that is, in order to remove the finished vulcanized tire gas is injected into the vulcanization mold through the ventilation channels. This last process, without the previous application of vacuum, is known from the United States patent. 4,812,281. German applications 22 00 314 and 25 24 538, as well as 31 42 288, disclose devices for manufacturing injection molded parts free of lateral flow. A single ventilation channel is arranged concentric with respect to the rotational axis of the cavity and opens towards an evacuation device which, before initiating the process of injection molding of the polymer mixture, essentially produces a total vacuum in the mold. The residual air pressure can be so small because a single sealing surface with a very short arc length is present. Shortly after the injection molding process is started, that is, before the cavity is completely filled with the polymer mixture, the ventilation channel is closed with a conical valve plate. The closure of the valve is caused directly (German Patent 22 00 314 and German Patent 31 42 288) by impact of the flow of polymeric mixture on the surface of the valve plate to one of the sides of the cavity (German Patent 25 24 538) indirectly by deformation of a plate caused by unilateral actuating transmission pressure, which is then transmitted by a mechanism of movement towards the valve plate. The premature lock of the valve ensures that no amount of polymer mixture can enter the gap between the seating surface and the tapered surface of the valve plate facing away from the cavity. This allows a total prevention of lateral flow, and problems of sticking to the valves from the beginning are avoided. Accordingly, it suffices to provide a weak coiled spring to open the valve when removing the finished vulcanized part, especially rubber seals. However, this ventilating technology has the problem that the residual amount of air in the vulcanization mold can not be vented after the valve lock, and instead it is compressed. This disadvantage can be tolerated in high quality injection molds, because very small amounts of residual air can be achieved by evacuation. In addition, the extruders, depending on the type, for transporting the polymer mixture, can reach a pressure of between 100 and 400 bar, and generally of about 300 bar. According to this, the minimum amount of residual air inside the injection mold can be compressed to an extreme degree, so that at the end of the filling process the residual amount of air is practically 0. Also, the high pressure also increases the amount of air which can dissolve in the rubber material. Since these small amounts of residual air are possible within the tire vulcanization molds due to the large volume (approximately greater by three powers of 10) and the numerous splices of sealing surfaces of very large arc length and since the pressure of injection for the manufacture of rims for passenger cars and motorcycles are approximately only 10 bars, 15 bars for heavy duty truck tires, this process of injection molding above, which is free of lateral flow, is not transferable to the manufacture of tires for pneumatic vehicles.

German Patent 36 22 598 discloses the arrangement of ventilation perforations in a molding tool for multi-component plastics on a manually displaceable push roller. By summarizing the prior art, it is noted that some of the aforementioned suggestions produced small improvements, but to date, a totally satisfactory solution has not been suggested to ventilate the tire vulcanization molds for vehicles that is more clearly evidenced by the fact to date, most of the tires, after being removed from the vulcanization mold, still have the undesirable spike-shaped lateral flow projections. Accordingly, it is an object of the present invention to provide a vulcanization mold that allows the manufacture of tires for pneumatic vehicles, practically free of lateral flow without retracting from cutting processes subsequent to vulcanization. SUMMARY OF THE INVENTION A vulcanization mold for manufacturing tires according to the present invention, which is characterized primarily by: Mold walls with 600 to 3000 ventilation holes; a valve inserted in each of the ventilation holes. The valve designed so that an unvulcanized one-piece advancement surface, inserted into the vulcanization mold to be vulcanized, closes the valve, where the valve is returned to the open position again, when the vulcanization rim is removed after the vulcanization. Preferably, the valve has a movable valve member comprising a valve shaft and a valve plate connected to the valve shaft, where the valve plate has the shape of a truncated cone, with an essentially flat surface facing the valve. inside the vulcanization mold, where the conical surface of the valve plate is oriented in the opposite direction to the inside of vulcanization mold, where the valve has a coinciding counter-surface of the conical surface, where the valve further comprises a spring for moving the valve to the open position where the valve is forced to the closed position when being contracted with a polymer mixture of the unvulcanized mixture during printing of the rim pattern and where the valve is returned to the open position by the spring , when the vulcanized valve is removed from the vulcanization mold. Preferably, the matching countersurface is installed in the mold walls. Preferably, the valve comprises a shell to which the valve member and the spring are securely connected.

The shell is preferably cylindrical. As an advantage, the counter surface is installed in the shell. Preferably, the shell has an external diameter of between 2 and 6 mm, where the external diameter is greater than the internal diameter of the ventilation hole before mounting the shell in the ventilation hole. Preferably, the valve comprises a limit of action, connected to the end of the valve which is facing away from the inside of the vulcanization mold to limit the action of the valve member in a direction towards the open position and to less than 2 mm. . Preferably, the action limiter is detachably mounted to the valve shaft, so that it can be removable to disassemble the valve member. To further advantage, to disassemble the valve member, the action limiter is in the form of a releasable connection for connecting the valve member to interact with the valve, to allow an opening and closing action of the valve member. As an advantage, the valve comprises a shell with an inner chamber, wherein the valve member and the spring are positioned, where the internal chamber of the shell has a first notch at one of the ends of the shell facing away from the inside of the vulcanization mold, wherein the first notch is placed in a plane extending perpendicularly to a longitudinal axis of the valve shell and with a first thickness of wl5 in a direction of the longitudinal axis of the valve shell, where the action limiter comprises a retention spring of a thickness of wl6 placed in the first notch where the action limiter further comprises a second notch with a second width wl7 provided on the valve axis, where the spring is attached to the second notch , and wherein at least one of the first and second thicknesses are greater than the thickness of the retention spring by an amount that the interaction P, defined by the equation P = l7 + l5 - 2 x 216, is at least as large as the action of the valve member. Preferably, the retention spring in plan view has a main C-shaped portion and has free ends connected to the main portion and bent outwardly relative to the main portion. The free ends are joined to the first notch. As an advantage, the retaining spring in another embodiment has a flat aspect in a C-shaped main portion and free ends connected to the main portion and bent inwardly relative to the main portion. The free ends are joined to the second notch. As an advantage, the valve shaft has a first end oriented in the opposite direction to the inside of the vulcanization mold, wherein the first end has a collar, wherein this collar has a splice surface facing the inside of the vulcanization mold to limit the action of the valve member towards the open position, wherein the first end has at least one slot to allow a compression of the diameter of the collar so that when compressing the collar, the valve member can be withdrawn from the valve. The splice surface is preferably truncated cone shaped so that a pushing action towards the inside of the vulcanization mold causes automatic compression of the collar to remove the valve member. As an advantage, a surface of the collar opposite the splicing surface has a truncated cone shape and the vent has a conical inwardly bevelled inlet facing the inside of the vulcanization mold so that when pushing the valve member from the Inside the vulcanization mold towards the ventilation hole, the collar is automatically compressed to insert the valve member towards the ventilation hole. Preferably, the valve comprises a shell with an internal chamber in which the valve member and the spring are positioned, wherein the shell has a conical inwardly bevelled inwardly facing vulcanization mold when assembled, wherein the surface of the collar opposite the splicing surface has a truncated cone shape, so that when pushing the valve towards the tapered inwardly bevelled inlet, the collar is automatically compressed to insert the valve member into the shell. Preferably, the collar in planar view deviates from the circular shape, so that the diameter of the collar that lies at a distance from at least one slot is greater than the diameter of the collar in the vicinity of at least one slot.

According to the present invention, each of the ventilation perforations comprises a valve that is designed so that it is closed by the advancing surface of the unvulcanized part during the injection and when the rim is removed it is opened so that the process of the unvulcanized part that must be subsequently molded and vulcanized, occurs again with open valves. Preferably, each of the valves ingeniously disposed within the ventilation perforations comprises a movable valve member with a valve shaft and a valve plate disposed there, which on the side facing away from the inside of the vulcanization mold It has a truncated cone shape, and on the side facing towards the inside of the vulcanization mold, it has an essentially flat surface. The truncated cone-shaped surface of the valve plate cooperates with a matching surface of the corresponding vulcanization mold segment, respectively, of a valve shell. Each of the valves is moved to the closed position upon impact of the polymer mixture during the printing step of the unvulcanized part, which is preferably an automatic vehicle rim. However, having a spring, each valve is forced to the open position, when removing the finished part (vulcanized). In the prior art injection mold, which is evacuated by a single valve that is essentially two to three times larger than the valves of the present invention, the evacuation valve is prematurely closed, in the solution suggested by the invention, which preferably operates without evacuation, the plurality of small valves close essentially more accurately with respect to the right moment.

Especially, they do not close prematurely, which is very important regarding safety considerations, because they are arranged at the end of a branch of polymer flow and not in the vicinity of its beginning. It is accepted that for a 100% prevention of lateral flow, some of the valves will close too late. The resulting circular side-stream projections have an annular diameter of 2.8 mm, an annular width of approximately 0.3 mm and an annular height of approximately 0.25 mm. Consequently, the lateral flow projections are so small that it makes obsolete a subsequent treatment of removal of lateral flow projections for most segments of the tire market. The savings resulting from manufacturing time, space requirements and rubber waste that is expensive to discard are beneficial. These savings exceed the monetary investments for vulcanization molds with respect to valve costs. Especially, the savings over male hours surprised critics of the invention, who initially feared that the man hours saved in conventional grinding machines would be so many that they would exceed the maintenance requirements for the enormous number of valves within the mold. vulcanization.

However, it was surprising that the first experimental vulcanization mold did not require any maintenance at any of the approximately 1600 valves. The remaining lateral flow projections essentially reduce the size of the remaining lateral flow protections with respect to the predominantly curved lateral flow projections of the prior art, which correspond in their aspect to those disclosed in the European patent application 0 311 550 discussed above. In contrast to many prior art suggestions regarding the right of narrow or rigid ventilation, accumulations of gum or residues of burned (carbonized) rubber are not observed in the device of the invention. The surprisingly clean operation of the cooperation valve and the surface of the valve plates seem to be based on the fact that, the amount of rubber that penetrates the valve gap results in a fast and almost complete sealing in relation to other rubber flows, due to the closing of the valve, so that the amount of rubber introduced per unit of gap is much less than in the previous suggestions to ventilate through stiffened gaps, and, on the other hand, due to the fact that the projections, which due to their smoothness, were seen as prone to rupture, do not break due to the opening of the valve, which is best effected by a spring, after vulcanization, which will not be attached to any portion of the projection. Especially, there are no side effects of gum compression, which result from the injection pressure, which would conventionally cause the clamp effect generally observed. In order to improve the clean operation of the two cooperating surfaces, preferably conical in the valve and the valve plate, it is possible to coat these surfaces with an anti-adhesive material. Polytetrafluoroethylene, or polydimethylsiloxane, which in general is known from German patent 39 03 899 and European patent application 0 228 652, is suggested as an anti-adhesive material. Instead of the forced opening with a spring, this refers to a valve transmission instead of pushing the valve member with the adhesion between the finished rim and the valve plate, and it is also possible to use a pneumatic pulse as equivalent to the spring when injecting air into the ventilation channels. However, this solution seems to be more expensive. Even when the European patent application 0 414 630 and the United States patent 4,812,281 already show air injection for the purpose of removing the rim, there are no valves present in these devices and therefore there is no valve pulse, and neither is it revealed a pneumatic impulse support. For an economical manufacture of the vulcanization molds of the present invention and for the purpose of a simple valve exchange, in the event that a valve can fail, it is suggested that each valve has its own shell, preferably cylindrical, in the that all the mobile components of the valve are connected so as not to become detached. The non-detachable term in this condition means that there are no individual parts during transport of valve manufacture during assembly, the non-detachable term in this connection means that individual pieces can not be lost or dropped during transport of the manufacture of the valve. valve during assembly or removal. This does not mean that the valve can not be disassembled. At least during the experimental stages, it was found to be advantageous that the valve plate can be easily disassembled for regular inspection, for example, with a detachable connection (no valve failures were observed). In the present two modalities of this type are revealed. Preferably, the shell of the valve 12 has an external diameter of between 2.0 and 6.0 mm for passenger vehicle rims, preferably between 2.0 and 4.5 mm, and for heavy truck tires, preferably between 3.0 and 6. 0 mm Since disassembly of valves occurs only infrequently, it is suggested that a snap connection be used in place of a rope connection to secure the valves within the segments of the mold. For this purpose, in the disassembled state of the valve, the outer diameter of the valve shell is greater than the internal diameter of the corresponding vent hole in the segment of the mold wall. For a shell diameter of 3.5 mm, the size relative to the hole should be between 50 to 150 μm. For larger shell diameters, they must be correspondingly larger, and for smaller shell diameters they must be correspondingly smaller. These sizes relate to a coupling of steel material for the valve shell and aluminum for the segments of the mold with the receiving perforations. Those skilled in the art know that for coupling rigid materials, for example steel / steel, a correspondingly smaller size can be selected. Preferably, each valve of the vulcanization mold of the present invention is provided with an action limiter on the side of the valve shaft facing the interior of the vulcanization mold. This action action limiter limits the action of the valve member in the closed position, preferably, for valves in tire molds for passenger vehicles, to an action of between 0.3 and 1.2 mm for tire molds of heavy trucks to an action between 0.5 and 2.0 mm. The action to which the valve opening movement is limited will be called valve action in the following text.

With this limitation of movement it is possible, in cooperation with a tension-free spring section, which is greater than the length of the spring mounted in the open position, that the spring in its forced introduction surface is always under the pressure load. . This simply and effectively prevents spring vibration, which could otherwise occur for a spring-to-play connection. In addition, for a valve stroke that is too long, the valve closure will be delayed and will cause a large excess of rubber projections between the cooperating and preferably conical sealing surfaces. Despite the fact that in all the conducted heat experiments all the valves worked properly, it is still advisable to provide inspection and exchange possibilities for the valve members. Accordingly, the valve members must be removable from the valve shell, respectively, for an arrangement of the valve member without shell directly within the respective segments of the mold of the mold segment even though an action limiter is provided. to limit the action of the valve. However, especially this action limiter prevents dismantling of the valve member in the direction towards the vulcanization mold. And as a solution to this problem, it is suggested to design the action limiter connection (splice) on the valve shaft removably, for example, with a corresponding rope. For this purpose, the end of the valve shaft facing away from the inside of the vulcanization mold can be provided with an external rope. The disc-shaped splice can be provided with a perforation that is received by the external cord and that could be subsequently secured with a nut. In order to reduce the number of parts, it is also possible to provide the perforation of the splice disc with a corresponding internal cord for the external cord of the spindle of the valve stem.

For rapid handling, it is suggested to provide the action limiter in the form of a releasable connection with clearance between the valve stem and the valve shell respectively, and the respective mold segment. In this way, all valve members can be disassembled without the need to loosen hundreds of connections with ropes. The detachable connection of each valve member should be designed so that a vigorous pulling in the direction towards the inside of the vulcanization mold, it results in disassembly, and a vigorous pressure in the opposite direction, results in its mounting. BRIEF DESCRIPTION OF THE DRAWINGS The objects and advantages of the present invention will become clearer from the following specification, in conjunction with the accompanying drawings, wherein: Figure shows, in longitudinal section, the left half of a mold segment in the area with which the tire portion of the rim is molded, inside a valve where a valve is placed in each ventilation hole in the wall of the mold and the green part is not spliced with the mold. Figure Ib shows, in longitudinal section, the same section of the mold segment, but with the piece not vulcanized or spliced, so that all the ventilation valves are in the closed position. Figure 2 shows, in the same transverse plane on a scale of 20: 1 an individual vented valve with a cord connection in the part facing the inside of the vulcanization mold to limit the opening action of the valve; Figure 3 shows the same cross-sectional plane on a scale of 20: 1, an individual vented valve with a limiter of action of the action of the valve with defined play, the action limiter in detachable connection mode comprising a spring of retention as a separate component; Figure 4a shows in the same scale, in plan view, the retaining spring of Figure 3 after being disassembled; Figure 4 shows in an analogous representation, another embodiment of the retaining spring of the Figure 3, and Figure 5 shows an analogous representation of the Figure 3, a single valve with an action limiter of the action of the valve with the defined play in a removable connection mode, where the spring action required for the removable action, is achieved by folding a separate retaining spring, otherwise When bending the inner groove end of the valve stem.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with the aid of several specific embodiments, using Figures from 1 to 5. The Figure shows the longitudinal section, the left half of a mold segment 10 of the vulcanizing mold of the invention 1. The vulcanization mold 1 in this embodiment is, as is conventional but not required for the present invention, divided radially in the cord portion so that the mold segments 10 can move radially. The mold segment 10 shown is part of the area forming the pattern for the rim. Conventionally, the radially divided molds have from 7 to 13 mold segments 10 with the drawing area, where the wheel rim molds of passenger vehicles generally have 7 or 9, for light truck rims they are between 9 and 11, and for heavy truck tires they generally have 11 or 13 mold segments. In contrast to the functional position of the finished rim with horizontal position of the axis of rotation, finished with functional position of the rim terminated in horizontal position of the rotation axis, the vulcanization molds are generally arranged in a horizontal arrangement with position vertical to the axis of rotation. Unvulcanized parts are easier to insert in this way and vulcanized tires can be removed more easily in this way: the side parts of the mold are accordingly called upper mold portion and lower mold portion. The need for ventilation is present for the radially movable mold segments 10 as well as for the lateral parts not shown. The number of ventilation openings required per surface area is however smaller in the side pieces than in the mold segments 10, because the shape that is printed on the rim is not so complicated in the side parts. Preferably, the ventilation in the axially movable side mold pieces 10 is carried out with the same valves 3 which are also placed in the radially movable mold segments 10. Since, with the exception of a less adjusted arrangement of the ventilation openings 2 , there is no difference between the ventilation the radially movable mold segments and the axially movable side parts 10, the number 10 is used for both mold parts.

It is important to note that in each ventilation perforation 2 a valve 3 is arranged. The mold segment 10 in the figure is represented without a vulcanization piece inserted therein. Accordingly, all of the vent valves 3, moved by a weak pressure spring 11, which is shown in greater detail in Figure 2, are open. The valve plates 6, as can be seen in Figure 2, therefore extends, radially inwardly, into the interior of the vulcanization mold. The spring 11, to reach the open position, should be as weak as possible, but as strong as needed, taking into consideration the weight, bending and manufacturing tolerances. In order to arrive reliably to the open position, it is sufficient, according to the experiments carried out, when the pre-effort, to be more precise the pre-compression of the spring, is 1.5 times the sum of the own weight of the valve member and half the weight of the spring.

In the mold, shown in Figure 1, with open ventilation channels 2, because the valves 3 are in the open position, an unvulcanized part 14 should be inserted in a manner known per se. Figure ib shows in a representation analogous to the Figure 1, the moment in which, at the end of the residual high, the unvulcanized piece that must be printed and vulcanized just comes into contact with the bottoms of the notches in the mold 1, which mold the portions that are projected (stops, ribs) of the resulting rim drawing. Most of the ventilation channels 2, are emitted towards the bottoms of the notches inside the mold. The contact with the rubber material, which already has a certain dimensioned stability, thus forces the valves 3 towards the closed position, (as shown) against the weak resistance of the respective pressure spring 11. The term residual lift in the tire technology refers to the remaining portion of the total elevation of the unvulcanized part. The elevation inside the vulcanization mold is achieved by injecting and results in the molding of the pattern pattern or, in the case of very deep drawings and / or reinforcements highly resistant to pulling, the completion of the molding process. Figure 2 shows in the same transverse plane as Figure 1 to the scale of 20: 1, an individual vent valve 3 with a valve member 4. The valve member 4 comprises a valve plate 6 and a valve stem 5 In the passage of the valve plate 6, the spring 11 remains centered. To limit the valve opening action, an action limiter or splice 13 with an internal cord is screwed into the external cord of the respective end of the valve stem 5, placed in the opposite direction to the inside of the vulcanization mold.

The valve plate 6 comprises an essentially flat end face 8 which matches the shape of the interior of the mold. The unvulcanized part is placed in this extreme face 8 during the residual high. The valve plate 6 is otherwise modalized as a truncated cone 7 which coincides with its diameter and with the cone of the angle the conical internal surface 9. The conical angle defined in relation to the dotted line indicating the longitudinal axis of the limb member. Valve should be between 15 and 60 °. Especially suitable is the angle shown, of 22 °. For better logistics with respect to the manufacture of the mold, for example, with regard to assigning the complete manufacture of the valve to a valve producer, it is suggested, as shown here, to provide each valve member 4 in a shell essentially separate cylindrical 12. Together with the pressure spring 11 and the splice 13, a construction unit results, which combines all the individual parts of the valve 3 so that it can not be lost. This valve 3 can be completely assembled by the valve manufacturer and can be inserted by the mold manufacturer into appropriately prepared ventilation holes from the inside of the vulcanization mold. The insertion is preferably performed by hammering the valve in a narrow bore. This results in a snap fit. In order to provide, on the one hand, a sufficiently secure fastening and, on the other hand, a possibility of disassembly that does not destroy the mold segment, it was found to be suitable as a practice to provide an outer shell diameter of 3.5 mm in a diameter of internal drilling of (see Figure la) of the 3.35 mm. In order to facilitate the hammering action, the shell 12 advantageously has a beveled portion at the end which faces away from the inside of the mold. The pressure spring 11 preferably has the shape of a helical spring of approximately 10 free turns and with an additional spliced turn, each placed on each of the ends. By providing greater tension to the turns of the spring, it seems possible to achieve for each opening and closing action, a small rotation of the valve member with respect to the longitudinal axis marked with the dotted line. Therefore, it will be possible to provide a closed action for an extended period of time, especially uniform over the entire circumference of the valve plant. When in a variant to Figure 2 the valve 3 has no shell, the internal conical surface 9 then provided directly at the corresponding place in the wall of the mold segment when drilling or cutting. Figure 3 shows in the same cross-sectional plane of Figure 2 and the same scale 20: 1 an individual ventilation valve 3, with a valve limiter in the form of a releasable connection to limit the valve stroke h by a defined play . The valve limiter comprises as a separate component a retaining spring 16. In the widest open position of the valve shown in the drawing, the valve pin 5 with the truncated conical surface 18.1 of the collar 18 facing the interior of the mold , it comes into contact with the end 16.3 of the inwardly facing free ends 16.1 of the retaining spring 16. This end surface 16.3 is oriented in the opposite direction in the direction of the mold. The collar 18 is connected to the end of the valve stem 5 which is oriented away from the interior of the mold. Figure 4a shows this retaining spring 18 in detail on the same scale in plan view with the main C-shaped portion facing outwards 16 2, which can be compressed to the extent that the spring 16 can be inserted from the oriented side in the opposite direction to the inside of the mold, ie in Figure 3 from below towards the inside of the shell where it is detachably attached in the notch 15 provided on the inner side of the valve shell 12, respectively, for a design without shell , in the ventilation perforation within the mold segment in a plane extending perpendicularly to the longitudinal axis of the valve 3. The retaining spring 16 has inwardly oriented elastically deformable free ends 16.1 which are designed in such a way that after being released are attached to the notch 16 of the valve stem 5 shown in Figure 3. The free ends 16.1 are close enough to each other that they ue, after the surface 16.3 of the spring 16 facing away from the inside of the mold comes into contact with the surface 18.1 of the collar 18 facing the interior of the mold, and a resistance is created against further removal of the valve member 4. Preferably, the free ends 16.1, by on the other hand, they must have sufficient distance between them, so that the valve member 4 can move without jamming on its longitudinal axis marked with the dotted line between the joints 18.1 and 17.1. These free ends 16.1, as can be seen in Figure 3, move away from each other when mounting the valve stem 5 from the direction of the interior of the mold by the conical guide surface 18.2 of the collar 18 whose surface is disposed at the end of the collar 18. oriented in the opposite direction to the interior of the mold. The collar 18 is connected to the end of the valve stem 5, facing away from the interior of the mold. After overlapping the thicker portion of the collar 18, the free ends 16.1 are joined together again as they float on the inversely oriented conical surface 18.1 so that the tang of the valve 5 can be removed only with a great force applied in the direction reverse towards the interior of the mold (especially with a force greater than that of spring 11). In order to secure the spring 16 more reliably against the removal of the notch 15 when mounting the valve member 4, it is possible to press fit or screw a sleeve from the side facing away from the inside of the mold against the spring . The inwardly oriented free ends 16.1 are joined to a notch 17 of the valve stem 5. The notch 17 is delimited to the side facing away from the interior of the mold by the conical surface 18.1 and to the side facing the inside of the mold by a flat preference surface 17.1. The width of the notch wl7 of the notch 17 is greater by a certain amount than the thickness of the spring 17. This amount is slightly greater than the valve action h, so that the position of the valve 3 closing the end side of the notch 17.1 following the closing movement does not advance to the end face 16.4 of the spring 16 facing the interior of the mold. Accordingly, an over-definition of the limitation of the action of the valve is prevented and an easy introduction of the external conical surface 7 of the valve plate 6 towards the inner conical surface 9 is possible. This effects a perfect closing of the valve 3 and eliminates the displacement between the end surface 8 of the valve plate 6 and the surrounding surface of the interior of the mold. This could also theoretically be achieved, with a smaller notch width wl7, when the notch width l5 is correspondingly greater according to the following equation: wl7 + wl5 = wl6 > h. However, when the main portion 16.2 had to be displaceable in relation to the shell 12, which could result in an additional play also the radial direction of the valve and in a tendency to tilt with its corresponding fluctuation coefficients. Thus, it is preferred that wl6 is only slightly less than wl5, so that the required set of approximately 20 μm is provided for the insertion. The aforementioned equation is then simplified as follows: wl7 - l6 > h. Figure 4b shows in a representation analogous to Figure 4a a variant of this type of retaining spring 16 where the main C-shaped portion, identified as 16.5, is provided with free ends that do not extend inwardly but outwardly and which are identified in 16.6. The free ends 16.6 are designed to be attached to the notch 15 in the shell, and the main C-shaped portion 16.5 is designed to be attached to the notch 17 of the valve stem 5. Figure 5 shows in a representation analogous to the Figure 3, a single vent valve 3 with an action limiter in the form of a detachable connection with defined play, wherein the classical compression required for the releasable connection is also achieved by bending, however, not as a bending of a separate retaining spring, but as a bending of the slotted end of the valve pin 5 facing away from the inside of the mold, and represented at the lower end of the drawing. In order to save manufacturing costs, the slot is preferably achieved by a single slot 19, as shown. In this embodiment, the slot 19 must be of a substantial width in order to allow a sufficient compression action of the two remaining tabs that are shown in the longitudinal section plane for insertion and removal of the valve pin 5 through the opening 12.1 of the breastplate 12 oriented in the opposite direction to the interior of the mold and also in the longitudinal section plane of the valve 13 extends perpendicular thereto. (This last transverse plane could be a cross section plane for the entire mold 1). However, a narrower slot mode could be possible if the collar 18 in the vicinity of the slot is flatter, ie, it will project less from the remaining surface from the pin 5, or when instead of the single slot 19 two criss-cross grooves will be provided at the end of the spigot 5 facing away from the interior of the mold. The collar 18 at the end of the valve stem 5 oriented in the opposite direction of the mold and a limiting surface 18.1 oriented towards the interior of the mold. The limiting surface functions as a splicing surface to limit the opening action of the valve and is positioned so that in the desired opening position, for which the valve plate diameter of approximately 2.8 mm and the conical angle to the shaft 22 ° longitudinal would require a valve action of approximately 0.5 mm, as shown, is spliced with the surface of the shell 12 facing away from the inside of the mold or an equivalent surface for a shellless mode. With this splicing surface the opening action is limited. The reverse movement, the closing movement, is not limited in any way by the collar 18. The limitation of the action is achieved exclusively by the external conical surface 7 of the valve plate 6 which comes into contact with the inner conical surface 9. For disassembly of this valve member 4 it is sufficient to pull the valve plate 6 vigorously in the direction of the interior of the mold for the preferred conical embodiment shown on the connecting surface 18.1. Otherwise, it would be required to elastically compress with the other hand, the tabs of the valve stem 6 so that the opening 12.1 of the shell 12 can be passed. For assembling, a conical shape of the other limiting surface 18.2 of the collar 18 is analogously efficient. Then, it is enough to press vigorously. The depth of the groove 19, respectively, of the groove of the end of the pin 5 facing away from the interior of the mold is small enough to provide sufficient resistance against the western removal of the valve member in cooperation with the resulting stiffness of the members. tabs, but it is, on the other hand, large enough to make the tabs sufficiently elastic to be easily disassembled. Detailed embodiments are designed to provide a person skilled in the art with a complete knowledge of the invention. However, the desired protection should not be limited by the details that are provided. The intention of the invention is simply that in each of the hundreds of ventilation perforations of a tire vulcanization mold a valve should be inserted, where each valve is closed by the advancing surface of the unvulcanized part and opened to the Remove the vulcanized tire. The present invention is not, of course, restricted to the specific disclosure or specifications of the drawings, which also encompasses any modification within the scope of the appended claims.

Claims (11)

1. R E I V I N D I C T I O N S 1. A vulcanization mold for making rims, where the vulcanization mold comprises: mold walls with 600 to 3000 ventilation holes; a valve inserted in each of the ventilation holes; the valve is designed such that the advancing surface of an unvulcanized part, inserted in the vulcanizing mold that must be vulcanized, closes each valve, where each valve is returned to the open position when the vulcanized tire is removed after vulcanization. A vulcanization mold according to claim 1, wherein the valve has a movable valve member, comprising a valve stem and a valve plate connected to the valve stem where the valve plate has the shape of a truncated cone with an essentially flat surface facing the inside of the vulcanization mold, wherein the conical surface of the valve plate is oriented in the opposite direction to the inside of vulcanization mold, where the valve has a corresponding counter-surface to the conical surface, wherein the valve further comprises a pressure spring for moving the valve to the open position, wherein each valve is forced into the closed position upon contact with the polymer mixture of the green part and upon printing the drawing pattern and where the valve is returned to the open position by the pressure spring, when the rim ulcanized is removed from the vulcanization mold. 3. A vulcanization mold according to claim 2, wherein the matching countersurface is provided in the walls of the mold. A vulcanization mold according to claim 2, wherein the valve comprises a shell to which the valve member and the pressure spring securely connect. 5. A vulcanization mold according to claim 4, wherein the shell is cylindrical. 6. A vulcanization mold according to claim 4, wherein the counter-surface is provided in the shell. A vulcanization mold according to claim 4, wherein the shell has a diameter of between 2 and 6 mm, wherein the external diameter is greater than the internal diameter of the ventilation perforation before mounting the shell in the shell. ventilation perforation. A vulcanization mold according to claim 1, wherein the valve comprises an action limiter, connected to one end of the valve facing away from the inside of the vulcanization mold, to limit the action of the valve member in one direction to the open position and less than 2 mm. A vulcanization mold according to claim 8, wherein the action limiter is detachably mounted to the valve stem so that it is removable to disassemble the valve member. A vulcanizing mold according to claim 8, wherein for dismounting the valve member the action limiter is in the form of a non-releasable connection for connecting the valve member with play inside the valve to allow an action to open and Close the valve member. A vulcanization mold according to claim 10, wherein the valve comprises a shell with an internal chamber, wherein the valve member and the pressure spring are positioned, wherein the internal chamber of the shell has a first notch at one end of the shell facing away from the inside of the vulcanization mold, wherein the first notch is connected in a plane extending perpendicularly to a longitudinal axis of the shell of the valve and with a first width wl5 at a direction of the longitudinal axis of the valve shell, where the action limiter comprises a pressure spring of a thickness wl6 placed in the first notch, wherein the action limiter also comprises a second notch having a second width wl7 provided in the valve stem, wherein the pressure spring is joined to the second notch, where at least one of the first and second widths second wl5 and wl7 is greater than the thickness wl6 of the pressure spring by an amount of the set P defined by the equation P = wl7 + wl5 - 2 x wl6, is at least as large as the action of the valve member. A vulcanization mold according to claim 11, wherein the flat view pressure spring has a main C-shaped portion and has free ends connected to the main portion and bent outward relative to this main portion, wherein the free ends are joined to the first notch. A vulcanization mold according to claim 11, wherein the flat-view pressure spring has a main C-shaped portion and has free ends connected to the main portion and bent inwardly in the main portion and bent toward in relation to the main portion, where the free ends join the second notch. A vulcanization mold according to claim 10, wherein in the valve stem it has a first end facing away from the inside of the vulcanization mold, where the first end has a collar, wherein the The collar has a splice surface facing the inside of the vulcanization mold to limit the action of the valve member towards the open position, wherein the first end has at least one slot in order to allow a compression of the diameter of the collar of the valve member. so that when compressing the collar the valve member is removable from the valve. A vulcanizing mold according to claim 14, wherein the splicing surface has a truncated cone shape, so that the pulling action towards the inside of the vulcanization mold results in automatic compression of the collar to remove the member valve. A vulcanizing mold according to claim 14, wherein a surface of the collar opposite the splice surface has a truncated conical shape and where the vent has a conical inwardly bevelled inlet facing the interior of the mold of vulcanization, so that by pushing the valve member from the inside of the vulcanization mold towards the ventilation hole, the collar is automatically compressed for insertion of the valve member towards the ventilation hole. A vulcanization mold according to claim 14, wherein the valve comprises a shell with an internal chamber, wherein the valve member and the pressure spring are positioned, where the shell has a tapered inwardly bevelled inlet, oriented towards the inside of the vulcanization mold when mounted, wherein a surface of the collar opposite the splicing surface has a truncated cone shape, so that by pushing the valve member toward the conical inwardly beveled entrance, the collar It is automatically compressed for the insertion of the valve member into the shell. 18. A vulcanization mold according to claim 14, wherein the collar in planar view deviates from the circular shape, such that a diameter of the remote collar of at least one slot is greater than the diameter of the collar in the collar. neighborhood of this one in at least one slot.