Claims:We claim:
1. An improved spring vent of tyre vulcanising moulds (1) comprising of: a vent housing (2) fixed inside an air vent hole present in a tyre mould; a movable vent core (3); and a spring (4); characterised in that,
the movable vent core (3) comprises of:
(i) a first tight winding (3a) near its bottom end;
(ii) a second tight winding (3b) at a distance (x) from the said first tight winding (3a);
(iii) a head (3c), the said head (3c) consisting of a socket (3d), the said socket (3d) designed to be paired with an independent tool, wherein the head of the said tool consists of protrusion, the said protrusion matching the design of socket (3d), whereby when the head of the said tool is fixed to the socket (3d) and the tool is then rotated, the two tight windings (3a, 3b) are engaged for rotation; and
the vent housing (2) comprises of a guide on its inner surface, specially designed to mate with the first tight winding (3a) and the second tight winding (3b) of the movable vent core (3).
2. The improved spring vent of tyre vulcanising moulds (1) as claimed by Claim 1 wherein, the socket (3d) is designed as two arcs on either side of the head (3c) of the movable vent core (3), the said arcs being concentric to the circumference of the head (3c).
3. The improved spring vent of tyre vulcanising moulds (1) as claimed by Claim 1 wherein, the number of pitches of the second tight winding (3b) is greater than the number of pitches of the first tight winding (3a).
4. A method of cleaning the underside of the head (3c) of the movable vent core (3) of the improved spring vent of tyre vulcanising moulds (1) as claimed in Claim 1 when it is blocked, the said method comprising the steps of:
(i) affixing the head of the independent tool on the socket (3d) present on the head (3c) of the movable vent core (3);
(ii) rotating the said tool until the second tight winding (3b) of the movable vent core (3) is engaged, which allows the said core (3) to project out of the vent housing (2); and,
(iii) using standard metal cleaning systems such as dry ice blasting, laser systems, or compressed air to clean the blocked spring vent.
5. A method of removal of the improved spring vent of tyre vulcanising moulds (1) as claimed in Claim 1, if the said spring vent needs repair or replacement, the said method comprising the steps of:
(i) affixing the head of the independent tool on the socket (3d) present on the head (3c) of the movable vent core (3);
(ii) rotating the said tool until it engages the first tight winding (3a) of the movable vent core (3), which allows the said core (3) to be removed out of the vent housing (2) for repair or replacement.

Dated this the 9th day of August, 2021
, Description:AN IMPROVED SPRING VENT OF TYRE VULCANISING MOULDS
FIELD OF INVENTION
The present invention generally belongs to the field of mechanical engineering, specifically to automotive engineering and more specifically relates to the field of spring vents present in tyre vulcanising moulds for expending air between the tyre and the vulcanising mould during vulcanisation of a tyre. More particularly, the present invention relates to an improved spring vent with enhanced maintainability and easier cleaning capability, thereby being cost effective as well as negating tyre defects when compared to existing spring vents.
BACKGROUND OF INVENTION
Spring vents were introduced into the tyre vulcanising moulds for expending air between the tyre and the vulcanising mould during vulcanisation of a tyre. During the vulcanisation process, the green tyre is placed into a curing press and held by means of a curing bladder which is placed inside the green tyre under low pressure. The mould segments close the green tyre from each side and down towards the bottom sidewall of the mould. Pressure is applied into the bladder which pushes the green tyre into the closed mould surface. During this time, air is trapped between the mould and the tyre. This trapped air must be given an escape route or it will distort the tyre and cause an unacceptable appearance on the surface of the tire. Therefore an escape route for the air is required and it started as a drilled hole in the mould initially. Air vents are required to avoid visible blemishes on moulded products but these air vents allow rubber to flow in, and take the shape of every open vent of the mould – which are easily 1000 in a single tyre. The larger hole diameter would let the air escape quickly. However, the finished appearance was still not acceptable as the spew of rubber which pushed the air out of the hole cured in the hole, giving the tyre a hairy appearance and therefore this had to be removed by post cure trimmers which are knives. These knives caused damage to the surface of the tire. Also, trimming the rubber vent is both labour intensive as well as needs machinery and gives an awkward looking tyre in a process that is wasteful in terms of loss of rubber also. This resulted in designing of smaller vent holes. However, the equipment to trim the tyres and dispose the spew pips became a larger problem. There was the additional problem of vent blockage after some use, and cleaning of the vent is an unavoidable requirement to avoid visible imperfections and defects in cured tyre, and thereby retain the attractive appearance of all tyres.
The tyre industry has moved in stages from various types of venting this air from inside the mould to outside the mould, through the solid mould. This does not detail cut vents, and knurling as well as vacuum venting that can also distribute and move the trapped air to reduce its accumulation.
First Generation – a traditionally standard 2 mm or 1.6 mm or 1 mm diameter drill vents that were directly drilled into the mould;
Second Generation – 0.8 to 0.6 mm micro vents that use an additional housing. But this needed trimming too. These dimensions were based on the availability and durability of drill bits for regular cleaning – and shows that cleaning was one of the key issues in maintenance of moulds and for the production of tyres even in earlier days.
Third Generation – Finally, spring loaded vents were found to give a class leading appearance and outstanding aesthetics, due to consistently flat visible surface. Therefore, in tyres where appearance is found to be fundamental requirement for selection for purchase by the customer, spring loaded vents are used.
The spring vent assembly comprising a stem with a head and a spring in a holder, was introduced into the vulcanising moulds, whereby the holder was designed to fit existing vent plug holes, making this process backward compatible and eliminating the cost of new moulds. After the introduction of the spring vents, tyres did not need trimming and the tyre appearance improved as compared to the micro or regular vents. The spring vents were designed such that it closes when the rubber pushes against the valve head during curing, thereby not allowing the rubber to flow into the inside of the spring vent. Presently, each tyre vulcanising mould consists of approximately more than 1000 of the said spring vents.
However, as mentioned earlier, all vents need cleaning maintenance, as they all get blocked after some use and it was observed by persons skilled in the art that spring loaded vents require cleaning maintenance in 3 days to 10 days and that tyres made from moulds with blocked spring vents have tyre defects. So each mould, which has approximately over 1000 spring vents, can get blocked in critical defect prone areas for about 10 to 80 spring vents, despite using brand new core or spring vent with housing, thereby causing visibly cured tyre defects, and this is not acceptable to the customer. These surface imperfections also affect some performance parameters like the seating on the tyre on the vehicle rims – and this is critical for several reasons like tyre centring and matching to the rim, as well as the ability to bear load using the pressurised air inside the tyre. Hence it is of high priority to avoid these appearance defects which have performance implications as well.
Existing designs of spring vent cannot be cleaned consistently or adequately as the tyre mould has to be taken out of the curing press to remove either core or both core and housing, and fix a new core or housing of the spring loaded vent at substantial cost as there are over 1000 vent holes and this has to be carried out for hundreds of moulds. This is because the spring vent core is not removable from the housing unless hammered gently from the back side of the mould, which needs removal of the mould. Currently, ultrasonic baths are being used for cleaning blocked spring vents wherein the whole mould is removed and placed in ultrasonic baths which is at a cost of Rupees 1 to 4 crores per bath. There is also excessive downtime for the mould with blocked spring vents to be removed, put through the cleaning queue and then be refitted in the tyre curing press and resetting all press settings. Another common practice of cleaning adopted currently in the industry is using ultrasonic tools, for example scalers, whereby the mould is first removed from the press and then the spring vents are cleaned using the said tools.
So the cost implications of spares, manpower, its management and upkeep, as well as the opportunity cost of moulds that cannot run, and lose still more in removal, cleaning, quality check and refitting after alignments and multiple systems checks, is rather high and therefore critical to running efficient and also viable operations of any tyre factory. Additional cost of multiple baths and its requirements, and its opportunity cost of poor utilisation of dirty moulds are adding to these overheads.
GENERAL INVENTIONS IN THE FIELD
Japanese Patent Application JP2016095574A discloses a cleaning method and cleaning device of air discharge mechanism (vent holes) provided in a mould for tire vulcanization moulding. According to the invention disclosed by the said patent document, a cylindrical holder is fitted into each of the plurality of vent holes provided on a moulding surface of the mould and has both end portions thereof open, and a cylindrical holder is provided so as to be fitted in the opening on the moulding surface side of the holder. A valve body reciprocates along the axial direction of the said holder. The air discharge mechanism further comprises a lower surface of the valve body and a pair of magnets provided so that the same magnetic poles face each other on the mould outer surface side in the holder wherein magnetic generation means for applying magnetism to the valve body of the air discharge mechanism is disposed in the internal cavity of the cylindrical mould and the magnetic field generated by the magnetic generation means is provided to the valve body of the air discharge mechanism and switching the magnetic poles at a predetermined frequency to continuously open and close the valve body so as to vibrate the valve body removes the rubber clogged in the air discharge mechanism.
US Patent Application 16/066,621 provides an apparatus for cleaning a vent hole provided on a moulding surface of a mould for vulcanizing a rubber product. The said apparatus disclosed by the patent document comprises a detecting means for detecting a shape of the moulding surface, a cleaning means for cleaning the vent hole, a controlling means for storing moulding surface information in advance and including shape information of the moulding surface including a position of the vent hole and for calculating the position of the vent hole by comparing the shape of the moulding surface obtained by the detecting means with the moulding surface information, and a guiding means for moving the cleaning means based on the calculated position of the vent hole.
Chinese Patent Application CN201880083831A provides an automatic plant for cleaning moulds for tyres, wherein the moulds are constituted of sectors and cheeks, and includes an apparatus for internal cleaning of the said sectors and cheeks and another apparatus for external cleaning of the said sectors and cheeks. The apparatus for internal cleaning of sectors and cheeks comprises fixing means for sectors and cheeks in a stable treatment position, a generating device for generating ultrasonic vibrations, transmitting means for transmitting the vibrations from the device to the sector or cheek treated, in such a way as to carry out cleaning of sectors or cheeks by subjecting them to vibrations.
However, the above said inventions are also not cost effective and involve use of complex apparatuses employed to the vulcanising mould which is an additional investment and not desirable. To save costs as well as to attain manufacturing efficiency, the spring vents in tyre vulcanising moulds should be self maintaining and cleanable. Therefore there is a need in the art to provide an improved spring vent with enhanced maintainability and easier cleaning capability, thereby being cost effective as well as negating tyre defects when compared to existing spring vents. To achieve this, the improved spring vent must not only be removable without requiring the tyre mould to be removed, but should also possess enhanced maintainability through self cleaning.
The information disclosed in this background of disclosure section is only for enhancement of understanding of the general background of the invention and should not be taken as acknowledgement or any form of suggestion that this information forms the prior art already known to person skilled in the art.
Further it will be apparent to those skilled in the art that the objects of this invention have been achieved by providing an improved spring vent which is unique in nature unlike existing systems as described in the above prior art. Various changes may be made in and without departing from the concept of the invention. Additional features of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiment as a basis for designing and modifying other methods and structures for carrying out the same purpose of the present invention. Further, features of some stages disclosed in this application may be employed with features of other stages. Therefore, the scope of the invention is to be determined by the terminology of the following claims and the legal equivalents thereof.
OBJECTS OF THE INVENTION
One or more problems of the conventional prior art may be overcome by various embodiments of the present invention.
It is the primary object of the present invention to provide an improved spring vent with enhanced maintainability as well as easier cleaning capability, for use in tyre vulcanising moulds.
Another object of the present invention is to provide an improved spring vent for use in tyre vulcanising moulds such that its cleaning and maintenance are cost effective when compared to existing spring vents.
Yet another object of the present invention is to provide an improved spring vent for use in tyre vulcanising moulds which negates tyre defects when compared to existing spring vents.
These and other objects and advantages of the present subject matter will be apparent to a person skilled in the art after consideration of the following detailed description taken into consideration with accompanying drawings in which the preferred embodiment of the present subject matter are illustrated.
SUMMARY OF THE INVENTION
The present invention embodies an improved spring vent of tyre vulcanising moulds (1) comprising of:
a) a vent housing (2) fixed inside an air vent hole present in a tyre mould;
b) a movable vent core (3);
c) a spring (4);
the movable vent core (3) comprises of:
(i) a first tight winding (3a) near its bottom end;
(ii) a second tight winding (3b) at a distance (x) from the said first tight winding (3a);
(iii) a head (3c), the said head (3c) consisting of a socket (3d), the said socket (3d)
the vent housing (2) comprises of a guide on its inner surface.
The present invention further discloses a method of cleaning the underside of the head (3c) of the movable vent core (3) of the improved spring vent of tyre vulcanising moulds (1) when it is blocked.
The present invention also discloses a method of removing the improved spring vent of tyre vulcanising mould (1) from the tyre vulcanising mould for repair and maintenance without having to remove the entire mould.
BRIEF DESCRIPTION OF THE DRAWINGS
The advantages and features of the present invention will be more readily apparent by persons skilled in the art when considered in reference to the following description and when taken in conjunction with the accompanying drawings listed below.
Figure 1 is the isometric view of the improved spring vent of tyre vulcanising moulds (1) of the present invention.
Figure 2 is the front view of the movable vent core (3) of the improved spring vent of tyre vulcanising moulds (1) of the present invention.
Figure 3A showcases the movable vent core (3) of improved spring vent of tyre vulcanising moulds (1) of the present invention.
Figure 3B is the top view of the movable vent core (3) of the improved spring vent of tyre vulcanising moulds (1) of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The following description is presented to enable any person skilled in the art to make and use the invention, and is provided in the context of particular applications of the invention and their requirements. The present invention can be configured as follows:
Construction
According to a preferred embodiment of the present invention, as shown in Figure 1, the present invention provides an improved spring vent of tyre vulcanising moulds (1) said assembly comprising of the following components: a vent housing (2) fixed inside an air vent hole present in a tyre mould; a movable vent core (3); and a spring (4); comprising of the following further parts,
the movable vent core (3) comprises of:
(i) a first tight winding (3a) near its bottom end;
(ii) a second tight winding (3b) at a distance (x) from the said first tight winding (3a);
(iii) a head (3c), the said head (3c) consisting of a socket (3d), the said socket (3d) designed to be paired with an independent tool wherein the head of the said tool consists of protrusion, the said protrusion matching the design of socket (3d), whereby when the head of the said tool is fixed to the socket (3d) and the tool is then rotated, the two tight windings (3a, 3b) are engaged for rotation; and,
the vent housing (2) comprises of a guide on its inner surface, specially designed to mate with the first tight winding (3a) and the second tight winding (3b) of the movable vent core (3).
Working
The present invention further discloses a method of cleaning the underside of the head (3c) of the movable vent core (3) of the improved spring vent of tyre vulcanising moulds (1) when it is blocked, the said method comprising the steps of:
(i) affixing the head of the independent tool on the socket (3d) present on the head (3c) of the movable vent core (3);
(ii) rotating the said tool until the second tight winding (3b) of the movable vent core (3) is engaged, which allows the said core (3) to project out of the vent housing (2); and,
(iii) using standard metal cleaning systems such as dry ice blasting, laser systems, or compressed air to clean the blocked spring vent.
According to a preferred embodiment of the present invention, when the independent tool is rotated after affixing it to the socket (3d), because of rotational force and the torque acting, the vent core (3) is made to rotate inside the vent housing (2). As the vent housing (2) comprises of a specially designed guide which mates with the vent core (3), when the vent core (3) is rotated, the vent housing (2) allows to make a clearance of more than 0.2 mm from the mould surface. This clearance enables dirt removal from the spring vent without having to remove the entire mould.
The present invention further discloses a method of removal of the improved spring vent of tyre vulcanising moulds (1) provided herein, if the said spring vent needs repair or replacement, the said method comprising the steps of:
(i) affixing the head of the independent tool on the socket (3d) present on the head (3c) of the movable vent core (3);
(ii) rotating the said tool until it engages the first tight winding (3a) of the movable vent core (3), which allows the said core (3) to be removed out of the vent housing (2) for repair or replacement.
The novelty and inventiveness of the improved spring vent of tyre vulcanising moulds (1) of the present invention lies in the specially design movable vent core (3) which comprises of (i) two tight windings (3a, 3b) and (ii) a head (3c) with socket (3d) wherein the design of the socket (3d) is replicated as protrusion on the head of an independent tool, the combination of which allows the movable vent core (3) to be rotated.
According to a preferred embodiment of the present invention, the spacing (x) between the first tight winding (3a) and the second tight winding (3b) of the movable vent core (3) allows the said core to be lifted up in a bolt action, due to action of the spring (4) on the movable vent core (3), when the head (3c) of the said core (3) is turned by fixing the head of the independent tool to the socket (3d) of the head (3c) of the core (3), so that on rotation of the said tool, when the second tight winding (3b) of the core (3) is engaged, the said core (3) provides a clearance of more than 0.2 millimetres from the mould surface, thereby allowing easy usage of standard metal cleaning systems including dry ice blasting, laser systems, and use of compressed air, to clean the blocked spring vent. In addition to the aforementioned, rotating the independent tool until the first tight winding (3a) present near the end of the core (3) is engaged will allow the whole core (3) to be removed for replacement/ repair.
In another preferred embodiment of the present invention, the socket (3d) is designed as two arcs present on either side of the head (3c), each arc concentric to the circumference of the head (3c). In the said embodiment, the protrusions on the head of the independent tool that is to be paired with the said socket (3d) are also designed to match the socket design i.e. two arcs as protrusions, present on either side of the head of the independent tool, the said arcs being concentric to the circumference of the said head.
Therefore without removing the mould from the press, it is possible to change the whole spring loaded vent itself using the improved spring vent provided by the present invention.
It is apparent from the above description that using the improved spring vent of tyre vulcanising moulds of the instant invention, the insides of the spring loaded vents can be cleaned even while it is inside the tyre curing press itself. Additionally, this new design with the presence of two tight windings on the movable core wherein the said tight windings are spaced apart, thereby enabling a bolt action of the core, is designed to enable a twin capability of keeping the spring loaded vent open in automatic as well as in manual methods, and avoids the serious output losses of removing heavy mould halves/ segments from the curing press, and washing it using ultrasonic methods to dislodge the rubber blocking the spring vents, and fixing back the mould with all alignments and setting checked again.
The improved spring vent disclosed by the present patent specification thus possesses enhanced maintainability, is easier to clean, is cost effective as it reduces the costs incurred by using ultrasonic baths for cleaning, saves time and manpower required for cleaning, and reduces possible damage to mould by avoiding the increased handling of mould when removed from the curing press for cleaning. It is also self cleaning as it does not require any other special apparatus unlike the afore cited prior arts.
While there has been shown and described what is considered to be preferred embodiments of the invention, it will, of course, be understood that various modifications and changes in form or detail could readily be made without departing from the spirit of the invention. It is therefore intended that the invention be not limited to the exact forms described and illustrated, but should be constructed to cover all modifications that may fall within the scope of the appended claims.
It will be apparent to those skilled in the art that the objects of this invention have been achieved by providing the above invention. However various changes may be made in the structure of the invention without departing from the concept of the invention. Therefore, the scope of the invention is to be determined by the terminology of the following claims and the legal equivalents thereof.