WO2000016969A1

WO2000016969A1 - Tire retreading apparatus

Info

Publication number: WO2000016969A1
Application number: PCT/KR1999/000519
Authority: WO
Inventors: Young-Shik Chung; Johng-Ryool Ahn
Original assignee: Chung, Sung-Soo
Priority date: 1998-09-23
Filing date: 1999-09-03
Publication date: 2000-03-30
Also published as: KR19990046189A; DE19945463B4; KR100263815B1; DE19945463A1; AU5533399A

Abstract

A tire retreading apparatus including a loading unit (10) for feeding a buffed tire (100) to a tire loading region defined in the tire retreading apparatus, and loading the buffed tire (100) in a lower mold portion of a mold (80) waiting at the tire loading region (P1), the mold (80) being one of molds (80) mounted on a carriage, a mold opening/closing unit (20) for coupling an upper mold portion of the mold to the lower mold portion loaded with the buffered tire (100) or separating the upper mold portion coupled to the lower mold, a rubber injection forming unit (30) for injection-forming uncured rubber onto a tread of the buffed tire (100) loaded in the mold (80) by use of a rubber pump or a rubber injection machine, a heating plate mounting unit for mounting an electrical heating plate to the mold, in which rubber is injection-formed, curing the molder rubber and separating the electrical heating plate from the mold, a curing unit (50) provided with the carriage, the curing unit (50) circulating along the guide rail (120) while curing the molded rubber for a desired period of time, thereby completely curing the molded tread of the tire, and a discharge unit (60) for unloading the completely cured tire from the mold, and outwardly discharging the tire from the tire retreading apparatus, whereby the tire retreading apparatus retreads buffed tires (100) sequenttially loaded in the molds (80) in a continuous fashion.

Description

TIRE RETREADING APPARATUS

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to an apparatus for retreading tires used for vehicles. More particularly, the present invention relates to a tire retreading apparatus capable of rapidly and accurately forming a new tread on a worn tire by loading the worn tire in a mold, forming rubber on the tire in accordance with a rubber injection forming process, and curing the rubber while circulating the mold.

Description of the Prior Art As well known, tires, which are mounted to the body of a vehicle in such a fashion that they are in contact with the ground, serve to support the entire weight of the vehicle and a load applied to the vehicle, to transfer a drive force generated from the engine of the vehicle to the ground, and to absorb impact transferred from the ground, thereby protecting the vehicle .

The tires also serve to transmit a braking force generated from a brake device included in the vehicle to the ground, thereby ensuring a safety running of the vehicle. Such a tire is mainly worn at its tread portion during the running of a vehicle to which the tire is mounted. In order to reuse such a worn tire, the worn tread portion of the tire is typically retreaded. Such tire retreading contributes greatly to reuse of resources and prevention of environmental pollution.

Fig. 1 is a cross-sectional view illustrating the structure of a typical tire.

As shown in Fig. 1, the tire, which is denoted by the reference numeral 100, includes a tread 101 constituting the outermost portion of the tire 100. The tread 101 is comprised of a thick rubber layer and adapted to be in direct contact with the ground. A groove mark 102 having a variety of patterns is formed on the tread 101 in order to allow the tread 101 to exhibit a frictional coefficient against the ground while maintaining a desired orientation of the tire 100.

A bead 103, which is comprised of a relatively thick portion of the rubber layer, is formed at the central portion of the tire 100. The bead 103 is fitted in a rim 104. The rim 104 is made of a metallic material having a sufficient strength and mounted to a vehicle. The rim 104 serves to transmit a drive force from the vehicle to the tire.

A valve 106 is attached to the rim 104 in order to inflate air into the interior of the tire 100. A plurality of bead wires 107, a belt 108, and a reinforcing member 109 made of fibers or steel wires are buried m the rubber layer of the tire 100 m order to provide a desired toughness and a desired tensile strength to the tire 100.

The tread 101 serving as a ground contact surface of the tire 100 is a tire portion which is most severely worn during the running of the vehicle. A tire, m which its worn tread is retreaded for reuse of the tire, is typically called a

"retreaded tire" .

Typically, tires have a variety of sizes for use depending on the requirement of the vehicle to which they are mounted. Where a tire is severely worn at its tread, it should be replaced with a new one because it cannot exhibit a desired performance.

In this regard, it is recommended that a worn tire be replaced with a completely new or retreaded tire before its tread decreases m depth to about 1.6 mm or less for cars or to about 3.2 mm or less for trucks and buses.

For a conventional tire retreading method, a curing method has been proposed. In accordance with the curing method, the remaining tread rubber of a worn tire is removed m accordance with a buffing process. The buffed portion of the tire is then subjected to a cementing process. Uncured rubber is attached to the cemented portion of the tire and then cured m a mold for a desired period of time. Thus, a new tread is bonded to the tire at a region where the worn tread was positioned.

For such a curing method, there are a hot curing method m which a rubber layer is bonded to a worn tire using a mold, and a precuring method m which a rubber layer is bonded to a worn tire without using any mold. The precuring method has a drawback m that the retreaded tire is crude m appearance. Additionally, elaborate handwork involving a lot of labor and high labor costs is required m the precuring method. Due to such drawbacks, use of the precuring method has been decreased. Therefore, no further description of the precuring method will be made.

On the other hand, the hot curing method has been mainly used because the retreaded tire exhibits a good appearance. In accordance with the precuring method, uncured rubber is built on the tread portion of a worn tire on a building machine while rotating the worn tire. The built tire is then cured using a curing machine. However, many building machines and curing machines are required, and they are expensive. Furthermore, this precuring method requires skilled labor. In order to eliminate the above mentioned drawbacks, a new method has been proposed m which forming of a tread is achieved m one pass. In accordance with this method, the remaining tread rubber of a worn tire is removed. The resultant tire is loaded m a mold and then molded with a tread m accordance with a direct rubber injection forming process .

Although this method uses the direct rubber injection forming process, it also requires use of a curing machine in order to cure the uncured rubber. Since the curing machine is expensive, it results in high investment costs. Use of a plurality of curing machines also requires a separate installation space. Thus, this method requires great investment costs.

Furthermore, the manufacture (or building and curing) of the retreaded tire in accordance with the above method should be conducted by skilled persons. This results in a delay of the entire manufacturing process. As a result, a degradation in productivity occurs.

SUMMARY OF THE INVENTION

Therefore, the present invention has been made in view of the above mentioned problems, and an object of the invention is to provide a tire retreading apparatus having a configuration for feeding a buffed tire to an initial processing position, loading a lower mold portion of a mold positioned at the initial processing position, coupling an upper mold portion to the lower mold portion, molding rubber on the tire in the mold in accordance with a rubber injection forming process by use of a rubber pump or rubber injection machine, fitting a heating plate around the rubber- formed mold, and circulating the mold mounted with the heating plate along a track, thereby being capable of automatically forming and curing a tread on the tire. In accordance with the present invention, this object is accomplished by providing a tire retreading apparatus comprising: a loading unit for feeding a buffed tire to a tire loading region defined in the tire retreading apparatus, and loading the buffed tire in a lower mold portion of a mold waiting at the tire loading region, the mold being one of molds mounted on a carriage; a mold opening/closing unit for coupling an upper mold portion of the mold to the lower mold portion loaded with the buffered tire or separating the upper mold portion coupled to the lower mold; a rubber injection forming unit to inject uncured rubber onto a tread of the buffed tire loaded in the mold by use of a rubber pump or a rubber injection machine; a heating plate mounting unit for mounting an electrical heating plate to the mold, in which rubber is injection- formed, curing the formed rubber, and separating the electrical heating plate from the mold; a curing unit provided with the carriage, the curing unic circulating along the guide rail while curing the formed rubber for a desired period of time, thereby completely curing the injection- formed tread of the tire; and a discharge unit for unloading the completely cured tire from the mold, and outwardly discharging the tire from the tire retreading apparatus; whereby the tire retreading apparatus retreads buffed tires sequentially loaded m the molds m a continuous fashion. In accordance with an embodiment of the present invention, the tire retreading apparatus may further comprise a mold exchanging unit at which the change of tread mold, sidewall mold, and etc. is made according to next production plan. The loading unit feeds a buffed tire to the tire loading region of the tire retreading apparatus by use of an entrance roller conveyor driven m accordance with a chain driving mechanism, and then loads the fed tire m the lower mold portion of a mold waiting at the tire loading region by use of a tire loader.

The mold opening/closing unit couples the upper mold portion of the mold loaded with the r/uffed tire to the corresponding lower mold portion by use of a mold locking plate and a driver, thereby closing the mold. The rubber injection forming unit injects uncured rubber into a tread region defined m the closed mold by use of a rubber pump or rubber injection machine. The injected rubber is supplied to the tread region via a cold runner block, sc that it is formed m the mold. The heating plate mounting unit fits a heating plate, which is a heat generating means, around the mold m order to cure the formed rubber.

The curing unit applies heat to the molds for a desired period of time while moving the carriage, which carries the molds, along the guide rail, m order to completely cure the tread of the tires loaded m the molds.

The discharge unit unloads the completely cured tire from each mold by use of a tire unloader, and then lays the unloaded tire on a discharge roller conveyor driven m accordance with a belt driving mechanism. The discharge roller conveyor feeds the unloaded tire to an external storing field.

The mold exchanging unit is used to change tread mold, sidewall mold, and etc. according to next production plan, includes a mold loader for unloading a selected one of the molds and then loading new ones, and a carriage for carrying the unloaded molds .

The tire retreading apparatus of the present invention is capable of automatically conducting feeding of buffed tires, loading of the fed tires into molds, coupling of upper and lower molds, mounting of heating plates, injection forming of rubber, circulation of molds, and curing of treads, thereby achieving a reduction m manufacturing time and labor, and an improvement m productivity and equipment investment. BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and aspects of the invention will become apparent from the following description of embodiments with reference to the accompanying drawings in which:

Fig. 1 is a cross-sectional view illustrating the structure of a typical tire;

Fig. 2 is a plan view schematically illustrating the entire configuration of a tire retreading apparatus according to the present invention;

Fig. 3 is a front view illustrating a mold opening/closing unit included in the tire retreading apparatus, along with a tire loader and a tire unloader; Fig. 4 is a sectional view illustrating a state in which a mold and a cold runner block are mounted on a carriage in accordance with the present invention;

Fig. 5 is a sectional view illustrating a state in which a heating plate is fitted around a mold in accordance with the present invention;

Fig. 6 is a front view illustrating a heating plate loader included in the tire retreading apparatus; and

Fig. 7 is a front view illustrating a mold loader included in the tire retreading apparatus, along with the carriage. DESCRIPTION OF THE PREFERRED EMBODIMENTS

Fig. 2 is a plan view schematically illustrating the entire configuration of a tire retreading apparatus according to an embodiment of the present invention.

As shown m Fig. 2, the tire retreading apparatus includes a loading unit 10 for sequentially feeding buffed tires 100 to a tire loading region, wnere molds 80 are sequentially positioned, and sequentially loading the buffed tires 100 m respective lower mold portions, that is, lower molds 82 (Fig. 4) , of the molds 80 at the tire loading region. In Fig. 2, the tire loading region is denoted by the reference character PI. In accordance with the present invention, the molds 80 are circulated so that they are subject to a variety of processes m a sequential fashion. The t re retreading apparatus also includes a mold opening/closing unit 20 for coupling an upper mold portion, that is, an upper mold 81

(Fig. 4), of the mold 80, which is positioned at the tire loading region PI after being loaded with the buffed tire 100, to the corresponding lower mold 82 of the mold 80, thereby closing the mold 80, or separating tne upper mold 81 coupled to the corresponding lower mold 82, thereby opening the mold 80. Also, there is a rubber injection forming unit 30 to inject uncured rubber onto a tread 101 of the buffed tire 100 loaded m the closed mold 80, which is positioned at a rubber injection forming region, by use of a rubber pump or rubber injection machine. In Fig. 2, the rubber injection forming region is denoted by the reference numeral P3. The tire retreading apparatus also includes a heating plate mounting unit 40 for mounting a heating plate 90, that is, an electrical heater, to the mold 80 positioned at the rubber injection forming region P3 after being injection- formed with rubber, and a curing unit 50 provided with a carriage 110 adapted to carry the molds 80 and to circulate along a guide rail 120. The curing unit 50 serves to cure the formed rubber for a desired period of time during the circulation of the carriage 110, thereby completely curing the formed tread 101 of each tire 100. The tire retreading apparatus further includes a discharge unit 60 for unloading the tires 100, completely cured at their treads, from the molds 80, respectively, and then outwardly discharging those tires 100 from the tire retreading apparatus, and a mold exchanging unit 70 at which the change of tread mold, sidewall mold, and etc. is made according to next production plan.

As shown m Figs. 2 and 3, the loading unit 10 includes an entrance roller conveyor 130 for feeding a buffed tire 100 to the tire loading region PI of the tire retreading apparatus, and a tire loader 140 for lifting the fed tire 100 from the entrance roller conveyor 130 and then loading the lifted tire 100 to the lower mold 82 waiting at the tire loading region PI .

The entrance roller conveyor 130 is driven m accordance with a chain driving mechanism. As shown m Fig. 3, the entrance roller conveyor 130 is horizontally arranged at a level vertically spaced from the ground by a desired height. The entrance roller conveyor 130 feeds tires 100 laid thereon to the tire loading region PI of the tire retreading apparatus . The tire loader 140 includes a post 141 extending vertically from the ground, and an arm 142 mounted at one end thereof to the post 141 m such a fashion that it rotates about the post 141 while moving vertically along the post 141. A chuck body 143 is fixed to the other end of the arm 142. A plurality of chucks are fixedly mounted to the lower end of the chuck body 143. Each chuck is operatively connected to a small air cylinder so that it is engaged with or disengaged from the bead 103 of the tire 100.

As shown m Fig. 3, the mold opening/closing unit 20 includes a support 150, an air cylinder 151 centrally mounted at its upper end to the lower end of the support 150, and a mold locking plate 152 mounted to the lower end of the air cylinder 151 m such a fashion that it is arranged at the tire loading region PI where one of the lower molds 82 to be opened or closed is positioned. The mold locking plate 152 serves to couple the upper mold 81 to the corresponding lower mold 82 positioned at the tire loading region PI or to separate the upper mold 81 from the lower mold 82.

The support 150 is a frame for firmly supporting the air cylinder 151 and the mold locking plate 152.

The air cylinder 151 extends downwardly from the central portion of the lower end of the support 150.

The mold locking plate 152 extends downwardly from the lower end of the air cylinder 151 and is vertically movable in accordance with extending and retracting movements of the air cylinder 151. A driver 153 is mounted to the lower end of the mold locking plate 152. The driver 153 serves to fasten nuts 161 to bolts 160 of the mold 80 positioned at the tire loading region PI or to release the nuts 161 fastened to the bolts 160.

As shown in Fig. 4, the rubber injection forming unit 30 includes a cold runner block 170 downwardly suspended from a support frame having the same structure as the support 150. The cold runner block 170 is vertically movable. The rubber injection forming unit 30 also includes a cover plate 180 fixedly mounted to the lower end of the cold runner block 170 in such a fashion that it is movable together with the cold runner block 170. The cover plate 180 serves to cover the mold 80 positioned at the tire loading region PI. Although not shown, the rubber injection forming unit 30 further includes a rubber pump or rubber injection machine for injecting uncured rubber into the mold 80 via the cold runner block 170.

A thermal medium of about 70 to 90 °C circulates m the interior of the cold runner block 170 in order to maintain a desired flowability of the injecting rubber, thereby preventing a reduction in the fluidability of the injecting rubber .

The cover plate 180 is arranged around the mold 80 m such a fashion that it completely encloses the mold 80. The cover plate 180 serves to align a rubber running path defined m the cold runner block 170 with a rubber injection path defined m the mold 80.

The rubber pump or rubber injection machine is mounted to one side portion of the rubber injection forming unit 30 m such a fashion that it communicates with the cold runner block

170, so that it supplies uncured rubber to the cold runner block 170.

The heating plate mounting unit 40 includes a heating plate loader 230 having the same configuration as the tire loader 140, and a cylindrical heating plate 90 fitted around the mold 80 which is positioned at the rubber injection forming region P3 after being injection- formed with rubber.

As shown m Fig. 6, the heating plate loader 230 includes a post 231 extending vertically from the ground, and an arm 232 mounted at one end thereof to the post 231 m such a fashion that it rotates about the post 231 while moving vertically along the post 231. A chuck body 233 is fixed to the other end of the arm 232. A plurality of chucks are fixedly mounted to the lower end of the chuck body 233. Each chuck is operatively connected to a small air cylinder so that it is engaged with or disengaged from the heating plate 90.

That is, the heating plate loader 230 serves to lift the heating plate 90 to fit it around the mold 80 or to remove it from the mold 80.

The heating plate 90, which is an electrical heater, heats the mold 80 fitted therein for a desired period of time, thereby curing rubber filled m the mold 80. The heating plate 90 is best shown m Fig. 5. The curing unit 50 includes the carriage 110 for carrying the molds 80, and the guide rail 120 providing a mam moving path for the carriage 110.

The carriage 110 includes a planar base plate 111 on which the molds 80 are mounted. A plurality of uniformly spaced guide rollers 112 are mounted to the lower end of the base plate 111. The guide rollers 112 are contact with the guide rail 120 such a fashion that they roll along the guide rail 120. The guide rail 120 includes a pair of circular rail members. The guide rollers 112 and guide rail 120 are configured so that they are prevented from being separated from each other.

As shown in Fig. 3, the discharge unit 60 includes a tire unloader 190 for unloading a cured tire 100 from the mold 80 returned to the tire loading region Pi after being circulated along the guide rail 120, and then laying the tire 100 on a discharge roller conveyor 200. The discharge roller conveyor 200, which is also included in the discharge unit 60, serves to feed the unloaded tire 100 to an external tire storing field. Similarly to the tire loader 140, the tire unloader 190 includes a post 191 extending vertically from the ground, and an arm 192 mounted at one end thereof to the post 191 in such a fashion that it rotates about the post 191 while moving vertically along the post 191. A chuck body 193 is fixed to the other end of the arm 192. A plurality of chucks are fixedly mounted to the lower end of the chuck body 193. Each chuck is operatively connected to a small air cylinder so that it is engaged with or disengaged from the bead 103 of the tire 100. Similarly to the entrance roller conveyor 130, the discharge roller conveyor 200 is driven in accordance with a chain driving mechanism. As shown in Fig. 2, the discharge roller conveyor 200 is horizontally arranged at a level vertically spaced from the ground by a desired height . The discharge roller conveyor 200 feeds tires 100 laid thereon to the external tire storing field.

The mold exchanging unit 70, at which at which the change of tread mold, sidewall mold, and etc. is made according to next production plan, includes a mold loader 210 for unloading a selected one of the molds 80 and then loading new ones, and a carriage 220 for carrying the unloaded molds 80.

Similarly to the tire loader 130 and tire unloader 190, the mold loader 210 includes a post 211 extending vertically from the ground, and an arm 212 mounted at one end thereof to the post 211 in such a fashion that it rotates about the post 211 while moving vertically along the post 211, as shown in Fig. 7. A chuck body 213 is fixed to the other end of the arm 212. A plurality of chucks are fixedly mounted to the lower end of the chuck body 213. Each chuck is operatively connected to a small air cylinder so that it is engaged with or disengaged from the mold 80.

Similarly to the carriage 110, the carriage 220 includes a planar base plate 221 on which the unloaded mold 80 or a new or modified mold is mounted. A plurality of uniformly spaced guide rollers 222 are mounted to the lower end of the base plate 221. The guide rollers 222 are in contact with the guide rail 120 in such a fashion that they roll along the guide rail 120.

Now, the operation and effect of the tire retreading apparatus according to the embodiment of the present invention will be described. For the simplicity of description, the following description will be made m conjunction with the procedure for retreading only one buffed tire.

When a buffed tire 100 is laid on the entrance roller conveyor 130 of the loading unit 10, it is fed to the tire loading region PI defined in the tire retreading apparatus by the entrance roller conveyor 130. As soon as the buffed tire 100 is introduced into the desired position of the roller conveyor, the entrance roller conveyor 130 is stopped. When the entrance roller conveyor 130 is stopped, the tire loader 140 operates to load the tire 100 the lower mold 82 positioned at the tire loading region PI.

After the loading of the tire 100 the lower mold 82, the driver 153, which is supported by the support 150 of the mold opening/closing unit 20, moves downwardly to couple the upper mold 81 to the lower mold 82.

The driver 153 fastens nuts 161 to bolts 160 extending through the upper and lower molds 81 and 82 and then moves upwardly to its original position. After the upward movement of the driver 153, a conduit unit (not shown) , which is arranged at the lower portion of the mold 80, is upwardly moved to the tire 100 order to inflate air into the interior of the tire 100. After inflating the tire 100, the conduit unit returns to its original position. Thereafter, the carriage 110 moves to feed the mold 80 loaded with the tire 100 to the rubber injection forming region P3. When the mold 80 reaches the rubber injection forming region P3 , the carriage 110 is stopped. In this state, the cold runner block 170 and cover plate 180 of the rubber injection forming unit 30 are lowered so that they are coupled to the upper end of the mold 80.

In this state, rubber is injected into the mold 80 from the rubber pump or rubber injection machine. The injected rubber is supplied to a tread region defined in the mold 80 via the rubber running path defined in the cold runner block

170, thereby forming a tread on the tire 100.

At this time, the thermal medium, which is contained in the cold runner block 170 and maintained at a temperature of about 70 to 90°C, serves to prevent the rubber from being solidified. That is, the thermal medium serves to provide a good fluidability to the rubber.

After the injection forming of rubber, the cold runner block 170 and cover plate 180 return to their original positions, respectively. Subsequently, the heating plate loader 230 of the heating plate mounting unit 40 firmly fits the heating plate 90 around the mold 80.

The heating plate 90, which is an electrical heater, serves to sufficiently heat the mold 80 for a desired period of time, thereby curing the formed rubber. After the fitting of the heating plate 90 around the mold 80, the carriage 110, on which the mold is laid, circulates along the guide rail 120.

During the circulation of the carriage 110, the heating plate 90 operates for a desired period of time.

In accordance with this operation of the heating plate 90, the new tread 101 formed on the tire 100 in the mold 80 is cured while the mold 80 laid on the carriage 110 circulates along the guide rail 120. When the completely cured tire 100 returns to the tire loading region PI, the conduit unit not shown is coupled to the tire 100 in order to deflate the tire 100.

Thereafter, the heating plate loader 230 of the heating plate mounting unit 40 removes the heating plate 90 fitted around the mold 80 and then returns to its original position. In this state, the driver 153 of the mold opening/closing unit 20 moves downwardly and then separates the upper mold 81 from the lower mold 82.

After the separation of the upper mold 81, the tire unloader 190 of the discharge unit 60 unloads the tire 100 from the lower mold 82 and then lays the unloaded tire 100 on the discharge roller conveyor 200.

The tire 100 is fed by the discharge roller conveyor 200 and then stored at an external storing field. As mentioned above, the mold exchanging unit 70 is used to change tread mold, sidewall mold, and etc. according to next production plan.

For example, the mold exchanging unit 70 is used when the number of molds to be moved along the guide rail 120 is to be increased or decreased, when a part of molds are to be repaired, or when new molds are required depending on next production plan.

The mold exchanging unit 70 may also be used to preheat the mold 80. The tire retreading apparatus of the present invention can manufacture retreaded tires in a continuous fashion by repeating the above mentioned operation.

When the carriage 110 reaches an outlet end of the curing unit 50 after circulating one turn along the guide rail 120, a sensing signal is generated which senses whether or not the mold opening/closing unit 20 positioned at the tire loading region corresponding to the outlet end of the curing unit 50 is empty. When the mold opening/closing unit 20 is not empty, the carriage 110 is waited at the outlet end of the curing unit 50. On the other hand, where the mold opening/closing unit 20 is empty, the carriage 110 moves to the mold opening/closing unit 20, namely, the initial position.

As apparent from the above description, the present invention provides a tire retreading apparatus capable of automatically conducting feeding of buffed tires, loading of the fed tires into molds, coupling of upper and lower molds, mounting of heating plates, injection forming of tread rubber, circulation of molds, and curing of treads, thereby achieving a reduction in manufacturing time and labor, and an improvement in productivity and equipment investment.

Since the tire retreading apparatus occupies a reduced space, it achieves a reduction in installation costs. Furthermore, the tire retreading apparatus exhibits a high production rate resulting in a reduction in the amount of buffed tires to be processed. In addition, the molds of the tire retreading apparatus can be used at a high rate. This results in a great reduction in the manufacturing costs of molds .

Although the preferred embodiments of the invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims .

Claims

WHAT IS CLAIMED IS:

1. A tire retreading apparatus comprising: a loading unit for feeding a buffed tire to a tire loading region defined in the tire retreading apparatus, and loading the buffed tire in a lower mold portion of a mold waiting at the tire loading region, the mold being one of molds mounted on a carriage; a mold opening/closing unit for coupling an upper mold portion of the mold to the lower mold portion loaded with the buffered tire or separating the upper mold portion coupled to the lower mold; a rubber injection forming unit for injection-forming uncured rubber onto a tread of the buffed tire loaded in the mold by use of a rubber pump or a rubber injection machine; a heating plate mounting unit for mounting an electrical heating plate to the mold, in which rubber is injection- formed, curing the molded rubber, and separating the electrical heating plate from the mold; a curing unit provided with the carriage, the curing unit circulating along the guide rail while curing the molded rubber for a desired period of time, thereby completely curing the formed tread of the tire; and a discharge unit for unloading the completely cured tire from the mold, and outwardly discharging the tire from the tire retreading apparatus; whereby the tire retreading apparatus retreads buffed tires sequentially loaded in the molds in a continuous fashion.

2. The tire retreading apparatus in accordance with claim

1, further comprising: a mold exchanging unit at which the change of tread mold, sidewall mold, and etc. is made according to next tire production plan.

3. The tire retreading apparatus in accordance with claim

2 , wherein the mold exchanging unit comprises : a mold loader including a post extending vertically from the ground, an arm mounted at one end thereof to the post in such a fashion that it rotates about the post while moving vertically along the post, a chuck body fixed to the other end of the arm, and a plurality of chucks fixedly mounted to a lower end of the chuck body, each of the chucks being operatively connected to a small air cylinder so that it is engaged with or disengaged from the mold; and a carriage including a planar base plate, on which a mold to be exchanged is mounted, a plurality of uniformly spaced guide rollers mounted to a lower end of the base plate, the guide rollers being in contact with the guide rail in such a fashion that they roll along the guide rail

4. The tire retreading apparatus in accordance with claim 1, wherein the loading unit comprises: an entrance roller conveyor driven in accordance with a chain driving mechanism and horizontally arranged at a level vertically spaced from the ground by a desired height, the entrance roller conveyor serving to feed a buffed tire laid thereon to the initial processing position of the tire retreading apparatus; and a tire loader for lifting the fed tire from the entrance roller conveyor and then loading the lifted tire to the lower mold portion of the mold positioned at the initial processing position, the tire loader including a post extending vertically from the ground, an arm mounted at one end thereof to the post in such a fashion that it rotates about the post while moving vertically along the post, a chuck body fixed to the other end of the arm, and a plurality of chucks fixedly mounted to a lower end of the chuck body, each of the chucks being operatively connected to a small air cylinder so that it is engaged with or disengaged from a bead of the tire.

5. The tire retreading apparatus in accordance with claim 1, wherein the mold opening/closing unit comprises: a vertically extending support having the form of a frame; a cylinder centrally mounted at an upper end thereof to a lower end of the support; and a mold locking plate mounted to a lower end of the cylinder and adapted to couple the upper mold portion of the mold arranged therebeneath to the corresponding lower mold portion or to separate the upper mold portion from the lower mold portion, the mold locking plate being provided at a lower end thereof with a driver adapted to fasten nuts to bolts extending through the upper and lower mold portions of the mold positioned beneath the mold locking plate.

6. The tire retreading apparatus in accordance with claim 1, wherein the rubber injection forming unit comprises: a cold runner block downwardly suspended from a support frame in such a fashion that it is vertically movable, the cold runner block being contained with a thermal medium of about 70 to 90°C circulating the interior of the cold runner block; a cover plate fixedly mounted to a lower end of the cold runner block in such a fashion that it is movable together with the cold runner block, the cover plate serving to cover the mold at a rubber injection forming region while aligning a rubber running path defined in the cold runner block with a rubber injection path defined in the mold; and a rubber pump or rubber injection machine for injecting uncured rubber into the mold via the cold runner block.

7. The tire retreading apparatus in accordance with claim 1, wherein the heating plate mounting unit comprises: a heating plate loader including a post extending vertically from the ground, an arm mounted at one end thereof to the post in such a fashion that it rotates about the post while moving vertically along the post, a chuck body fixed to the other end of the arm, a plurality of chucks fixedly mounted to a lower end of the chuck body, each of the chucks being operatively connected to a small air cylinder so that it is engaged with or disengaged from a cylindrical electrical heating plate; and the cylindrical electrical heating plate fitted around the mold at the rubber injection forming region, the heating plate serving to heat the mold fitted therein for a desired period of time, thereby curing rubber filled in the mold.

8. The tire retreading apparatus in accordance with claim 1, wherein the curing unit comprises: the carriage including a planar base plate, on which the molds are mounted, and a plurality of uniformly spaced guide rollers mounted to a lower end of the base plate, the guide rollers being in contact with the guide rail in such a fashion that they roll along the guide rail to move the molds; and the guide rail including a pair of circular rail members and serving to form a main moving path for the carriage.

9. The tire retreading apparatus in accordance with claim 1, wherein the discharge unit comprises: a tire unloader for unloading the tire from the mold returned to the tire loading region, where the mold is positioned for its opening or closing, after being circulated along the guide rail, and then laying the tire on a discharge roller conveyor, the tire unloader including a post extending vertically from the ground, an arm mounted at one end thereof to the post in such a fashion that it rotates about the post while moving vertically along the post, a chuck body fixed to the other end of the arm, and a plurality of chucks fixedly mounted to a lower end of the chuck body, each of the chucks being operatively connected to a small air cylinder so that it is engaged with or disengaged from a bead of the tire; and the discharge roller conveyor driven in accordance with a chain driving mechanism and horizontally arranged at a level vertically spaced from the ground by a desired height, the discharge roller conveyor serving to feed the unloaded tire laid thereon to an external tire storing field.