JP7618428B2 - Method for manufacturing non-pneumatic tires - Google Patents

Description

The present invention relates to a method for manufacturing non-pneumatic tires.

Non-pneumatic tires, which are constructed without the need for air, have the advantage of not requiring maintenance for things like loss of air pressure or punctures.

The non-pneumatic tire described in Patent Document 1 includes a support structure that supports the load from the vehicle, and a tread member that is provided on the outer periphery of the support structure. The support structure includes an inner annular portion, an outer annular portion that is provided concentrically on the outside of the inner annular portion, and a number of connecting portions that connect the inner annular portion and the outer annular portion. Patent Document 1 also describes buffing the outer periphery of the molded support structure.

JP 2011-219009 A

In the non-pneumatic tire described in Patent Document 1, random unevenness is formed on the outer peripheral surface of the support structure when the outer peripheral surface is buffed. Abrasive powder generated by the buffing process may remain on the uneven outer peripheral surface. If the tread member is bonded with the abrasive powder remaining, the adhesive strength becomes uneven, and the tread member is likely to peel off in areas where the adhesive strength is insufficient.

The present invention was made in consideration of these circumstances, and its purpose is to provide a method for manufacturing a non-pneumatic tire that can suppress insufficient adhesion between the support structure and the tread member.

One aspect of the present invention is a method for manufacturing a non-pneumatic tire. The method for manufacturing a non-pneumatic tire includes a molding process for molding a ring-shaped support structure that is connected to an axle and has a tread member attached to its outer peripheral surface, a removal process for irradiating the outer peripheral surface with a laser beam to remove a release agent, and an attachment process for attaching the tread member to the outer peripheral surface.

The present invention makes it possible to prevent insufficient adhesion between the support structure and the tread member.

FIG. 1 is a side view of a non-pneumatic tire. 2 is a cross-sectional view of the non-pneumatic tire taken along line AA shown in FIG. 1. 3 is a view of the connecting member as seen from a direction B shown in FIG. 2 . 1 is a flowchart showing a method for manufacturing a non-pneumatic tire. FIG. 2 is a block diagram showing a functional configuration of a release agent removal device used in a release agent removal step. FIG. 2 is a schematic diagram for explaining a scanning route of a laser beam. 10 is a flowchart showing a method for manufacturing a non-pneumatic tire according to a modified example. 13A and 13B are schematic diagrams for explaining irradiation of laser light according to a modified example.

The present invention will be described below based on a preferred embodiment with reference to Figures 1 to 8. The same or equivalent components and parts shown in each drawing are given the same reference numerals, and duplicated explanations will be omitted as appropriate. Furthermore, the dimensions of the parts in each drawing are enlarged or reduced as appropriate to facilitate understanding. Furthermore, some of the parts that are not important for explaining the embodiment will be omitted in each drawing.

(Embodiment)
Fig. 1 is a side view of a non-pneumatic tire 100, and Fig. 2 is a cross-sectional view of the non-pneumatic tire 100 taken along line A-A shown in Fig. 1. The non-pneumatic tire 100 has a wheel 10, an inner ring 20, an outer ring 30, and a connecting member 40. The inner ring 20 is cylindrical, and the wheel 10 is attached to its inner periphery. The wheel 10 is circular in side view, and an axle is attached to its center. The inner ring 20 is connected to the axle via the wheel 10.

The outer ring 30 is cylindrical and is provided radially outward of the inner ring 20. The outer ring 30 has a cylindrical base portion 31 and a cylindrical tread member 32 that is bonded to the outer periphery of the base portion 31, and the outer periphery of the tread member 32 comes into contact with the ground.

The connecting member 40 is an elongated plate with a plate surface facing the tire circumferential direction, and connects the inner ring 20 and the outer ring 30. As shown in FIG. 2, the connecting member 40 has a first plate member 41 that extends from one end of the inner ring 20 in the width direction (axial direction) to the other end of the outer ring 30 in the width direction, and a second plate member 42 that extends from the other end of the inner ring 20 in the tire width direction (axial direction) to one end of the outer ring 30 in the width direction.

Figure 3 is an arrow view of the connecting member 40 as seen from direction B shown in Figure 2. The connecting member 40 has first plate members 41 and second plate members 42 arranged alternately in the tire circumferential direction. Returning to Figure 2, the inner ring 20, the base portion 31 of the outer ring 30, and the connecting member 40 constitute a support structure 50 that supports the load from the vehicle. The inner ring 20, the base portion 31 of the outer ring 30, and the connecting member 40 that constitute the support structure 50 are all made of resin and are formed by integral molding. The support structure 50 uses a material such as thermosetting urethane.

The tread member 32 of the outer ring 30 is made of rubber and is bonded to the outer peripheral surface 31a of the integrally molded support structure 50. The tread member 32 is bonded to the outer peripheral surface 31a of the base portion 31 using, for example, an adhesive, double-sided tape, etc.

Figure 4 is a flowchart showing a method for manufacturing a non-pneumatic tire 100. The non-pneumatic tire 100 is manufactured through a molding process (S1) of the support structure 50, a process (S2) of removing the release agent, and a process (S3) of attaching the tread member 32.

In the molding process (S1) of the support structure 50, a mold release agent is applied to the mold die, which is filled with resin, heated (e.g., 100°C to 160°C), and then cooled. After cooling, the support structure 50 is removed from the die. After the molding process of the support structure 50, the outer peripheral surface 31a of the support structure 50 is left with residual release agent adhering thereto. The release agent may be, for example, a composite coating type of fluorine compound and silicone, which improves the releasability of the support structure 50. The release agent is applied to the mold die by a method such as spraying.

FIG. 5 is a block diagram showing the functional configuration of a release agent removing device 60 used in the release agent removing process. The release agent removing device 60 includes a laser irradiation unit 61, a control table 62, and a control unit 63, and irradiates the outer peripheral surface 31a of the support structure 50 with a laser beam to sublimate and remove the release agent. The laser irradiation unit 61 has a laser oscillator 61a and an optical scanning unit 61b. The laser oscillator 61a can be, for example, a _CO2 laser, a fiber laser, or a YAG laser. The type of laser to be used may be appropriately selected since the absorption rate of the laser beam changes depending on the material of the support structure 50. For example, a _CO2 laser exhibits performance such as a wavelength of 1064 nm and an output of 40 W.

The optical scanning unit 61b irradiates the target object with the laser light output by the laser oscillator 61a using a reflection and focusing optical system. The optical scanning unit 61b rotates and drives optical elements such as a reflecting mirror and a focusing lens to move the spot onto which the laser light is irradiated in one or two dimensions. The laser irradiation unit 61 is capable of laser scanning with a spot diameter of 20 μm, a scanning range of 200 mm x 200 mm, and a scanning speed in the range of 10 to 1200 mm/s, for example.

The control table 62 supports the support structure 50 so that it can rotate around the tire axis, and has a rotation drive unit 62a that rotates the support structure 50. The control table 62 also has a position drive unit 62b that adjusts the relative position between the support structure 50 and the laser irradiation unit 61 in three axial directions.

The control unit 63 controls the on/off of the laser light irradiation by the laser irradiation unit 61 and the movement of the laser light spot position. The control unit 63 also controls the position adjustment of the support structure 50 by the control table 62 and the rotation of the support structure 50 around the tire axis. Information such as the external shape of the support structure 50 is input from the input unit 64.

Returning to FIG. 4, in the release agent removal process (S2), information such as the external shape of the support structure 50 is input to the control unit 63 of the release agent removal device 60, and the support structure 50 is attached to the control table 62. The support structure 50 is positioned at the start position for irradiating the laser light, and a route for scanning the laser light from the start position to the end position is set based on the spot diameter of the laser light.

6 is a schematic diagram for explaining the scanning route of the laser light. The laser light spot S travels along a route that repeats one revolution in the tire circumferential direction and a distance L1 in the tire width direction on the outer peripheral surface 31a of the support structure 50 from the starting position to the terminal position. The laser light spot S is moved so as to overlap with each revolution. That is, if the diameter of the laser light spot S is D, the following formula is satisfied.
L1<D...(1)

When irradiating the laser light, the control table 62 rotates the support structure 50 around the tire axis. In addition, the movement of the laser light spot S in the tire width direction may be performed by moving the irradiation position of the laser light by the laser irradiation unit 61, or the control table 62 may move the support structure 50 in the tire width direction.

In the release agent removal process, the outer peripheral surface 31a of the support structure 50 is irradiated with laser light without leaving any gaps, thereby sublimating and removing the release agent.

In the tread member 32 attachment process (S3), adhesive is applied to the outer peripheral surface 31a of the support structure 50, and after drying for a predetermined time, the tread member 32 is placed on the outer peripheral surface 31a. The adhesive is dried, for example, at a temperature of 80°C for a predetermined time of 10 minutes. The surface layer of the tread member 32 in contact with the adhesive is vulcanized, for example, at 110°C or higher, to complete the adhesion.

Figure 7 is a flowchart showing a method for manufacturing a non-pneumatic tire 100 according to a modified example. This manufacturing method includes a step of forming irregularities on the outer peripheral surface (S13) after the release agent removal step. Steps S11, S12, and S14 are similar to steps S1, S2, and S3 in Figure 4 described above, respectively, and therefore will not be described.

In the step of forming irregularities on the outer peripheral surface (S13), the output of the laser light is increased or decreased as appropriate from the step of removing the release agent to obtain the output for forming irregularities. FIG. 8 is a schematic diagram for explaining the irradiation of laser light according to a modified example. In the step of forming irregularities on the outer peripheral surface (S13), the laser light is irradiated onto the outer peripheral surface 31a from the starting position to the end position by repeatedly turning the laser light on and off intermittently and moving the spot position of the laser light.

In the process of forming the irregularities on the outer peripheral surface, the diameter D of the spot is made smaller than the distance L2 between the center of the spot S irradiated with the laser light and the center of the adjacent spot S, so that the spots do not overlap. In other words, the following formula is satisfied.
D<L2...(2)

In the process of forming the irregularities on the outer peripheral surface, recesses are formed on the outer peripheral surface 31a, and the spaces between the recesses are convex, resulting in an overall irregular state. The diameter of the recesses formed on the outer peripheral surface 31a by the process of forming the irregularities on the outer peripheral surface may be set to a range of, for example, 3 μm or more and 20 μm or less, depending on the spot diameter of the laser light.

The depth of the recess can be set appropriately depending on the material of the support structure 50, the irradiation energy of the laser light, and the spot diameter. The adhesive penetrates into the recess formed in the outer peripheral surface 31a, thereby increasing the adhesive strength of the tread member 32.

Next, the operation of the non-pneumatic tire 100 will be described based on each step in the manufacturing method described above. In the release agent removal step, the release agent attached to the outer peripheral surface 31a of the support structure 50 of the non-pneumatic tire 100 is sublimated and removed by irradiation with laser light, so that no abrasive powder is generated, which is generated, for example, by buffing, and insufficient adhesion between the support structure 50 and the tread member 32 can be suppressed.

In the release agent removal process, the laser light spots are scanned on the outer peripheral surface 31a of the support structure 50 so as to satisfy the relationship of the above-mentioned formula (1), so that the spots overlap and the release agent can be removed without gaps. Since the intensity distribution within the laser light spot is large at the center of the spot and small on the periphery, the overlapping of the spots during scanning of the laser light on the outer peripheral surface 31a makes it possible to uniformize the irradiation energy.

The condition for the overlapping of the laser light spots is as shown in formula (1) above, but in order to achieve uniformity in the irradiation energy, the laser light may be irradiated under the further condition L1<D/2.

As shown in the modified example, after the release agent removal process, a step of forming irregularities on the outer peripheral surface 31a by intermittently irradiating the laser light on and off may be added. By forming irregularities on the outer peripheral surface 31a, the adhesive will enter the recesses and increase the adhesive strength.

In the process of forming the irregularities on the outer peripheral surface 31a, the laser light spots are scanned so as to satisfy the above-mentioned formula (2), so that the spots do not overlap and recesses can be easily formed. If the surface roughness Ra of the outer peripheral surface 31a is about 10 μm, peeling of the tread member in the support structure 50 is unlikely to occur. Note that the surface roughness Ra represents the arithmetic mean roughness.

The support structure 50 is made up of an inner ring 20, an outer ring 30 (base portion 31), and a connecting member 40 that connects the inner ring 20 and the outer ring 30, which allows for a reduction in weight.

The connecting member 40 is constructed by arranging first plate members 41 and second plate members 42 alternately in the circumferential direction. The first plate member 41 extends from one end of the inner ring 20 in the width direction to the other end of the outer ring 30 in the width direction. The second plate member 42 extends from the other end of the inner ring 20 in the width direction to one end of the outer ring 30 in the width direction. The first plate member 41 and the second plate member 42 can provide high rigidity to the non-pneumatic tire 100.

In the above embodiment, an example was shown in which the laser light spot repeats a route that moves around the outer peripheral surface 31a of the support structure 50 in the tire circumferential direction in the release agent removal process, but it may also repeat a route that goes back and forth in the tire width direction. In this case, the laser light spot moves from a starting position on the outer peripheral surface 31a from one end to the other end in the tire width direction, moves in the tire circumferential direction, and then moves from the other end to the one end again, repeating the back and forth route.

Next, features of the manufacturing method of the non-pneumatic tire 100 according to the embodiment will be described.
The manufacturing method of the non-pneumatic tire 100 according to the embodiment includes a molding step of the support structure 50, a release agent removal step, and a tread member 32 attachment step. The molding step of the support structure 50 molds a ring-shaped support structure 50 that is connected to an axle and has the tread member 32 attached to its outer circumferential surface 31a. The release agent removal step irradiates the outer circumferential surface 31a with a laser beam to remove the release agent. The tread member 32 attachment step attaches the tread member 32 to the outer circumferential surface 31a. According to this manufacturing method of the non-pneumatic tire 100, the release agent is sublimated and removed by irradiation with a laser beam, so that no abrasive powder is generated, for example, in a buffing process, and insufficient adhesion between the support structure 50 and the tread member 32 can be suppressed.

In addition, the release agent removal process is performed by scanning the outer peripheral surface 31a with overlapping spots of laser light. According to this method for manufacturing the non-pneumatic tire 100, the spots overlap when the laser light is scanned on the outer peripheral surface 31a, thereby making it possible to uniformize the irradiation energy.

In addition, after the release agent removal process, the method further includes an unevenness forming process in which laser light is intermittently irradiated on and off to form unevenness on the outer peripheral surface. According to this manufacturing method for non-pneumatic tire 100, unevenness is formed on outer peripheral surface 31a, and adhesive enters the recesses, increasing the adhesive strength of tread member 32.

In addition, in the unevenness forming process, the laser light is applied so that the spots do not overlap. According to this manufacturing method for the non-pneumatic tire 100, the spots do not overlap, and recesses can be easily formed.

The support structure 50 also has an inner ring 20 that is connected to the axle, a base portion 31 of an outer ring 30 to which a tread member 32 is attached, and a connecting member 40 that connects the inner ring 20 and the outer ring 30. This manufacturing method for a non-pneumatic tire 100 can reduce the weight of the non-pneumatic tire 100 that is manufactured.

The connecting member 40 is configured by circumferentially arranging a first plate member 41 extending from one end of the inner ring 20 in the width direction to the other end of the outer ring 30 in the width direction, and a second plate member 42 extending from the other end of the inner ring 20 in the width direction to one end of the outer ring 30 in the width direction. According to this manufacturing method for the non-pneumatic tire 100, it is possible to increase the rigidity of the manufactured non-pneumatic tire 100.

The above describes the embodiments of the present invention. These embodiments are illustrative, and it will be understood by those skilled in the art that various modifications and changes are possible within the scope of the claims of the present invention, and that such modifications and changes are also within the scope of the claims of the present invention. Therefore, the descriptions and drawings in this specification should be treated as illustrative rather than restrictive.

20 Inner ring, 30 Outer ring, 31a Outer circumferential surface,
32 tread member, 40 connecting member, 41 first plate member,
42 Second plate member, 50 Support structure, 100 Non-pneumatic tire.

Claims (6)

a molding process for molding a ring-shaped support structure that is connected to an axle and has a tread member attached to an outer peripheral surface thereof;
a step of supporting the support structure rotatably around a tire axis and attaching the support structure to a control stand having a rotation drive unit that rotates the support structure;
a removing step of removing the release agent by irradiating the outer peripheral surface with a laser beam by repeatedly moving a spot of the laser beam in a tire circumferential direction or reciprocating in a tire width direction ;
a bonding step of bonding the tread member to the outer circumferential surface;
A method for manufacturing a non-pneumatic tire, comprising: The method for manufacturing a non-pneumatic tire according to claim 1, characterized in that the removal process scans the outer peripheral surface with overlapping spots of laser light. The method for manufacturing a non-pneumatic tire according to claim 1 or 2, further comprising a step of forming irregularities on the outer peripheral surface by intermittently irradiating a laser beam on and off after the removal step. The method for manufacturing a non-pneumatic tire according to claim 3 , wherein in the unevenness forming step , the laser light is irradiated so that the spots do not overlap each other. The method for manufacturing a non-pneumatic tire according to any one of claims 1 to 4, characterized in that the support structure has an inner ring connected to an axle, an outer ring to which the tread member is attached, and a connecting member connecting the inner ring and the outer ring. The method for manufacturing a non-pneumatic tire according to claim 5, characterized in that the connecting member is composed of a first plate member extending from one end of the inner ring in the width direction to the other end of the outer ring in the width direction, and a second plate member extending from the other end of the inner ring in the width direction to one end of the outer ring in the width direction, arranged in the circumferential direction.

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