Method for forming road surface of tire testing machine and tire testing machine

Abstract

To improve workability of attaching a ground sheet to reproduce an actual road surface.SOLUTION: A road surface forming method of a tire testing machine 10 comprises: forming a plurality of sheet pieces 27 to be attached to a traveling surface 23e on which a pneumatic tire 1 rolls out of a road surface part 23 made of an endless body so as to have a length shorter than the peripheral length of the traveling surface 23e; arranging and attaching the sheet pieces 27 side by side over the entire circumference of the traveling surface 23e; and forming the road surface part 23 including a grounding sheet 26 composed of the plurality of sheet pieces 27.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a road surface portion forming method for a tire testing machine and a tire testing machine. [Background technology]

[0002] Patent Document 1 discloses a tire testing machine in which a ground contact sheet for reproducing an actual road surface is attached to the outer surface of a rotating drum that constitutes the road surface portion. Abrasive paper with a specified roughness is used for the ground contact sheet. The ground contact sheet is made by attaching a continuous piece of abrasive paper around the entire circumference. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-300725 A Summary of the Invention [Problem to be solved by the invention]

[0004] During testing, the ground contact sheet may tear or be damaged if a strong load is applied from the pneumatic tire. If even a part of the ground contact sheet is torn or damaged, it must be replaced, but it is not easy to attach the ground contact sheet to the entire circumference of the road surface while under tension. Patent Document 1 does not take such workability of attaching the ground contact sheet into consideration.

[0005] An object of the present invention is to improve the efficiency of attaching a ground contact sheet to a tire testing machine in order to reproduce an actual road surface. [Means for solving the problem]

[0006] In one aspect of the present invention, a plurality of sheet pieces to be attached to a running surface on which a pneumatic tire rolls of a road surface portion made of an endless body are provided on the running surface. The total circumferential length Formed with a length shorter than the circumference, A pair of cutting edges formed at both ends in the circumferential direction are formed so as to be inclined with respect to the circumferential direction on the running surface,The sheet pieces are aligned and attached over the entire circumference of the running surface, forming the road surface portion having a ground contact sheet made up of the plurality of sheet pieces.

[0007] In this embodiment, the grounding sheet is divided into a plurality of sheet pieces. Therefore, even if a strong force is applied to the grounding sheet during the test and some of the sheet pieces are torn or damaged, the road surface portion can be repaired by replacing only the torn or damaged sheet pieces. Moreover, since the divided sheet pieces are short, the workability of pasting can be improved. In addition, the range and time of pasting can be minimized, so that the operation time related to the test can be increased.

[0008] In this embodiment, since the cut edges at both ends of the sheet piece are inclined, when a test is performed with the pneumatic tire inclined with respect to the circumferential direction of the road surface portion to apply a slip angle, the shear force applied to the joint where the cut edges of adjacent sheet pieces are butted together can be reduced, thereby preventing the sheet piece from peeling off from the joint.

[0009] The plurality of sheet pieces are formed so that the maximum length (Lb) in the circumferential direction is 250 cm or less.

[0010] In this embodiment, the maximum length of the sheet piece is 250 cm or less. This reduces the storage space required for the preformed sheet pieces, and they can be stored in a flat, stretched state. Moreover, because the dimensions are optimal for workers to handle, the sheet pieces can be reliably attached to the road surface under tension.

[0011] The sheet piece is formed so that the pair of cutting edges have the same inclination angle.

[0012] In this embodiment, since the inclination angles of the pair of cut edges are the same, the storability of the preformed sheet pieces can be improved. In addition, since there is no need to select a specific sheet piece when attaching the sheet pieces, and the sheet pieces are not placed in the wrong position, the ease of attachment can be improved.

[0013] The sheet piece is formed such that the pair of cut edges do not overlap in the circumferential direction.

[0014] In this embodiment, the dimensions of the sheet pieces are set so that the cut edges at both ends do not overlap in the circumferential direction of the road surface portion, which prevents the pneumatic tire from contacting the ground across the cut edges at both ends, thereby preventing two or more adjacent sheet pieces from being torn or damaged at the same time due to the load from the pneumatic tire.

[0015] The sheet piece is formed so that the circumferential length (Lc) between inner ends of the pair of cut edges located toward the circumferential center of the sheet piece is longer than the contact length of the pneumatic tire.

[0016] In this embodiment, the length from one to the other of the inner ends of the pair of cut edges is longer than the ground contact length of the pneumatic tire, so that the pneumatic tire can be prevented from contacting the ground across both cut edges, thereby preventing the two adjacent sheet pieces from being simultaneously torn or damaged by the load from the pneumatic tire.

[0017] The sheet piece is formed so that the length (Ld) of the cut edge in the circumferential direction is longer than the contact length of the pneumatic tire.

[0018] In this embodiment, since the circumferential length of the cut edge is longer than the contact length of the pneumatic tire, the joint where the cut edges of adjacent sheet pieces butt together protrudes in the circumferential direction of the road surface from the contact area of ​​the pneumatic tire and has a portion that is not subjected to load from the pneumatic tire, thereby preventing the sheet piece from peeling off from the joint.

[0019] The above The circumferential length between a pair of cutting edges (La) In front The length of the tire that is in contact with the ground is longer than that of the pneumatic tire. , the plurality of sheet pieces Form do.

[0020] The plurality of sheet pieces are formed so that the lengths (La) in the circumferential direction are the same.

[0021] In this embodiment, since there is only one type of sheet piece, the workability when forming the sheet piece can be improved. Also, the workability can be improved when forming a new ground contact sheet by attaching the sheet piece to the road surface portion and when replacing a given sheet piece.

[0022] Of the plurality of sheet pieces stuck to the road surface portion, only the damaged sheet piece is peeled off, and a previously formed, undamaged, unused sheet piece is stuck to the portion of the road surface portion from which the sheet piece was peeled off.

[0023] Another aspect of the present invention provides a tire testing machine which is a rotatable endless body comprising a road surface portion having a running surface on which a pneumatic tire rolls, and a ground contact sheet affixed around the entire circumference of the running surface, the ground contact sheet being composed of a plurality of sheet pieces divided in the circumferential direction of the road surface portion, and a pair of cut edges formed at both ends in the circumferential direction of the sheet pieces being inclined with respect to the circumferential direction on the running surface. Also, The above The length (La) in the circumferential direction between a pair of cut edges formed on both ends of the sheet piece in the circumferential direction is longer than the contact length of the pneumatic tire. stomach. Effect of the Invention

[0024] The present invention can improve the efficiency of attaching a ground contact sheet to a tire testing machine in order to reproduce an actual road surface. [Brief description of the drawings]

[0025] [Figure 1] 1 is a plan view of a tire testing machine according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a side view of the tire testing machine of FIG. 1. [Diagram 3] FIG. 2 is a cross-sectional view of a portion taken along line III-III in FIG. [Figure 4] 4 is a perspective view showing a manufacturing method of the sheet pieces that constitute the ground sheet. FIG. [Diagram 5] FIG. [Figure 6A] FIG. 2 is a schematic diagram showing the relationship between a ground contact sheet and a pneumatic tire. [Figure 6B] FIG. 2 is a schematic diagram showing the relationship between a ground contact sheet and a pneumatic tire to which a slip angle is applied. [Figure 7A] FIG. 6 is a schematic diagram showing the relationship between the ground contact sheet and a pneumatic tire according to a second embodiment. [Figure 7B] FIG. 11 is a schematic diagram showing the relationship between the ground contact patch of the second embodiment and a pneumatic tire to which a slip angle is applied. [Figure 8] FIG. 11 is a side view of a tire testing machine according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0027] (First embodiment) 1 and 2 show a tire testing machine 10 according to a first embodiment of the present invention. This tire testing machine 10 is a device for checking the wear characteristics and cornering characteristics of a pneumatic tire 1. The pneumatic tire 1 may be for a general passenger car, or for a truck or bus. In the following description, the pneumatic tire 1 may be simply referred to as a tire.

[0028] 1 and 2, a tire testing machine 10 includes a support device 15 that supports a tire 1, and a rolling device 20 that rolls the tire 1. In this embodiment, the workability of attaching a ground contact sheet 26 to a belt (road surface portion) 23 that constitutes the rolling device 20 is improved.

[0029] The support device 15 includes a support portion 16 that rotatably supports the tire 1, and a load applying portion 17 that applies a predetermined ground contact load to the tire 1.

[0030] The support portion 16 is a member that supports the tire 1 rotatably around the rotation axis A1, and functions as a so-called axle. The tire 1 mounted on the wheel 2 is removably attached to the support portion 16.

[0031] The load application unit 17 is a mechanism for placing the tire 1 with respect to the rolling device 20 at a predetermined pressure. The load application unit 17 of this embodiment moves the support unit 16 in a direction approaching and receding from the rolling device 20 (up and down directions in FIG. 2 ) and places the tire 1 on the rolling device 20. Furthermore, the load application unit 17 can also apply a rotational driving force, a braking force, and a slip angle to the tire 1 in addition to the ground contact load.

[0032] The rolling device 20 includes two rollers 21A, 21B, an endless belt 23 attached across the rollers 21A, 21B, and a grounding sheet 26 attached to the belt 23.

[0033] Roller 21A is mechanically connected to motor 22A, and roller 21B is mechanically connected to motor 22B. Rotation axis A2 of roller 21A and rotation axis A3 of roller 21B extend parallel to rotation axis A1 of support portion 16. Rollers 21A and 21B are rotated in the same direction (clockwise in FIG. 2) by motors 22A and 22B, respectively. Motors 22A and 22B are controlled to a predetermined rotation speed by a control device (not shown). However, only one of two rollers 21A and 21B may be rotated by the motor, and the other may be rotated by the belt 23.

[0034] The belt 23 is a road surface portion on which the tire 1 rolls, and is wound between the two rollers 21A, 21B and moves (rotates) as the rollers 21A, 21B rotate.

[0035] The belt 23 has flat portions 23a, 23b that are not in contact with the rollers 21A, 21B, and curved portions 23c, 23d that are in contact with the rollers 21A, 21B. The flat portions 23a, 23b and the curved portions 23c, 23d of the belt 23 change sequentially as the belt rotates.

[0036] The belt 23 is configured as a steel belt in which at least the surface against which the tire 1 is pressed is made of stainless steel. In this embodiment, the tire 1 is pressed against the outer surface 23e of the flat surface 23a located on the upper side, and the tire 1 rolls at a predetermined rotation speed as the belt 23 rotates. In other words, the outer surface 23e of the belt 23 is the running surface on which the tire 1 rolls. However, the tire testing machine 10 may be configured such that the tire 1 is pressed against the inner surface 23f of the flat surface 23a or 23b.

[0037] The grounding sheet 26 is made of an abrasive cloth having a predetermined roughness (for example, a grit size of #120) and is attached to the outer surface 23e of the belt 23 over the entire circumference.

[0038] 3, the ground sheet 26 includes a sheet body 26a, an abrasive portion 26b provided on the outer surface of the sheet body 26a, and an adhesive portion 26c provided on the inner surface of the sheet body 26a. The abrasive portion 26b is formed by attaching an abrasive material to the sheet body 26a. The adhesive portion 26c is formed by attaching an adhesive to the sheet body 26a. A double-sided tape may be used for the adhesive portion 26c. For the ground sheet 26 (sheet roll 25), for example, Safety Walk (registered trademark) manufactured by 3M may be used.

[0039] Referring to FIG. 1, the ground contact sheet 26 is attached to the central region of the width direction W of the belt 23. The width direction W of the belt 23 is a direction perpendicular to the circumferential direction C of the belt 23 on the belt 23, and is the same as the direction in which the rotation axes A2, A3 of the rollers 21A, 21B extend. The width direction of the ground contact sheet 26 is also the same as the width direction W of the belt 23. The width W1 of the ground contact sheet 26 is smaller than the width W0 of the belt 23 and larger than the width W2 of the tire 1. For example, the width W0 of the belt 23 is 100 cm, and the width W1 of the ground contact sheet 26 is set in a range of 0.7 to 0.9 times the width W0 of the belt 23, and is 50 cm in this embodiment. The width W2 varies depending on the type of the tire 1.

[0040] 1 and 2, the grounding sheet 26 is composed of a plurality of sheet pieces 27 divided in the circumferential direction C of the belt 23. In FIG. 1, the grounding sheet 26 is composed of three sheet pieces 27.

[0041] 4, each sheet piece 27 is formed by cutting the spirally wound sheet roll 25 to a set length La. In other words, the grounding sheet 26 is formed by arranging and attaching a plurality of sheet pieces 27 cut from the sheet roll 25 all around the circumference of the belt 23. The circumferential length La of the sheet piece 27 is shorter than the circumferential length of the grounding sheet 26.

[0042] 5, the sheet piece 27 is defined by a pair of side edges 27a located on both the upper and lower sides in FIG. 5, and cut edges 27b, 27c located on both the left and right ends in FIG.

[0043] The pair of side edges 27a correspond to both side edges of the sheet roll 25 (see FIG. 4) in a direction perpendicular to the unwinding direction, and extend parallel to each other. The width W1 of the sheet piece 27, which is the dimension between the pair of side edges 27a, is the same as the width W1 of the ground sheet 26 shown in FIG.

[0044] Cut edge 27b is cut before cut edge 27c and is an inclined edge located on the front side in the payout direction of sheet roll 25 (see FIG. 4). Cut edge 27c is cut after cut edge 27b and is an inclined edge located on the rear side in the payout direction of sheet roll 25 (see FIG. 4). Sheet piece 27 is attached such that length direction X of sheet piece 27 corresponds to circumferential direction C of belt 23. Cut edges 27b and 27c are inclined with respect to circumferential direction C of belt 23 on belt 23 and each extend linearly.

[0045] The inclination angle θ1 of the cut edge 27b and the inclination angle θ2 of the cut edge 27c are both the same value, and the sheet piece 27 has a parallelogram shape as a whole. Here, the inclination angle θ1 is defined as the smaller angle between the side edge 27a and the cut edge 27b, and the inclination angle θ2 is defined as the smaller angle between the side edge 27a and the cut edge 27c. These inclination angles θ1 and θ2 can be calculated from the width W1 of the sheet piece 27 and the circumferential length Ld of the cut edges 27b and 27c in the longitudinal direction X.

[0046] Cut edge 27b has inner end 27d located on the center side of sheet piece 27 in the length direction X, and outer end 27e located on the outside of sheet piece 27 in the length direction X. Cut edge 27c has inner end 27f located on the center side of sheet piece 27 in the length direction X, and outer end 27g located on the outside of sheet piece 27 in the length direction X.

[0047] In FIG. 5, La indicates the circumferential length of the sheet piece 27, Lb indicates the maximum length of the sheet piece 27, Lc indicates the circumferential length between the inner ends 27d and 27f of the cut edges 27b and 27c, and Ld indicates the circumferential length of each of the cut edges 27b and 27c. The circumferential length La is defined as the dimension between the pair of cut edges 27b and 27c, that is, the total length of the side edge 27a. The maximum length Lb is defined as the dimension in the longitudinal direction X from the outer end 27e of the cut edge 27b to the outer end 27g of the cut edge 27c, that is, the total length of the sheet piece 27. The circumferential length Lc is defined as the dimension in the longitudinal direction X from the inner end 27d of the cut edge 27b to the inner end 27f of the cut edge 27c, that is, the dimension in the longitudinal direction X of the portion of the sheet piece 27 where the cut edges 27b and 27c do not exist. The circumferential length Ld of each of the cutting edges 27b, 27c is defined as the dimension in the longitudinal direction X from the inner ends 27d, 27f to the outer ends 27e, 27g of each of the cutting edges 27b, 27c.

[0048] All of the sheet pieces 27 have the same circumferential length La. For example, when the circumferential length of the belt 23 is 400 cm, the grounding sheet 26 is made up of three sheet pieces 27 as shown in FIG. 1, and the circumferential length La of each sheet piece 27 is equal to the circumferential length of the belt 23 divided into three.

[0049] The number of sheet pieces 27 constituting the grounding sheet 26 can be changed as necessary as long as it is two or more, but taking into consideration the storage properties of the sheet pieces 27 and the ease of application, it is preferable that the maximum length Lb of the sheet pieces 27 be 250 cm or less.

[0050] Here, the sheet piece 27 immediately after cutting the sheet roll 25 shown in FIG. 4 has a tendency to return to a roll shape. This tendency becomes greater as the remaining amount of the sheet roll 25 decreases and the diameter becomes smaller. Since such a tendency impedes the work of attaching the sheet piece 27 to the belt 23, it is preferable to store the sheet piece 27 in a flat state until the tendency disappears. However, if the maximum length Lb of the sheet piece 27 is excessively large, a large storage space is required. In addition, the sheet piece 27 (ground sheet 26) needs to be attached to the belt 23 under tension, but if the sheet piece 27 is excessively long, it is difficult to handle for one person to perform the work. In order to prevent these inconveniences, it is preferable that the maximum length Lb of the sheet piece 27 is 250 cm or less.

[0051] However, if the circumferential length La or maximum length Lb of the sheet piece 27 is made excessively small, the tire 1 may come into contact with two or more sheet pieces 27 adjacent to each other in the circumferential direction C of the belt 23 at the same time, and two or more sheet pieces 27 may be torn or damaged at the same time. Therefore, it is preferable to set the circumferential length Lc between the inner ends 27d, 27f of the cut edges 27b, 27c to be larger than the contact length GL of the tire 1 (see FIG. 6A) so that the cut edges 27b, 27c at both ends of the sheet piece 27 do not overlap in the longitudinal direction X.

[0052] 6A, the contact length GL means the dimension in the circumferential direction C of the contact area 1a where the tire 1 is in close contact with the belt 23 when the tire 1 is placed on the belt 23 with a predetermined load applied thereon. The reference contact length GL may be the contact length of the tire with the largest tire diameter among multiple types of tires 1 tested by the tire testing machine 10, or a different contact length may be used for each tire 1.

[0053] Setting the lengths La to Lc of the sheet pieces 27 as described above makes it possible to prevent the tire 1 from simultaneously contacting the cut edges 27b, 27c at both ends of the sheet piece 27. This makes it possible to prevent two or more sheet pieces 27 adjacent to each other in the circumferential direction C of the belt 23 from being torn or damaged at the same time. Moreover, it is possible to prevent an excessive increase in the number of sheet pieces 27 attached to the belt 23.

[0054] The circumferential length Ld of the cut edges 27b, 27c is related to the inclination angles θ1, θ2 of the cut edges 27b, 27c described above. It is preferable to set the circumferential length Ld so that the ratio (Ld / W1) of the circumferential length Ld to the width W1 of the sheet piece 27 is 0.5 or more. If these ratios are made too small, the extension direction of the cut edges 27b, 27c becomes close to the width direction W of the belt 23 (sheet piece 27). In this case, during a test in a slip angle-applied state (see FIG. 6B) in which the tire 1 is inclined with respect to the circumferential direction C of the belt 23, the load on the sheet piece 27 due to the shear force between the tire 1 increases, and the sheet piece 27 may peel off from the cut edges 27b, 27c. In order to prevent such inconvenience, it is preferable that the cut edges 27b, 27c of the sheet piece 27 are inclined with respect to the circumferential direction C, and it is more preferable that the ratio of the circumferential length Ld to the width W1 is 0.5 or more.

[0055] Next, there will be described a method for forming the belt (road surface portion) 23 having the ground contact sheet 26 made up of a plurality of sheet pieces 27. In the following description, the three sheet pieces may be referred to as 27A, 27B, and 27C.

[0056] 4, sheet roll 25 is cut to a predetermined length La and at inclination angles θ1 and θ2 to form a plurality of sheet pieces 27. The number of sheet pieces 27 formed is greater than the number required to form ground sheet 26, and it is preferable to store undamaged, unused sheet pieces 27 spread out flat until they no longer tend to be curved into a roll.

[0057] 1 and 2, the sheet pieces 27A to 27C that have been freed from any curved tendency are aligned and attached to the entire circumference of the center of the width direction W of the outer surface 23e of the belt 23. Specifically, the sheet piece 27A is attached to the belt 23 along the circumferential direction C, and then the sheet piece 27B is attached from the end of the length direction X of the sheet piece 27A along the circumferential direction C, and then the sheet piece 27C is attached from the end of the length direction X of the sheet piece 27B along the circumferential direction C. Adjacent sheet pieces 27A to 27C are attached so that their cut edges 27b, 27c butt up against each other.

[0058] In this way, the belt (road surface portion) 23 having the ground contact sheet 26 made up of the multiple sheet pieces 27A to 27C is completed.

[0059] The sheet piece 27 needs to be attached under tension. Therefore, the sheet pieces 27A to 27C are attached at the curved portion 23c or 23d of the belt 23 supported by the rollers 21A and 21B. In addition, when the sheet piece 27 is long, the sheet piece 27 is difficult to handle, and two or more workers are required. However, the sheet piece 27 of this embodiment is 250 cm or less, so it is easy to handle even for one worker. Therefore, even one worker can attach the sheet piece 27 while applying tension by, for example, holding one end of the sheet piece 27 and pulling the other end, thereby improving the workability of attaching the sheet piece 27.

[0060] When testing the tire 1, the tire 1 mounted on the wheel 2 is attached to the support part 16 which has been moved away from the rolling device 20. After that, the support part 16 is lowered by the load applying part 17, and the tire 1 is placed on the ground contact sheet 26 as shown in Fig. 2. In this state, the motors 22A and 22B are driven to rotate the belt 23.

[0061] When checking the wear characteristics of tire 1 during straight-line driving, as shown in Fig. 6A, the circumferential direction C of belt 23 (see Fig. 1) is aligned with the circumferential direction of tire 1, and the slip angle α (see Fig. 6B) is set to 0 degrees. When checking the cornering characteristics of tire 1, as shown in Fig. 6B, tire 1 is tilted with respect to the circumferential direction C of belt 23 (see Fig. 1), and a predetermined slip angle α is applied.

[0062] When checking the cornering characteristics, a force F acting on the tire 1 in the traveling direction (circumferential direction C of the belt 23) acts on the tire 1, and a force acting in the opposite direction to the force F acts on the belt 23. If this force is excessively applied to the cut edges 27b, 27c, the cut edges 27b, 27c may roll up and the sheet piece 27 may peel off from the belt 23. However, in this embodiment, the cut edges 27b, 27c are inclined, and the ratio (Ld / W1) of the circumferential length Ld to the width W1 of the cut edges 27b, 27c is set to 0.5 or more. Therefore, in the joint portion where the cut edges 27b, 27c of the adjacent sheet pieces 27A to 27C are butted against each other, a portion protruding from the ground contact area 1a of the tire 1 and not coming into contact with the tire 1 can be secured. Therefore, peeling of the sheet piece 27 caused by testing the tire 1 can be suppressed.

[0063] On the other hand, the ground contact sheet 26 may be torn or damaged when a strong load is applied from the tire 1. In contrast, in this embodiment, the ground contact sheet 26 is divided into a plurality of sheet pieces 27. Therefore, even if a strong force is applied to the ground contact sheet 26 during testing and some of the sheet pieces 27 are torn or damaged, the ground contact sheet 26 constituting the road surface portion can be repaired by simply replacing only the torn or damaged sheet piece 27. Furthermore, if the ground contact sheet 26 is composed of a single continuous sheet, there is a possibility that tears will be chained over a wide range in the circumferential direction. However, in this embodiment, even if one sheet piece 27 is torn, the tears will not be chained to the adjacent sheet pieces 27 in the circumferential direction, so that the ground contact sheet 26 can be prevented from being torn over a wide range.

[0064] Specifically, when the ground contact sheet 26 is broken or damaged, one of the multiple sheet pieces 27A-27C that is broken or damaged is peeled off from the belt 23. Thereafter, an unused, undamaged sheet piece 27 that has been cut in advance is affixed to the portion of the belt 23 from which the sheet piece 27 was peeled off. This completes the repair of the ground contact sheet 26 that constitutes the road surface portion.

[0065] The road surface portion forming method and tire testing machine 10 configured in this manner have the following features.

[0066] The ground contact sheet 26 attached to the belt 23 that constitutes the road surface portion is composed of multiple sheet pieces 27 divided in the circumferential direction C. Therefore, even if one sheet piece 27 is torn or damaged due to the load from the tire 1, repairs can be performed by simply replacing only the torn or damaged sheet piece 27. Moreover, since the divided sheet pieces 27 are short, the workability of attachment can be improved. In addition, the replacement range and replacement time can be minimized, so that the operating time for testing can be increased.

[0067] The multiple sheet pieces 27 are all of the same type, with the same circumferential length La. This improves workability when cutting the sheet roll 25 to form the sheet pieces 27. It also improves workability when attaching the sheet pieces 27 to the belt 23 to form a new grounding sheet 26 and when replacing a broken or damaged sheet piece 27.

[0068] The maximum length Lb of the sheet piece 27 is 250 cm or less. Therefore, the storage space for the preformed sheet piece 27 can be reduced, and the sheet piece 27 can be stored in a flat, stretched state. Moreover, since the dimensions are optimal for handling by a single worker, the sheet piece 27 can be reliably attached to the belt 23 with tension applied.

[0069] Cut edges 27b, 27c at both ends of the sheet piece 27 are inclined with respect to the circumferential direction C of the belt 23. Therefore, during a test with the slip angle α applied, the shear force applied to the joints (cut edges 27b, 27c) of the adjacent sheet pieces 27A to 27C can be reduced. This makes it possible to prevent the sheet piece 27 from peeling off from the joints.

[0070] The inclination angles θ1, θ2 of the pair of cut edges 27b, 27c are the same. In other words, the sheet piece 27 is of only one type, which has the same length and shape. This improves the storability of the preformed sheet piece 27. In addition, when attaching, there is no need to select a specific sheet piece 27, and the sheet piece 27 will not be placed in an incorrect position, improving the ease of attachment.

[0071] The sheet piece 27 is sized so that the cut edges 27b, 27c at both ends do not overlap in the circumferential direction C of the tire 1. This can prevent the tire 1 from contacting the ground across the cut edges 27b, 27c at both ends. As a result, it can prevent two or more adjacent sheet pieces 27A-27C from being torn or damaged at the same time due to the load from the tire 1.

[0072] Of the inner ends 27d, 27f of the cut edges 27b, 27c at both ends, the circumferential length Lc from one to the other is longer than the contact length GL of the tire 1. This makes it possible to prevent the tire 1 from contacting the ground across the cut edges 27b, 27c at both ends. As a result, it is possible to prevent two adjacent sheets of the multiple sheet pieces 27A-27B from being torn or damaged at the same time due to the load from the tire 1.

[0073] The ratio of the circumferential length Ld of the cut edges 27b, 27c to the width W1 is set to be 0.5 or more. Therefore, a region where the tire 1 does not contact the ground can be secured at the joint portion where the cut edges 27b, 27c of the adjacent sheet pieces 27A to 27C are butted together. This makes it possible to prevent the sheet piece 27 from peeling off from the joint portion due to the load from the tire 1.

[0074] Second embodiment 7A and 7B show a sheet piece 27 used in a tire testing machine of a second embodiment. This second embodiment differs from the first embodiment in that the circumferential length Ld of the cut edges 27b, 27c of the sheet piece 27 is longer than the contact length GL of the tire 1 (Ld>GL). More specifically, the ratio of the circumferential length Ld of the cut edges 27b, 27c to the width W1 of the sheet piece 27 is set to 1.

[0075] In the second embodiment thus configured, the circumferential length Ld of the cut edges 27b, 27c is longer than the contact length GL of the tire 1. Therefore, when the tire 1 is positioned on the joint portion where the cut edges 27b, 27c of the adjacent sheet pieces 27A to 27C are butted together, the joint portion can have a long portion that protrudes from the contact region 1a of the tire 1 in the circumferential direction C and does not receive load from the tire 1. This can significantly prevent the sheet piece 27 from peeling off from the joint portion.

[0076] Third embodiment 8 shows a tire testing machine 10 of a third embodiment. The tire testing machine 10 of the third embodiment differs from the tire testing machine 10 of the first embodiment in that the road surface portion of the rolling device 20 is configured with a drum 30 that can be rotated by a motor (not shown). The drum 30 shown in FIG. 8 is a cylindrical member made of wood or stainless steel, and has a sufficiently large radius of curvature compared to the tire 1.

[0077] In this drum-type tire testing machine 10, the ground contact sheet 26 is also attached to the entire circumference of the drum (road surface portion) 30. The ground contact sheet 26 is composed of a plurality of sheet pieces 27 divided in the circumferential direction C of the drum 30. This makes it possible to obtain the same functions and effects as the first embodiment.

[0078] The road surface portion forming method and tire testing machine 10 of the present invention are not limited to the configurations of the above-described embodiments, and various modifications are possible.

[0079] For example, the circumferential lengths La of the multiple sheet pieces 27 may be different from one another. The inclination angles θ1, θ2 of the cut edges 27b, 27c at both ends of the sheet piece 27 may be different. The cut edges 27b, 27c are not limited to being straight, and may be slightly curved as long as they are configured to gradually widen outward in the circumferential direction C (length direction X) from the inner ends 27d, 27f toward the outer ends 27e, 27g. In addition, the cut edges 27b, 27c at both ends of the sheet piece 27 may be perpendicular to the circumferential direction C of the belt 23 and extend along the width direction W of the belt 23. [Explanation of symbols]

[0080] 1. Pneumatic tires 1a Ground area 2 Wheels 10 Tire testing machine 15 Support device 16 Support part 17 Load application section 20 Rolling device 21A, 21B Roller 22A, 22B Motor 23 Belt (road surface) 23a, 23b flat part 23c, 23d Curved section 23e External surface (running surface) 23f Inside 25 sheet roll 26 Grounding Sheet 26a Seat body 26b Polishing section 26c Adhesive part 27 Sheet Piece 27a Side edge 27b, 27c Cutting edge 27d inner end 27e outer edge 27f inner end 27g outer end 30 Drum (road surface) La Circumferential length of sheet piece Lb Maximum length of sheet piece Lc Circumferential length of the part where no cutting edge exists Ld Circumferential length of the cutting edge W Sheet width θ1,θ2 Inclination angle of cutting edge α Slip angle

Claims

1. a plurality of sheet pieces to be attached to a running surface on which a pneumatic tire rolls, among the road surface portion made of an endless body, are formed to have a length shorter than a circumferential length, which is the entire circumferential length of the running surface, and a pair of cut edges formed at both ends in the circumferential direction are formed so as to be inclined with respect to the circumferential direction on the running surface; The sheet pieces are aligned and attached to the entire circumference of the running surface to form the road surface portion having a ground contact sheet made up of the plurality of sheet pieces. A method for forming a road surface of a tire testing machine.

2. 2. The method for forming a road surface portion for a tire testing machine according to claim 1, wherein the plurality of sheet pieces are formed so that the maximum length (Lb) in the circumferential direction is 250 cm or less.

3. The method for forming a road surface portion for a tire testing machine according to claim 1 or 2, wherein the sheet piece is formed so that the pair of cut edges have the same inclination angle.

4. The method for forming a road surface portion for a tire testing machine according to claim 3 , wherein the sheet piece is formed with a dimension such that the pair of cut edges do not overlap in the circumferential direction.

5. 5. A method for forming a road surface portion of a tire testing machine as described in claim 3 or 4, wherein the sheet piece is formed so that the circumferential length (Lc) between the inner ends of the pair of cut edges located toward the circumferential center of the sheet piece is longer than the contact length of the pneumatic tire.

6. 6. The method for forming a road surface portion of a tire testing machine according to claim 3, wherein the sheet piece is formed so that a circumferential length (Ld) of the cut edge is longer than a contact length of the pneumatic tire.

7. A method for forming a road surface portion of a tire testing machine described in any one of claims 1 to 6, wherein the multiple sheet pieces are formed so that the circumferential length (La) between the pair of cutting edges is longer than the contact length of the pneumatic tire.

8. The method for forming a road surface portion for a tire testing machine according to claim 1 , wherein the plurality of sheet pieces are formed so that the lengths (La) in the circumferential direction are the same.

9. Peeling off only the damaged sheet piece from among the plurality of sheet pieces attached to the road surface portion; attaching a preformed, undamaged, unused sheet piece to the portion of the road surface from which the sheet piece has been peeled off; A method for forming a road surface portion of a tire testing machine according to any one of claims 1 to 8.

10. A road surface portion that is a rotatable endless body and has a running surface on which the pneumatic tire rolls; A grounding sheet attached to the entire circumference of the running surface; Equipped with The ground contact sheet is composed of a plurality of sheet pieces divided in the circumferential direction of the road surface portion, a pair of cut edges formed on both ends of the sheet piece in the circumferential direction are inclined with respect to the circumferential direction on the running surface; Tire testing machine.

11. A tire testing machine as described in Claim 10, wherein the circumferential length (La) between a pair of cut edges formed at both circumferential ends of the sheet piece is longer than the contact length of the pneumatic tire.

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