A method for calculating the width of the drum of a heavy-loaded all-steel radial tire

Abstract

The present invention discloses a method for calculating the drum width of a heavy-loaded all-steel radial tire forming drum. The calculation formula for the drum width of the forming machine is as follows: C=(2ac / (1+t))-2[L-B]-z, wherein: ac is the length of the carcass cord from the crown center to the lower end point of the tire bead; t is the elongation rate of the carcass cord of the all-steel tire; L is the length of the drum shoulder curve; B is the height of the drum shoulder curve; and z is a coefficient. By accurately calculating the width of the forming drum, it is avoided that the cost waste caused by reprocessing the forming drum due to inappropriate design of the drum width of the forming drum is avoided. And according to the characteristics of uniform distribution of the head material of the heavy-loaded all-steel radial tire, the head curve is designed to avoid the problems of material accumulation and rolling difficulty in the forming process due to uneven material distribution in the forming head, which can effectively ensure the smooth progress of the secondary forming machine project.

Description

Technical Field

[0001] The invention belongs to the technical field of tires, and in particular relates to a method for calculating the width of a heavy-load all-steel radial tire building drum. Background Art

[0002] In the Chinese tire heavy-duty market (load factor above 2.5), current heavy-duty tire manufacturers are studying the use of secondary forming machines to produce heavy-duty tires, because the tire bead collar and other parts produced by the secondary forming machine do not pile up, and the reversed carcass cord is parallel to the carcass (see Figure 1 and Figure 2 ), the features of solid pressing of the sub-mouth etc. cannot be achieved by the one-step forming machine.

[0003] The forming drum design of the secondary forming machine mainly includes the head curve design and the drum width design.

[0004] If the molding die curve is not designed properly, there will be too much material at the die, resulting in uneven transition of the molding die material and severe bulges. That is, if the die material bulges too high and is unevenly distributed, it will cause pressure adjustment during the die rolling and the die pressing will not be solid.

[0005] The head curve design of heavy-duty products is from the distribution of molding materials Figure 1 It can be seen that heavy-load products are very different from standard-load products and ordinary-load products: the main difference is that there is too much material at the nose, which makes the material too thick, and the material distribution at the nose is uneven. The shoulder position of the nose is too thick, resulting in uneven transition of the tire mouth.

[0006] References for drum width design include: bias tire drum, semi-steel radial tire drum, and flat width setting of one-step drum. However, there is no theoretical basis for the design of the drum of the secondary forming machine for heavy-duty all-steel radial tires. The error of using bias and semi-steel formulas is large. The flat width setting of the one-step forming machine is the process flat width. The value is set in the program, and the position of the spacing inside the wire ring is the position of the flat width. There is no problem of setting the drum width of the one-step forming machine, and the process flat width can be adjusted arbitrarily.

[0007] The bias tire design has large deviations in both the head curve and the width of the forming drum. Because heavy-loaded all-steel radial tires have more materials distributed at the forming machine head, the material distribution of heavy-loaded products has more layers at the head than ordinary products. Severe material stacking often leads to uneven material distribution and pressure jumps when the pressure rollers roll. In addition, the tire body stretch of the heavy-loaded all-steel wire secondary forming method is different from that of the bias tire, and the drum width calculated using the formula for the bias tire has a large error. Therefore, how to develop a method for calculating the width of the heavy-loaded all-steel wire radial tire forming drum to reduce the error is of great practical significance. Summary of the invention

[0008] The present invention aims at the characteristics of heavy-duty all-steel with many bonding material layers at the nose, according to the nose curve and the inner profile 2ac (see Figure 3 ), a method for calculating the width of a drum of a heavy-loaded all-steel radial tire secondary forming machine is proposed. This invention will fill the gap in the design of heavy-loaded all-steel radial tire forming drums in China.

[0009] The technical solution adopted by the present invention is:

[0010] A method for calculating the drum width of a heavy-load all-steel radial tire building drum, wherein the calculation formula for the drum width of the building machine is as follows:

[0011] C=(2ac / (1+t))-2[LB]-z

[0012] In the formula: ac is the length of the carcass cord from the center of the crown to the lower end point of the bead;

[0013] t is the elongation of the carcass cord of the all-steel tire;

[0014] L is the length of the drum shoulder curve;

[0015] B is the height of the drum shoulder curve;

[0016] z is the coefficient.

[0017] Furthermore, a is the center of the tread crown; c is the intersection between the horizontal extension line of the bottom of the wire ring and the tire body.

[0018] Further, L=ef, e is the tangent point between the shoulder curve of the building drum and the transverse outer plane of the building drum; f is the tangent point between the shoulder curve of the building drum and the longitudinal outer plane of the building drum.

[0019] Furthermore, B is the vertical height between the tangent point f between the shoulder curve of the building drum and the longitudinal outer plane of the building drum and the transverse outer plane of the building drum.

[0020] Furthermore, the z is constrained by the flipping angle of the steel ring during shaping, and its value is 2-12, with the maximum value being half of the steel ring width.

[0021] Furthermore, the forming drum is prepared by a secondary forming machine.

[0022] Furthermore, one forming drum of the secondary forming machine corresponds to one drum width.

[0023] Furthermore, the styles of the forming drum of the secondary forming machine are divided into: half-drum type or half-core wheel type.

[0024] Furthermore, the diameter of the forming drum is set to 595 mm, and the thickness of the internal filling rubber is 16 mm.

[0025] Furthermore, the head curve of the molding machine realizes rolling compaction of the sub-mouth by controlling the uniform distribution of materials at the head of the molding machine. By reasonably designing the height and width of the molding head curve, the material distribution at the head is controlled to be uniform, avoiding excessive accumulation of materials and avoiding the phenomenon of excessive protrusion at the sub-mouth.

[0026] Furthermore, the calculated value of the forming drum width is the same as the actual value of the forming drum width.

[0027] The beneficial effects of the present invention are:

[0028] The purpose of the present invention is to design a heavy-duty all-steel secondary forming machine drum, and to avoid the waste of cost caused by re-processing the forming drum due to inappropriate design of the drum width by accurately calculating the width of the forming drum. In addition, according to the characteristics of uniform distribution of the head material of the heavy-duty all-steel radial tire, the head curve is designed to avoid the problems of material accumulation and rolling difficulty in the forming process due to uneven material distribution in the forming head, which can effectively ensure the smooth progress of the secondary forming machine project. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the carcass turn-up and carcass cord of a tire produced by a secondary molding machine;

[0030] Figure 1 Among them, 1. carcass cord 2. wire ring 3. carcass turn-up cord.

[0031] Figure 2 It is a schematic diagram of the carcass turn-up and carcass cord of a tire produced by a one-step forming machine;

[0032] Figure 2 Among them, 1. carcass cord; 2. wire ring; 3. carcass turn-up cord.

[0033] Figure 3 It is a schematic diagram of the tire cross section;

[0034] Figure 3 1. tread; 2. belt layer; 3. sidewall; 4. inner liner; 5. carcass; 6. cushion rubber; 7. wear-resistant rubber; 8. wire mouth wrapping cloth; 9. nylon wrapping cloth; 10. wire ring; 11. upper filling rubber; 12. lower filling rubber;

[0035] Figure 3 In the figure, a is the center of the tire crown; b is the intersection of the horizontal extension line of the inner end point of the wire ring and the tire body;

[0036] c is the intersection between the horizontal extension line of the bottom of the wire ring and the carcass;

[0037] ab-the length of the carcass cord from the center of the crown to the inner end point of the bead;

[0038] ac - the length of the carcass cord from the center of the crown to the lower end of the bead;

[0039] Figure 4 It is a schematic diagram of the semi-finished product of the secondary forming drum after lamination, which contains the codes of various parts of the forming drum;

[0040] Figure 5 It is a schematic diagram of the secondary forming drum after the semi-finished product is bonded to the forming drum;

[0041] Figure 6 It is a schematic diagram of the material distribution on the shoulder of the forming machine after the semi-finished product of the secondary forming drum is bonded;

[0042] Figure 4 , Figure 5 and Figure 6 1. tread; 2. belt layer; 3. sidewall; 4. inner liner; 5. carcass; 6. cushion rubber; 7. wear-resistant rubber; 8. wire mouth wrapping cloth; 9. nylon wrapping cloth; 10. wire ring; 11. upper filling rubber; 12. lower filling rubber;

[0043] A, forming machine head width; B, forming machine head curve height; C, forming drum width; D, forming drum diameter; E, forming drum tile width; F, forming drum tile thickness; H, machine head height; R1, R2, R3, R4 are guide arcs;

[0044] Figure 7 This is a tire X-ray diagram when the drum width is set too large;

[0045] Figure 8 Is the drum width set appropriately, tire X-ray diagram;

[0046] Fig. 9 This is a tire X-ray diagram when the drum width is set too small. DETAILED DESCRIPTION

[0047] The present invention is further described below in conjunction with the accompanying drawings.

[0048] A drum width design for a heavy-loaded all-steel radial tire building drum: The process flat width of a one-step building machine for an all-steel radial tire is equivalent to the width of a building drum of a two-step building machine.

[0049] This parameter setting affects the performance of the tire. If the flat width is set too large or too small, it will affect the performance of the tire, causing an increase in tire waste or early tire damage.

[0050] If the flat width is set too small, the inner liner will be too thin, which will cause early damage during tire use. Figure 7 shown.

[0051] If the flat width is set too large, the carcass cord will bend, resulting in waste and defective products. Fig. 9 shown.

[0052] Therefore, the flat width must be set accurately to ensure that the stretch value of the carcass cord is constant. Figure 8 shown.

[0053] The flat width setting of the one-step forming machine is the process flat width. The value is set in the program, and the position of the spacing inside the wire ring is the flat width position. There is no problem of setting the drum width of the one-step forming machine, and the process flat width can be adjusted arbitrarily.

[0054] The two-step forming machine has one forming drum corresponding to one drum width. Generally, the styles of the forming drum of the two-step forming machine are divided into: half-drum type or half-core wheel type.

[0055] The calculation accuracy of the width of the forming drum of the secondary forming machine is related to the progress and development cost of the product. Generally, the cost of the forming drum is 30,000 yuan, and the processing cycle is 45 days. If the design of the secondary forming drum is unreasonable, the originally processed forming drum will be scrapped and the development cycle will be delayed.

[0056] The building drum designed in this paper has been verified through trial production and mass production. The calculation formula of the building drum width can meet the design of the building drum width of the heavy-loaded all-steel secondary forming machine. X-rays show that the carcass cord angle and cord stretch are qualified. After actual inspection, the design and calculation of the present invention can achieve accurate calculation of the building drum width of the heavy-loaded all-steel secondary forming machine. It provides a theoretical basis for determining the design of building drums of various specifications.

[0057] In addition, the economic value of this invention is that it can accurately design the heavy-duty TBR secondary forming machine drum at one time, avoiding secondary processing errors caused by inaccurate calculation of the forming drum, and ensuring the trial production and normal production of the product, shortening the product development cycle.

[0058] The setting of drum width of heavy-duty forming machine. The search for information shows that there are relevant information on the calculation formulas for drum width, including bias tire, semi-steel radial tire, and one-step forming drum width. However, there is no corresponding formula for the design of drum width of heavy-duty TBR all-steel radial tire forming machine. The error is too large to be applied when using the bias and semi-steel formulas to calculate the drum width of TBR two-step forming drum. This design introduces the design of drum width of all-steel two-step forming drum, which has been repeatedly verified and is accurate and reliable. After calculation, the width of the forming drum can be determined once, and the specific discussion is as follows:

[0059] Code Code meaning D Outer diameter A Head curve width H Head height B Nose curve height F Thickness of forming drum tile R1 Forming machine head curve connection arc R2 Guide arc R3, R4 Guide arc C Width of forming drum

[0060] pass Figure 1 and Figure 2By comparison, it can be seen that the tire carcass turn-up cords formed by the secondary method remain parallel to the carcass cords, while the tire carcass turn-up cords formed by the single method are at an angle of 35 degrees to the carcass cords.

[0061] pass Figure 3 You can see the names of the various parts of the tire section and understand how the inner contours 2ab and 2ac are defined.

[0062] pass Figure 4 It can be seen that the meaning of the codes of each part of the forming drum.

[0063] pass Figure 5 It can be used to see the condition of the semi-finished product after being bonded on the forming drum.

[0064] pass Figure 6 The material distribution of the shoulder of the enlarged forming machine head can be seen.

[0065] pass Figure 7 It can be seen from the X-ray diagram that when the drum width is too small, the carcass cord is too straight, resulting in a thin inner liner.

[0066] pass Figure 8 A normal X-ray diagram can be seen.

[0067] pass Fig. 9 It can be seen from the X-ray diagram that the carcass cord is bent when the drum width is too large.

[0068] Example 1

[0069] There are three calculation formulas for drum width: [1] drum width of bias tire forming drum, [2] drum width of flat drum of all-steel one-step forming machine, and [3] drum width of semi-steel one-step forming drum.

[0070] 【1】Calculation method of the building drum width of bias tires:

[0071] C=(2ab / (1+e1)*cos(b))-2[L*cos(b)-A]……Formula 1

[0072] C-forming machine head width;

[0073] 2ab- the cord length between the inner end points of the two wire rings, the inner contour cord length of the tire;

[0074] e1- assumed cord elongation value;

[0075] b-carcass cord angle;

[0076] L- drum shoulder curve length;

[0077] A-Drum shoulder width;

[0078] Comparative Example 2

[0079] 【2】Calculation formula for the flat drum width of the all-steel one-step forming machine:

[0080] C=(2ab / (1+t))……Formula 2

[0081] 2ab- the cord length between the inner end points of the two wire rings, the inner contour cord length of the tire;

[0082] tTBR tire carcass cord elongation;

[0083] Comparative Example 3

[0084] Semi-steel radial tire

[0085] 【3】Calculation formula for the width of semi-steel forming drum in one-step process:

[0086] C=2ab / (1+e1)-2(L+x*sin(n)-A)……Formula 3

[0087] 2ab- the cord length between the inner end points of the two wire rings, the inner contour cord length of the tire;

[0088] e1- assumed cord elongation value;

[0089] L- drum shoulder curve length;

[0090] x*sin(n)-process correction factor;

[0091] x-the distance from the outer edge of the wire ring to the machine head;

[0092] n- the torsion angle of the bead cord wrapped around the wire ring (when expanding and shaping);

[0093] A-Drum shoulder width;

[0094] The following example illustrates

[0095] like:

[0096] Calculate using formula 1

[0097] 2ab(mm) e1 L(mm) A(mm) b 762 0.02 55.2 50 90

[0098] C=736.65

[0099] Calculate using formula 3

[0100] 2ab(mm) e1 L(mm) x(mm) n(°) sin(n) A(mm) 762 0.02 55.2 13.6 3 0.14112 50

[0101] C = 711.9. Since the change of n value has a great influence on C value, the angle cannot be determined accurately. Therefore, this formula cannot be applied in TBR.

[0102] According to the relationship between 2a'b' in the material distribution diagram on the molding machine head and 2ab in the material inner contour length of the finished product material distribution diagram: 2ab / (1+e1=2a'b'

[0103] After measurement and calculation, C = 685mm (actual 668mm)

[0104] From the above calculations, it can be seen that the calculation of material distribution on the building drum is closest to the actual value, but there is still a large error.

[0105] Summary: Using the above three methods to calculate drum width will lead to carcass cord bending. Fig. 9 It can be seen that formulas 1 and 3 cannot be applied to the calculation of the width of the heavy-loaded TBR building drum. There is also a large error when calculating using material distribution.

[0106] Example 2

[0107] The laminating materials at the head of the heavy-duty all-steel radial tire forming machine are as follows: 4 layers of nylon cover cloth, 2 layers of carcass, 2 layers of bead cover cloth, lower filling rubber, upper filling rubber, inner liner, 2 types of rubber (such as Figure 3 There are 13 layers of semi-finished products with various thicknesses stacked together.

[0108] The design principle of the nose curve of the forming drum of the heavy-loaded all-steel secondary forming machine is to ensure uniform distribution of materials at the forming head and avoid excessive protrusion at the forming head that causes large deformation of the sub-mouth.

[0109] The size design of the molding machine head is as follows:

[0110] D-Outer diameter: The diameter of the 20-inch secondary forming drum is set to 595mm.

[0111] according to Figure 5 The distribution of molding materials can determine the actual effect of fitting the semi-finished product on the molding drum, and the size parameters of the molding drum can be determined through repeated calculations.

[0112] The dimensions of the forming drum are detailed in the table below: (For specific codes, see Figure 4 )

[0113]

[0114]

[0115] The following is a design formula for the drum width of a heavy-duty TBR secondary forming machine:

[0116] C=(2ac / (1+t))-2[LB]-z……Formula 4

[0117] a c-1 / 2 the inner contour cord length of the finished tire (bottom of the wire ring);

[0118] t- is the elongation of the carcass cord of the all-steel TBR tire, and the elongation of the TBR all-steel carcass is 2%;

[0119] L-drum shoulder curve length L=ef, where L is the arc curve length between ef, e is the tangent point between the forming drum shoulder curve and the transverse outer plane of the forming drum; f is the tangent point between the forming drum shoulder curve and the longitudinal outer plane of the forming drum.

[0120] B-drum shoulder curve height; specifically: the vertical height between the tangent point f between the drum shoulder curve and the longitudinal outer plane of the drum and the transverse outer plane of the drum.

[0121] z-factor. z is constrained by the flip angle of the steel ring when it is shaped, and its value ranges from 2 to 12, with the maximum value being half the steel ring width.

[0122] 2ac t L B z 769.4 0.02 55.2 14.35 4

[0123] C=668.6 (actual 668mm)

[0124] After design and production verification, Formula 4 can meet the design of the width of the heavy-duty all-steel secondary forming machine drum. X-rays show that the carcass cords are qualified and the X-ray shape meets the requirements. Figure 8 After actual testing, the calculation can achieve accurate calculation of the width of the forming drum of a heavy-loaded all-steel secondary forming machine.

[0125] The above description is not a limitation of the present invention. It should be pointed out that for ordinary technicians in this technical field, several changes, modifications, additions or substitutions can be made without departing from the essential scope of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for calculating the width of a heavy-load all-steel radial tire building drum, characterized in that: The forming drum is prepared by a secondary forming machine, and the calculation formula of the width of the forming drum is as follows: C=(2ac / (1+t))-2[LB]-z In the formula, ac is the length of the carcass cord from the center of the tread to the lower end of the bead; a is the center of the tread; c is the intersection of the horizontal extension line of the bottom of the wire ring and the carcass; t is the elongation of the carcass cord of the all-steel tire; L is the length of the drum shoulder curve, where L=ef, e is the tangent point between the drum shoulder curve and the transverse outer plane of the drum; f is the tangent point between the drum shoulder curve and the longitudinal outer plane of the drum; B is the height of the drum shoulder curve, that is, the vertical height between the tangent point f between the drum shoulder curve and the longitudinal outer plane of the drum and the transverse outer plane of the drum; z is a coefficient, which is constrained by the flipping angle of the steel ring when it is formed, and its value is 2-12, and the maximum value is half of the width of the steel ring.

2. The method for calculating the width of a heavy-load all-steel radial tire building drum according to claim 1, characterized in that: One forming drum of the secondary forming machine corresponds to one drum width.

3. The method for calculating the width of a heavy-load all-steel radial tire building drum according to claim 1, characterized in that: The styles of the forming drum of the secondary forming machine are divided into: half-drum type or half-core wheel type.

4. The method for calculating the width of a heavy-load all-steel radial tire building drum according to claim 1 is characterized in that: The head curve of the molding machine realizes the sub-mouth rolling compaction by controlling the uniform distribution of materials at the head of the molding machine.

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