Calculating the inner diameter of the wheel part reflecting the thermal expansion between different materials and the method of manufacturing the wheel

Abstract

The present invention relates to a method for calculating the inner diameter of a wheel part and a method for manufacturing a wheel that reflects thermal expansion between different materials. By processing the inner diameter of the wheel part to reflect thermal expansion, a bearing part (aluminum, steel, etc.) and a wheel part (urethane, MC Nylon, etc.), which are made of different materials with different coefficients of thermal expansion, are firmly joined by fitting. The method for calculating the inner diameter of a wheel portion and manufacturing a wheel reflecting thermal expansion between different materials according to the present invention comprises: a first step of obtaining a dimensional change amount (A) according to the material and temperature of the inner bearing portion; a second step of obtaining a dimensional change amount (B) according to the material and temperature of the outer wheel portion, which is a different material having a different coefficient of thermal expansion from the bearing portion; a third step of obtaining a thickness correction dimensional change amount (C) of the wheel portion; a fourth step of obtaining a thermal expansion weighting factor (D) by adding the dimensional change amount of the bearing portion (A) obtained in the first step, the dimensional change amount of the wheel portion (B) obtained in the second step, and the thickness correction dimensional change amount of the wheel portion (C) obtained in the third step; and a fifth step of determining the value obtained by subtracting the thermal expansion weighting factor (D) obtained in the fourth step from the design inner diameter (E) of the wheel portion as the processed inner diameter (F) of the wheel portion, and then processing the inner diameter of the wheel portion. The method includes a 20th step of fitting and joining a bearing part inside the wheel part processed through the 10th step above, wherein the 20th step involves heating the wheel part processed through the 10th step to a heating temperature reflected in the method for calculating the inner diameter of the wheel part reflecting the thermal expansion between the dissimilar materials to induce thermal expansion of the wheel part, and then cooling after fitting and joining the bearing part inside the wheel part.

Description

Technology Field

[0001] The present invention relates to a method for calculating the inner diameter of a wheel part and a method for manufacturing a wheel that reflects thermal expansion between different materials. More specifically, it relates to a method for calculating the inner diameter of a wheel part and a method for manufacturing a wheel that firmly interlocks a bearing part (aluminum, steel, etc.) and a wheel part (urethane, MC Nylon, etc.) made of different materials having different coefficients of thermal expansion. Background Technology

[0002] This section provides background information related to the content of the present application and does not necessarily constitute prior art.

[0003] The Baggage Handling System (BHS) is a system that provides a service for the rapid and accurate sorting and transportation of checked baggage—which passengers do not carry on board—within the airport terminal to the aircraft they are boarding (or from the aircraft to the airport terminal).

[0004] When departure baggage is placed on the check-in counter by a passenger, the baggage handling system weighs it and transfers it to a collection conveyor, where it performs security screening. The system then loads the baggage that has passed screening onto trays and transports it to the departure area where the passenger will board the aircraft.

[0005] In such baggage handling systems, wheels are used for various purposes, such as transmitting power to trays, transporting trays, transmitting power to various conveyor belts, adjusting tension, or controlling belt skewness.

[0006] Conventional wheels are composed of a bearing part made of metal (aluminum, steel, etc.) and a wheel part made of non-metal (urethane, MC Nylon, polymer compounds, etc.), taking into consideration power transmission and driving noise.

[0007] Registered Patent No. 10-1716484 describes a wheel for a baggage handling facility comprising: a hub; a coating film formed by coating a wheel coating composition for a baggage handling facility using a polyurethane polymer on the outer circumferential surface of the hub; and a bearing assembled on the inner circumferential surface of the hub.

[0008] Registered Patent No. 10-1516799 describes a structure in which a ring-shaped auxiliary wheel made of metallic material is inserted and coupled to the center outer diameter of the outer circumference of a main body wheel made of plastic material.

[0009] Registered Patent No. 10-0320066 describes a method for manufacturing a cushioning wheel in which a polymer material is injection-molded and bonded as a cushioning material to the outer periphery of an inner wheel made of iron or non-ferrous metal, the method comprising: a first step of applying an adhesive to the outer periphery of the inner wheel first, drying it with hot air at 100 to 195°C, applying an adhesive a second time on top thereof, and drying it with hot air at the same temperature; and a second step of inserting the inner wheel coated with adhesive from the first step into the center of a circular injection mold while heated to 180 to 200°C, injecting molten polyurethane resin into the mold for 10 to 120 seconds at a pressure of 50 to 120 kg / cm² onto the outer periphery of the inner wheel, and then cooling it to 60 to 70°C to form the wheel. The method for manufacturing a buffer wheel includes a third process of applying high frequency to the metal inner wheel of the buffer wheel formed from the second process above using a high frequency induction heating device to heat it to 180 to 200°C for 2 to 3 seconds.

[0010] In addition, there are wheels in which the bearing and wheel sections are assembled for consideration of productivity and maintenance. In this case, the bearing and wheel sections cannot be joined using traditional welding methods. Although specialized technologies for joining dissimilar materials are being developed, they offer poor productivity, and when applied to wheels, the weak bonding strength between the bearing and wheel sections leads to the detachment of the wheel section or causes driving noise. Prior art literature

[0011] Registered Patent No. 10-1716484 Registered Patent No. 10-1516799 Registered Patent No. 10-0320066 The problem to be solved

[0012] The present invention aims to solve the aforementioned problems by providing a method for calculating the inner diameter of a wheel part reflecting thermal expansion between dissimilar materials and a method for manufacturing a wheel, wherein the inner diameter of the wheel part is processed to reflect thermal expansion, thereby firmly fitting together a bearing part (aluminum, steel, etc.) and a wheel part (urethane, MC Nylon, etc.) of dissimilar materials having different coefficients of thermal expansion. means of solving the problem

[0013] A method for calculating the inner diameter of a wheel portion and manufacturing a wheel reflecting thermal expansion between different materials according to the present invention comprises: a first step of obtaining a dimensional change amount (A) according to the material and temperature of the inner bearing portion; a second step of obtaining a dimensional change amount (B) according to the material and temperature of the outer wheel portion, which is a different material having a different coefficient of thermal expansion from the bearing portion; a third step of obtaining a thickness correction dimensional change amount (C) of the wheel portion; a fourth step of obtaining a thermal expansion weighting factor (D) by adding the dimensional change amount of the bearing portion (A) obtained in the first step, the dimensional change amount of the wheel portion (B) obtained in the second step, and the thickness correction dimensional change amount of the wheel portion (C) obtained in the third step; and a fifth step of determining the value obtained by subtracting the thermal expansion weighting factor (D) obtained in the fourth step from the design inner diameter (F) of the wheel portion as the inner diameter (E) of the wheel portion. The method includes a 20th step of fitting and coupling a bearing part inside the wheel part processed through the 10th step above, wherein the 20th step is characterized by maintaining the wheel part processed through the 10th step at a heating temperature condition reflected in the method for calculating the inner diameter of the wheel part reflecting the thermal expansion between the dissimilar materials, thereby inducing thermal expansion of the wheel part, fitting and coupling the bearing part inside the wheel part, and then cooling.

[0014] The method for calculating the inner diameter of a wheel portion and manufacturing a wheel reflecting thermal expansion between different materials according to the present invention comprises: a first step of calculating the inner diameter of a wheel portion in accordance with the outer diameter of a bearing portion and machining the wheel portion with the inner diameter; and a second step of fitting and coupling a bearing portion into the interior of the wheel portion machined through the first step. The first step comprises a first step of calculating a thermal expansion weighting factor by determining the dimensional change amount and the thickness correction dimensional change amount of the wheel portion, respectively, and adding them together; and a second step of determining the inner diameter of the wheel portion by subtracting the thermal expansion weighting factor obtained in the first step from the design inner diameter of the wheel portion (outer diameter of the bearing portion). The second step is characterized by maintaining the wheel portion machined through the first step at a heating temperature condition reflected when calculating the dimensional change amount of the wheel portion, thereby inducing thermal expansion of the wheel portion, fitting and coupling the bearing portion into the interior of the wheel portion, and then cooling. Effects of the invention

[0015] According to the method for calculating the inner diameter of a wheel part and the method for manufacturing a wheel that reflects thermal expansion between different materials according to the present invention, the inner diameter of the wheel part is processed to reflect thermal expansion, thereby enabling assembly without separate special equipment by firmly fitting together a bearing part (aluminum, steel, etc.) and a wheel part (urethane, MC Nylon, etc.) of different materials having different coefficients of thermal expansion, thus improving productivity.

[0016] In addition, since the wheel section maintains a solid connection with the bearing section, it does not cause driving noise and prevents the derailment of trays, thereby improving the reliability of the baggage handling system (BHS) and enhancing work efficiency by improving the working environment for baggage handling system operators.

[0017] In addition, when the thermal expansion of the bearing part is taken into account along with the wheel part, the heat generation characteristics of the wheel during use are considered. Even if the wheel part generates heat and causes thermal deformation of the wheel and bearing parts, the bonding strength between the wheel and bearing parts can be maintained, ultimately resolving issues such as wheel detachment and driving noise.

[0018] In addition, the localization of ICS (Individual Carrier System) components for baggage handling systems can also contribute to national development. Brief explanation of the drawing

[0019] FIG. 1 is a process diagram for calculating the inner diameter of a wheel part and manufacturing a wheel reflecting thermal expansion between different materials according to Example 1 of the present invention. FIG. 2 is a process diagram for calculating the inner diameter of a wheel part and manufacturing a wheel reflecting thermal expansion between different materials according to Example 2 of the present invention. FIG. 3 is a diagram of a wheel configuration for explaining the present invention. Specific details for implementing the invention

[0020] In the following description of the present invention, specific descriptions of related known functions or configurations will be omitted if it is determined that such descriptions would unnecessarily obscure the essence of the invention. Furthermore, the terms described below are defined in consideration of their functions within the present invention, and these definitions may vary depending on the intentions or practices of the user or operator. Therefore, such definitions should be based on the content throughout this specification.

[0021] First, as shown in FIG. 3, the wheel manufactured according to the present invention is described as follows: the wheel (10) is composed of a bearing part (11) and a wheel part (12), the bearing part (11) is made of aluminum, steel, etc., and the wheel part (12) is made of urethane, MC Nylon, etc. The present invention relates to the combination of different materials having different coefficients of thermal expansion, and is not limited to the aforementioned materials.

[0022] The factors used in the mathematical formula of the present invention are as follows.

[0023] Lb: outer diameter of the bearing part (11), Lw: inner diameter of the wheel part (11), W: width of the wheel part (12), α: coefficient of thermal expansion according to material

[0024] <Example 1>

[0025] As shown in FIG. 1, this embodiment incorporates the thermal expansion of the bearing portion (11) along with the wheel portion (12), and the specific method is as follows.

[0026] 1. Calculation of the amount of dimensional change (A) during use of the bearing part.

[0027] [Mathematical Formula 1]

[0028] A = α*(T2-T1)*Lb

[0029] (A: dimensional change amount by material, α: coefficient of thermal expansion by material, T2: maximum temperature when wheel is driven (e.g., 50℃), T1: minimum temperature when wheel is stopped (e.g., 18℃), Lb: outer diameter of the bearing part (11))

[0030] The amount of dimensional change during use of the bearing part (11) is calculated using the above [Mathematical Formula 1].

[0031] To briefly explain the background of Equation 1, the coefficient of thermal expansion is an inherent property of a material and is classified into the coefficient of volume expansion and the coefficient of linear expansion depending on the increase in volume or length when the temperature rises by 1°C; the greater the change in temperature, the greater the change in length. If the temperature of a solid changes by ΔT (=Tmax-Tmin), and the change in length of the solid, which had an initial length of L1, is denoted as ΔL, then since ΔL is proportional to ΔT, it can be expressed by the following equation.

[0032] ΔL = α*L1*ΔT

[0033] In this equation, the proportionality constant α is called the coefficient of linear expansion, and the change in solid length, ΔL, can be determined.

[0034] And, the representative coefficients of linear expansion for each material are as follows.

[0035] Material classification Thermal expansion coefficient (α) by material Still 12.7*10^-6 aluminum 23.8*10^-6 Urethane 180*10^-6 MC Nylon 140*10^-6

[0036] 2. Calculation of the change in dimensions of the wheel part (B).

[0037] [Mathematical Formula 2]

[0038] B = α*(Tmax-Tmin)*Lw

[0039] (B: Dimensional change by material, α: Thermal expansion coefficient by material, Tmax: Heating temperature, Tmin: Cooling temperature, Lw: Inner diameter of the wheel)

[0040] The amount of change in dimensions (B) of the wheel part (12) is calculated using the above mathematical formula 2.

[0041] 3. Calculation of the change in the thickness correction dimension (C) of the wheel part.

[0042] [Mathematical Formula 3]

[0043] C = α*(Tmax-Tmin)*2W^ε

[0044] (C: change in thickness correction dimension of the wheel part, α: coefficient of thermal expansion by material, Tmax: heating temperature, Tmin: cooling temperature, W: thickness, ε: constant for calculating the wheel part thickness correction index (ε = 0.6). Here, the thickness can also be calculated as outer diameter minus inner diameter, in which case 2W in the above mathematical formula 2 is used as W.) The above constant must be raised to a power less than 1 to prevent the calculation of the change amount from becoming too large when the thickness of the wheel part is too thick and to reduce the influence of the change amount, and 0.6 is a constant derived as an optimal value.

[0045] The change amount (C) of the thickness correction dimension of the wheel part (12) is calculated using the above mathematical formula 3.

[0046] 4. Calculation of thermal expansion weight (D).

[0047] The thermal expansion weight (D) is calculated by adding the dimensional change amount (A) of the bearing part (11) obtained in the above process, the dimensional change amount (B) of the wheel part (12), and the thickness correction dimensional change amount (C) of the wheel part (Equation 4).

[0048] The thermal expansion weight (D) takes into account both the thermal expansion deformation of the bearing part (11) and the wheel part (12).

[0049] [Mathematical Formula 4]

[0050] D = A+B+C

[0051] 4. Calculation of the machined inner diameter (F) of the wheel part.

[0052] The design inner diameter (E, outer diameter of the bearing part (11)) of the current wheel part (12) and the thermal expansion weight (D) obtained in the previous process are subtracted (Equation 5) to obtain the machined inner diameter (F) (machined dimension) of the wheel part (12). That is, the machined inner diameter (F) of the wheel part (12) reflects the thermal expansion magnitude at the heating temperature of the wheel part (12) and the thermal expansion magnitude of the bearing part (11) during use.

[0053] [Mathematical Formula 5]

[0054] F = ED

[0055] The inner diameter of the wheel part (12) calculated in this way is smaller than the outer diameter of the bearing part (12).

[0056] The method for manufacturing a wheel according to the present invention is as follows.

[0057] 1. Wheel section machining.

[0058] a. Heating (processing)

[0059] Since the inner diameter of the wheel part (12) is smaller than the outer diameter of the bearing part (11), assembly is difficult, and the wheel part (12) is processed (heated) to assemble the two (11, 12).

[0060] The heating temperature at this time is the temperature reflected when calculating the inner diameter of the wheel part described above, and is a temperature at which the inner diameter of the wheel part (12) becomes larger than the outer diameter of the bearing part (11) so that the bearing part (11) can be fitted and coupled inside the wheel part (12), and is a temperature that does not cause deformation of the wheel part (12), and since it varies depending on the material, it cannot be limited to a numerical value (e.g., 24 degrees ~ 80 degrees).

[0061] That is, when the wheel part (12) is heated to the above heating temperature, the inner diameter of the wheel part (12) is deformed to a size larger than the outer diameter of the bearing part (11), and the two (11, 12) are changed to a state where assembly is possible.

[0062] B. Assembly (insertion, interference fit).

[0063] After taking the wheel part (12) out of the oven, the bearing part (11) is fitted and connected to fit the inner diameter.

[0064] C. Cooling.

[0065] After assembling the bearing part (11) and the wheel part (12), they are cooled (a separate cooling unit may also be used if necessary). When this happens, the wheel part (12) undergoes thermal deformation, causing its inner diameter to decrease and become firmly connected to the circumference of the bearing part (11).

[0066] A specific example of this embodiment is described as follows.

[0067] When manufacturing a wheel by assembling a bearing part (11) made of steel with an outer diameter of 220 mm and a wheel part (12) made of MC Nylon with an outer diameter of 250 mm and an inner diameter of 220 mm, a heating temperature (e.g., 70°C) and a cooling temperature (e.g., 21°C) are determined.

[0068] By the method described above, the change in dimensions of the bearing part (11), the change in dimensions of the wheel part (12), and the change in dimensions of the thickness correction of the wheel part (C) (e.g., 0.09, 1.501, 0.053) are each calculated, and the thermal expansion weight (1.644) is calculated by adding them, and then the thermal expansion weight is subtracted from 220 to determine the inner diameter of the wheel part (12) as 218.36 (=220-1.644), and the inner diameter of the wheel part (12) is machined to match this inner diameter.

[0069] Place the wheel part (12) inside the oven and heat it at 60 degrees for 40 to 70 minutes (since the temperature and time vary depending on the material, the above temperature and time are just examples).

[0070] In this way, the inner diameter of the wheel part (12) increases, and the bearing part (11) can be fitted and assembled inside.

[0071] Afterward, the temperature is lowered to a cooling temperature. Accordingly, as the temperature is lowered to a cooling temperature, the wheel portion (12) undergoes thermal deformation, and this thermal deformation is a shrinkage deformation that is firmly joined to the outer diameter of the bearing portion (11).

[0072] <Example 2>

[0073] As shown in FIG. 2, this embodiment considers only the thermal expansion of the wheel portion (12) without considering the thermal expansion of the bearing portion (11), and this is possible when assembling the bearing portion (11) and the wheel portion (12) under temperature conditions where the bearing portion (11) does not undergo thermal deformation or undergoes thermal deformation within an error range.

[0074] The method for calculating the machined inner diameter (F) of the wheel part (12) is to calculate the dimensional change amount (B) and the thickness correction dimensional change amount (C) through mathematical formulas 2 and 3 included in the aforementioned embodiment 1, and to subtract the dimensional change amounts (F=ED) from the design inner diameter (E).

[0075] [Mathematical Formula 6]

[0076] B = α*(Tmax-Tmin)*Lw

[0077] (B: Dimensional change by material, α: Thermal expansion coefficient by material, Tmax: Heating temperature, Tmin: Cooling temperature, Lw: Inner diameter of the wheel).

[0078] [Mathematical Formula 7]

[0079] C = α*(Tmax-Tmin)*2W^ε

[0080] (C: change in thickness correction dimension of the wheel part, α: coefficient of thermal expansion by material, Tmax: heating temperature, Tmin: cooling temperature, W: thickness, ε: constant for calculating the thickness correction index of the wheel part (ε= 0.6)). Here, the thickness can also be calculated as outer diameter minus inner diameter, in which case 2W in the above mathematical formula 2 is used as W.

[0081] The wheel manufacturing method according to the present embodiment comprises a process of calculating the inner diameter of the wheel part by subtracting the amount of change in dimensions from the design inner diameter after calculating the amount of change in dimensions of the wheel part, a process of manufacturing the wheel part with the inner diameter, and a process of assembling the bearing part and the wheel part. Since this can be implemented from the aforementioned embodiment 1, a detailed description is omitted. Explanation of the symbols

[0082] 10: Wheel, 11: Bearing part 12 : Wheel section,

Claims

Claim 1 A method for calculating the inner diameter of a wheel portion reflecting thermal expansion between different materials, characterized by comprising: a first step of obtaining a change in dimension (A) according to the material and temperature of the inner bearing portion; a second step of obtaining a change in dimension (B) according to the material and temperature of the outer wheel portion, which is made of a different material having a different coefficient of thermal expansion from the bearing portion; a third step of obtaining a change in dimension (C) for thickness correction of the wheel portion; a fourth step of obtaining a thermal expansion weight (D) by adding the change in dimension (A) of the bearing portion obtained in the first step, the change in dimension (B) of the wheel portion obtained in the second step, and the change in dimension (C) for thickness correction of the wheel portion obtained in the third step; and a fifth step of determining the value obtained by subtracting the thermal expansion weight (D) obtained in the fourth step from the design inner diameter (E) of the wheel portion as the machined inner diameter (F) of the wheel portion. Claim 2 A method for calculating the inner diameter of a wheel portion reflecting thermal expansion between dissimilar materials, wherein the first step is characterized by calculating the change in dimensions of the bearing portion through the mathematical formula A = α*(T2-T1)*Lb (A: change in dimensions by material, α: coefficient of thermal expansion by material, T2: maximum temperature when the wheel is driven, T1: minimum temperature when the wheel is stopped, L: outer diameter). Claim 3 A method for calculating the inner diameter of a wheel portion reflecting thermal expansion between different materials, wherein, in claim 1 or claim 2, the second step is characterized by calculating the change in dimensions of the wheel portion through the mathematical formula B = α*(Tmax-Tmin)*Lw(B: change in dimensions by material, α: coefficient of thermal expansion by material, Tmax: heating temperature, Tmin: cooling temperature, Lw: inner diameter of the wheel portion). Claim 4 A method for calculating the inner diameter of a wheel portion reflecting thermal expansion between different materials, wherein the third step is characterized by obtaining the change in the thickness correction dimension (C) of the wheel portion through the above mathematical formula C = α*(Tmax-Tmin)*2W^ε (C: change in the thickness correction dimension of the wheel portion, α: coefficient of thermal expansion by material, Tmax: heating temperature, Tmin: cooling temperature, W: thickness, ε: constant for calculating the thickness correction index of the wheel portion (ε= 0.6)). Claim 5 A method for manufacturing a wheel that reflects thermal expansion between different materials, comprising: a 10th step of calculating the inner diameter of a wheel portion by means of a method for calculating the inner diameter of a wheel portion that reflects thermal expansion between different materials according to claim 1, and processing the wheel portion with the inner diameter; and a 20th step of fitting and coupling a bearing portion inside the wheel portion processed through the 10th step, wherein the 20th step is characterized by heating the wheel portion processed through the 10th step to a heating temperature reflected in the method for calculating the inner diameter of a wheel portion that reflects thermal expansion between different materials to induce thermal expansion of the wheel portion, fitting and coupling the bearing portion inside the wheel portion while in a state of thermal expansion of the wheel portion, and then cooling. Claim 6 The method comprises a 100th step of calculating the inner diameter of a wheel portion capable of assembling a bearing portion and machining the wheel portion to that inner diameter; and a 200th step of fitting and coupling a bearing portion inside the wheel portion machined through the 100th step, wherein the 100th step comprises a 110th step of calculating a thermal expansion weight (D) by adding the thickness correction dimensional change amount (C) of the wheel portion obtained in the 3rd step after calculating the dimensional change amount of the wheel portion and the thickness correction dimensional change amount (C) of the wheel portion using the following mathematical formulas 2 and 3; B = α*(Tmax-Tmin)*Lw ------------[Mathematical Formula 2](B : dimensional change amount by material, α : thermal expansion coefficient by material, Tmax : heating temperature, Tmin : cooling temperature, Lw : inner diameter of the wheel portion) C = α*(Tmax-Tmin)*2W^ε ------------[Mathematical Formula 3] (C : thickness correction dimensional change amount of the wheel portion, α : thermal expansion coefficient by material, Tmax : Heating temperature, Tmin: cooling temperature, W: thickness, ε: constant for calculating the wheel thickness correction index (ε = 0.6). Here, the thickness may be calculated as outer diameter minus inner diameter, in which case 2W in the above mathematical formula 2 is used as W.) A method for manufacturing a wheel that reflects thermal expansion between different materials, comprising a step 120 in which the value obtained by subtracting the thermal expansion weight (D) obtained in step 110 from the design inner diameter (E) of the wheel part is determined as the machined inner diameter (F) of the wheel part, and step 200 is characterized by maintaining the wheel part and bearing part machined through step 100 at a heating temperature condition reflected when calculating the dimensional change amount of the wheel part, thereby inducing thermal expansion of the wheel part, fitting and joining the bearing part inside the wheel part, and then cooling.

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