Method for applying grease and assembly method for wheels with brake discs

Abstract

To provide a grease application method that can further stabilize axial force generated when tightening with a predetermined torque value compared with the case of manual tightening, and a method for assembling a wheel with a brake disc that has stable axial force and more accurately determines suitability for assembling a wheel axle.SOLUTION: The grease application method includes the steps of: quantitatively placing semi-solid grease pushed out from a nozzle of a quantitative supply device around an axis of a bolt that fastens a brake disc to a center portion of a railway wheel along a screw thread; and screwing a nut screwed onto the bolt and spreading the grease placed along the screw thread. The method for assembling a wheel with a brake disc includes: a natural length measurement step of measuring a natural length of the bolt; a grease placement step of quantitatively placing grease around an axis of the bolt; a bolt fastening step of constructing a wheel with a brake disc by tightening while the nut screwed onto each bolt is threaded to spread the grease; and an axial force confirmation step of calculating axial force of each bolt by comparing the natural length and a length of the bolt in the fastened state.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a grease application method and an assembly method for a wheel with a brake disk.

Background Art

[0002] Conventionally, mechanical elements composed of a pair of bolts and nuts are widely used as fastening means in all places.

[0003] Among them, in places where high safety and robustness are required, axial force management is performed to maintain an appropriate fastening pressure state with respect to the fastened member.

[0004] As a specific example of such axial force management, for example, a disc bolt used for a wheel with a brake disk of a high-speed railway such as the Shinkansen can be mentioned (for example, see Patent Document 1).

[0005] The disc bolt is a bolt used when fastening the wheel hub portion and the brake disk. In order to prevent the bolt or the brake disk from falling off due to loosening or breakage, it is extremely important to fasten within an appropriate axial force range that is not too large or too small.

[0006] On the other hand, it is usually difficult to fasten a bolt subject to such axial force management until it reaches a desired axial force while measuring the axial force in real time and screwing the nut. Therefore, currently, a fastening operation targeting a predetermined torque value is performed prior to the axial force inspection. That is, by utilizing the fact that the torque value has a correlation with the axial force, the nut is screwed until it reaches a predetermined torque value estimated to be within an appropriate axial force range for fastening, and then the axial force is measured in the subsequent axial force inspection to determine the adequacy of the fastening state.

[0007] In addition, the relationship between the torque value and the axial force is easily affected by individual differences between bolts and nuts, particularly the frictional force acting between the bolt and the nut, and is derived from minute differences in the surface state of the thread portion. Even when fastened with a certain torque value, the axial force exhibits individual differences for each bolt-nut pair.

[0008] Therefore, in order to reduce individual differences (variations) in axial force that occur when tightened to a predetermined torque value, grease is applied to the bolts before fastening. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2010-255665 [Overview of the project] [Problems that the invention aims to solve]

[0010] Thus, by applying grease to the conventional bolts as described above, fastening within an appropriate axial force range targeting a certain torque value is achieved.

[0011] However, the inventors, who have been involved in the maintenance of railway vehicles for many years, have gained insights into areas for further improvement by conducting further intensive research on the generation of axial force within the appropriate range that had already been met.

[0012] Specifically, regarding the grease application process, while the conventional grease application method described above involved careful control of the amount applied, the application process itself was done manually. This resulted in subtle variations in the amount of grease applied depending on the worker and the application area, and although it remained within the appropriate axial force range, it was found to significantly increase the variation in axial force due to individual differences.

[0013] The present invention has been made in view of these circumstances, and provides a grease application method that can further stabilize the axial force generated when tightening at a predetermined torque value compared to manual application.

[0014] Furthermore, the present invention also provides a method for assembling a wheel with a brake disc that provides stable axial force and allows for more accurate determination of the suitability of the wheelset assembly. [Means for solving the problem]

[0015] To solve the above-mentioned conventional problems, the grease application method according to the present invention comprises (1) the step of quantitatively applying semi-solid grease, extruded from the nozzle of a quantitative supply device, along the threads of a bolt that fastens a brake disc to the wheel center of a railway wheel, around the axis, and the step of screwing in a nut fitted onto the bolt to spread the grease applied along the threads.

[0016] Furthermore, the grease application method according to the present invention also has the following features. (2) The area where grease is placed on the threaded portion of the bolt is approximately the same as the threaded area when the fastened object is fastened with a predetermined axial force by the nut. (3) The position on which the grease is placed relative to the screw threads is at the top of the screw threads. (4) The quantitative supply device is configured such that the nozzle from which the grease is quantitatively dispensed is moved parallel to the axis of rotation in synchronization with the pitch of the threads of the bolt which rotates at a constant speed with the axis of rotation of the shaft, and the nozzle is provided with a nozzle position adjustment means for finely adjusting the position of the nozzle so that the grease is dispensed at the top of the threads.

[0017] Furthermore, the method for assembling a wheel with a brake disc according to the present invention is: (5) A method for assembling a wheel with a brake disc, wherein a brake disc is bolted to the wheel center of a railway wheel, comprising: a natural length measurement step of measuring the natural length by ultrasonic waves by bringing a probe into contact with each of a plurality of bolts to which a unique identifier has been assigned; a grease application step of quantitatively applying semi-solid grease extruded from the nozzle of a quantitative supply device along the threads around the axis of each bolt; and mounting the bolts to which the grease has been applied into a plurality of fastening holes of a temporary assembly in which the brake disc is arranged to the wheel center of the wheel, and tightening the nuts screwed onto each bolt until a predetermined seating torque is reached. The system includes a bolt fastening step in which the bolts are screwed in to spread the grease, and then tightened using the angle method to fasten the wheel and brake disc together to construct a wheel with a brake disc, and an axial force verification step in which the length of the bolts in the fastened state on the wheel with the brake disc is measured ultrasonically using the probe, the natural length of the same bolt is compared with the length of the bolt in the fastened state based on the identifier to calculate the axial force of each bolt, and if any bolts are outside the predetermined appropriate axial force range, the wheel with the brake disc is deemed a non-conforming product, while if no bolts are outside the predetermined axial force range, it is deemed a conforming product and can be used for wheelset assembly. [Effects of the Invention]

[0018] The grease application method according to the present invention includes the steps of quantitatively applying semi-solid grease, extruded from the nozzle of a quantitative supply device, along the threads of a bolt that fastens a brake disc to the wheel center of a railway wheel, and screwing in a nut fitted onto the bolt to spread the grease along the threads. Therefore, it is possible to provide a grease application method that can further stabilize the axial force generated when tightening to a predetermined torque value compared to manual application.

[0019] Moreover, according to the method for assembling a wheel with a brake disk according to the present invention, which is a method for assembling a wheel with a brake disk formed by bolt-fastening a brake disk to a hub portion of a railway wheel, a natural length measurement step of measuring a natural length by ultrasonic waves by bringing a probe into contact with each of a plurality of bolts to which unique identifiers are assigned, a grease placement step of quantitatively placing semi-solid grease extruded from a nozzle of a metering device along a thread around the axis of each bolt, a bolt fastening step of attaching each of the bolts on which the grease is placed to a plurality of fastening holes of a temporary assembly in which a brake disk is arranged at the hub portion of the wheel, screwing a nut screwed onto each bolt until a predetermined seating torque is reached to spread the grease, and further performing final tightening by an angle method to fasten the wheel and the brake disk to construct a wheel with a brake disk, and an axial force confirmation step of measuring the length of the bolt in the fastened state in the wheel with a brake disk by ultrasonic waves using the probe, calculating the axial force of each bolt by comparing the natural length and the length of the bolt in the fastened state for the same bolt based on the identifier, and if there is a bolt not within a predetermined proper axial force range, regarding the wheel with a brake disk as a non-conforming product, while if there is no bolt not within a predetermined axial force range, providing it for axle assembly as a conforming product. Therefore, it is possible to provide a method for assembling a wheel with a brake disk having a stable axial force and enabling a more accurate determination of the assembly suitability of the axle.

Brief Description of the Drawings

[0020] [Figure 1] It is an explanatory diagram schematically showing a general configuration of a wheel with a brake disk. [Figure 2] It is an explanatory diagram showing the configuration of an assembly work site of a wheel with a brake disk in a plan view. [Figure 3] It is an explanatory diagram showing the configuration of the work site in the direction of arrow G2. [Figure 4] It is a flow chart showing a series of flows of an assembly process of a wheel with a brake disk. [Figure 5] It is a front view showing the configuration of a grease placement device. [Figure 6]It is an explanatory view showing the state where the main body of the device faces from the right side. [Figure 7] It is an explanatory view showing the state of grease in the screw portion.

Embodiment for Carrying Out the Invention

[0021] The present invention provides a grease application method for fastening means composed of a pair of a bolt and a nut. More specifically, it provides a grease application method capable of further stabilizing the axial force generated during tightening at a predetermined torque value as compared with the case of manual operation.

[0022] As described above, for example, in the case of a disc bolt used for a railway wheel with a brake disc, in the conventional grease application, first, heat-resistant grease (for example, molybdenum grease) is adhered to the tip of a brush, and while rotating the bolt held in one hand around its axis, the tip of the brush is rubbed against a predetermined position on the screw portion of the bolt with the other hand to perform the operation. That is, the operation of arranging the grease on the screw portion of the bolt and the operation of spreading the arranged grease were simultaneously performed manually in one step.

[0023] On the other hand, the feature of the grease application method according to the present embodiment is that it has two steps of a grease placement step and a grease spreading step.

[0024] The grease placement step is a step of quantitatively placing the semi-solid grease extruded from the nozzle of the quantitative supply device along the thread around the axis of the bolt, and the grease spreading step is a step of screwing in the nut screwed onto the bolt to spread the grease placed along the thread.

[0025] The quantitative supply device has the function of supplying a predetermined amount of paste-like (semi-solid) grease, which can maintain its shape when discharged from a nozzle, per unit length of circumference along the threads of a bolt. For example, it can be used in which a nozzle that quantitatively dispenses grease is moved parallel to the axis of rotation, synchronized with the pitch of the threads of a bolt that rotates at a constant speed with the axis of rotation of the bolt's shaft, or a device that changes the parallel movement speed according to the rotation speed while being synchronized with the pitch of the threads.

[0026] Furthermore, while the quantitative application of grease is not particularly limited as long as it is done with sufficient precision to stabilize the axial force generated when tightening to a predetermined torque value compared to manual grease application, for example, for bolts with a pitch of about 1.5 to 2.0 mm, it is desirable to apply grease in the range of about 0.5 to 5.0 mg per centimeter in the circumferential direction along the threads. The grease application device 15 used in this embodiment, described later, is capable of adjusting the amount of grease dispensed (applied) with an accuracy of applying 1 mg per centimeter, or even higher accuracy.

[0027] Furthermore, the nozzle shape of the quantitative supply device can be such that it can be applied with at least enough accuracy to distinguish it from adjacent threads, relative to the bolt pitch and thread size, and more preferably, a nozzle shape that can be applied to the tops and flanks of the threads.

[0028] The grease used should be one that can stabilize the axial force generated when tightening to a specified torque value, compared to manual grease application. Furthermore, it is desirable to use a grease suitable for the environment of the fastening part, and in the case of bolts for fastening brake discs, for example, molybdenum grease with excellent heat resistance should be used.

[0029] Regarding the application of grease, application along the screw threads means applying the grease in a helical pattern around the shaft while synchronizing with the pitch of the screw threads. This includes not only applying the grease to the top of the screw threads or to the flank, but also applying it while spanning both of these areas.

[0030] It is preferable that the grease is spread by tightening the screwed nut. For example, if the nut is screwed in and out to spread the grease, and then the nut is screwed in and tightened again, the grease spreading process is performed separately prior to tightening, resulting in the grease being spread in different directions multiple times (forward → return → forward), which is undesirable because it is likely to cause uneven application of grease in the threaded portion.

[0031] Furthermore, this configuration eliminates quantitative inconsistencies in grease placement (application) to the threaded portion, prevents inconsistencies caused by variations in spreading method and force during application, suppresses buffering inconsistencies resulting from variations in grease application that should buffer individual differences in bolts and nuts, and makes it possible to further stabilize the axial force generated when tightening to a predetermined torque value compared to manual application (spreading with a brush).

[0032] Furthermore, after the conventional manual application process, the bolts with grease applied were placed on a balance that could accurately measure to within 10 mg and compared to their weight before application to confirm that the specified amount of grease had been applied. However, with quantitative grease dispensing, variations between bolt-nut pairs are reduced, making it possible to omit the grease quantity check and improving work efficiency.

[0033] Furthermore, in the grease application method according to this embodiment, the grease placement area on the threaded portion of the bolt may be substantially the same as the threaded area when the fastened object is fastened with a predetermined axial force using a nut.

[0034] In other words, the area on the threaded portion of the bolt that is approximately the same as the threaded area of ​​the nut when the fastened objects are fastened with a predetermined axial force is designated as the grease application area, while the areas on the tip side and base side (head side) of this grease application area are designated as non-grease application areas.

[0035] This configuration helps to stabilize axial force by suppressing uneven application caused by excess grease. Furthermore, it allows for savings on grease usage.

[0036] Furthermore, in the grease application method according to this embodiment, the placement position of the grease on the screw thread may be the top of the screw thread.

[0037] Here, the term "thread crest" includes not only the crest itself but also the upper part of the flank near the crest. In other words, it is practically difficult to place the grease strip only on the thread crest, so placing grease on the thread crest simply means placing the grease strip in a position that is in contact with the crest.

[0038] Furthermore, applying grease to the flank portion of the screw thread means applying a grease strip to the flank surface that does not come into contact with the apex.

[0039] In both cases, whether the grease is placed on the top or the flank, it is not necessary for the entire length of the grease strip to be in the top or flank position. Based on the inventors' experience, if approximately 90% of the grease is in the desired position, a stable axial force can be achieved.

[0040] Furthermore, by positioning the grease on the screw threads at the top of the threads, the distance from the nozzle becomes appropriate, allowing for precise application of the grease.

[0041] Furthermore, in the grease application method according to this embodiment, the quantitative supply device is positioned such that the nozzle, which quantitatively dispenses the grease in synchronization with the pitch of the threads of the bolt that rotates at a constant speed with the shaft axis as the axis of rotation, moves parallel to the axis of rotation, and the nozzle position adjustment means may be provided to finely adjust the position of the nozzle so that the grease is dispensed at the top of the threads.

[0042] In particular, the nozzle position adjustment means may automatically detect the position of the top of the screw threads under electrical control and adjust the nozzle position, or it may be a means of adjusting the nozzle position visually and manually via a mechanism such as a micrometer that converts large rotational movements into minute linear movements.

[0043] Furthermore, by providing such a nozzle position adjustment mechanism, the nozzle position can be finely adjusted to ensure that the grease is positioned at the top of the threads, even for bolts where the thread positions differ due to individual variations.

[0044] Furthermore, this invention also provides an assembly method for a wheel with a brake disc that provides stable axial force and allows for more accurate determination of the suitability of the wheelset assembly.

[0045] In particular, the assembly method for a wheel with a brake disc according to this embodiment is characterized by comprising a natural length measurement step for measuring the natural length of the bolts, a grease application step for quantitatively applying grease around the axis of the bolts, a bolt fastening step for constructing a wheel with a brake disc by screwing nuts fitted onto each bolt and fastening them while spreading the grease, and an axial force confirmation step for calculating the axial force of each bolt by comparing the natural length with the length of the bolt in the fastened state.

[0046] To explain each process in more detail, the natural length measurement process involves bringing a probe into contact with each of several bolts, each assigned a unique identifier, and using ultrasound to measure the natural length, which is the axial length of the bolt before it is used in the assembly of the wheel with the brake disc.

[0047] This process allows for accurate measurement of the natural length using ultrasound, thereby improving the accuracy of axial force measurement.

[0048] The grease application process involves quantitatively applying semi-solid grease, extruded from the nozzle of the quantitative supply device, along the threads around the axis of each bolt, and its contents are substantially the same as described above.

[0049] The bolt fastening process involves inserting bolts, each fitted with grease, into multiple fastening holes of a temporary assembly in which a brake disc is positioned at the wheel center of the wheel; screwing nuts onto each bolt until a predetermined seating torque is reached to spread the grease; and then performing final tightening using the angle method to fasten the wheel and brake disc together, thereby constructing a wheel with a brake disc.

[0050] The axial force verification process involves measuring the length of the bolts in the fastened state on the wheel with the brake disc using ultrasonic waves with the probe, comparing the natural length of the same bolt with the length of the bolt in the fastened state based on the identifier, calculating the axial force of each bolt, and if any bolts are outside the predetermined appropriate axial force range, the wheel with the brake disc is deemed a non-conforming product. Conversely, if no bolts are outside the predetermined axial force range, the wheel is deemed a compliant product and used for wheelset assembly.

[0051] Furthermore, by incorporating these steps, the assembly method for a wheel with a brake disc according to this embodiment provides a method for assembling a wheel with a brake disc that provides stable axial force and allows for more accurate determination of the suitability of the wheelset assembly.

[0052] Furthermore, the assembly method for the wheel with brake disc according to this embodiment may include a feedback process (calibration process) as needed.

[0053] In other words, if the feedback process includes a feedback process (calibration process) that compares the predetermined axial force of a bolt obtained in the axial force confirmation process with the ideal axial force or axial force range further defined within the predetermined axial force range, and increases or decreases the seating torque in the bolt fastening process or the tightening angle during final tightening in accordance with the difference, then a stable axial force can be achieved even with changes in the working environment temperature.

[0054] The following will provide a more detailed explanation of the grease application method and the assembly method of the wheel with brake disc according to this embodiment, with reference to the drawings. First, the configuration of the wheel with brake disc will be briefly described, and then the assembly method of the wheel with brake disc according to this embodiment will be explained in a series of steps, along with the grease application method according to this embodiment.

[0055] Figure 1 is a schematic diagram illustrating the general configuration of a wheel with a brake disc. Figure 1(a) is a plan view (inner surface) of the wheel with a brake disc, and Figure 1(b) is a side view.

[0056] The brake disc wheel W, as shown by the shading in Figure 1(a), is a wheel in which a brake disc 2 is arranged on the wheel body 1, and is a wheel used on the wheelset of a railway vehicle that employs a disc brake. In particular, this embodiment shows a wheel used in high-speed rail, and especially a wheel used in Shinkansen vehicles. In the figure, reference numeral 3 indicates the boss portion 3, and reference numeral 4 indicates the flange portion 4.

[0057] As shown in Figures 1(a) and 1(b), the brake disc 2, which constitutes the wheel W with a brake disc, is fastened and fixed to the wheel body 1 by disc bolts 5 and nuts 6.

[0058] Here, the fastening structure will be explained in detail with reference to Figure 1(c). Figure 1(c) is an exploded view of the G1-G1 cross-section of Figure 1(a), where the brake disc 2 shown at the top (inner surface side of the wheel body 1) is shown removed from the wheel body 1, and the other brake disc 2 on the outer surface side of the wheel body 1 is shown mounted on the wheel body 1 with only its end face visible.

[0059] As shown in Figure 1(c), the brake disc 2 has multiple bolt insertion holes 2a for inserting disc bolts 5, which are drilled at equal intervals in the circumferential direction with a constant radius R centered on the axle axis 7 when the wheelset is assembled (see Figure 1(a). Here, there are a total of 12 holes at 30-degree intervals).

[0060] Furthermore, bolt insertion holes 8a are drilled in the wheel center portion 8 of the wheel body 1, opposite to the bolt insertion holes 2a when the brake disc 2 is mounted.

[0061] Then, brake discs 2 are mounted on both the inner and outer sides of the wheel center portion 8 of the wheel body 1, and fastening holes 9 are formed as shown in Figure 1(b) by the communication between the bolt insertion holes 2a of the inner brake disc 2, the bolt insertion holes 8a of the wheel center portion 8, and the bolt insertion holes 2a of the outer brake disc 2.

[0062] By inserting the disc bolt 5 through this and screwing on the nut 6 and tightening it, a wheel with brake discs W is assembled in which the two brake discs 2 are fastened to the wheel center portion 8 of the wheel body 1. In Figure 1, a wheel with an inner circumference fastening brake disc, in which the radius R to the fastening hole 9 is small and the fastening is performed relatively close to the boss portion 3, is illustrated and explained, but this is shown as a representative example to explain the general configuration of a wheel with brake discs. The following explanation will also refer to an inner circumference fastening brake disc, but this does not limit the present invention in any way, and it goes without saying that the grease application method and the assembly method of the wheel with brake disc according to this embodiment can be applied to other wheels with brake discs, such as a wheel with a central fastening brake disc.

[0063] Next, we will explain the sequence of steps for assembling a wheel with a brake disc. Figure 2 is a diagram showing the configuration of the assembly workshop F for the wheel with a brake disc W in a plan view, and Figure 3 is a diagram showing the configuration of the same workshop as seen from arrow G2 in Figure 2. As shown in Figures 2 and 3, the assembly line A for the wheel with a brake disc W is constructed in the assembly workshop F by arranging various devices.

[0064] As shown in Figure 1, assembly line A consists of a conveyor 11, an identifier assignment unit 13, an axial force measuring device 14, a grease application device 15, and a nut tightening device 16.

[0065] The conveyor 11 is a roll conveyor that extends horizontally in the plane of the paper as shown in Figures 2 and 3, and is used to transport heavy objects such as wheels with brake discs W. Above this conveyor 11 is a measurement work area E3, which is the fixed position of the wheel with brake discs W when the axial force is measured by the axial force measuring device 14 on the wheel with brake discs W placed on the conveyor 11.

[0066] The identifier assignment unit 13 is a part for assigning a bolt number as a unique identifier to the tip surface of the disk bolt 5. In this embodiment, the bolt number is assigned in the identifier assignment unit 13 by handwriting with a marker pen 13a, but it can also be assigned mechanically using other known means.

[0067] The axial force measuring device 14 is a device consisting of an ultrasonic measuring device 17 and a control device 18. It measures the natural length of the disc bolts 5 to which bolt numbers have been assigned by the identifier assignment work unit 13, and measures the length of the disc bolts 5 of the brake disc-equipped wheel W in the fastened state (hereinafter also referred to as the fastened length) to calculate the axial force (axial force measurement). In addition to the ultrasonic measuring device 17, the control device 18 also has the role of communicating with and controlling each device that makes up the assembly line A.

[0068] The grease application device 15 is a device for applying grease to predetermined positions on the disk bolts 5 whose natural length has been measured, and is located on the workbench 15a.

[0069] The nut tightening device 16 is located on the extension of the conveyor 11, and in this embodiment, near one end of the conveyor 11 (near the right end of the page). It is a device for tightening the nuts 6 of the temporary assembly Wa to construct the wheel W with a brake disc. The nut tightening device 16 is equipped with multiple nut runner sections (not shown) and is configured to simultaneously tighten multiple nuts 6 on the temporary assembly Wa. The end of the conveyor 11 faces into the nut tightening device 16, allowing the temporary assembly Wa to be introduced from the conveyor 11 to the nut tightening device 16, and the wheel W with a brake disc after tightening to be led back to the conveyor 11. In this embodiment, the nut tightening device 16 is equipped with six nut runner sections, allowing six nuts 6 to be tightened simultaneously, every other nut 6 of the twelve nuts 6 that are screwed onto the disc bolts 5 of the temporary assembly Wa.

[0070] Thus, the assembly line A for the brake disc-equipped wheel W is equipped with a device arrangement that allows for efficient assembly work.

[0071] Figure 4 is a flowchart showing the sequence of steps in the assembly process of a wheel with a brake disc, in which the assembly method for a wheel with a brake disc according to this embodiment is implemented. Next, the work in each step will be explained in detail according to this flowchart.

[0072] [1. Identifier Assignment Process] In the assembly process of the wheel with brake disc, first, an identifier assignment process is performed in which a bolt number is assigned as a unique identifier to each of the multiple disc bolts 5 used to construct the wheel with brake disc W (step S10).

[0073] The identifier assignment step is a measurement preparation step for accurately measuring the axial force of multiple disk bolts 5, and consists of two work steps: the bolt number entry step S10a and the bolt storage step S10b.

[0074] Step S10a involves writing the bolt number on the flat surface of the bolt tip of the disc bolt 5 (hereinafter referred to as the bolt tip surface 5a). This step assigns an identification code consisting of letters, numbers, symbols, etc., that allows each disc bolt 5 to be distinguished from other disc bolts 5 as the bolt number.

[0075] The bolt housing step S10b is a step in which the disk bolts 5, which have been assigned bolt numbers, are stored and installed in the rack 107 as objects for measurement of their natural length, as described later.

[0076] As shown in Figure 2, a rack 107 is placed in the work placement area E1 defined near the identifier assignment work unit 13, and the worker places the disk bolts 5, to which the bolt number has been assigned by the identifier assignment work unit 13, into the rack 107 in an inverted state (with the tip facing upwards and the head facing downwards).

[0077] The bolt number entry step S10a and the bolt storage step S10b are interchangeable. For example, the bolt number entry step S10a may be performed by assigning an identifier to each bolt tip surface 5a facing upward after passing through the bolt storage step S10b, using the identifier assignment work unit 13.

[0078] The rack 107 containing the disk bolts 5 is placed in the workpiece placement area E2 for natural length measurement, which is set up near the axial force measuring device 14, as shown in Figure 2.

[0079] [2. Natural length measurement process] Next, in the assembly process of the wheel with brake discs, a natural length measurement process is performed (step S11). This natural length measurement process S11 is a process in which various operations are performed, mainly on the axial force measuring device 14, such as a medium settling operation, a probe contact operation, and a measurement value acquisition operation, in order to measure the natural length of the disc bolts 5, and the measurement values ​​are saved in the control device 18. It consists of six work steps: bolt number reading step S11a, coupling medium application step S11b, probe contact step S11c, medium settling step S11d, measurement value acquisition step S11e, and data saving step S11f.

[0080] First, the configuration of the axial force measuring device 14, which functions as a natural length measuring device in this process, will be described, followed by a description of each step from the bolt number reading step S11a to the data saving step S11f. Since the axial force measuring device 14 functions as both a natural length measuring device and an axial force measuring device, and many operations are common to both the natural length measuring step S11 and the axial force confirmation step S14 described later, some operations related to axial force measurement will be mentioned below, along with the configuration and operation related to natural length measurement.

[0081] (2-1. Configuration of the axial force measuring device) As shown in Figures 2 and 3, the axial force measuring device 14 is equipped with an ultrasonic measuring device 17 and a control device 18.

[0082] The ultrasonic measuring device 17 is configured by connecting the measuring main unit 50 and the probe 102 with a cable 50a.

[0083] The transducer 102 is equipped with an ultrasonic wave transmitter and a receiver that captures the reflected ultrasonic waves transmitted from the transmitter.

[0084] The measuring unit 50 controls the ultrasonic emission of ultrasonic waves to the transducer 102 and, upon receiving the reflected wave signal from the receiver of the transducer 102, measures the length of the disk bolt 5, which is the object to be measured, based on the difference in timing between emission and reception.

[0085] The measuring unit 50 is also provided with an input operation unit (not shown) that allows the bolt number to be entered. The measuring unit 50 is connected to the control device 18 for communication and transmits information about the length of the measured disc bolt 5 (for example, information about the natural length or length after tightening) along with the bolt number entered by the operator to the control device 18 for storage.

[0086] The control device 18 performs two functions: a programmable logic controller (PLC) function for controlling the operation of various devices, and a management PC function for receiving and storing information on the individual lengths (natural length and length after tightening) of the disk bolts 5 from the measurement main unit 50, and for saving and managing axial force information calculated based on these lengths.

[0087] (2-2. Explanation of each step in the natural length measurement process) Next, based on the configuration of the axial force measuring device 14 described above, we will explain each step of the natural length measurement process S11 in the assembly process flow of the wheel with brake disc shown in Figure 2, namely from the bolt number reading step S11a to the data saving step S11f.

[0088] The bolt number reading step S11a is a step in which the operator reads the bolt number assigned to the disc bolt 5 and inputs the bolt number via the input section of the ultrasonic measuring device 17.

[0089] The bolt number temporarily recorded in the ultrasonic measuring device 17 is transmitted to the control device 18 along with the length information of the disk bolt 5 acquired in the data storage step S11f described later.

[0090] The coupling medium application step S11b is a step in which a coupling medium is applied to the tip surface 5a of each bolt. Basically, this is done by an operator applying an appropriate amount of glycerin paste as the coupling medium to the tip surface 5a of each disc bolt 5.

[0091] The probe contact step S11c is the step of bringing the probe 102 into contact with the bolt tip surface 5a of the disk bolts 5 which are aligned in an inverted state on the rack 107, as shown by the dashed line probe 102a in Figure 2.

[0092] The medium-setting step S11d is a step in which the operator uses the probe 102 to spread and distribute the coupling medium applied to the bolt tip surface 5a. This medium-setting action of the probe 102 fills the space between the probe 102 and the bolt tip surface 5a with the coupling medium, improving the transmission of ultrasonic waves.

[0093] Step S11e, the measurement acquisition step, is performed after the medium acclimation step S11d, by allowing the coupling medium to settle and the ultrasonic waves to stabilize, and then acquiring the measurement value of the axial length (natural length).

[0094] This makes it possible to obtain measurement values ​​at the optimal timing when the ultrasonic waves transmitted and received by the transducer 102 have settled down, and reduces the likelihood of variations in measurement values ​​at each disk bolt 5.

[0095] The data storage step S11f is a step in which the measured value of the natural length of the disk bolt 5 obtained in the measurement value acquisition step S11e is transmitted to the control device 18 along with the bolt number entered in the bolt number reading step S11a and stored. In other words, the measured value of the natural length is assigned and stored for each disk bolt 5 based on the bolt number. The bolt number is also looked up and used in other steps, such as the axial force confirmation step S14 and the appropriate axial force determination step S14g, when assigning data such as the measured values ​​of the disk bolt 5, such as the natural length, the length at fastening, and the axial force, as described later.

[0096] The rack 107 containing the disk bolts 5 that have undergone the natural length measurement process S11 is placed in a workpiece placement area (not shown) for grease placement work, which is set up near the grease placement device 15.

[0097] [3. Grease application process] As shown in Figure 4, after the natural length measurement process S11 is completed, the next step in the assembly process of the wheel with brake disc is the grease application process S12.

[0098] In the grease application process S12, the worker takes out the disk bolt 5, whose natural length has been measured, from the rack 107 located in the workpiece placement area (not shown) for grease application and sets it in the grease application device 15. To explain this process, first the configuration of the grease application device 15 will be described, followed by an explanation of the implementation details of this process.

[0099] (3-1. Configuration of the grease dispensing device) Figure 5 is a front view showing the configuration of the grease storage device 15, and Figure 6 is an explanatory diagram showing the main body 22 of the grease storage device 15 as viewed from the right side. In the following explanation, the left-right direction of the paper in Figure 5 will be referred to as the X-axis direction, the left direction as the positive X-axis direction, and the right direction as the negative X-axis direction. The up-down direction of the paper will be referred to as the Z-axis direction, the down direction as the positive Z-axis direction, and the up direction as the negative Z-axis direction. The front-to-back depth direction of the paper, i.e., the left-right direction of the paper in Figure 6, will be referred to as the Y-axis direction, the right direction (depth direction in Figure 5) as the positive Y-axis direction, and the left direction (front-to-back direction in Figure 5) as the negative Y-axis direction.

[0100] As shown in Figure 5, the grease dispensing device 15 consists of a discharge volume control unit 20, a drive control unit 21, and a device body 22.

[0101] The discharge volume control unit 20 is a device that controls the amount of grease discharged from the nozzle 40 located on the main body 22 of the device. An operating unit 20a is located on the front of the discharge volume control unit 20, and the operator can adjust the amount of grease discharged from the nozzle 40 located on the main body 22 of the device by inputting a predetermined discharge volume, etc., on the operating unit 20a.

[0102] The drive control unit 21 is a device for controlling the movement of each drive unit located in the main unit 22 of the device, and is configured to communicate electrically with the main unit 22 of the device.

[0103] The main body of the device 22 is a device that applies grease to the disc bolt 5 set by the operator. The grease application device 15, including the main body of the device 22, is characterized in that it applies grease to the disc bolt 5, but does not apply or spread it.

[0104] The main body of the device 22 is broadly composed of a base section 30, a bolt rotation section 31, and a nozzle movement section 32.

[0105] The base portion 30 functions as the base for the bolt rotating portion 31 and the nozzle moving portion 32. As shown in Figure 6, the bolt rotating portion 31 is positioned towards the front of the base (closer to the negative Y-axis direction), and the nozzle moving portion 32 is positioned overhanging the base portion 30 and the bolt rotating portion 31 via the support column portion 36 on the rear of the base (closer to the positive Y-axis direction).

[0106] The base portion 30 is also equipped with a Y-axis moving stage 33 on its surface. This Y-axis moving stage 33 is a plate-like body that moves in the Y-axis direction by a Y-axis moving mechanism (not shown) installed inside the base portion 30. By fixing the bolt rotating portion 31 on this Y-axis moving stage 33, the bolt rotating portion 31 can be moved in the Y-axis direction relative to the base portion 30, as shown by the long dashed line in Figure 6.

[0107] As shown in Figure 5, the bolt rotation section 31 is constructed by arranging a chuck section 34 and a tip support section 35 on a base plate 31a fixedly positioned on the Y-axis moving stage 33. The chuck section 34 is configured to allow the operator to fit and fix the head of the disc bolt 5 in a rotatable state, and to support the disc bolt 5 with its shaft axis 5c oriented in the X-axis direction.

[0108] Furthermore, the chuck portion 34 has a built-in motor (not shown) that, under the control of the drive control unit 21, can rotate around the shaft axis 5c at a predetermined speed (here, it can rotate counterclockwise when viewed in the positive X-axis direction).

[0109] The tip support portion 35 is a part that supports the tip of the disc bolt 5, which is supported by fitting its head into the chuck portion 34. It is configured with bearings to prevent wobbling during rotation while still being able to follow the rotation.

[0110] The nozzle moving section 32 is a part for positioning the nozzle 40, which discharges grease, at a desired position on the threaded portion 5b of the disc bolt 5, which is rotatably supported by the bolt rotating section 31, and consists of a support column 36, an X-axis beam 37, an X-axis moving body 38, and a discharge unit 39.

[0111] The support column 36 is a part that provides height to position the nozzle 40 above the bolt rotation section 31. An X-axis beam 37 is installed between the two support column sections 36 that are erected on the rear side of the base section 30.

[0112] The X-axis beam 37 is a beam for moving the X-axis movable body 38 along the X-axis beam 37, as shown by the long dashed line in Figure 5. An X-axis movement mechanism (not shown) is installed inside the X-axis beam 37, and the X-axis movable body 38 can be moved in the X-axis direction relative to the X-axis beam 37 via a connecting arm (not shown) installed between the X-axis beam 37 and the X-axis movable body 38.

[0113] The X-axis moving body 38 is a member that can move in the X-axis direction along the X-axis beam 37, and moves the Z-axis moving plate 41 (see Figure 6), which is located on the front side, in the Z-axis direction relative to the X-axis moving body 38 as shown by the long dashed line by a Z-axis moving mechanism (not shown).

[0114] The discharge unit 39 is fixed to the Z-axis moving plate 41, and as the Z-axis moving plate 41 moves under the control of the drive control unit 21, the discharge unit 39 moves in the Z-axis direction relative to the X-axis moving body 38, as shown by the long dashed line in Figures 5 and 6. The Y-axis moving mechanism of the base portion 30, the X-axis moving mechanism of the X-axis beam 37, and the Z-axis moving mechanism of the X-axis moving body 38 (hereinafter collectively referred to as each axis moving mechanism) all have the capability to position the nozzle 40 with an accuracy of about 0.1 mm in each axis direction.

[0115] The discharge unit 39 is a unit for supplying molybdenum grease, which is stored in a grease tank (not shown), to the nozzle 40 via a predetermined supplying means such as a pump. The supplying means is not particularly limited, but for example, a mono pump can be used.

[0116] The discharge unit 39 is also equipped with a fine adjustment device (not shown) that allows for manual adjustment of the nozzle position in the X-axis direction. This fine adjustment device is equipped with a micrometer mechanism consisting of a precise fine adjustment screw structure, and by replacing displacement with the rotation angle of the fine adjustment screw, a fine adjustment device is realized that allows for precise adjustment of the nozzle position in the X-axis direction relative to the disk bolt 5 (for example, fine adjustment that allows for placement on the top of the screw thread or the flank).

[0117] Furthermore, the feeding means is connected to the discharge volume control unit 20, and by inputting a predetermined program into the discharge volume control unit 20 in advance, it is configured to be able to supply a fixed amount of material while synchronizing with the pitch of the screw portion 5b according to the rotation speed of the chuck portion 34 and the movement speed of the X-axis moving body 38. In particular, in this embodiment, at least a nozzle approach operation program, a bolt rotation operation program, a discharge operation program, a bolt stop operation program, and a nozzle retraction operation program are pre-programmed.

[0118] The nozzle approach operation program specifies that each axis movement mechanism is driven mainly in the positive Y-axis direction and the positive Z-axis direction (with the X-axis direction adjusted as appropriate) to position the nozzle 40 at an upper position (discharge start position) near the fourth thread from the head side to the tip side of the complete threaded portion 5b of the disk bolt 5, which consists of approximately 20 threads.

[0119] The bolt rotation operation program specifies that the motor of the chuck unit 34 is driven at a predetermined speed to rotate the disk bolt 5 at a constant speed.

[0120] The discharge operation program specifies that, in synchronization with the apparent thread movement speed in the X-axis direction corresponding to the rotational speed of the disk bolt 5, the X-axis moving body 38 is moved at a constant speed in the positive X-axis direction relative to the X-axis moving mechanism of the X-axis beam body 37 from the head side to the tip side, covering approximately 8 threads from near the 4th thread to near the 11th thread. At the same time, a predetermined amount of grease is discharged from the nozzle 40 via the discharge volume control unit 20, and the discharge of grease is stopped when the nozzle reaches the position near the 11th thread (discharge end position).

[0121] The bolt stopping operation program specifies that the motor of the chuck unit 34 will be stopped, thereby stopping the rotation of the disk bolt 5.

[0122] The nozzle retraction operation program specifies that the operation of each axis movement mechanism should be driven so that the nozzle 40 is positioned so as not to interfere with the worker's work when removing the disc bolt 5 from the grease placement device 15.

[0123] It goes without saying that each of the above-mentioned programs (collectively referred to as the grease application operation program) may be entered as separate programs, or some or all of the programs may be entered as a set, and further programs defining other operations may be implemented. Also, the bolt rotation operation program may be executed approximately simultaneously with the start of the discharge operation program, or it may be executed beforehand. Similarly, the bolt stop operation program may be executed approximately simultaneously with the grease discharge stop operation, but it is also possible to execute the bolt stop operation program after the discharge operation program has finished.

[0124] (3-2. Details of the grease application process) Then, in the grease application process S12, the worker sets the disc bolt 5 on the grease application device 15 configured in this way and operates the grease application device 15.

[0125] Then, the grease dispensing device 15 precisely drives each axis movement mechanism under the control of the drive control unit 21, moving the nozzle 40 freely in the X, Y (mainly in the positive Y-axis direction) and Z-axis direction (mainly in the positive Z-axis direction) while approaching and positioning it at the discharge start position.

[0126] Next, the grease dispensing device 15 executes a bolt rotation operation program and a discharge operation program, and moves the nozzle 40 at a constant speed in the positive X-axis direction parallel to the rotation axis in synchronization with the pitch of the threads of the disk bolt 5 which rotates at a constant speed.

[0127] At this time, as shown in Figure 7(a), the semi-solid molybdenum grease 40a extruded from the nozzle 40 is quantitatively placed along the threads 5d around the axis of the disc bolt 5.

[0128] Another characteristic of the grease application method according to this embodiment is that the molybdenum grease placement area on the threaded portion 5b of the disc bolt 5 is controlled by the drive control unit 21 that executes the aforementioned grease placement operation program, and is approximately the same as the threaded area when the brake disc 2 is fastened with a nut with the appropriate axial force in the bolt fastening process S13 described later, as a wheel with a brake disc W that can be used for wheel axle assembly (in this embodiment, an area of ​​approximately 8 threads from the vicinity of the 4th thread to the vicinity of the 11th thread from the head side of the disc bolt 5).

[0129] Therefore, it is possible to suppress the occurrence of uneven application due to excess molybdenum grease and stabilize the axial force of the fastened disc bolt 5. In addition, it is possible to save on the amount of grease used.

[0130] When the nozzle 40 reaches the discharge end position and finishes applying grease around the axis of the disc bolt 5, the grease application device 15 executes a bolt stop operation program and a nozzle retraction operation program, moving the nozzle 40 mainly in the negative Z-axis direction and the negative Y-axis direction (the X-axis direction as appropriate) to separate the nozzle 40 from the disc bolt 5, making it possible for the operator to remove the disc bolt 5 from the grease application device 15.

[0131] The worker removes the disc bolt 5, on which grease has been placed, from the grease placement device 15 and places it in the container 108 located in the workpiece placement area E4 shown in Figure 2.

[0132] The container 108 containing the disc bolts 5 that have undergone the grease application process S12 is moved and positioned in a workpiece placement area (not shown) for bolt fastening work.

[0133] [4. Bolt fastening process] As shown in Figure 4, after the grease application process S12 is completed, the next step in the assembly process of the wheel with brake disc is the bolt fastening process S13.

[0134] In the bolt fastening process S13, the worker takes out the disc bolt 5, which has been coated with grease, from the container 108 located in the workpiece placement area (not shown) for bolt fastening work, and inserts it together with a washer into each fastening hole 9 of the wheel body 1, which has brake discs 2 on its inner and outer surfaces but does not yet have disc bolts 5 etc. installed, and screws on the nut 6 to construct the temporary assembly Wa.

[0135] Next, the worker screws the nut 6 to the seating position. At this time, as shown in Figure 7(b), the molybdenum grease 40a that was placed along the threads 5d of the threaded portion 5b in the grease application step S12 is spread. It is preferable to screw the nut 6 in mechanically using a nut runner or the like, but it may also be screwed in by hand. This is because the movement of the nut is considerably restricted compared to the movement of a brush when working by hand, and even when screwed in by hand, unevenness in grease application can be dramatically suppressed.

[0136] As a result, in addition to eliminating quantitative inconsistencies in grease placement (application) to the threaded portion by using the aforementioned grease application device 15, inconsistencies due to the way the grease is spread and the amount of force applied are prevented. This suppresses buffering inconsistencies caused by variations in the application of molybdenum grease 40a, which should buffer individual differences in the disc bolts 5 and nuts 6, and makes it possible to further stabilize the axial force generated when tightening to a predetermined torque value compared to manual tightening.

[0137] Furthermore, in this embodiment, as shown in Figures 7(a) and 7(b), the placement position of the molybdenum grease 40a on the screw thread 5d is the top 5e of the screw thread 5d.

[0138] Therefore, as shown in Figure 7(b), the molybdenum grease 40a is applied uniformly from the top 5e to the flank surface on the head side as the nut 6 is screwed in, and the grease that reaches the valleys is scooped up by the screwing of the nut 6 and applied uniformly to the flank surface on the tip side, thus achieving uniform and even grease application.

[0139] Furthermore, in order to reliably achieve the application of molybdenum grease 40a to the top 5e of the screw thread 5d, the grease application device 15 is equipped with a fine adjustment device as a nozzle position adjustment means, as described above.

[0140] Therefore, even for disc bolts 5 where the position of the thread 5d differs due to individual variations, the position of the nozzle 40 can be easily fine-tuned to a position where the molybdenum grease 40a is placed at the top 5e of the thread 5d.

[0141] Next, as shown in Figure 2, the worker moves the temporary assembly Wa on the second conveyor 12 and introduces it into the nut tightening device 16, and then tightens the nuts 6 with the nut runner.

[0142] Specifically, first, the nut 6, which is screwed onto the disc bolt 5, is screwed in using a nut runner until it reaches a predetermined seating torque. The seating torque is the tightening torque value at which the desired predetermined axial force (a predetermined axial force) can be expected to be generated by performing the action of tightening and rotating the nut by a predetermined angle (final tightening action).

[0143] At the point when the nut 6 is pre-tightened to the seating torque value, the disc bolt 5 has an ideal coating of molybdenum grease 40a, and this ideal grease coating stabilizes the axial force that would occur if the final tightening operation were to follow (hereinafter referred to as the state in which axial force variation can be suppressed).

[0144] Next, the nut 6, which has been temporarily tightened to a predetermined seating torque value, is subjected to a tightening and rotation operation by a predetermined angle, i.e., a final tightening operation by the angle method, to a state in which it is estimated that a desired predetermined axial force (a predetermined axial force) has been generated, and the wheel body 1 and the brake disc 2 are fastened together to construct the wheel W with a brake disc.

[0145] In this way, by tightening the nut 6 to the disc bolt 5, which is in a state where axial force variation can be suppressed, using the angle method, it is possible to ensure solid stabilization of the axial force generated after tightening.

[0146] The wheel W with brake disc, constructed through the bolt fastening process S13, is moved along the conveyor 11 and positioned in the measurement work area E3.

[0147] [5. Axial force confirmation process] As shown in Figure 4, after the bolt fastening process S13 is completed, the next step in the assembly process of the wheel with brake disc is the axial force confirmation process S14.

[0148] The axial force confirmation process S14 is a process in which the axial force of the disc bolts 5 of the brake disc-equipped wheel W after fastening is measured and it is determined whether the axial force is within the appropriate range set in advance in the control device 18. For each individual disc bolt 5 of the brake disc-equipped wheel W located in the measurement work stationary area E3, a series of axial force confirmation operations are performed, namely various exploration operations centered on the probe 102, such as the aforementioned medium settling operation, probe contact operation, and measurement value acquisition operation using the axial force measuring device 14.

[0149] Specifically, in the axial force confirmation process S14, similar to the natural length measurement process S11, one unmeasured bolt to be measured is selected from among the multiple (12) disc bolts 5 of the wheel W with brake discs. Six work steps are performed on that bolt: bolt number reading step S14a, coupling medium application step S14b, probe contact step S14c, medium settling step S14d, measurement value acquisition step S14e, and data storage step S14f. In addition, an appropriate axial force determination step S14g is performed, and these steps are repeated for multiple (12) bolts. These six work steps, from the bolt number reading step S14a to the data saving step S14f, are generally the same as the natural length measurement step S11, and most of the explanation will be omitted here. For example, in the probe contact step S14c, the probe 102 is brought into contact with the tip surface 5a of the fastened disc bolt 5 assembled to the wheel W with the brake disc, as shown by the dashed line probe 102b in Figure 2.

[0150] Furthermore, in the data storage step S14f, the ultrasonic measuring device 17 transmits the fastening length obtained in the measurement value acquisition step S14e, along with the bolt number entered by the operator in the bolt number reading step S14a, to the control device 18, similar to the natural length measurement step S11. Upon receiving this data, the control device 18 stores the fastening length obtained in the measurement value acquisition step S14e in association with the bolt information corresponding to the bolt number, particularly the natural length information obtained in the previous step, from the bolt information stored in a predetermined storage area of ​​the recording medium provided by the control device 18.

[0151] The appropriate axial force determination step S14g is a process in which, following this memory operation, the control device 18 calculates the elongation of the disk bolt 5 from the difference between the tightening length and the natural length of the disk bolt 5 currently being measured, calculates the axial force from the calculated value, and further determines whether that axial force is within the appropriate range set in advance in the control device 18, that is, within a predetermined appropriate axial force range that can be accepted as the desired predetermined axial force (pre-defined axial force).

[0152] Here, the axial force is calculated by automatically multiplying the difference between the natural length and the length when fastened by an axial force conversion constant. If the calculated axial force of the disc bolt 5 is within the appropriate axial force range, the disc bolt 5 is judged as normal; if it deviates from the appropriate axial force range, the disc bolt 5 is judged as abnormal. Then, the wheel with brake disc W containing the disc bolt 5 judged as abnormal is judged as a non-conforming product for wheelset assembly, while the wheel with brake disc W that does not contain the disc bolt 5 judged as abnormal is used for wheelset assembly as a conforming product.

[0153] Furthermore, the results of the judgment regarding the normality or abnormality of the disc bolts 5 in this process, as well as the judgment regarding the suitability of the brake disc wheel W, are ultimately reflected in the monitor unit 161 (see Figure 3) of the control device 18. In addition, if the axial force of even one of the disc bolts 5 of the brake disc wheel W is outside the appropriate range (i.e., it is a non-conforming product), information that allows the operator to identify the abnormal disc bolt 5, such as the bolt number, is displayed on the monitor unit 161.

[0154] In this case, the worker removes the abnormal disc bolt 5 from the wheel with brake disc W, replaces it with another disc bolt 5 that was measured in the natural length measurement process S11 and subjected to the grease application process S12, and performs the tightening work in the same procedure as the previous bolt fastening process S13. The wheel with brake disc W, with the newly replaced disc bolt 5 in this way, is then subjected to the axial force confirmation process S14 again. Hereinafter, this process will be referred to as the reconstruction process.

[0155] In this way, the axial force of each bolt is calculated by comparing the natural length and the length at fastening of the same disc bolt 5 based on the bolt number. If a wheel W with a brake disc is found to contain a disc bolt 5 that is deemed abnormal and outside the predetermined appropriate axial force range, the wheel W is deemed a non-conforming product. Conversely, if a wheel W does not contain a disc bolt 5 deemed abnormal, it is deemed a compliant product and can be used for wheel axle assembly. This ensures that the fastening of the fastened components is such that "the wheel body 1 and the brake disc 2 are fastened together with high axial force by multiple disc bolts 5," thereby satisfying the requirements for the robustness and reliability of the fastened components.

[0156] Furthermore, in terms of a method for measuring the axial force of fastening bolts such as disc bolts 5 using the axial force measuring device 14, the axial force of the fastening bolt is calculated based on the difference between the measured natural length of the fastening bolt before fastening the fastened members, such as the wheel body 1 and the brake disc 2, and the measured length of the fastening bolt after fastening the fastened members, and the appropriateness of the axial force is determined by using the measured value obtained by ultrasonic measurement. Therefore, it is possible to provide an assembly method for a wheel with a brake disc that has a stable axial force and allows for a more accurate determination of the suitability of the wheelset assembly.

[0157] In particular, by setting both the workpiece placement area E2 and the measurement work stationary area E3 near the axial force measuring device 14, both the disc bolts 5 before assembly while housed in the rack 107 and the disc bolts 5 after assembly to the brake disc-equipped wheel W can be efficiently measured using the same axial force measuring device 14, variations in axial force measurement results are avoided, and reconstruction work according to the evaluation inspection results can be responded to immediately, thereby reducing labor and improving the efficiency of inspection work.

[0158] [6. Stabilization confirmation test for axial force measurement] Next, tests were conducted to confirm that the grease application method according to this embodiment can stabilize the axial force compared to manual grease application.

[0159] Here, the stability was verified by checking the average value and standard deviation of the axial force when grease was applied to multiple bolts by hand (brush application) and when grease was applied using the grease application device 15 and nut tightening device 16 (in the case of the grease application method according to this embodiment).

[0160] As a result, it was shown that the grease application method according to this embodiment has a smaller standard deviation and less variation in axial force compared to manual application, meaning that it is a grease application method that can further stabilize the axial force generated when tightening at a predetermined torque value compared to manual application.

[0161] Furthermore, this indicates that the assembly method for a wheel with a brake disc according to this embodiment, which includes a natural length measurement step of measuring the natural length of a bolt using an axial force measuring device 14, a grease application step of quantitatively applying grease around the axis of a bolt, a bolt fastening step of constructing a wheel with a brake disc by fastening nuts screwed onto each bolt while spreading the grease, and an axial force confirmation step of calculating the axial force of each bolt by comparing the natural length with the length of the bolt in the fastened state, can provide an assembly method for a wheel with a brake disc that has a stable axial force and allows for a more accurate determination of the suitability of the wheelset assembly.

[0162] As described above, the grease application method according to this embodiment includes a step (e.g., grease application step S12) in which semi-solid grease (e.g., molybdenum grease 40a) extruded from a nozzle (e.g., nozzle 40) of a quantitative supply device (e.g., grease application device 15) is quantitatively applied along the threads (e.g., threads 5d) around the axis of a bolt (e.g., disc bolt 5) that fastens a brake disc (e.g., brake disc 2) to the wheel center (e.g., wheel center 8) of a railway wheel (e.g., wheel body 1) (e.g., grease application step S12), and a step (e.g., bolt fastening step S13) in which a nut (e.g., nut 6) screwed onto the bolt is screwed in to spread the grease applied along the threads (e.g., bolt fastening step S13). Therefore, it is possible to provide a grease application method that can further stabilize the axial force generated when tightening to a predetermined torque value compared to manual work.

[0163] Furthermore, according to the assembly method for a wheel with a brake disc according to this embodiment, the assembly method for a wheel with a brake disc (e.g., wheel with brake disc W) is formed by bolting (e.g., disc bolts 5 and nuts 6) a brake disc (e.g., brake disc 2) to the wheel center portion (e.g., wheel center portion 8) of a railway wheel (e.g., wheel body 1), wherein a probe (e.g., probe 102) is brought into contact with each of a plurality of bolts (e.g., disc bolts 5) that have been assigned a unique identifier (e.g., bolt number) and A natural length measurement step (e.g., natural length measurement step S11) in which the natural length is measured using sound waves; a grease application step (e.g., grease application step S12) in which semi-solid grease (e.g., molybdenum grease 40a) extruded from a nozzle (e.g., nozzle 40) of a quantitative supply device (e.g., grease application device 15) is quantitatively applied around the axis of each bolt along the thread (e.g., thread 5d); and grease is applied to a plurality of fastening holes (e.g., fastening holes 9) of a temporary assembly (e.g., temporary assembly Wa) in which a brake disc is arranged on the wheel center of the wheel. The method includes a bolt fastening step (e.g., bolt fastening step S13) in which the bolts are attached, nuts (e.g., nuts 6) screwed onto each bolt are screwed in until a predetermined seating torque is reached to spread the grease, and then the wheel and brake disc are fastened by the angle method to construct a wheel with a brake disc (e.g., wheel with a brake disc W); and an axial force confirmation step (e.g., axial force confirmation step S14) in which the length of the bolts in the fastened state on the wheel with a brake disc is measured ultrasonically using the probe, the natural length of the same bolt and the length of the bolt in the fastened state (e.g., length when fastened) are compared based on the identifier to calculate the axial force of each bolt, and if the wheel with a brake disc contains bolts that are not within a predetermined appropriate axial force range, the wheel with a brake disc is deemed unsuitable, while if it does not contain bolts that are not within a predetermined axial force range, it is deemed suitable and can be used for wheelset assembly. As a result, a method for assembling a wheel with a brake disc can be provided that has a stable axial force and allows for a more accurate determination of the suitability of the wheelset assembly.

[0164] Finally, the above-described embodiments are merely examples of the present invention, and the present invention is not limited to the embodiments described above. Therefore, it goes without saying that various modifications can be made to embodiments other than those described above, as long as they do not depart from the technical spirit of the present invention, depending on the design and other factors. [Explanation of symbols]

[0165] 1. Wheel body 2 Brake discs 5 Disc bolts 5a Bolt tip surface 5d thread 5e Top 6 nuts 8 Wheel center 9 Fastening hole 13. Identifier Assignment Work Unit 14 Axial force measuring device 15. Grease Dispenser 16. Nut tightening device 17. Ultrasonic measuring device 18 Control device 40 nozzles 40a Molybdenum Grease 102 Probe A Assembly Line S10a Bolt number entry step S11 Natural length measurement process S12 Grease application process S13 Bolt fastening process S14 Axial force confirmation process Wheels with brake discs Wa Temporary assembly

Claims

1. A process of quantitatively applying semi-solid grease, extruded from the nozzle of a quantitative supply device, along the threads of a bolt that fastens a brake disc to the wheel center of a railway wheel, and A grease application method characterized by comprising the step of screwing a nut, which is screwed onto the bolt, inwards to spread the grease placed along the threads.

2. The grease application method according to claim 1, characterized in that the grease application area on the threaded portion of the bolt is substantially the same as the threaded area when the fastened object is fastened with a predetermined axial force by the nut.

3. The grease application method according to claim 1 or 2, characterized in that the position where the grease is placed on the screw thread is at the top of the screw thread.

4. The quantitative supply device is arranged such that the nozzle, which quantitatively dispenses the grease in synchronization with the pitch of the threads of the bolt that rotates at a constant speed with the axis of rotation of the shaft, moves parallel to the axis of rotation, The grease application method according to claim 1, further comprising nozzle position adjustment means for finely adjusting the position of the nozzle so that the grease is positioned at the top of the screw threads.

5. A method for assembling a wheel with a brake disc, wherein the brake disc is bolted to the wheel center of the railway wheel, A natural length measurement process in which a probe is brought into contact with each of several bolts that have been assigned a unique identifier, and the natural length is measured using ultrasound, A grease application step in which semi-solid grease extruded from the nozzle of a quantitative supply device is quantitatively applied along the threads around the axis of each bolt, A bolt fastening process is performed to construct a wheel with a brake disc by fastening the wheel and brake disc together by inserting the bolts, which have grease placed on them, into multiple fastening holes of a temporary assembly in which a brake disc is positioned at the wheel center of the wheel, screwing the nuts attached to each bolt until a predetermined seating torque is reached to spread the grease, and then performing final tightening by angle method, thereby fastening the wheel and brake disc together. A method for assembling a wheel with a brake disc, characterized by comprising an axial force verification step in which the length of the bolts in the fastened state is measured ultrasonically using the probe on the wheel with the brake disc, the natural length of the same bolt is compared with the length of the bolt in the fastened state based on the identifier to calculate the axial force of each bolt, and if the wheel with the brake disc contains any bolts that are not within a predetermined appropriate axial force range, the wheel with the brake disc is deemed a non-conforming product, while if it does not contain any bolts that are not within the predetermined axial force range, it is deemed a conforming product and is used for wheelset assembly.

Images