Self-drilling screw testing station

Abstract

This disclosure provides a self-tapping screw testing station, comprising a base, a first metal plate, and a second metal plate. The base extends longitudinally, with a vertically recessed receiving cavity formed at its top, and a support portion formed within the base at the bottom periphery of the receiving cavity. The first metal plate has at least a plurality of first through holes spaced apart longitudinally. The second metal plate has at least a plurality of second flanged holes spaced apart longitudinally. The first and second metal plates are housed within the receiving cavity and stacked on the support portion, with each of the first through holes and the second flanged holes corresponding one-to-one. By providing a self-tapping screw testing station, the performance testing of self-tapping screws can be facilitated, thereby screening out unqualified screws before mainframe assembly and thus avoiding impact on the mainframe production schedule.

Description

Technical Field

[0001] This disclosure relates to a test bench, specifically a test bench for testing self-tapping screws. Background Technology

[0002] Self-tapping screws are mostly used for connecting thin metal plates. During connection, the pre-drilled holes in the metal plates being connected are not pre-threaded. Instead, the self-tapping screw first taps the pre-drilled holes to form internal threads, and then the connected parts are locked in place as the self-tapping screw is further screwed in.

[0003] Currently, in the home appliance industry, sheet metal parts are primarily connected using self-tapping screws. If these screws are substandard, stripping can occur. Self-tapping screws are typically supplied by vendors, and during incoming material inspection, manufacturers usually only check the appearance and dimensions of the screws and sheet metal parts. If a batch of self-tapping screws is substandard, it may not be detected during incoming material inspection. Consequently, stripping can occur during assembly on the production line, forcing production to stop and analyze the cause, impacting planned production schedules. Furthermore, during the analysis, manufacturers cannot determine whether the problem originates from the sheet metal parts or the self-tapping screws. This leads to suppliers of both screws and sheet metal parts shifting blame and passing the buck, making it difficult to assign responsibility for quality incidents and resolve problems. Additionally, manufacturers are forced to replace the entire batch of self-tapping screws, bearing the resulting losses themselves. Utility Model Content

[0004] To overcome the problems existing in related technologies, this disclosure provides a self-tapping screw test bench, which can be used for testing the performance of self-tapping screws to verify whether different batches of self-tapping screws are qualified.

[0005] This disclosure provides a self-tapping screw testing station, comprising a base, a first metal plate, and a second metal plate. The base extends longitudinally, with a vertically recessed receiving cavity formed at its top, and a support portion formed within the base at the bottom periphery of the receiving cavity. The first metal plate has at least a plurality of first through holes spaced apart longitudinally. The second metal plate has at least a plurality of second flanged holes spaced apart longitudinally. The first and second metal plates are housed within the receiving cavity and stacked on the support portion, with each of the first through holes and the second flanged holes corresponding one-to-one.

[0006] In some embodiments, the first metal plate is further provided with a plurality of first flanged holes spaced apart along the longitudinal direction, and the second metal plate is further provided with a plurality of second through holes spaced apart along the longitudinal direction; when the first metal plate and the second metal plate are stacked and housed in the housing cavity, the plurality of second through holes and the plurality of first flanged holes correspond one-to-one.

[0007] In some embodiments, the first metal plate and the second metal plate have identical structures.

[0008] In some embodiments, the perimeter of the aforementioned receiving cavity is equivalent to the perimeter of the first and second metal plates.

[0009] In some embodiments, when the first metal plate and the second metal plate are stacked and housed in the aforementioned housing cavity, the aforementioned support portion supports the edge of the first metal plate or the second metal plate.

[0010] The technical solutions provided by one or more embodiments of this disclosure may include the following beneficial effects: by setting up a self-tapping screw test bench, the performance testing of self-tapping screws can be facilitated, thereby screening out unqualified screws before main unit assembly, and thus avoiding affecting the main unit production plan. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is an exploded perspective view of the test bench and the self-tapping screw to be tested in one embodiment of the present disclosure;

[0013] Figure 2 yes Figure 1 The diagram shows a cross-sectional view after the self-tapping screw is screwed into the test bench.

[0014] Figure 3 This is a connection diagram of the self-tapping screw testing system disclosed herein during screw performance testing in one embodiment;

[0015] Figure 4 yes Figure 1 The diagram shows the torque change curve during the process of screwing the self-tapping screw into the test bench.

[0016] Figure 5 Through Figure 3 The diagram shows the torque variation curve obtained by the self-tapping screw testing system when performing performance tests on a randomly selected group (ten) of self-tapping screws from a certain batch.

[0017] Figure 6 This is a flowchart illustrating the steps in one embodiment of the self-tapping screw performance testing method disclosed herein. Detailed Implementation

[0018] The embodiments shown will now be described in detail with reference to the accompanying drawings. However, these embodiments do not represent all embodiments consistent with this disclosure, and any structural, methodological, or functional modifications made by those skilled in the art based on these embodiments are included within the scope of protection claimed in the appended claims.

[0019] like Figure 1 and Figure 2 As shown, the self-tapping screw test stand includes a first metal plate 31, a second metal plate 32, and a base 33. The base 33 extends longitudinally and is generally rectangular. A vertically recessed receiving cavity 332 is formed on the top of the base 33 to accommodate the first metal plate 31 and the second metal plate 32. Support portions 331 protrude inwardly from the inner walls of the base 33 to support the first metal plate 31 or the second metal plate 32, and these support portions 331 are located at the bottom periphery of the receiving cavity 332. In some embodiments, the support portions need not be arranged on the inner walls of the base 33, but may be arranged in pairs on opposite inner walls of the base.

[0020] Both the first metal plate 31 and the second metal plate 32 are rectangular. In some embodiments, their perimeter dimensions are the same and comparable to the perimeter dimensions of the receiving cavity 332. That is, the perimeter dimensions of the receiving cavity 332 are the same as or slightly larger than the perimeter dimensions of the first and second metal plates 31 and 32, so that the first and second metal plates 31 and 32 can be received within the receiving cavity 332 without moving or shaking. The first metal plate 31 has at least a plurality of (e.g., ten) first through holes 311 spaced apart along the longitudinal direction, and the second metal plate 32 has at least a plurality of second flanged holes 323 spaced apart along the longitudinal direction. The first metal plate 31 and the second metal plate 32 are received within the receiving cavity 332 and stacked on the support portion 331, and the number and spacing of the plurality of first through holes 311 and the plurality of second flanged holes 323 are the same, so that they can correspond one-to-one. In some embodiments, the first metal plate 31 is further provided with a plurality of first flanged holes 313 spaced apart along the longitudinal direction, and the second metal plate 32 is further provided with a plurality of second through holes 321 spaced apart along the longitudinal direction; when the first metal plate 31 and the second metal plate 32 are stacked and housed in the housing cavity 332, the plurality of second through holes 321 and the plurality of first flanged holes 313 correspond one-to-one. The flanged holes (taking the first flanged hole as an example) are usually stamped on the metal plate to form flanged holes 313 surrounded by flanges 312.

[0021] In some embodiments, the first metal plate 31 and the second metal plate 32 have identical structures, meaning that the first and second metal plates 31 and 32 can be made from the same mold, thus reducing manufacturing costs. The self-tapping screw 40 includes a head and a screw 41 extending vertically downwards from the white head. The head shape can be round, flat round, pan, countersunk, semi-countersunk, cylindrical, flared, hexagonal, etc. A thread is formed on the outer circumferential surface of the screw 41, and its end can be flat or pointed. During testing, a group of screws to be tested can be randomly selected from a batch of self-tapping screws; the number of screws in a group can be ten, twenty, or other numbers. The first metal plate 31 and the second metal plate 32 are stacked in a top-to-bottom order and housed in the receiving cavity 332. At this time, the second metal plate 32 constitutes the connected part, the support portion 331 supports the edge of the second metal plate 32, and the screw 41 of the self-tapping screw 40 passes through the first through hole 311 and enters the second flanged hole 323. When there are a large number of screws to be tested, such as twenty in a group, ten screws are first passed through the first through hole 311 and screwed into the second flange hole 323. Then, the first and second metal plates 31 and 32 connected together are flipped and placed into the receiving cavity 332. At this time, the first metal plate 31 constitutes the connected part, which is stacked under the second metal plate 32. The support part 331 supports the edge of the first metal plate 31. Then, the screws 41 of the remaining ten self-tapping screws 40 pass through the second through hole 321 and are driven into the first flange hole 313.

[0022] Setting up a self-tapping screw test bench can help test the performance of self-tapping screws, thereby screening out unqualified screws before main unit assembly and thus avoiding impact on the main unit production plan.

[0023] Reference Figure 3 The self-tapping screw testing system shown includes the aforementioned self-tapping screw test bench, an electric screwdriver 10, and a torque tester 20. The electric screwdriver 10 can be an Atlas EBL series, such as the EBL55, which has a cutting head 11. The torque tester can be a Desoutter DELTA 6D product, which includes a sensor 21 mounted on the electric screwdriver cutting head 11 to collect torque data. Figure 4This document details the torque variation curves of a self-tapping screw throughout the entire process of screwing it into the flanged hole of a metal plate, tightening, and stripping failure. During the tapping stage, i.e., as the self-tapping screw creates a complete thread within the flanged hole of the metal plate, the screw initially experiences its maximum torque, termed the insertion torque Ti. As the thread gradually forms, the torque gradually decreases, reaching its minimum value Tc when a complete thread is formed within the flanged hole. With further screwing, the tightening stage begins, and the torque gradually increases, the curve rising. At a certain value, the screw locks the connector and the connected components, such as the first and second metal plates in the above embodiment; this torque is the locking torque TL. Continuing to apply torque further tightens the screw, and the torque continues to rise. After reaching its maximum value, the screw strips and fails. Subsequently, the torque decreases due to screw slippage. The maximum torque during the tightening stage is termed the breaking torque To. In practice, the locking torque TL is usually determined by measuring the insertion torque Ti and the breaking torque To. That is, the locking torque TL is set as a value between the insertion torque Ti and the breaking torque To, such as an intermediate value, and this is used as the torque setting value for the electric screwdrivers used by operators on the production line to drive screws.

[0024] Reference Figure 6 The self-tapping screw performance testing method in one embodiment of this disclosure is shown. First, standard values ​​for the insertion torque Tis and breaking torque Tos of the self-tapping screw are provided (step 501). These standard values ​​are obtained by the OEM based on specified self-tapping screws and sheet metal parts (such as the first and second metal plates in the above embodiment). A self-tapping screw testing system as described above is provided (step 502), namely a test bench, an electric screwdriver 10, and a torque tester 20. When the supplier produces a batch of self-tapping screws, a group of self-tapping screws is randomly selected and tested one by one (step 503). This testing can be completed during the OEM's incoming material inspection or before the supplier ships the product. (See reference...) Figures 1 to 3 As shown, in some embodiments, the selected self-tapping screws 40 are passed one by one through the first through hole 311 of the first metal plate 31 and screwed into the second flange hole 323 of the second metal plate 32 using an electric screwdriver 10. Then, the insertion torque Tin and breaking torque Ton of each self-tapping screw are determined based on the data collected by the torque tester 20 (step 504). (Refer to reference...) Figure 5 As shown in the specific example, the torque curve of each self-tapping screw can be plotted based on the data collected by the torque tester 20. For example, in this example, a group of ten screws are randomly selected, so ten torque curves can be obtained. Then, the value of the highest point of each torque curve in the tapping stage is determined as the insertion torque Tin of the self-tapping screw, and the value of the highest point of each torque curve in the tightening stage is determined as the breaking torque Ton of the self-tapping screw.

[0025] Subsequently, the insertion torque Ti and breaking torque To of the group of self-tapping screws are determined based on the insertion torque Tin and breaking torque To of each self-tapping screw (step 505). Regarding the determination of the insertion torque Ti of the group of self-tapping screws, in some embodiments, the maximum value among all insertion torques of the group of self-tapping screws is first determined, and then the maximum value of the insertion torque, or the sum of the maximum value plus a predetermined number of standard deviations, is determined as the insertion torque Ti of the group of self-tapping screws; in other embodiments, the average value of all insertion torques of the group of self-tapping screws is first calculated, and then the average value of the insertion torque, or the sum of the average value plus a predetermined number of standard deviations, is determined as the insertion torque Ti of the group of self-tapping screws. Regarding the determination of the breaking torque To of the group of self-tapping screws, in some embodiments, the minimum value among all breaking torques of the group of self-tapping screws is first determined, and then the minimum value of the breaking torque, or the difference between the minimum value and a predetermined number of standard deviations, is determined as the breaking torque To of the group of self-tapping screws; in other embodiments, the average value of all breaking torques of the group of self-tapping screws is first calculated, and then the average value of the breaking torque, or the difference between the average value and a predetermined number of standard deviations, is determined as the breaking torque To of the group of self-tapping screws. Figure 5 In the example shown, the insertion torque Ti of the group of self-tapping screws is the sum of the average insertion torque of the ten selected self-tapping screws plus three standard deviations. The breaking torque To of the group of self-tapping screws is the difference between the average breaking torque of the ten selected self-tapping screws and three standard deviations. Here, the standard deviation is the square root of the arithmetic mean of the squared deviations from the mean (i.e., the variance), usually denoted by σ, and its formula is:

[0026]

[0027] Where n is the total amount of data, such as n = 10 in this example;

[0028] Xi represents the set of values, such as the ten insertion torques or ten breaking torques in this example.

[0029] μ is the average value of the set of values, such as the average of the ten insertion torques or the average of the ten breaking torques in this example.

[0030] Determine whether the insertion torque Ti of the self-tapping screws in this group is less than or equal to the standard value Tis of the insertion torque, and whether the breaking torque To of the self-tapping screws in this group is greater than or equal to the standard value Tos of the breaking torque (step 506). If so, it indicates that the performance test of the self-tapping screws in this batch is qualified (step 507), because the locking torque TL, which is between the standard value Tis of the insertion torque and the standard value Tos of the breaking torque, must also fall within the range between the insertion torque Ti and the breaking torque To of the self-tapping screws in this group. Otherwise, it indicates that the performance test of the self-tapping screws in this batch is unqualified (step 508), because the locking torque TL may fall outside the range between the insertion torque Ti and the breaking torque To of the self-tapping screws in this group.

[0031] By testing the performance of self-tapping screws, unqualified batches of self-tapping screws can be screened out before the main unit is assembled, so as to prevent unqualified screws from entering the production line and affecting the main unit's production plan. It also helps to determine responsibility and analyze and solve quality problems when quality incidents occur.

[0032] In the description of the above embodiments in this disclosure, the orientations or positional relationships indicated by terms such as "longitudinal", "lateral", "vertical", "radial", "circumferential", "horizontal", "length", "width", "thickness", "up", "down", "left", "right", "front", and "rear" are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of description and simplification. They are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this disclosure.

[0033] In the above disclosure, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, the designation "first," "second," etc., may explicitly or implicitly include at least one of those features. In the above description, terms such as "several," "multiple," etc., mean at least two, such as two, three, etc., unless otherwise explicitly specified.

[0034] In the foregoing disclosure, unless otherwise expressly specified and limited, the terms "installation," "adjacent," "connected," "linked," and "fixed," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. For those skilled in the art, the specific meaning of the above terms in this disclosure can be understood according to the specific circumstances.

[0035] It should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A self-tapping screw testing platform, characterized in that: The test bench includes The base extends longitudinally, and its top has a vertically recessed receiving cavity, and a support portion is formed at the bottom periphery of the receiving cavity inside the base; A first metal plate having at least a plurality of first through holes spaced apart along the longitudinal direction; The second metal plate has at least a plurality of second flanged holes spaced apart along the longitudinal direction. in The first metal plate and the second metal plate are housed in the receiving cavity and stacked on the support, and the plurality of first through holes and the plurality of second flange holes correspond one-to-one.

2. The self-tapping screw test bench according to claim 1, characterized in that: The first metal plate is also provided with a plurality of first flanged holes spaced apart along the longitudinal direction, and the second metal plate is also provided with a plurality of second through holes spaced apart along the longitudinal direction; when the first metal plate and the second metal plate are stacked and housed in the housing cavity, the plurality of second through holes and the plurality of first flanged holes correspond one-to-one.

3. The self-tapping screw test bench according to claim 2, characterized in that: The first metal plate and the second metal plate have the same structure.

4. The self-tapping screw test bench according to claim 1, characterized in that: The perimeter of the receiving cavity is approximately equal to the perimeter of the first and second metal plates.

5. The self-tapping screw test bench according to claim 2, characterized in that: When the first metal plate and the second metal plate are stacked and housed in the housing cavity, the support portion supports the edge of the first metal plate or the second metal plate.

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