A device and test method for measuring the softness and hardness of office chair seat surface

Abstract

The present invention discloses a device and a test method for measuring the softness and hardness of an office chair seat surface. When the softness and hardness of an office chair seat surface needs to be measured, the softness and hardness factor is used for judgment; when the softness and hardness of the seat surface fabric of an office chair needs to be measured, the relaxation factor is used for judgment; when the softness and hardness of the internal material of the seat surface of an office chair needs to be measured, the thickness factor is used for judgment. The technical problem to be solved by the present invention is to provide a device and a test method for measuring the softness and hardness of an office chair seat surface, which can simultaneously meet the requirements of measuring the seat surface hardness of the entire office chair, the relaxation of the seat surface fabric, and the softness and hardness of the internal material of the seat surface, and has low cost and strong practicality.

Description

Technical Field

[0001] The invention belongs to the field of product design, and in particular relates to a device and a testing method for measuring the softness and hardness of an office chair seat surface. Background Art

[0002] The measurement of hardness is a conventional measurement item in the measurement field. The common instruments for measuring hardness include Leeb hardness tester, Rockwell hardness tester, Brinell hardness tester, Shore hardness tester, Shore hardness tester, Barcol hardness tester, microhardness tester, Mohs hardness tester, Vickers hardness tester, etc. Their measurement range includes ferrous metal materials, non-ferrous metal materials, ceramics, rubber, fiberglass products and other fields. In the field of polyurethane foam, the device for measuring hardness needs to provide standard samples according to the national standard for measurement. However, due to the unique seat structure of office chairs, it is impossible to provide suitable standard samples for monitoring. Even if the specifications are determined according to the standard, there is a certain gap between the actual seat surface. The softness and hardness are important parameters for the design of seat shaping cotton. Measuring the softness and hardness of the whole chair can understand the comfort range of the seat surface, thereby ensuring product quality. As for the current softness and hardness testing equipment, there is no device specifically used to measure the softness and hardness of the whole office chair and the device for accurately measuring the softness and hardness of shaping cotton. Although some high-precision instruments such as mechanical testing machines can achieve the purpose of measuring the indentation hardness by technical means, they will be inaccurate and fail to meet the standard requirements when used to measure shaping cotton. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a device and a testing method for measuring the softness and hardness of the seat of an office chair, which can simultaneously meet the requirements of measuring the seat hardness of the entire office chair, the looseness of the seat fabric, and the softness and hardness of the internal material of the seat, with low cost and strong practicality.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] A test method for measuring the softness and hardness of an office chair seat. When the softness and hardness of an office chair seat needs to be measured, the softness and hardness factor is used for judgment; when the softness and hardness of the fabric of the office chair seat needs to be measured, the relaxation factor is used for judgment; when the softness and hardness of the internal material of the office chair seat needs to be measured, the thickness factor is used for judgment.

[0006] Furthermore, the determination process of the softness and hardness factor includes the following steps:

[0007] Step 1.1: Paste the flexible capacitive sensor on the seat of the office chair;

[0008] Step 1.2: Apply force downward to the flexible capacitive sensor on the seat surface of the office chair at a speed of V1, and load it to 800N to obtain a relationship curve between the seat surface force and capacitance of the office chair;

[0009] Step 1.3: Calculate the softness and hardness factor of the office chair seat:

[0010]

[0011] Among them, H z Indicates the hardness factor of the office chair seat surface, H z The larger the H, the higher the hardness of the office chair seat surface. z The smaller the value, the softer the seat of the office chair. d(c) represents the differential of capacitance. The total area enclosed by the capacitance change curve in the range of 0N to 800N and the applied force on the curve representing the relationship between the seat force and capacitance of the office chair, K 1 It represents the average slope of the curve of the relationship between the seat force and capacitance of the office chair when the force is the X-axis and the capacitance is the Y-axis.

[0012] Preferably, in step 1.3, K 1 The calculation formula is:

[0013]

[0014] Wherein, n is the number of different force value points in the force range of 300N-700N, and d(ci) / d(Fi) represents the slope of the relationship curve between the seat force and capacitance of the office chair when the force value is i.

[0015] Preferably, n=3, i takes three values: 340N, 460N and 580N, that is, K 1 Calculation method:

[0016]

[0017] Furthermore, the determination process of the relaxation factor includes the following steps:

[0018] Step 2.1: Paste the flexible capacitive sensor on the seat of the office chair;

[0019] Step 2.2: Pull the seat fabric upward at a speed of V2 and load it to the upper limit force value F. 0 , and obtain the relationship curve between seat surface material force and capacitance;

[0020] Step 2.3: Calculate the relaxation factor of the seat fabric:

[0021]

[0022] Among them, Sm represents the relaxation factor of the seat fabric. The larger the Sm, the higher the hardness of the seat fabric. The smaller the Sm, the lower the hardness of the seat fabric. 2 The curve showing the relationship between seat surface material force and capacitance is at the upper limit force value F of the material. 0 Department, The curve showing the relationship between seat surface force and capacitance, 0N~F 0 Range is the total area enclosed by the capacitance change curve and the applied force.

[0023] Preferably, F 0 ≤100N.

[0024] Furthermore, the thickness factor determination process includes the following steps:

[0025] Step 3.1: Take samples of the shaping cotton inside the seat of the office chair;

[0026] Step 3.2: Cut the shaped cotton sample based on the fixed length, width and height so that the shaped cotton sample is a uniform rectangular block;

[0027] Step 3.3: Apply a downward fixing force Fg to the shaped cotton sample;

[0028] Step 3.4: Obtain the thickness d2 of the styling cotton sample under the pressure Fg through the thickness sensor, and calculate the thickness change difference of the styling cotton, which is d1-d2, where d1 is the height of the styling cotton sample;

[0029] Step 3.5: Determine the hardness of the shaping cotton based on the difference in thickness change of the shaping cotton. The smaller the difference in thickness change of the shaping cotton, the higher the hardness of the shaping cotton. The larger the difference in thickness change of the shaping cotton, the lower the hardness of the shaping cotton.

[0030] The present invention also provides a testing device for measuring the softness and hardness of an office chair seat surface, comprising a rectangular base, peripheral frames are fixedly provided on the short sides of the rectangular base, two crossbeams parallel to the long sides of the rectangular base are fixedly provided on the tops of the two peripheral frames, and the distances between the crossbeams and the two long sides of the rectangular base are equal, a telescopic rod in a vertical direction is fixedly provided at the middle position of the crossbeam, a mechanical sensor is provided on the telescopic rod, a pressure pad is fixedly provided at the bottom of the telescopic rod, a test bench is detachably provided at the middle position of the rectangular base, a thickness sensor is provided on the test bench, and when the telescopic rod is in an extended position, the pressure pad is in contact with the test bench When it is necessary to measure the softness and hardness of the internal material of the office chair seat, the internal material sample is placed on the test bench; when it is necessary to measure the softness and hardness of the office chair seat, the office chair seat is placed on the placement table, or the test bench is removed, the office chair is placed on the rectangular base, and a flexible capacitive sensor is detachably provided on the seat of the office chair, and the pressure pad applies force downward at a speed of V1; when it is necessary to measure the softness and hardness of the seat fabric of the office chair, the office chair seat is placed on the placement table, or the test bench is removed, the office chair is placed on the rectangular base, and a flexible capacitive sensor is detachably provided on the seat of the office chair, and the flexible capacitive sensor is connected to the flexible capacitive sensor and the pressure pad at the same time, and the pressure pad pulls the seat fabric upward at a speed of V2.

[0031] Preferably, the test bench includes a transverse plate and a support shaft, a convex ring is provided at the bottom of the transverse plate, a convex ring is provided at the top of the support shaft, the convex ring is matched with the convex ring, a plurality of equidistant brackets are provided at the bottom of the support shaft, and the brackets are hinged to the support shaft.

[0032] Preferably, a groove is provided at the bottom of the rectangular base, a matching cover is provided on the groove, a hole is provided in the groove, the hole is snap-fitted with the bottom of the support shaft, the center position of the groove is a regular polygon, the number of the brackets is the number of corners of the regular polygon, and the bottom of the bracket is placed on the corner of the regular polygon.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The technical problem to be solved by the present invention is to provide a device and a testing method for measuring the softness and hardness of the seat of an office chair, which can simultaneously meet the requirements of measuring the seat hardness of the entire office chair, the looseness of the seat fabric, and the softness and hardness of the internal material of the seat, with low cost and strong practicality.

[0035] 1. The present invention applies a certain force to the pressure pad through a force sensor, and then measures the capacitance accumulation of the force-bearing seat surface through a flexible strain sensor, and calculates the hardness value of the seat surface through a force-capacitance nonlinear relationship curve, which is simple and easy to implement.

[0036] 2. The present invention can also measure the thickness of the shaping cotton on the seat of an office chair, filling the gap that there is no professional equipment to test the thickness of the shaping cotton. It combines the test of the entire chair seat with the test of the shaping cotton to meet the different needs of enterprises and has extremely high practical value.

[0037] 3. The present invention can also measure the relaxation factor of the fabric on the finished seat separately, so as to know the influence of the fabric on the softness and hardness of the seat surface, which provides convenience for enterprises to conduct comfort research on fabrics.

[0038] 3. The present invention can measure the seat surface separately and can also measure the softness and hardness of the seat surface on the whole chair without disassembling the seat surface. The device is simple and easy to operate.

[0039] 4. The present invention can well ensure the stability of the test bench through the clamping structure of the hole and the support shaft, and the contact support of the bracket and the regular polygon structure of the groove. In addition, the design of the cover plate makes the rectangular base in the storage state flat, so that the office chair can be directly moved under the pressure pad without using the test bench to directly measure the softness and hardness of the office chair seat surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A schematic diagram of a device for measuring the softness and hardness of an office chair seat surface according to the present invention;

[0041] Figure 2 A schematic diagram of an embodiment of a device for measuring the softness and hardness of an office chair seat surface of the present invention;

[0042] Figure 3 A schematic diagram of another embodiment of the device for measuring the softness and hardness of an office chair seat surface of the present invention;

[0043] Figure 4 A schematic diagram of pulling the seat fabric for measuring the slackness of the seat fabric of an office chair according to the present invention;

[0044] Figure 5 This is a schematic diagram of the connection between the cover plate and the base of the present invention;

[0045] Figure 6 This is a schematic diagram of the connection between the support rod and the base of the present invention;

[0046] Figure 7 Schematic diagram of the connection between the test bench and the support rod of the present invention

[0047] 1- rectangular base, 2- outer frame, 3- crossbeam, 4- telescopic rod, 5- pressure pad, 6- mechanical sensor, 7- flexible capacitive sensor, 8- thickness sensor, 9- test bench, 10- support shaft, 11- bracket, 12- cover plate, 13- groove, 14- hole. DETAILED DESCRIPTION

[0048] The present invention will be further described below in conjunction with the accompanying drawings.

[0049] Example 1

[0050] The invention provides a testing device and method for measuring the softness and hardness of an office chair seat surface.

[0051] like Figure 1 As shown, it includes a rectangular base 1, on the short sides of which peripheral frames 2 are fixed respectively, and the tops of the two peripheral frames 2 are fixed with beams 3 parallel to the long sides of the rectangular base 1, and the distances between the beams 3 and the two long sides of the rectangular base 1 are equal, a telescopic rod 4 in the vertical direction is fixedly provided in the middle position of the beam 3, a mechanical sensor 6 is provided on the telescopic rod 4, a pressure pad 5 is fixedly provided at the bottom of the telescopic rod 4, a test bench 9 is detachably provided in the middle position of the rectangular base 1, and a thickness sensor 8 is provided on the test bench 9, when the telescopic rod 4 is in the extended position, the pressure pad 5 is in contact with the test bench 9, and when it is necessary to measure the softness and hardness of the internal material of the office chair seat surface, the internal material sample is placed on the test bench 9.

[0052] Preferably, the pressure pad 5 is hip-shaped. The hip-shaped pressure pad imitates the shape of the human buttocks, restores the most realistic pressure value of the human body to the greatest extent, and improves the measurement accuracy.

[0053] The present invention adopts flexible capacitive sensing technology. As the seat surface is deformed by force, the capacitance value changes, and the change of the capacitance of the compressed object with stress and strain is tested.

[0054] When it is necessary to measure the softness and hardness of the internal material of the office chair seat, the thickness factor is used for judgment.

[0055] Specifically, the thickness factor determination process includes the following steps:

[0056] Step 3.1: Take samples of the shaping cotton inside the seat of the office chair;

[0057] Step 3.2: Cut the shaped cotton sample based on the fixed length, width and height so that the shaped cotton sample is a uniform rectangular block;

[0058] Step 3.3: Apply a downward fixing force Fg to the shaped cotton sample;

[0059] Step 3.4: Obtain the thickness d2 of the styling cotton sample under the pressure Fg through the thickness sensor, and calculate the thickness change difference of the styling cotton, which is d1-d2, where d1 is the height of the styling cotton sample;

[0060] Step 3.5: Determine the hardness of the shaping cotton based on the difference in thickness change of the shaping cotton. The smaller the difference in thickness change of the shaping cotton, the higher the hardness of the shaping cotton. The larger the difference in thickness change of the shaping cotton, the lower the hardness of the shaping cotton.

[0061] Example 2

[0062] The only difference between Example 2 and Example 1 is that the structure of the test bench is limited so that it can be disassembled while having a certain stability.

[0063] Specifically, Figure 7 As shown, the test bench 9 includes a transverse plate and a support shaft 10, a convex ring is provided at the bottom of the transverse plate, a convex circle is provided at the top of the support shaft 10, the convex ring is matched with the convex circle, and a plurality of equidistant brackets 11 are provided at the bottom of the support shaft 10, and the brackets 11 are hinged to the support shaft 10.

[0064] Preferably, the convex ring and the convex circle are provided with matching internal threads and external threads.

[0065] Example 3

[0066] The only difference between Example 3 and Example 2 is that the stability of the test bench is further enhanced.

[0067] Specifically, Figure 6 As shown, the bottom of the rectangular base 1 is provided with a groove 13, and a matching cover plate 12 is provided on the groove 13. Figure 5 As shown, the cover plate 12 is hinged to the groove 13. A hole 14 is provided in the groove 13, and the hole 14 is snap-fitted to the bottom of the support shaft 10. The center position of the groove 13 is a regular polygon. The number of the brackets 11 is the number of the corners of the regular polygon, and the bottom of the brackets 11 is placed on the corners of the regular polygon. The stability of the test bench can be well guaranteed by the snap-fitting structure of the hole 14 and the support shaft 10, and the contact support of the bracket 11 and the regular polygon structure of the groove. In addition, the design of the cover plate 12 makes the rectangular base 1 flat in the storage state, so that the office chair can be directly moved to the bottom of the pressure pad 5 without going through the test bench 9, and the softness and hardness of the office chair seat surface can be directly measured.

[0068] Example 4

[0069] The only difference between Example 4 and Example 1 is that the device is used to test the softness and hardness of the office seat surface.

[0070] When the softness and hardness of the office chair seat surface needs to be measured, the office chair seat surface is placed on the placement table. Figure 2 As shown, or the test bench is removed, the office chair is placed on the rectangular base 1, as shown Figure 3 As shown, a flexible capacitive sensor 7 is detachably provided on the seat surface of the office chair, and a pressure pad 5 applies force downward at a speed V1. The pressure pad 5 can contact the flexible capacitive sensor 7 downward. The bottom of the flexible capacitive sensor 7 and the top of the seat surface of the office chair are respectively provided with matching Velcro, so that the flexible capacitive sensor 7 is attached to the seat surface of the office chair.

[0071] When you need to measure the softness and hardness of an office chair seat, use the hardness factor to determine.

[0072] Specifically, the determination process of the softness and hardness factor includes the following steps:

[0073] Step 1.1: Paste the flexible capacitive sensor on the seat of the office chair;

[0074] Step 1.2: Apply force downward to the flexible capacitive sensor on the seat surface of the office chair at a speed of V1, and load it to 800N to obtain a relationship curve between the seat surface force and capacitance of the office chair;

[0075] Step 1.3: Calculate the softness and hardness factor of the office chair seat:

[0076]

[0077] Among them, H z Indicates the hardness factor of the office chair seat surface, Hz The larger the H, the higher the hardness of the office chair seat surface. z The smaller the value, the softer the seat of the office chair. d(c) represents the differential of capacitance. The total area enclosed by the capacitance change curve in the range of 0N to 800N and the applied force on the curve representing the relationship between the seat force and capacitance of the office chair, K 1 It represents the average slope of the curve of the relationship between the seat force and capacitance of the office chair when the force is the X-axis and the capacitance is the Y-axis.

[0078] Preferably, in step 1.3, K 1 The calculation formula is:

[0079]

[0080] Wherein, n is the number of different force value points in the force range of 300N-700N, and d(ci) / d(Fi) represents the slope of the relationship curve between the seat force and capacitance of the office chair when the force value is i.

[0081] Preferably, n=3, i takes three values: 340N, 460N and 580N, that is, K 1 Calculation method:

[0082]

[0083] Example 5

[0084] The difference between this embodiment and embodiment 1 is that it is used to measure the softness and hardness of fabrics. When it is necessary to measure the softness and hardness of the seat fabric of an office chair, Figure 2 As shown, the office chair seat is placed on the placement table, or the test table is removed, such as Figure 3 As shown, the office chair is placed on a rectangular base 1, and a flexible capacitive sensor 7 is detachably provided on the seat surface of the office chair. The flexible capacitive sensor 7 is connected to the flexible capacitive sensor 7 and the pressure pad 5 at the same time, and the pressure pad 5 pulls the seat surface fabric upward at a speed V2. The upper and lower surfaces of the flexible capacitive sensor 7 are provided with adhesive materials, such as Velcro, and correspondingly, the contact parts of the flexible capacitive sensor 7, the pressure pad 5 and the seat surface of the office chair are also provided with Velcro, the top of the flexible capacitive sensor 7 is adapted to the bottom Velcro of the pressure pad 5, and the bottom of the flexible capacitive sensor 7 is adapted to the Velcro on the top of the seat surface of the office chair.

[0085] When it is necessary to measure the softness and hardness of the seat fabric of an office chair, the relaxation factor Sm, which represents the tension of the fabric, is used for judgment. Figure 4 As shown in the figure, the seat fabric of the office chair will have different tensions when the same deformation is applied due to the different materials and elasticity of the fabrics. The factors that affect this characteristic of the fabric are collectively called relaxation factor Sm. This parameter has a certain impact on the overall softness and hardness of the seat.

[0086] Specifically, the determination process of the relaxation factor includes the following steps:

[0087] Step 2.1: Paste the flexible capacitive sensor on the seat of the office chair;

[0088] Step 2.2: Pull the seat fabric upward at a speed of V2 and load it to the upper limit force value F. 0 , and obtain the relationship curve between seat surface material force and capacitance;

[0089] Step 2.3: Calculate the relaxation factor of the seat fabric:

[0090]

[0091] Among them, Sm represents the relaxation factor of the seat fabric. The larger the Sm, the higher the hardness of the seat fabric. The smaller the Sm, the lower the hardness of the seat fabric. 2 The curve showing the relationship between seat surface material force and capacitance is at the upper limit force value F of the material. 0 Department, The curve showing the relationship between seat surface force and capacitance, 0N~F 0 The total area enclosed by the range capacitance change curve and the applied force. 0 The fabric can be tensioned. 0 ≤100N.

[0092] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A test method for measuring the softness and hardness of an office chair seat surface, characterized in that: When it is necessary to measure the softness and hardness of the seat of an office chair, it is determined by the softness and hardness factor; when it is necessary to measure the softness and hardness of the seat fabric of an office chair, it is determined by the relaxation factor; when it is necessary to measure the softness and hardness of the internal material of the seat of an office chair, it is determined by the thickness factor; The determination process of the softness and hardness factor includes the following steps: Step 1.1: Paste the flexible capacitive sensor on the seat of the office chair; Step 1.2: Apply force downward to the flexible capacitive sensor on the seat surface of the office chair at a speed of V1, and load it to 800N to obtain a relationship curve between the seat surface force and capacitance of the office chair; Step 1.3: Calculate the softness and hardness factor of the office chair seat: ； Among them, H z Indicates the hardness factor of the office chair seat surface, H z The larger the H, the higher the hardness of the office chair seat surface. z The smaller the value, the softer the seat of the office chair. d(c) represents the differential of capacitance. It represents the total area enclosed by the capacitance change curve in the range of 0N to 800N and the applied force on the relationship curve between the seat force and capacitance of the office chair. K1 represents the average slope of the relationship curve between the seat force and capacitance of the office chair when the force is the X-axis and the capacitance is the Y-axis. The calculation formula for K1 in step 1.3 is: ； Where n is the number of different force value points in the force range of 300N-700N. It indicates the slope of the curve of the relationship between the seat force and capacitance of the office chair when the force value is i; The determination process of the relaxation factor includes the following steps: Step 2.1: Paste the flexible capacitive sensor on the seat of the office chair; Step 2.2: Pull the seat fabric upward at a speed of V2 and load it to the upper limit of the fabric loading force. , and obtain the relationship curve between seat surface material force and capacitance; Step 2.3: Calculate the relaxation factor of the seat fabric: ； Among them, Sm represents the relaxation factor of the seat surface fabric. The larger the Sm, the higher the hardness of the seat surface fabric. The smaller the Sm, the lower the hardness of the seat surface fabric. K2 represents the relationship curve between the seat surface fabric force and capacitance at the upper limit force value of the fabric loading. Department, The curve showing the relationship between seat surface force and capacitance is 0N~ Range is the total area enclosed by the capacitance change curve and the applied force; The determination process of thickness factor includes the following steps: Step 3.1: Take samples of the shaping cotton inside the seat of the office chair; Step 3.2: Cut the shaped cotton sample based on the fixed length, width and height so that the shaped cotton sample is a uniform rectangular block; Step 3.3: Apply a downward fixing force Fg to the shaped cotton sample; Step 3.4: Obtain the thickness d2 of the styling cotton sample under the pressure Fg through the thickness sensor, and calculate the thickness change difference of the styling cotton, which is d1-d2, where d1 is the height of the styling cotton sample; Step 3.5: Determine the hardness of the shaping cotton based on the difference in thickness change of the shaping cotton. The smaller the difference in thickness change of the shaping cotton, the higher the hardness of the shaping cotton. The larger the difference in thickness change of the shaping cotton, the lower the hardness of the shaping cotton.

2. A test method for measuring the softness and hardness of an office chair seat surface according to claim 1, characterized in that: n=3, i takes three values: 340N, 460N and 580N, that is, the calculation method of K1 is: 。 3. A test method for measuring the softness and hardness of an office chair seat surface according to claim 2, characterized in that: ≤100N。 4. A device for measuring the softness and hardness of an office chair seat surface according to any one of claims 1 to 3, characterized in that: The invention comprises a rectangular base (1), wherein peripheral frames (2) are fixedly provided on the short sides of the rectangular base (1), and crossbeams (3) parallel to the long sides of the rectangular base (1) are fixedly provided on the tops of two of the peripheral frames (2), and the crossbeams (3) are equidistant from the two long sides of the rectangular base (1), and a telescopic rod (4) in a vertical direction is fixedly provided in the middle of the crossbeam (3), and a mechanical sensor (6) is provided on the telescopic rod (4), and a pressure pad (5) is fixedly provided at the bottom of the telescopic rod (4), and a test bench (9) is detachably provided in the middle of the rectangular base (1), and a thickness sensor (8) is provided on the test bench (9), and when the telescopic rod (4) is in an extended position, the pressure pad (5) and the test bench (9) are in a tensioned state. ), when it is necessary to measure the softness and hardness of the internal material of the office chair seat surface, the internal material sample is placed on the test bench (9); when it is necessary to measure the softness and hardness of the office chair seat surface, the office chair seat surface is placed on the placement table, or the test bench is removed, the office chair is placed on the rectangular base (1), and a flexible capacitive sensor (7) is detachably provided on the office chair seat surface, and the pressure pad (5) applies force downward at a speed V1; when it is necessary to measure the softness and hardness of the office chair seat surface fabric, the office chair seat surface is placed on the placement table, or the test bench is removed, the office chair is placed on the rectangular base (1), and a flexible capacitive sensor (7) is detachably provided on the office chair seat surface, and the flexible capacitive sensor (7) is connected to the flexible capacitive sensor (7) and the pressure pad (5) at the same time, and the pressure pad (5) pulls the seat surface fabric upward at a speed V2.

5. A device for measuring the softness and hardness of an office chair seat surface according to claim 4, characterized in that: The test bench (9) comprises a transverse plate and a support shaft (10); a convex ring is provided at the bottom of the transverse plate; a convex circle is provided at the top of the support shaft (10); the convex ring is matched with the convex circle; a plurality of equidistant brackets (11) are provided at the bottom of the support shaft (10); the brackets (11) are hingedly connected to the support shaft (10).

6. The device for measuring the softness and hardness of an office chair seat surface according to claim 5, characterized in that: The bottom of the rectangular base (1) is provided with a groove (13), a matching cover plate (12) is provided on the groove (13), a hole (14) is provided in the groove (13), the hole (14) is engaged with the bottom of the support shaft (10), the center position of the groove (13) is a regular polygon, the number of the brackets (11) is the same as the number of corners of the regular polygon, and the bottom of the bracket (11) is placed on the corner of the regular polygon.

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