An instrument for measuring the coefficient of friction of cards and its measuring method

Abstract

The present invention is aimed at the fact that the existing friction coefficient measuring instruments are not suitable for products such as cards, and the experimental results measured by other measuring instruments are far from the actual situation. An instrument for measuring the friction coefficient between cards and a matching measurement method are designed. An instrument for measuring the friction coefficient of cards, including: a base, an adjustment device and a friction coefficient measuring device; the friction coefficient between cards can be directly measured by this experimental instrument, so there is no need to perform sample cutting, which greatly improves the work efficiency of data measurement; because the measuring instrument uses pressure value sampling per unit time, the pressure change per second can be intuitively understood, and because the friction coefficient between cards may be different at all times, it is more scientific to adopt this data recording method, and it meets the actual production needs.

Description

Technical Field

[0001] The present invention relates to the field of friction coefficient measurement, and particularly to an instrument for measuring the friction coefficient of cards and a measurement method compatible with the instrument. Background Art

[0002] Existing friction coefficient measurement instruments are diverse and can measure the friction coefficient of the surface of different objects. Generally, a planar friction coefficient instrument is used for detecting the friction coefficient of paper. Its test principle is that two test surfaces are placed flat together, and under a certain contact pressure, the two surfaces are moved relative to each other, and the required force is recorded. Dividing the tested force by the gravity of the slider gives the friction coefficient value. This process can detect the static friction coefficient and the dynamic friction coefficient. However, since this planar friction coefficient instrument is a general-purpose design, it is usually large in size and the tested force is obtained through calculation and conversion. If it is to be applied to the existing planar friction coefficient instrument, first, the card paper needs to be cut and sampled, data is calculated based on the sample, and finally, the data is converted into the actual working force. The process is complex and error-prone, and the efficiency is relatively low. For products such as cards, there is no dedicated measurement instrument and measurement method. The format size of a single card is small, and there are various printing processes on the card. The experimental results measured by other measurement instruments have a large gap from the actual situation, and the measurement is unstable. Its measurement results cannot provide data support for actual production needs. Therefore, it is necessary to develop a friction coefficient measurement instrument for cards. Summary of the Invention

[0003] The present invention aims at the deficiencies of the prior art and provides an instrument for measuring the friction coefficient between cards, and also provides a measurement method applicable to the friction coefficient between cards.

[0004] The present invention provides an instrument for measuring the friction coefficient of cards, including: a base, an alignment device, and a friction coefficient measurement device;

[0005] The friction coefficient measurement device includes: a lower slider, a slider driving device, and a set of thrust sensor devices arranged in groups;

[0006] The base includes a housing and a bottom plate, and the housing and the bottom plate form a cavity;

[0007] Two parallel slot holes are provided on the top surface of the housing. The slider driving device is arranged in the cavity, and the movable end passes through the slot holes and is detachably connected to the lower slider, and the lower slider slides along the direction of the slot holes;

[0008] The thrust sensor devices are arranged symmetrically in the moving direction of the lower slider, the sensing surfaces face the upper pressing block, and the device bodies are fixedly connected to the housing;

[0009] The alignment device is arranged on the upper side of the friction coefficient measuring device on the base, and includes: a set of parallel lead screws, a slide rail frame arranged on the lead screws, a slide block sleeve sliding along the slide rail arranged on the slide rail frame, an upper pressing block and a pressing block supporting device;

[0010] The axis of the slide rail is perpendicular to the axis of the lead screw. A guide hole is arranged on the slide block sleeve, and a guide rod is arranged on the top surface of the upper pressing block. The guide rod is inserted into the guide hole to limit the position of the upper pressing block along with the slide block sleeve;

[0011] The pressing block supporting device is arranged in the cavity, and the movable end passes through the housing and cooperates with the upper pressing block to work.

[0012] The split design of the lower slide block and the slide block driving device is beneficial to replacing the lower slide block when different card sizes are involved, and is also beneficial to directly rotating the same lower slide block by 180 degrees for secondary work; the cooperation between the upper pressing block and the slide block sleeve is the same, facilitating the replacement of the upper pressing block.

[0013] The parallel arrangement of the lead screws in the alignment device can adjust the forward and backward movement of the slide rail frame on the lead screws. When the slide rail frame is offset, it will drive the slide block sleeve to offset forward and backward, thereby driving the upper pressing block and the card adhered to the upper pressing block to offset, so as to calibrate the front and back positions.

[0014] The slide block sleeve is installed with pulleys at the bottom, and the pulleys are mounted on the slide rail frame, so that the slide block sleeve can offset left and right along the slide rail frame. When it is necessary to adjust the left and right offset, only need to push the slide block sleeve to adjust the upper pressing block and the card adhered to the upper pressing block to offset.

[0015] The thrust sensor device includes: a mounting cross beam, a sensor mounting plate and a sensor front plate; the mounting cross beam is used to limit the overall position of the device, the sensor mounting plate is slidably connected to the mounting cross beam to facilitate the adjustment of the actual position of the sensor front plate; a thrust sensor is installed between the sensor front plate and the sensor mounting plate, and the sensor front plate can adapt to the upper pressing block with adjusted front and back positions, avoiding the need for a sensor array and increasing the complexity of the overall device.

[0016] The length of the sensor front plate is consistent with the width of the upper pressing block.

[0017] When the cards adhered to the lower slide block and the upper pressing block move relative to each other due to the action of the slide block driving device, the upper pressing block will be driven due to the friction between the cards, so that the upper pressing block will top against the thrust sensor device, and the thrust sensor device will calculate the friction between the two cards.

[0018] Preferably, the pressing block supporting device includes: a support column lifting knob, a rotating rod is arranged on one side of the knob, the rotating rod penetrates into the housing, and two lifting wheels are sleeved on the rotating rod;

[0019] The top surface of the housing is provided with a group of support rod holes. Support rods are arranged in the support rod holes. The top surface of the support rod cooperates with the upper pressing block, and the bottom surface of the support rod abuts against the lifting wheel.

[0020] The lifting wheel is of a cam structure, and both ends of the support rod are spherical surfaces.

[0021] An ear plate extends from the middle section of the long side of the upper pressing block, and the ear plate cooperates with the support rod.

[0022] Preferably, a slider is arranged on the bottom surface of the slide rail frame and sleeved on the lead screw of the alignment device, so that the slide rail frame slides back and forth along the lead screw.

[0023] A synchronous belt is arranged at one end of the lead screw to make the two lead screws rotate synchronously.

[0024] The slide rail surface of the slide rail frame is a 1 / 5 circular arc concave surface. The 1 / 5 circular arc concave surface can limit the front and back positions of the pulley while ensuring the free rolling of the pulley, so as to ensure that the slide rail frame can drive the slide plate sleeve to adjust back and forth when adjusting back and forth.

[0025] Preferably, the top surface of the lower slider has the same size as the bottom surface of the upper pressing block, and a rubber layer with equal thickness is laid on both. The rubber layer can provide an effective adsorption layer for adhering the static film, avoiding the slipping phenomenon of the static film sleeved on the metal block.

[0026] Preferably, the slider driving device includes: a pair of parallel transmission lead screws, a driving motor and a transmission slider.

[0027] The transmission lead screw is arranged on the bottom plate, and the transmission slider is sleeved on the transmission lead screw; a transmission device is arranged at one end of the transmission lead screw, and a driving motor is arranged on the bottom plate on the same side of the transmission device. The power end of the driving motor is in transmission connection with the transmission lead screw through the transmission device.

[0028] Two parallel protrusions are arranged on the top surface of the transmission slider, and two parallel grooves are arranged on the bottom surface of the lower slider. The protrusions of the transmission slider are inserted into the grooves of the lower slider.

[0029] Preferably, the sum of the weights of the upper pressing block and the guide rod is 500 g. The reason for selecting this weight is to simulate the real production environment, and the pressure of the bottom two cards of the automatic card dispenser is about 500 g.

[0030] The present invention also provides a method for measuring the friction coefficient of cards, including the following steps:

[0031] Step 1, select two cards without creases, select an upper pressing block and a lower slider that match the size of the cards, and adhere the cards to the upper pressing block and the lower slider.

[0032] Step 2: After installing the upper pressing block and the lower sliding block, use the alignment device to align the edges of the two cards;

[0033] Step 3: Adjust the thrust sensor device so that the sensing surface is aligned with the edge of the card and the sensor reading is 0;

[0034] Step 4: Use the device to move the lower sliding block to one side, keep the moving speed at 5 mm / s and record the reading;

[0035] Step 5: After completing one test, lift the upper pressing block through the pressing block support device and reset the lower sliding block;

[0036] Step 6: Repeat Step 4 and Step 5 at least 10 times;

[0037] Step 7: Switch the direction and repeat Step 4 and Step 5 at least 10 times;

[0038] Step 8: Judge the data in Step 6. If less than 5 values in all the data are less than or equal to the standard value, it is judged that the relative movement in the first direction is qualified; if 5 or more values are greater than the standard value, it is judged that the relative movement in the first direction is unqualified;

[0039] Step 9: Judge the data in Step 7. If less than 5 values in all the data are less than or equal to the standard value, it is judged that the relative movement in the second direction is qualified; if 5 or more values are greater than the standard value, it is judged that the relative movement in the second direction is unqualified.

[0040] Preferably, in Step 1, the following sub-steps are included:

[0041] Sub-step 1-1: Attach an electrostatic film to the surfaces of the upper pressing block and the lower sliding block, and the thickness of the electrostatic film is not less than 100 um;

[0042] Sub-step 1-2: Apply evenly distributed glue on the surface of the electrostatic film, and stick the two cards on the electrostatic film of the upper pressing block and the electrostatic film of the lower sliding block respectively.

[0043] If the size of the card is A mm × B mm, the sizes of both the upper pressing block and the lower sliding block are (A - 1) mm × (B - 1) mm. The purpose is to prevent excessive pressure at the edge position of the card, which may cause adverse effects on the measurement of the friction coefficient when the edge position moves.

[0044] The substantial effect of the present invention is that the friction coefficient between cards can be directly measured by this experimental instrument, thus eliminating the need for sample cutting work and greatly improving the work efficiency of data measurement. Since the measurement instrument uses pressure value sampling per unit time, the pressure change per second can be intuitively understood. And because the friction coefficient between cards may vary at all times, using this data recording method is more scientific and meets the actual production needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 is an axonometric view of an instrument for measuring the friction coefficient of cards according to the present invention;

[0046] Figure 2 is a front part detail view of an instrument for measuring the friction coefficient of cards according to the present invention;

[0047] Figure 3 is a rear part detail view of an instrument for measuring the friction coefficient of cards according to the present invention;

[0048] Figure 4 is an internal structure view of the base of an instrument for measuring the friction coefficient of cards according to the present invention;

[0049] Figure 5 is a structural view of the thrust sensor device of an instrument for measuring the friction coefficient of cards according to the present invention;

[0050] In the figure: 1. Base, 1-1. Display screen, 1-2. Buttons, 1-3. Printer, 1-4. Support column lifting knob, 1-5. Lifting column A, 1-6. Lifting column B, 1-7. Slot A, 1-8. Slot B, 1-9. Lifting wheel A, 1-10. Lifting wheel B;

[0051] 2. Alignment device, 2-1 Column A, 2-2. Column B, 2-3. Column C, 2-4. Column D, 2-5. Screw rod A, 2-6. Screw rod B, 2-7. Rolling nut A, 2-8. Rolling nut B, 2-9. Slide block A, 2-10. Slide block B, 2-11. Slide block C, 2-12. Slide block D, 2-13. Cross beam A, 2-14. Cross beam B, 2-15. Guide rail A, 2-16. Guide roller B, 2-17. Synchronous belt, 2-18. Synchronous belt pulley A, 2-19. Synchronous belt pulley B;

[0052] 3. Friction coefficient measurement device,

[0053] 3-1. Skateboard sleeve, 3-2. Guide rod A, 3-3. Guide rod B, 3-4. Pulley A, 3-5. Pulley B, 3-6. Pulley C, 3-7. Pulley D, 3-8. Upper pressing block, 3-9. Lower sliding block, 3-10. Thrust sensor device A, 3-11. Thrust sensor device B, 3-12. Transmission guide rod, 3-13. Transmission lead screw, 3-14. Driving motor, 3-15. Gear A, 3-16. Gear B.

[0054] 3-10-1. Installation crossbeam, 3-10-2. Sensor guide rod A, 3-10-3. Sensor guide rod B, 3-10-4. Sensor screw, 3-10-5. Spring, 3-10-6. Adjusting nut, 3-10-7. Sensor mounting plate, 3-10-8. Sensor front plate, 3-10-9. Pressure sensor. Detailed implementation manner

[0055] The technical solution of the present invention will be further specifically described below through specific embodiments in conjunction with the accompanying drawings. Embodiment

[0056] As Figure 1 、 Figure 2 、 Figure 3 and Figure 4 shown, an instrument for measuring the coefficient of friction of playing cards includes 1 base, 2 calibration device and 3 coefficient of friction measurement device.

[0057] The 1 base includes a housing and a bottom plate. A display screen 1-1 is installed on the housing. Below the display screen 1-1, there are keys 1-2. A printer 1-3 is located on one side of the display screen 1-1; a support column 1-4 lifting knob is installed on the bottom plate of the base. On the rod of the support column 1-4 lifting knob, there are a lifting wheel A 1-9 and a lifting wheel B 1-10. The lifting wheel A 1-9 and the lifting wheel B 1-10 are cam structures. The lower end of the lifting column A 1-5 is tangent to the lifting wheel A 1-9, and the lifting column B 1-6 is tangent to the lifting wheel B 1-10; when the support column 1-4 lifting knob rotates, the lifting column A 1-5 and the lifting column B 1-6 move up and down synchronously.

[0058] The slot A 1-7 and the slot B 1-8 are located on the top surface of the housing. The lower sliding block 3-9 is detachably connected to the transmission slider under the slot A 1-7 and the slot B 1-8. The transmission slider moves along the slot driven by the transmission lead screw 3-13.

[0059] The structure of the lower sliding block 3-9 and the transmission slider facilitates the 180° rotation of the lower sliding block 3-9 and also facilitates the replacement of the lower sliding block of the corresponding size according to the size of the playing card. And the surface of the lower sliding block 3-9 for fixing the playing card should be made of soft rubber material to facilitate the adsorption of the static film.

[0060] The transmission guide rod 3-12 and the transmission lead screw 3-13 are installed on the side plate turned up on the side of the base bottom plate. A driving motor 3-14 is also provided below the transmission lead screw 3-13. A gear B3-16 is installed on the driving motor 3-14, and the gear B3-16 meshes with a gear A3-15 installed at one end of the transmission lead screw 3-13. When the driving motor 3-14 rotates, the transmission lead screw 3-13 rotates and drives the lower slider 3-9 to move in a straight line.

[0061] Column A2-1, column B2-2, column C2-3 and column D2-4 are also provided on the bottom plate. Both ends of the lead screw A2-5 are installed on column A2-1 and column C2-3, and both ends of the lead screw B2-6 are installed on column B2-2 and column D2-4.

[0062] A cross beam A2-13 is provided in parallel above the lead screw A2-5. Slider A2-9, slider B2-10 and rolling nut A2-7 are installed below the cross beam A2-13. The cross beam A2-13 is installed by cooperating with the slider, the rolling nut and the lead screw A2-5.

[0063] A cross beam B2-14 is provided in parallel above the lead screw B2-6. Slider C2-11, slider D2-12 and rolling nut B2-8 are installed below the cross beam B2-14. The cross beam B2-14 is installed by cooperating with the slider, the rolling nut and the lead screw B2-6.

[0064] At the upper ends of the cross beam A2-13 and the cross beam B2-14, a guide rail A2-15 and a guide roller B2-16 are also installed. The guide rail A2-15 and the guide roller B2-16 are parallel to each other and perpendicular to the cross beam A2-13 and the cross beam B2-14. The cross sections of the cross beam A2-13 and the cross beam B2-14 are structures with a 1 / 5 arc on the upper surface. Its function is to guide the pulley A3-4, pulley B3-5, pulley C3-6 and pulley D3-7 to roll in a straight line without deviation.

[0065] Synchronous belt wheels A2-18 and B2-19 are respectively installed at one ends of the lead screw A2-5 and the lead screw B2-6. The two synchronous belt wheels are connected by a synchronous belt 2-17. When the handwheel of the lead screw A2-5 is rotated, the lead screw A2-5 and the lead screw B2-6 rotate in the same direction, and the cross beam A2-13 and the cross beam B2-14 will move along the direction of the lead screw.

[0066] Above the lower slider 3-9, an upper pressing block 3-8 is provided. The bottom surface of the upper pressing block 3-8 is made of rubber material to form a rubber layer, which is convenient for adsorbing the static electricity film. Above the upper pressing block 3-8, two smooth guide rods are installed: guide rod A3-2 and guide rod B3-3. The total weight of the upper pressing block 3-8, guide rod A3-2 and guide rod B3-3 is 500 g. The slide plate sleeve 3-1 is on the guide rod A3-2 and guide rod B3-3 and can slide up and down smoothly and freely. At the four corners of the slide plate sleeve 3-1, pulley A3-4, pulley B3-5, pulley C3-6 and pulley D3-7 are installed, and the four pulleys can be placed in the arcs of cross beam A2-13 and cross beam B2-14.

[0067] On both sides of the upper pressing block 3-8, a thrust sensor device A3-10 and a thrust sensor device B3-11 are also provided. The thrust sensor device A3-10 and the thrust sensor device B3-11 have the same structure and are symmetrically installed on both sides of the upper pressing block 3-8.

[0068] The thrust sensor device A3-10 includes an installation cross beam 3-10-1, and the installation cross beam 3-10-1 is fixed on the shell of the base. Sensor guide rod A3-10-2 and sensor guide rod B3-10-3 are sleeved on the installation cross beam 3-10-1. The sensor screw 3-10-4 is located in the middle of the installation cross beam 3-10-1 and passes through the through hole on the installation cross beam 3-10-1. The sensor mounting plate 3-10-7 is fixedly installed with one end of the sensor guide rod A3-10-2, the sensor guide rod B3-10-3 and the sensor screw 3-10-4. The pressure sensor 3-10-9 is fixed on the sensor mounting plate 3-10-7. In front of the pressure sensor 3-10-9, a sensor front plate 3-10-8 is also installed. The length of the sensor front plate 3-10-8 is consistent with the width of the upper pressing block 3-8.

[0069] A spring 3-10-5 is installed at the tail of the sensor screw 3-10-4. One end of the spring 3-10-5 is closely attached to the installation cross beam 3-10-1, and the other end is closely attached to the tail of the sensor screw 3-10-4. The adjusting nut 3-10-6 is installed in cooperation with the sensor screw 3-10-4 through threads and is closely attached to the other side of the installation cross beam 3-10-1. By rotating the adjusting nut 3-10-6, the distance between the sensor front plate 3-10-8 and the upper pressing block 3-8 can be adjusted.

[0070] The working principle of the instrument provided by the present invention is to select the upper pressing block 3-8 and the lower sliding block 3-9 that match the size of the card to be measured. The size requirement is that if the size of the card is A mm×B mm, the sizes of both the upper pressing block and the lower sliding block are (A - 1) mm×(B - 1) mm. That is, the sizes of the upper pressing block and the lower sliding block are slightly smaller than the card. The purpose is to prevent excessive pressure at the edge position of the card, which may cause adverse effects on the measurement of the friction coefficient when the edge position moves. Fix one card to be measured to the upper pressing block 3-8 and another card to be measured to the lower sliding block 3-9. By moving the lower sliding block 3-9, the upper pressing block 3-8 moves relatively. At this time, the thrust sensor device A 3-10 and the thrust sensor device B 3-11 block the upper pressing block 3-8. The pressure magnitudes measured by the thrust sensor device A 3-10 and the thrust sensor device B 3-11 at this time are the frictional forces between the two cards.

[0071] A method for measuring the friction coefficient of cards

[0072] Step 1: Select two cards with no scratches and no creases on the surface; and select the corresponding upper pressing block and lower sliding block according to the selected cards. The size requirement is that if the size of the card is A mm×B mm, the sizes of both the upper pressing block and the lower sliding block are (A - 1) mm×(B - 1) mm; and ensure that the total weight of the upper pressing block 3-8, the guide rod A 3-2, and the guide rod B 3-3 is 500 g. The reason for selecting this weight is to simulate the real production environment, and the pressure on the two bottom cards of the automatic card feeder is approximately 500 g.

[0073] Step 2: Attach static films to the surfaces of the upper pressing block 3-8 and the lower sliding block 3-9. The thickness of the static film is not less than 100 μm; apply glue evenly on the surface of the static film, stick the two cards to the static films on the upper pressing block 3-8 and the lower sliding block 3-9 respectively, and then press the upper pressing block 3-8 on the lower sliding block 3-9 and let it stand for 10 minutes to wait for the glue to dry.

[0074] Step 3: Put the slide plate sleeve 3-1 on the guide rod A 3-2 and the guide rod B 3-3, and ensure that the pulley A 3-4, the pulley B 3-5, the pulley C 3-6, and the pulley D 3-7 are in full contact with the guide rail A 2-15 and the guide roller B 2-16 respectively.

[0075] Step 4: Turn on the power of the instrument. At this time, the lower sliding block 3-9 is at the middle position on the top surface of the housing, and the upper pressing block 3-8 is between the thrust sensor device A 3-10 and the thrust sensor device B 3-11.

[0076] Step 5: First, push the slide plate sleeve 3-1 by hand to align the upper pressing block 3-8 with the edge of the card on the lower slide block 3-9 in the horizontal direction. Then, rotate the handwheel of the lead screw A2-5 to adjust the position of the upper pressing block 3-8, requiring the upper pressing block 3-8 to be aligned with the edge of the card on the lower slide block 3-9 in the vertical direction.

[0077] Step 6: Rotate the adjusting nut 3-10-6 on the thrust sensor device A3-10 to slowly bring the sensor front plate 3-10-8 into contact with the upper pressing block 3-8. Observe the reading of the pressure sensor 3-10-9 on the display screen 1-1. When the reading of the pressure sensor 3-10-9 changes from 0 to a reading greater than 0, then slowly rotate the adjusting nut 3-10-6 in the reverse direction until the number on the display screen 1-1 becomes 0; similarly adjust the sensor device B.

[0078] Step 7: Start the experiment and select leftward movement. At this time, the lower slide block 3-9 moves leftward driven by the transmission lead screw 3-13, and its moving speed is maintained at 5 mm / s; at this time, the upper pressing block 3-8 also has a tendency to move leftward, but is blocked by the sensor front plate 3-10-8. At this time, the pressure sensor 3-10-9 starts to record the pressure between the sensor front plate 3-10-8 and the upper pressing block 3-8, and records the time-pressure data in seconds.

[0079] The lower slide block 3-9 keeps moving leftward, while the upper pressing block 3-8 remains stationary. During this process, the contact area between the upper pressing block 3-8 and the card on the lower slide block 3-9 gradually decreases. However, under the action of the guide rod A3-2 and the guide rod B3-3, the upper pressing block 3-8 will not tilt, still ensuring sufficient contact between the two cards until the contact area of the cards is 0; when the contact area between the two cards is 0, the upper pressing block 3-8 starts to fall under the action of gravity. At this time, the lifting columns A1-5 and B1-6 are both at the low points, and the upper pressing block 3-8 will be supported by the lifting columns A1-5 and B1-6, preventing the card on the upper pressing block 3-8 from contacting the housing.

[0080] Step 8: The lower slide block 3-9 stops moving leftward. Click the print button, and the printer 1-3 prints the time-pressure data during the movement time of the lower slide block 3-9.

[0081] Step 9: Rotate the lifting knob of the support column 1-4. At this time, the lifting columns A1-5 and B1-6 lift the upper pressing block 3-8 to ensure that the two cards will not collide and rub when the lower slide block 3-9 moves rightward.

[0082] Step 10: Click the button 1-2 to make the lower slide block 3-9 move rightward. When the lower slide block 3-9 moves to the middle position of the housing, stop moving; at this time, a set of measurements of the friction coefficient between the two cards is completed.

[0083] Step 11. Repeat Steps 7 to 10 to complete the acquisition of 10 groups of data.

[0084] Step 12. Switch the direction to move right, and repeat Steps 7 to 10 to complete the acquisition of 10 groups of data.

[0085] Judge the data in Step 11 and the data in Step 12 respectively. If all the data measured in the experiment are less than the standard value, it means that the friction coefficient of the two cards is qualified during the relative leftward movement. If there is a situation where the value is greater than the standard value at a certain point, it is necessary to discuss it case by case. If, during multiple measurements, there are 5 or more pressure values greater than the standard value within a certain time period when the cards are in relative leftward friction, it indicates that the friction coefficient at this moment does not meet the standard when the two cards are in contact, and it is necessary to improve the printing process between the two cards at this time, otherwise there may be a phenomenon of double cards in the card feeder.

[0086] If, during multiple measurements, there are less than 5 pressure values greater than the standard value within a certain time period, it can be considered that the friction coefficient of the card meets the standard.

[0087] Since the data records time-pressure data, and the moving speed of the lower slider 3-9 is 5 mm / s, we can perform reverse inference through time to know in what area the friction coefficient between the two cards is the largest, so as to accurately improve the printing process in this area.

[0088] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An instrument for measuring the coefficient of friction of cards, characterized in that, it includes: a base, an alignment device and a coefficient of friction measurement device; The coefficient of friction measurement device includes: a lower slider, a slider driving device and a set of thrust sensor devices; The base includes a housing and a bottom plate, and the housing and the bottom plate form a cavity; Two parallel slot holes are opened on the top surface of the housing. The slider driving device is arranged in the cavity, and the movable end passes through the slot hole and is detachably connected to the lower slider, and the lower slider slides along the direction of the slot hole; The thrust sensor devices are arranged in the moving direction of the lower slider, symmetrically arranged, the sensing surfaces face the upper pressing block, and the thrust sensor devices are fixedly connected to the housing; The alignment device is arranged on the upper side of the coefficient of friction measurement device on the base, and includes: a set of parallel lead screws, a slide rail frame arranged on the lead screws, a slide plate sleeve arranged on the slide rail frame and sliding along the slide rail, an upper pressing block and a pressing block support device; The axis of the slide rail is perpendicular to the axis of the lead screw. A guide hole is provided on the slide plate sleeve, and a guide rod is provided on the top surface of the upper pressing block. The guide rod is inserted into the guide hole so that the position of the upper pressing block is restricted by the slide plate sleeve; The pressing block support device is arranged in the cavity, and the movable end passes through the housing and cooperates with the upper pressing block; The pressing block support device includes: a support column lifting knob, a rotating rod is arranged on one side of the knob, the rotating rod penetrates into the housing, and two lifting wheels are sleeved on the rotating rod; A set of support rod holes are arranged on the top surface of the housing, support rods are arranged in the support rod holes, the top surface of the support rods cooperates with the upper pressing block, and the bottom surface of the support rods abuts against the lifting wheels; The lifting wheel is of a cam structure, and both ends of the support rod are spherical surfaces; An ear plate extends from the middle section of the long side of the upper pressing block, and the ear plate cooperates with the support rod; The top surface of the lower slider is the same size as the bottom surface of the upper pressing block, and a rubber layer with the same thickness is laid on both; One measured card is fixed to the upper pressing block, and another measured card is fixed to the lower slider.

2. An instrument for measuring the coefficient of friction of cards according to claim 1, characterized in that, a slider is arranged on the bottom surface of the slide rail frame, and is sleeved on the lead screw of the alignment device, so that the slide rail frame slides back and forth along the lead screw; A synchronous belt is arranged at one end of the lead screw to make the two lead screws rotate synchronously; The slide rail surface of the slide rail frame is a concave surface of a 1 / 5 arc.

3. An instrument for measuring the coefficient of friction of cards according to claim 1, characterized in that, The slider driving device includes: a pair of parallel transmission lead screws, a driving motor and a transmission slider; The transmission lead screws are arranged on the bottom plate, and the transmission slider is sleeved on the transmission lead screws; a transmission device is arranged at one end of the transmission lead screws, and a driving motor is arranged on the bottom plate on the same side of the transmission device. The power end of the driving motor is in transmission connection with the transmission lead screws through the transmission device; Two parallel protrusions are arranged on the top surface of the transmission slider, and two parallel grooves are arranged on the bottom surface of the lower slider. The protrusions of the transmission slider are inserted into the grooves of the lower slider.

4. An instrument for measuring the coefficient of friction of cards according to claim 1, characterized in that, the total weight of the upper pressing block and the guide rod is 500 g.

5. A method for measuring the friction coefficient of cards, using the instrument for measuring the friction coefficient of cards described in claim 1, characterized in that, it includes the following steps: Step 1: Select two cards without creases, select an upper pressing block and a lower sliding block that match the size of the cards, and adhere the cards to the upper pressing block and the lower sliding block; Step 2: After installing the upper pressing block and the lower sliding block, use the alignment device to align the edges of the two cards; Step 3: Adjust the thrust sensor device so that the sensing surface is aligned with the edge of the card and the sensor reading is 0; Step 4: Use the slider driving device to move the lower sliding block to one side, keep the moving speed at 5 mm / s and record the reading; Step 5: After completing one test, lift the upper pressing block through the pressing block support device and reset the lower sliding block; Step 6: Repeat Step 4 and Step 5 at least 10 times; Step 7: Switch the direction and repeat Step 4 and Step 5 at least 10 times; Step 8: Judge the data in Step 6. If less than 5 values in all the data are less than or equal to the standard value, it is judged that the relative movement in the first direction is qualified; if 5 or more values are greater than the standard value, it is judged that the relative movement in the first direction is unqualified; Step 9: Judge the data in Step 7. If less than 5 values in all the data are less than or equal to the standard value, it is judged that the relative movement in the second direction is qualified; if 5 or more values are greater than the standard value, it is judged that the relative movement in the second direction is unqualified.

6. The method for measuring the friction coefficient of cards according to claim 5, characterized in that, in the said Step 1, it includes the following sub-steps: Sub-step 1-1: Attach an electrostatic film to the surfaces of the upper pressing block and the lower sliding block, and the thickness of the electrostatic film is not less than 100 um; Sub-step 1-2: Apply evenly distributed glue on the surface of the electrostatic film, and stick the two cards on the electrostatic film of the upper pressing block and the electrostatic film of the lower sliding block respectively.

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