Roll gap measuring device
By positioning a gap measurement sensor unit and a capacitive sensor in the bearing housing, the roller gap is accurately measured, solving the problem of inaccurate gap measurement in the prior art, realizing precise control of the roller gap, and improving the manufacturing quality of electrode sheets.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- LG ENERGY SOLUTION LTD
- Filing Date
- 2025-04-03
- Publication Date
- 2026-07-31
AI Technical Summary
Existing technologies cannot accurately measure the gap between rollers, resulting in uneven pressing or defects in the electrode sheets, and traditional LVDT sensors have low accuracy.
A gap measurement sensor unit is positioned in the bearing housing. The actual gap value is calculated by measuring the distance between the rotating shaft and the sensor unit, combined with the gap between the rollers measured by a capacitive sensor.
It enables precise measurement of the roller gap, detects and compensates for gap widening caused by bearing clearance, ensures pressing effect, and improves the manufacturing quality of electrode sheets.
Smart Images
Figure CN122497583A_ABST
Abstract
Description
Technical Field
[0001] Cross-references to related applications
[0002] This application is based on and claims priority to Korean Patent Application No. 10-2024-0046633, filed with the Korean Intellectual Property Office on April 5, 2024, the disclosure of which is incorporated herein by reference in its entirety. Technical Field
[0004] This disclosure relates to a device for measuring roll gap. Background Technology
[0005] Secondary batteries have been used in small applications such as mobile devices or laptops, but recently, research has expanded to medium and large applications, and secondary batteries are widely used in applications that require high voltage and large capacity, such as energy storage systems (ESS) or electric vehicles (EVs).
[0006] Such a secondary battery can be manufactured in the form of an electrode assembly in which electrodes and separators are alternately stacked and housed in a box or housing. In this case, the electrodes can be in the form of electrode sheets coated with electrode active materials, etc., cut into a predetermined size or shape.
[0007] This electrode sheet undergoes, for example, at least one pressing process. Typically, the pressing of the electrode sheet is performed by pressing rollers. The gap between the pressing rollers serves as a fundamental data point for controlling their operation. This gap can refer to the narrowest possible gap (or space) formed between a pair of pressing rollers, and if the gap is too large, the electrode sheet may not be sufficiently pressed. This can lead to various problems, such as uneven manufacturing or defects in the pressed electrode sheet. Furthermore, when using pressing rollers, the surfaces of the rollers that contact the electrode sheet wear, and if the diameter decreases due to wear or if a portion is damaged, forming grooves, etc., there is a problem where some or all of the contact portions of the electrode sheet passing between the multiple pressing rollers are not pressed.
[0008] Typically, when the substrate is fed into two main rollers and pressed, there is a problem that the gap between the rollers is wider than the set gap.
[0009] This is because there is a gap between the roller and the bearing, and the gap between the rollers has been widened to increase the size of that gap.
[0010] Therefore, determining how much the gap has been widened has become an important technical issue. However, current methods for measuring the actual gap involve directly contacting the gap with an LVDT sensor, but the accuracy is quite low. Summary of the Invention
[0011] Technical issues
[0012] One aspect of this disclosure is to provide a roller gap measuring device capable of accurately measuring the gap between a pair of rollers.
[0013] Technical solution
[0014] According to an embodiment of the present disclosure, a roller gap measuring device measures the gap between a pair of rollers, and the roller gap measuring device includes a gap measuring sensor unit for measuring the gap between the pair of rollers, wherein each pair of rollers includes a rotating shaft extending in one direction and a bearing unit mounted on the rotating shaft, wherein the bearing unit includes a bearing mounted on the outer surface of the rotating shaft and a bearing housing accommodating the bearing, wherein the gap measuring sensor unit is positioned in the bearing housing and measures the distance between the rotating shaft and the gap measuring sensor unit to measure the gap between the pair of rollers.
[0015] Beneficial effects
[0016] According to this disclosure, the actual gap between a pair of rollers can be accurately measured by positioning the gap measuring sensor unit in the bearing housing of a bearing unit on which a pair of rollers are mounted and measuring the distance between the rotating shaft and the gap measuring sensor unit.
[0017] Furthermore, by further positioning the roller gap measuring sensor unit between the ends of a pair of rollers and measuring the gap between the pair of rollers, the actual gap between a pair of rollers can be measured very accurately. Attached Figure Description
[0018] Figure 1 This is a perspective view showing a roller gap measuring device in use according to an embodiment of the present disclosure.
[0019] Figure 2 This is a cross-sectional view showing a roller gap measuring device in use according to an embodiment of the present disclosure.
[0020] Figure 3 This is a cross-sectional view showing a gap measuring sensor unit in a roller gap measuring device according to an embodiment of the present disclosure.
[0021] Figure 4 yes Figure 3 An enlarged cross-sectional view of region A in the image.
[0022] Figure 5 This is a perspective view showing the sensor ring of the gap measuring sensor unit in a roller gap measuring apparatus according to an embodiment of the present disclosure.
[0023] Figure 6 yes Figure 2 An enlarged cross-sectional view of region B in the image.
[0024] Figure 7 This is a plan view showing the roll gap measuring sensor unit in a roll gap measuring device according to an embodiment of the present disclosure. Detailed Implementation
[0025] The objectives, specific advantages, and novel features of this disclosure will become more apparent from the following detailed description and preferred embodiments taken in conjunction with the accompanying drawings. It should be noted that, in this specification, when affixing reference numerals to elements in each drawing, the same reference numerals are affixed to the same elements whenever possible, even if the same elements are shown in different drawings. Furthermore, this disclosure can be implemented in many different forms and is not limited to the embodiments described herein. And, in describing this disclosure, detailed descriptions of related known technologies that may unnecessarily obscure the essential points of this disclosure will be omitted.
[0026] Roller gap measuring device according to embodiments of the present disclosure
[0027] Figure 1 This is a perspective view showing a roller gap measuring device in use according to an embodiment of the present disclosure, and Figure 2 This is a cross-sectional view showing a roller gap measuring device in use according to an embodiment of the present disclosure.
[0028] Reference Figure 1 and Figure 2 The roller gap measuring device 100 according to an embodiment of the present disclosure measures the gap (g) between a pair of rollers 30, and the roller gap measuring device 100 includes a gap measuring sensor unit 110 for measuring the gap (g) between a pair of rollers 30, wherein each pair of rollers 30 includes a rotating shaft 31 extending in one direction and a bearing unit 60 mounted on the rotating shaft 31, wherein the bearing unit 60 includes a bearing 61 mounted on the outer surface of the rotating shaft 31 and a bearing housing 62 accommodating the bearing 61. Additionally, the roller gap measuring device 100 according to an embodiment of the present disclosure may also include a roller spacing measuring sensor unit 120.
[0029] More specifically, the roller gap measuring device 100 according to an embodiment of the present disclosure can measure the gap (g) between a pair of rollers 30 in contact with the material sheet.
[0030] The sheet material can be constructed as a sheet electrode.
[0031] Roll 30 may extend longitudinally in a cylindrical shape. Roll 30 may be made of a metallic material. In this case, roll 30 may be configured as a calendering roll. Furthermore, roll 30 has a rotating shaft 31 extending along its central axis, allowing the rotating shaft 31 to rotate and the roll 30 to rotate as well.
[0032] Each pair of rollers 30 may include a rotating shaft 31 extending in one direction and a bearing unit 60 mounted on the rotating shaft 31.
[0033] The bearing unit 60 may include a bearing 61 mounted on the outer surface of the rotating shaft 31 and a bearing housing 62 that houses the bearing 61.
[0034] Additionally, a pair of rollers 30 may include a first roller 10 and a second roller 20.
[0035] The first roller 10 may include a first rotating shaft 11 extending in one direction and a first bearing unit 40 mounted on the first rotating shaft 11.
[0036] The second roller 20 may include a second rotating shaft 21 extending in one direction and a second bearing unit 50 mounted on the second rotating shaft 21.
[0037] The first bearing unit 40 may include a first bearing 41 mounted on the outer surface of the first rotating shaft 11 and a first bearing housing 42 accommodating the first bearing 41.
[0038] The second bearing unit 50 may include a second bearing 51 mounted on the outer surface of the second rotating shaft 21 and a second bearing housing 52 that houses the second bearing 51.
[0039] Figure 3 This is a cross-sectional view showing a gap measuring sensor unit in a roller gap measuring device according to an embodiment of the present disclosure. Figure 4 yes Figure 3 An enlarged cross-sectional view of region A in the image, and Figure 5 This is a perspective view showing the sensor ring of the gap measuring sensor unit in a roller gap measuring apparatus according to an embodiment of the present disclosure.
[0040] Reference Figures 2 to 5 The gap measurement sensor unit 110 measures the gap (g) between a pair of rollers 30.
[0041] The gap measuring sensor unit 110 is positioned in the bearing housing 62 and measures the gap (g) between a pair of rollers 30 by measuring the distance between the rotating shaft 31 and the gap measuring sensor unit 110.
[0042] The gap measurement sensor unit 110 can be positioned inside the first bearing housing 42 and the second bearing housing 52, respectively.
[0043] The gap measurement sensor unit 110 may include a first measurement sensor 111 and a second measurement sensor 112 positioned on both sides inside the bearing housing 62. Therefore, the gap (g) between a pair of rollers 30 can be measured by measuring the distances of the first measurement sensor 111 and the second measurement sensor 112 from the rotation axis 31 of the pair of rollers 30, respectively.
[0044] The gap measuring sensor unit 110 may further include a sensor ring 113, on which a first measuring sensor 111 and a second measuring sensor 112 are positioned. In this case, the sensor ring 113 can be positioned between the rotating shaft 31 and the bearing housing 62.
[0045] The outer peripheral surface of the sensor ring 113 can be attached to the inner peripheral surface of the bearing housing 62.
[0046] The sensor ring 113 can be formed in a circular shape, and the first measuring sensor 111 and the second measuring sensor 112 can be positioned on the inner circumferential surfaces of the two sides 113a and 113b of the sensor ring 113. That is, the sensor ring 113 can be formed in a circular shape, and the first measuring sensor 111 and the second measuring sensor 112 can be positioned on the inner circumferential surfaces of one side 113a and the other side 113b of the sensor ring 113, respectively.
[0047] In the sensor ring 113, a first receiving groove 113a-1 in which a first measuring sensor 111 is positioned and a second receiving groove 113b-2 in which a second measuring sensor 112 is positioned can be formed on the inner circumferential surface of the sensor ring 113. Here, the first receiving groove 113a-1 and the second receiving groove 113b-2 can be open toward the rotation shaft 31.
[0048] The first measuring sensor 111 and the second measuring sensor 112 can be spaced apart from the rotating shaft 31 by a predetermined distance so as to measure the distance in a non-contact manner.
[0049] Furthermore, the first measuring sensor 111 and the second measuring sensor 112 can be arranged in a direction parallel to the arrangement direction of the pair of rollers 30. That is, for example, referring to... Figure 2 The first measuring sensor 111 and the second measuring sensor 112 can be arranged in the vertical direction, which is the arrangement direction of the pair of rollers 30. However, in the roller gap measuring device 100 according to the embodiment of the present disclosure, the first measuring sensor 111 and the second measuring sensor 112 are not necessarily limited to being attached to the sensor ring 113, and as another example, the first measuring sensor 111 and the second measuring sensor 112 can be attached to the inner wall of the bearing housing 62 without the sensor ring 113.
[0050] Furthermore, the first measuring sensor 111 and the second measuring sensor 112 may include capacitive sensors. In a specific example, the capacitive sensor may be a capacitive displacement sensor.
[0051] A capacitive sensor can sense changes in capacitance and measure the distance between the first and second measuring sensors 111 and 112 (which are also capacitive sensors) and the rotation axis 31 of the roller 30, thereby determining the gap value between the pair of rollers 30. For example, when an alternating current of a specific frequency flows toward a conductive measurement target in the capacitive sensor, the amplitude of the alternating voltage is proportional to the distance from the measurement target, and therefore the distance between the capacitive sensor and the measurement target can be measured.
[0052] Furthermore, the roller gap measuring device 100 according to the embodiments of this disclosure may also include a calculation unit (not shown). In this case, the first measuring sensor 111 and the second measuring sensor 112 are capacitive sensors, which can measure the distance between the first measuring sensor 111 and the second measuring sensor 112 and the rotation axis 31 of the roller 30 and transmit the measured gap value to the calculation unit. Here, the calculation unit can calculate the gap value between a pair of rollers 30 using the received measured gap value. Also, the connection lines between the first measuring sensor 111 and the second measuring sensor 112 and the calculation unit are omitted in the figures; however, as examples, they can be connected in various forms of wired or wireless connections, or they can be mounted on or included in the first measuring sensor 111 and the second measuring sensor 112.
[0053] Meanwhile, the calculation unit can calculate the gap value between a pair of rollers 30 by receiving the measured gap value of the first rotating shaft 11 of the first roller 10 and the measured gap value of the second rotating shaft 21 of the second roller 20, which are respectively measured by the first measuring sensor 111 and the second measuring sensor 112 located inside the first bearing housing 42 and the second bearing housing 52.
[0054] Here, the calculation unit can determine the change by subtracting the initial measured gap values for the first rotation axis 11 of the first roller 10 and the second rotation axis 21 of the second roller 20 stored in memory from the average of the sum of the measured gap values for the first rotation axis 11 of the first roller 10 and the measured gap values for the second rotation axis 21 of the second roller 20. The actual gap value between the first roller 10 and the second roller 20 can be determined by adding the change to the initial gap value between the first roller 10 and the second roller 20 stored in memory (not shown). Since the change in the rotation axis 31 can be estimated to be equal to the change between the first roller 10 and the second roller 20, the gap between the first roller 10 and the second roller 20 can be determined by measuring the change in the rotation axis 31. In this case, the memory can be included in the calculation unit or can be included in a device external to the calculation unit and electrically connected to the calculation unit.
[0055] In other words, when the calculation unit defines the measured gap value for the first rotation axis 11 of the first roller 10 as (a) after device processing or after the distance adjustment of a pair of rollers 30, the measured gap value for the second rotation axis 21 of the second roller 20 as (b), the initial measured gap value (i.e., the average of the sum of the initial measured gap value for the first rotation axis 11 of the first roller 10 and the measured gap value for the second rotation axis 21 of the second roller 20 stored in memory before device processing) as T, the gap change between the first roller 10 and the second roller 20 as E, and the gap value of the first roller 10 and the second roller 20 measured after device processing as (g), the following condition Equation 1 is satisfied:
[0056] (a+b) / 2 - T = E Conditional Equation 1
[0057] Furthermore, when the change in gap between the first roller 10 and the second roller 20 is E, the initial gap value between the first roller 10 and the second roller 20 stored in the memory before device processing is Z, and the gap value between the first roller 10 and the second roller 20 measured after device processing is (g), the following condition Equation 2 is satisfied:
[0058] E + Z = g Conditional Equation 2
[0059] Here, for a specific example, when the measured gap value (a) for the first rotating shaft 11 of the first roller 10 is +11 μm, the measured gap value (b) for the second rotating shaft 21 of the second roller 20 is +11 μm, and the initial measured gap value T (i.e., the average of the sum of the initial measured gap values for the first rotating shaft 11 of the first roller 10 and the measured gap values for the second rotating shaft 21 of the second roller 20 stored in memory before device processing) is 1 μm, the gap change E between the first roller 10 and the second roller 20 can be obtained by the above conditional equation 1 as (11 μm + 11 μm) / 2 - 1 μm = 10 μm. Furthermore, when the initial gap value Z between the first roller 10 and the second roller 20 stored in memory before device processing is 100 μm, the gap value (g) of the first roller 10 and the second roller 20 measured after device processing can be obtained by the above conditional equation 2 as 10 μm + 100 μm = 110 μm.
[0060] Figure 6 yes Figure 2 An enlarged cross-sectional view of region B in the image, and Figure 7 This is a plan view showing the roll gap measuring sensor unit in a roll gap measuring device according to an embodiment of the present disclosure.
[0061] Reference Figure 2 , Figure 6 and Figure 7 The roller gap measuring sensor unit 120 can be positioned between the ends of a pair of rollers 30 and measures the gap (g) between the pair of rollers 30.
[0062] The ends of the pair of rollers 30 may be formed with stepped portions 12 and 22 of reduced diameter. In this case, the stepped portions 12 and 22 may be formed at the ends of the bodies of the pair of rollers 30. Here, the bodies of the pair of rollers 30 may be any part other than the rotating shaft 31.
[0063] The end of the roller gap measuring sensor unit 120 can be positioned between the step portions 12 and 22 of a pair of rollers 30, and the gap (g) of a pair of rollers 30 can be measured by measuring the gap between the step portions 12 and 22 of a pair of rollers 30.
[0064] At the end of the roller gap measuring sensor unit 120, sensing portions 121 and 122 for sensing distances d1 and d2 to the step portions 12 and 22 of the pair of rollers 30 can be respectively positioned on the two sides of the end of the roller gap measuring sensor unit 120 facing the step portions 12 and 22 of the pair of rollers 30.
[0065] The sensing portions 121 and 122 may include capacitive sensors. In a particular example, the capacitive sensor may be a capacitive displacement sensor.
[0066] At this time, the sensing units 121 and 122 may include capacitive sensors that can measure the distances d1 and d2 to the measured steps 12 and 22 of the pair of rollers 30 and transmit the measured gap values to the calculation unit. Furthermore, for example, the calculation unit may be connected to a control unit that controls the drive of the pair of rollers 30.
[0067] Simultaneously, for example, the stepped portions 12 and 22 can be processed to a depth of, for example, 500 μm on two sides in the longitudinal direction of the pair of rollers 30. That is, the distance from the stepped portion 12 of the first roller 10 to the stepped portion 22 of the second roller 20 can be, for example, 1000 μm, but this disclosure is not limited thereto. Here, if the thickness of the end of the roller gap measuring sensor unit 120 where the sensing portions 121 and 122 are positioned is 900 μm and the initial gap value between the first roller 10 and the second roller 20 before device processing, stored in the memory, is 0 μm, then the distance from the roller gap measuring sensor unit 120 to the stepped portions 12 and 22 of the pair of rollers 30, measured by the sensing portions 121 and 122 respectively positioned on the two sides of the end of the roller gap measuring sensor unit 120, can be measured as 100 μm. Furthermore, the measured distance of 100 μm to the stepped portions 12 and 22 of the pair of rollers 30 can be stored in the memory as an initial value.
[0068] Subsequently, if the gap between the first roller 10 and the second roller is changed after processing or after adjusting the roller spacing to make the actual gap 100 μm, the distance from the roller spacing measuring sensor unit 120 to the step portions 12, 22 of the pair of rollers 30 is measured to be 200 μm. Therefore, the calculation unit can estimate the gap between the first roller 10 and the second roller 20 to be 100 μm by subtracting the initial value of 100 μm stored in memory from 200 μm (i.e., the distance from the roller spacing measuring sensor unit 120 to the step portions 12, 22 of the pair of rollers 30).
[0069] Reference Figure 2The roller gap measuring device 100 constructed as described above according to an embodiment of the present disclosure can accurately measure the actual gap or a gap value close to the actual gap generated between the pair of rollers 30 during processing by positioning the gap measuring sensor unit 110 in the bearing housing 62 of the bearing unit 60 on which the rotating shaft 31 of the pair of rollers 30 is mounted and measuring the distance between the rotating shaft 31 and the gap measuring sensor unit 110. Therefore, by detecting the gap (g) between the pair of rollers 30 that is close to the actual gap due to bearing clearance during processing, the insufficient pressing amount can be calculated, and there is an effect that allows feedback control to be implemented to allow additional pressing to compensate for the corresponding widening. Furthermore, after the operator adjusts and resets the gap (g) between the pair of rollers 30, it is easy to check by the gap measuring sensor unit 110 whether the reset pair of rollers 30 is properly positioned in the bearing unit 60 or whether there is any abnormality in the connected state.
[0070] Furthermore, by further positioning the roller gap measuring sensor unit 120 between the ends of a pair of rollers 30 and measuring the gap (g) between the pair of rollers 30, the gap value between the pair of rollers 30 widened during processing, or very close to the actual gap, can be measured very accurately.
[0071] The present disclosure has been described in detail above with reference to specific embodiments; however, this is intended to be a concrete description of the present disclosure, and the present disclosure is not limited thereto. It can be said that those skilled in the art can make various modifications and variations within the technical concept of the present disclosure.
[0072] Furthermore, the specific scope of protection of this disclosure will become clear from the appended claims of this patent.
[0073] [List of reference numerals]
[0074] 10: First Roller
[0075] 11: First Rotation Axis
[0076] 12: Step section
[0077] 20: Second roller
[0078] 21: Second Rotation Axis
[0079] 22: Step section
[0080] 30: Roller
[0081] 31: Rotation axis
[0082] 40: First bearing unit
[0083] 41: First Bearing
[0084] 42: First bearing housing
[0085] 50: Second bearing unit
[0086] 51: Second bearing
[0087] 52: Second bearing housing
[0088] 60: Bearing Unit
[0089] 61: Bearing
[0090] 62: Bearing housing
[0091] 100: Roller gap measuring device
[0092] 110: Gap Measurement Sensor Unit
[0093] 111: First measuring sensor
[0094] 112: Second measuring sensor
[0095] 113: Sensor Loop
[0096] 113a: A side
[0097] 113a-1: First receiving groove
[0098] 113b: Another side
[0099] 113b-2: Second receiving groove
[0100] 120: Roller gap measurement sensor unit
[0101] 121, 122: Sensing section
[0102] d1, d2: Distance
[0103] g: gap
Claims
1. A roller gap measuring device for measuring the gap between a pair of rollers, the roller gap measuring device comprising: A gap measuring sensor unit that measures the gap between the pair of rollers. Each of the pair of rollers includes a rotating shaft extending in one direction and a bearing unit mounted on the rotating shaft. The bearing unit includes a bearing mounted on the outer surface of the rotating shaft and a bearing housing that accommodates the bearing. The gap measuring sensor unit is positioned in the bearing housing and measures the distance between the rotating shaft and the gap measuring sensor unit to measure the gap between the pair of rollers.
2. The roller gap measuring device according to claim 1, in, The pair of rollers includes a first roller and a second roller. The first roller includes a first rotating shaft extending in one direction and a first bearing unit mounted on the first rotating shaft. The second roller includes a second rotating shaft extending in one direction and a second bearing unit mounted on the second rotating shaft. The first bearing unit includes a first bearing mounted on the outer surface of the first rotating shaft and a first bearing housing accommodating the first bearing. The second bearing unit includes a second bearing mounted on the outer surface of the second rotating shaft and a second bearing housing that accommodates the second bearing. The gap measurement sensor unit is located inside the first bearing housing and the second bearing housing, respectively.
3. The roller gap measuring device according to claim 2, in, The gap measurement sensor unit includes a first measurement sensor and a second measurement sensor positioned on both sides inside the bearing housing, and The gap between the pair of rollers is measured by measuring the distances of the first and second measuring sensors from the rotation axis of the pair of rollers, respectively.
4. The roller gap measuring device according to claim 3, in, The gap measurement sensor unit further includes a sensor ring, on which the first measurement sensor and the second measurement sensor are positioned. The sensor ring is positioned between the rotating shaft and the bearing housing.
5. The roller gap measuring device according to claim 4, in, The sensor ring is circular in shape, and the first measuring sensor and the second measuring sensor are positioned on the inner circumferential surfaces of two sides of the sensor ring.
6. The roller gap measuring device according to claim 5, in, In the sensor ring, A first receiving groove for positioning the first measuring sensor and a second receiving groove for positioning the second measuring sensor are formed on the inner circumferential surface of the sensor ring. The first receiving groove and the second receiving groove are open toward the rotation axis.
7. The roller gap measuring device according to claim 6, in, The first and second measuring sensors are spaced a predetermined distance from the rotating axis to measure distance in a non-contact manner.
8. The roller gap measuring device according to claim 5, in, The outer peripheral surface of the sensor ring is attached to the inner peripheral surface of the bearing housing.
9. The roller gap measuring device according to claim 3, in, The first measuring sensor and the second measuring sensor are arranged in a direction parallel to the arrangement direction of the pair of rollers.
10. The roller gap measuring device according to any one of claims 3 to 9, in, The first and second measuring sensors include capacitive sensors.
11. The roller gap measuring device according to claim 3, further comprising: The calculation unit calculates the gap value between the pair of rollers by receiving measurement gap values obtained by measuring the distance between the first measurement sensor and the second measurement sensor and the rotation axis of the pair of rollers, respectively.
12. The roller gap measuring device according to claim 11, in, The calculation unit calculates the change by subtracting the initial measured gap values for the first and second rotating axes of the first and second rollers stored in the memory from the average of the sum of the measured gap values for the first and second rotating axes of the first and second rollers, and adds the change to the initial gap value between the first and second rollers stored in the memory to obtain the gap value between the first and second rollers.
13. The roller gap measuring device according to claim 1, further comprising: A roller gap measuring sensor unit is positioned between the ends of the pair of rollers and measures the gap between the pair of rollers.
14. The roller gap measuring device according to claim 13, in, The ends of the pair of rollers form stepped portions with decreasing diameters, and The end of the roller gap measuring sensor unit is positioned between the stepped portions of the pair of rollers, and the gap between the pair of rollers is measured by measuring the distance between the stepped portions of the pair of rollers.
15. The roller gap measuring device according to claim 14, in, At the end of the roller spacing measuring sensor unit, Sensing portions for sensing the distance to the stepped portion of the pair of rollers are respectively positioned on two sides of the stepped portion facing the pair of rollers at the end of the roller spacing measuring sensor unit.
16. The roller gap measuring device according to claim 15, in, The sensing component includes a capacitive sensor.