processing device

Abstract

The processing apparatus (2) includes a main roller (6) having a plurality of grooves (26) for spiral winding of wire (1) formed at predetermined intervals (P) along the circumferential direction and in the axial direction (X). The main roller (6) has: a shaft portion (20); a resin layer (22) covering the outer peripheral surface (20a) of the shaft portion (20) and forming a plurality of grooves (26); and a holding portion (24) holding the resin layer (22) in the axial direction (X). The resin layer (22) allows a plurality of regenerated grooves (26) to be formed by the groove regeneration assembly (30) by peeling the surface layer of the resin layer (22) along its outer periphery. The grooves (26) formed in the resin layer (22) and the groove forming width (L1) in the axial direction (X) of the regenerated grooves (26) are smaller than the resin forming width (L) in the axial direction (X) of the resin layer (22).

Description

Technical Field

[0001] This invention relates to processing apparatus, and more particularly to processing apparatus such as wire saws and wire electrical discharge machining apparatuses for cutting workpieces with wire. Background Technology

[0002] Wire saws and wire electrical discharge machining (EDM) devices are processing devices that cut workpieces using wire. The processing device described above includes a main roller with multiple grooves formed at predetermined intervals along the circumferential direction and along the axial direction for the wire to be spirally wound. The main roller has a shaft portion (core material) and a resin layer covering the outer circumferential surface of the shaft portion and forming the aforementioned multiple grooves.

[0003] Patent Document 1 discloses a processing roller for a wire saw, in which a resin layer is molded and coated on the outer periphery of the shaft, and multiple grooves for mounting wire are formed on the outer peripheral surface of the resin layer. A metal detection ring for detecting the thermal expansion displacement of the resin layer is integrally molded and fixed to the end face of the resin layer.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 11-277399 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] Because the wire is wound around and slides in contact with the grooves in the resin layer formed on the main roller, the resin layer is prone to expansion due to processing heat generated during the operation of the processing device. Therefore, due to the thermal expansion of the resin layer, the position of the grooves in the resin layer changes, resulting in changes in the thickness and warpage of the wafer after cutting, which may affect the quality of the wafer. However, in Patent Document 1, although a detection ring is provided for detecting the thermal expansion displacement of the resin layer, the detection ring does not suppress the thermal expansion displacement of the resin layer itself.

[0009] Furthermore, since the wire is wound around and slides in contact with the grooves formed in the resin layer on the main roller, the grooves formed in the resin layer wear and deform with the operation of the processing equipment. Therefore, the grooves are periodically regenerated by peeling off the surface layer of the resin layer along its outer periphery using a groove regeneration assembly.

[0010] However, in Patent Document 1, interference occurs between the inspection ring and the trench regeneration assembly, potentially making the surface peeling of the resin layer difficult. Furthermore, in order to perform the surface peeling process of the resin layer via the trench regeneration assembly, the inspection ring needs to be removed and reassembled after the operation, thus reducing wafer production efficiency.

[0011] The present invention was made in view of the following problems, and its object is to provide a processing apparatus that can improve the quality of processed products by suppressing the positional change of the groove caused by the thermal expansion of the resin layer of the main roller, and can improve the production efficiency of processed products by efficiently regenerating the groove.

[0012] Solution for solving the problem

[0013] To achieve the above objectives, the processing apparatus described in Scheme 1 is a processing apparatus for cutting workpieces with wire. The processing apparatus is characterized by having a main roller with a plurality of grooves formed at predetermined intervals along the circumferential direction and in the axial direction for spirally winding the wire. The main roller has: a shaft portion; a resin layer covering the outer circumferential surface of the shaft portion and forming the plurality of grooves; and a holding portion holding the resin layer in the axial direction. The resin layer allows a groove regeneration assembly to form a plurality of regeneration grooves by peeling off the surface layer of the resin layer along its outer circumference. The groove forming width in the axial direction of the plurality of grooves and the regeneration grooves in the resin layer is smaller than the resin forming width in the axial direction of the resin layer.

[0014] Furthermore, the invention described in Scheme 2 is characterized in that, in Scheme 1, the width difference between the groove forming width and the resin forming width is the size at which the groove regeneration component does not interfere with the holding part.

[0015] Furthermore, the invention described in Scheme 3 is characterized in that, in Scheme 2, the tank regeneration assembly forms multiple regeneration tanks through the cooperation of a rotating assembly that rotates the main roller, a horizontal moving assembly that moves the cutting tool along the axial direction, and a lifting moving assembly that moves the cutting tool up and down toward the resin layer. The difference between the tank forming width and the resin forming width is the size at which the cutting tool does not contact the holding part when the regeneration tank is formed by the tank regeneration assembly.

[0016] Furthermore, the invention described in Scheme 4 is characterized in that, in Scheme 3, the width difference between the groove forming width and the resin forming width is set according to at least one of the cutting edge angle, cutting edge width, and the descent angle of the cutting tool.

[0017] Invention Effects

[0018] Therefore, the processing apparatus described in Scheme 1 can improve the quality of the processed products by suppressing the positional change of the tank caused by the thermal expansion of the resin layer of the main roller, and can improve the production efficiency of the processed products by efficiently regenerating the tank.

[0019] Furthermore, according to the invention described in Scheme 2, the thermal expansion displacement of the resin layer can be suppressed by the retaining part, thereby suppressing the positional change of the tank, and the desired regeneration tank can be reliably formed without removing the retaining part.

[0020] Furthermore, according to the invention described in Scheme 3, the thermal expansion displacement of the resin layer can be suppressed by the retaining part, thereby suppressing the positional change of the groove, and the desired regenerated groove can be reliably formed by the cutting tool without removing the retaining part.

[0021] Furthermore, according to the invention described in Scheme 4, tank regeneration can be reliably performed with the main roller equipped with a retaining part. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a wire saw according to one embodiment of the present invention.

[0023] Figure 2 This is a cross-sectional view of the main roller.

[0024] Figure 3 It is an enlarged cross-sectional view of the groove formed in the resin layer.

[0025] Figure 4 This is a schematic diagram of a groove processing device.

[0026] Figure 5A This diagram represents the stage before tank regeneration in the tank regeneration process.

[0027] Figure 5B This is a diagram illustrating the resin layer peeling process.

[0028] Figure 5C This is a diagram illustrating the tank regeneration process.

[0029] Figure 5D This diagram represents the state after three stripping and tank regeneration processes. Detailed Implementation

[0030] Hereinafter, the processing apparatus according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0031] Figure 1 This is a schematic diagram of a wire saw 2, an example of a processing apparatus for cutting workpiece W using wire 1. The wire saw 2 includes a roller unit 4, which has a pair of main rollers 6. The pair of main rollers 6 are arranged separately on the wire path 8 and are respectively fastened to a rotating shaft (not shown) of the roller unit 4. By driving these rotating shafts with a motor (not shown), each main roller 6 can rotate in both directions.

[0032] The wire saw 2 includes a pair of spools 10 and a pair of guide rollers 12. Each spool 10 is arranged separately from each other on the wire path 8 at a position between the roller unit 4 and each guide roller 12, and can be rotated in both directions by a motor (not shown). Each spool 10 is used as a reel for unwinding or reeling depending on the direction of rotation.

[0033] The spool 10, used as a release spool, releases the wire 1 as it rotates. The released wire 1 is guided along the wire path 8 towards the roller unit 4 via a guide roller 12. Each guide roller 12 is a direction-changing roller and is separately arranged on the wire path 8 at a position separated from the roller unit 4.

[0034] The wire released from the spool 10 is guided to the roller unit 4 via a guide roller 12. After being wound a predetermined number of times between a pair of main rollers 6, the wire 1 guided to the roller unit 4 is exited from the roller unit 4 and wound onto the spool 10, which is used as a take-up reel, via another guide roller 12.

[0035] Each spool 10 is connected to a traverse control mechanism (not shown), which causes the connected spool 10 to reciprocate along its axial direction. This allows for the stable release or winding of the wire 1 in the wire path 8. A lifting platform 14 is positioned between a pair of main rollers 6 above the roller unit 4. An adhesive portion 16 is provided on the lower surface of the lifting platform 14, where a workpiece W, intended for cutting, is assembled.

[0036] As wire 1 travels through roller unit 4, workpiece W gradually descends together with lifting platform 14 and is cut into multiple pieces by wire 1 located between a pair of main rollers 6. At this time, coolant is supplied to the wire located between the main rollers 6.

[0037] The coolant is used as a cooling fluid for cooling the wire 1 and each of the main rollers 6. If the coolant contains abrasive particles, it can also be used as a grinding fluid for cutting the workpiece W. If the coolant does not contain abrasive particles, the abrasive particles are fixed to the wire 1 itself. After being supplied to the wire 1 located between the main rollers 6, the coolant is recycled in the recovery tank 18.

[0038] Figure 2 This is a cross-sectional view of the main roller 6. The main roller 6 has a hollow shaft portion 20 as the core material, a resin layer 22 covering the outer peripheral surface 20a of the shaft portion 20, and a pair of annular retaining portions 24 holding the resin layer 22 on both sides in the axial direction X of the shaft portion 20. The rotation shaft of the roller unit 4 is inserted into and fastened to the inner peripheral surface 20b of the shaft portion 20.

[0039] A plurality of grooves 26 are formed in the resin layer 22 along the circumference of the shaft portion 20 and in the axial direction X at predetermined intervals (groove spacing) for the wire 1 to be wound in a spiral a predetermined number of times. The groove forming width L1 in the axial direction X of the resin layer 22 where the plurality of grooves 26 are formed is smaller than the resin forming width L in the axial direction X of the resin layer 22. Furthermore, at both ends in the axial direction X of the resin layer 22, the width difference ΔL between the groove forming width L1 and the resin forming width L is ensured.

[0040] Figure 3This is an enlarged cross-sectional view showing the grooves 26 formed in the resin layer. Each groove is formed as an inverted trapezoid with a specified groove depth D, a specified groove angle θ, and a specified groove bottom width Wa. Each groove has a specified groove spacing P and a specified top width Wb, and multiple grooves are formed on the outer peripheral surface 22a of the resin layer 22. These specified values ​​are appropriately set according to the specifications of the main roller 6. Also... Figure 2 As shown, corner portions 28 are formed at the outermost ends (left and right ends) of the grooves 26 located on both sides along the axial direction X of the resin layer 22 and at the boundary of the outer peripheral surface 22a of the resin layer 22. That is, the groove forming width L1 is defined as the distance between each corner portion 28 at the outermost end of the groove 26 along the axial direction X.

[0041] Since the wire 1 is wound around and slides in contact with the multiple grooves 26 formed in the resin layer 22 of the main roller 6, the resin layer 22 is prone to expansion due to processing heat generated during the operation of the wire saw 2. Because of the thermal expansion of the resin layer 22, the position of the grooves 26 in the resin layer 22 changes, which can alter the thickness and warpage of the wafer after cutting, potentially affecting the quality of the wafer. However, in this embodiment, the thermal expansion of the resin layer 22, particularly in the axial direction X, is suppressed by a pair of retaining portions 24, and the positional change of the grooves 26 in the resin layer 22 is also suppressed.

[0042] Figure 4 This is a schematic diagram of a groove forming apparatus 30 that forms grooves 26 on the main roller 6. The groove forming apparatus 30 includes a rotating unit (rotating assembly) 32, a cutting tool 34, a fixed table 36, a horizontal moving unit (horizontal moving assembly) 38, and a lifting moving unit (lifting moving assembly) 40. The rotating unit 32 centers the shaft portion 20 of the main roller 6 and supports the shaft portion 20 of the main roller 6 so that it is rotatable. The cutting tool 34 has a cutting edge 34a at its tip for forming grooves 26 in the resin layer 22 of the main roller 6.

[0043] The cutting tool 34 is fixed to the fixed table 36 with its cutting edge 34a pointing downwards in the vertical direction (axial direction) Y. The horizontal movement unit 38 has a track 38a that supports the fixed table 36 so that it can move in the horizontal direction (axial direction X). By moving the fixed table 36 along the track 38a, the cutting tool 34 moves along the axial direction X. The lifting movement unit 40 supports the fixed table 36 and the cutting tool 34 so that they can be raised and lowered relative to the main roller 6. Through the cooperation of the rotation unit 32, the horizontal movement unit 38, and the lifting movement unit 40, the aforementioned plurality of grooves 26 can be formed in the resin layer 22 of the main roller 6.

[0044] Here, since the wire 1 is wound around and slides in contact with the groove 26 formed in the resin layer 22 of the main roller 6, the groove 26 formed in the resin layer 22 wears and deforms with the operation of the wire saw 2. Therefore, the groove 26 is periodically regenerated by using the groove processing device 30. That is, in the wire saw 2 of this embodiment, the resin layer 22 of the main roller 6 is protected from thermal expansion by a pair of holding portions 24, and a regenerated groove is formed by the groove regeneration assembly using the groove processing device 30.

[0045] Figures 5A to 5D This is a schematic diagram illustrating the process of regenerating the tank in stages using the upper section of the main roller 6. Figure 5A This indicates the stage before tank regeneration. The resin layer 22 is formed by the wear and deformation of each tank 26 in the tank forming area 42 of the tank forming width L1. Figure 5B This indicates the peeling process of resin layer 22, which is a pre-stage of the groove regeneration process. First, by driving the horizontal moving unit 38, as shown by the single-dot dashed line, the tip of the cutting edge 34a of the cutting tool 34 is positioned at one end of the groove forming width L1 (in...). Figure 5B The upper side of corner 28 (left end side) and slightly outward in the axial direction than corner 28 (in Figure 5B (The middle position is slightly to the left).

[0046] Next, the driving lifting and moving unit 40 lowers the cutting tool 34 vertically downwards, as shown by the dotted line, so that the tip of the cutting edge 34a of the cutting tool 34 is positioned on the outer peripheral surface 22a of the resin layer 22, and the tip bites into the peeling start position 44 of the peeling depth D1 of the resin layer. The peeling start position 44 is located within the width difference ΔL in the axial direction X, and is the position where the cutting tool 34 does not contact the holding part 24. Furthermore, the peeling depth D1 is greater than or equal to the groove depth D.

[0047] Next, the drive unit 32 and the horizontal movement unit 38 rotate the main roller 6 while moving the cutting tool 34 horizontally, as shown by the solid line, so that the tip of the cutting tool 34 is located at the other end of the groove forming width L1 (in Figure 5B The middle part is on the right side) and is slightly outside the corner 28 in the X-axis direction (in Figure 5B The peeling end position 46 is slightly to the right. Next, the lifting and moving unit 40 is driven, as shown by the double-dotted line, to raise the cutting tool 34 vertically upward and retract it.

[0048] As a result, the surface layer of resin layer 22 with multiple grooves 26 is peeled off along its outer periphery, forming a peeling region 48 in resin layer 22. The peeling region 48 is formed into an inverted trapezoidal cross section by a peeling peripheral surface 48a without grooves 26 and peeling side surfaces 48b formed on both sides in the axial direction X of the peeling region 48.

[0049] The peeling peripheral surface 48a is shaped such that the peeling depth D1 is recessed from the outer peripheral surface 22a of the resin layer 22 along the entire circumference of the resin layer 22. The peeling side surface 48b is an inclined surface formed from the peeling peripheral surface 48a to the outer peripheral surface 22a, and the inclination angle α with respect to its axial direction X is an angle corresponding to the cutting edge angle β and the cutting edge width Wc of the cutting tool 34.

[0050] Furthermore, even after the peeling region 48 is formed, a width difference ΔL is ensured at both ends of the outer peripheral surface 22a of the resin layer 22 in the axial direction of the resin layer. The width difference ΔL is determined based on the cutting edge angle β, the cutting edge width Wc of the cutting tool 34's cutting edge 34a, and the descent angle of the cutting tool 34 relative to the vertical direction Y (in the vertical direction Y). Figure 5B At least one of the following elements (e.g., 0° in the case of 0°) is set as the size at which the groove machining device 30 does not interfere with the holding part 24, that is, the size at which the cutting tool 34 does not contact the holding part 24.

[0051] In detail, in order to perform groove regeneration without the cutting tool 34 contacting the holding part 24, a large width difference ΔL needs to be ensured in advance when the cutting edge angle β and cutting edge width Wc of the cutting edge 34a of the cutting tool 34 are relatively large. Furthermore, a large width difference ΔL needs to be ensured in advance when the descent angle of the cutting tool 34 relative to the vertical direction is greater than 0°, that is, when the cutting tool 34 descends obliquely downward along the peeling side 48b.

[0052] then, Figure 5C This indicates a groove regeneration process performed after the peeling process. By driving the rotary unit 32, the horizontal moving unit 38, and the lifting moving unit 40, the main roller 6 is rotated while the cutting tool 34 gradually moves along the axial direction X, forming multiple grooves 26 in the peeling area 48. Next, the lifting moving unit 40 is driven to raise and retract the cutting tool 34. As a result, a groove forming area 42 is formed on the peeling peripheral surface 48a of the resin layer 22.

[0053] The groove forming width L1 of the groove forming region 42 formed on the peeling peripheral surface 48a is the same as the groove forming width L1 in the initial stage before groove regeneration. Furthermore, at both ends in the axial direction X of the resin layer 22, a width difference ΔL, the same as that in the initial stage, is ensured between the groove forming width L1 and the resin forming width L. Additionally, the regenerated groove 26 has the same shape as before wear, formed with the same groove spacing P.

[0054] Figure 5DThis indicates the state after three peeling and trench regeneration processes. In the peeling area 48, the peeling circumferential surface 48a is formed to a depth of peeling depth D3, which is three times the peeling depth D1 in the first trench regeneration. In the second and third peeling processes, the peeling start position 44 and the peeling end position 46 are offset towards each other in the axial direction X.

[0055] Thus, the peeling side 48b formed in the third peeling process is formed as a continuous inclined surface maintaining an inclination angle α from the peeling side 48b formed in the first peeling process. This is achieved through repeated... Figure 5B The peeling process shown and Figure 5C The tank regeneration process shown can be repeated periodically until the thickness t of the remaining resin layer 22 becomes a predetermined thickness (e.g., the thickness of the resin layer that can ensure the strength of the tank 26), or until the tank forming width L cannot be ensured in the tank forming region 42.

[0056] As described above, the wire saw 2 of this embodiment includes a holding portion 24 that holds the resin layer 22 of the main roller 6 in the axial direction X. Moreover, the groove forming width L1 in the axial direction X of the multiple grooves 26 formed in the resin layer 22 and the regenerated grooves 26 is set to be smaller than the resin forming width L in the axial direction X of the resin layer 22.

[0057] Therefore, by suppressing the thermal expansion displacement of the resin layer 22 through the holding part 24, the positional change of the groove 26 is suppressed, and groove regeneration can be performed using the groove regeneration assembly of the groove processing apparatus 30 even without removing the holding part 24. Thus, in the wire saw 2, the quality of the wafer as the processed product can be improved, and the production efficiency of the wafer as the processed product can be improved by efficiently performing groove regeneration.

[0058] Furthermore, the width difference ΔL between the tank forming width L1 and the resin forming width L is set to a size that prevents interference with the tank regeneration assembly using the tank processing device 30. As a result, thermal expansion displacement of the resin layer 22 can be suppressed by the holding part 24, thereby suppressing positional changes in the tank 26, and reliably forming the desired regeneration tank without removing the holding part.

[0059] More specifically, the groove regeneration assembly of the groove processing apparatus 30, through the cooperation of the rotation unit 32, the horizontal movement unit 38, and the lifting movement unit 40, can form multiple regenerated grooves 26. Furthermore, the width difference ΔL between the groove forming width L1 and the resin forming width L is set to a size such that the cutting tool 34 does not contact the holding portion 24 when forming the groove 26 using the groove regeneration assembly of the groove processing apparatus 30. Therefore, the thermal expansion displacement of the resin layer 22 can be suppressed by the holding portion 24, thereby suppressing positional changes in the groove 26, and the desired regenerated groove 26 can be reliably formed by the cutting tool 34 without removing the holding portion 24.

[0060] Furthermore, the width difference ΔL between the groove forming width L1 and the resin forming width L is set based on at least one of the cutting edge angle β of the cutting edge 34a of the cutting tool 34, the cutting edge width Wc, and the descent angle of the cutting tool 34. By ensuring that the width difference ΔL is large in advance based on these factors, groove regeneration can be reliably performed with the holding part 24 assembled on the main roller 6.

[0061] This concludes the description of one embodiment of the present invention. However, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, as long as the thermal expansion displacement of the resin layer 22 can be suppressed, thereby suppressing the positional change of the groove 26, only one holding part 24 may be provided according to the configuration of the main roller 6 and the roller unit 4, and the resin layer 22 may be held only on one side in the axial direction X.

[0062] Furthermore, as long as it does not hinder tank regeneration, the width difference ΔL between the tank forming width L1 and the resin forming width L can also have different sizes at both ends in the axial direction X of the resin layer 22. Moreover, as long as an appropriate width difference ΔL can be ensured that the cutting tool 34 does not contact the holding part 24, the tank forming width L1 can be changed during tank regeneration according to changes in the specifications of the wire saw 2 and the main roller 6.

[0063] Furthermore, in this embodiment, since groove regeneration can be performed without removing the retaining portion 24, the retaining portion 24 and the shaft portion 20 can be integrally formed. Additionally, as... Figure 2 and Figures 5A to 5D As shown, the retaining portion 24 is formed with a shaft diameter smaller than that of the resin layer 22. However, it is not limited to this. As long as the thermal expansion displacement of the resin layer 22 can be suppressed by the retaining portion 24, thereby suppressing the positional change of the groove 26 and performing groove regeneration, the shaft diameter of the retaining portion 24 can also be larger than that of the resin layer 22.

[0064] In addition, Figure 5D In the state shown, as long as an appropriate width difference ΔL can be ensured to prevent the cutting tool 34 from contacting the holding part 24, the peeling start position and peeling end position can be kept from shifting towards each other in the axial direction X during each peeling operation. Furthermore, the present invention is not limited to the wire saw 2 described in the above embodiment, but can be widely applied to processing apparatuses that use wire to cut workpieces, including wire electrical discharge machining apparatuses, etc.

[0065] Explanation of reference numerals in the attached figures

[0066] 1: Cable;

[0067] 2: Wire saw (processing device);

[0068] 6: Main roller;

[0069] 20: Shaft portion;

[0070] 20a: Outer peripheral surface;

[0071] 22: Resin layer;

[0072] 24: Maintaining section;

[0073] 26: Tank (regeneration tank);

[0074] 30: Tank processing device (tank regeneration component);

[0075] 32: Rotating unit (rotating assembly);

[0076] 34: Cutting tools;

[0077] 34a: blade;

[0078] 38: Horizontal movement unit (horizontal movement component);

[0079] 40: Lifting and moving unit (lifting and moving assembly);

[0080] W: Workpiece;

[0081] X: Axis direction;

[0082] P: Slot spacing (interval);

[0083] L1: Groove width;

[0084] L: Resin formation width;

[0085] ΔL: Width difference;

[0086] β: Rim angle;

[0087] Wc: Blade width.

Claims

1. A processing apparatus that performs cutting processing on a workpiece with a wire, the processing apparatus comprising: a main roller in which a plurality of grooves in which the wire is spirally wound are formed at a prescribed interval in a circumferential direction and an axial direction; the main roller having: a shaft portion; a resin layer that covers an outer peripheral surface of the shaft portion and forms the plurality of grooves; and a holding portion that holds the resin layer in the axial direction; the resin layer allowing a groove regenerating assembly to form a plurality of regenerated grooves by peeling a surface layer of the resin layer along an outer periphery thereof; a groove formation width of the plurality of grooves and the regenerated grooves in the axial direction of the resin layer being smaller than a resin formation width of the resin layer in the axial direction; and a width difference between the groove formation width and the resin formation width being a size at which the groove regenerating assembly does not interfere with the holding portion.

2. The processing apparatus according to claim 1, wherein: the groove regenerating assembly forms the plurality of regenerated grooves in cooperation with a rotation assembly that rotates the main roller, a horizontal movement assembly that moves a cutting tool in the axial direction, and a lift movement assembly that lifts the cutting tool toward the resin layer; and the width difference between the groove formation width and the resin formation width is a size at which the cutting tool does not contact the holding portion when the regenerated grooves are formed by the groove regenerating assembly.

3. The processing apparatus according to claim 2, wherein: the width difference between the groove formation width and the resin formation width is set in accordance with at least any one of a blade angle of a blade of the cutting tool, a blade width, and a descent angle of the cutting tool. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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