Flexible flywheel automatic detection device
By designing an automatic testing device for flexible flywheels, an axial pressure is applied to the flexible flywheel using a rotating mechanism and a clamping mechanism. Combined with multiple measuring mechanisms, this solves the problem of the inability to test under axial pressure in existing technologies, and enables accurate measurement of flexible flywheels.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- FRIEDRICH MEASUREMENT INSTR CO LTD
- Filing Date
- 2022-12-14
- Publication Date
- 2026-06-05
AI Technical Summary
Existing flexible flywheel testing equipment cannot measure data under axial pressure, and cannot simulate the subtle deformation changes when axial pressure is applied, resulting in inaccurate testing.
An automatic testing device for flexible flywheels was designed, comprising a rotating mechanism, a clamping mechanism, an end face and tooth tip measuring mechanism, a meshing measuring mechanism, and an inner diameter measuring mechanism. The clamping mechanism applies axial pressure to the flexible flywheel, the rotating mechanism rotates it, and multiple sensors and measuring mechanisms are used for accurate measurement.
It enables precise measurement of the end face runout, tooth tip circle runout, and pitch circle runout of a flexible flywheel under axial pressure, improving the accuracy and comprehensiveness of the detection.
Smart Images

Figure CN116086372B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of gear testing technology, and more specifically to an automatic testing device for flexible flywheels. Background Technology
[0002] During the production of flexible flywheels, the manufactured flywheels need to be inspected. Specifically, the inner diameter, end face runout, tooth tip circle runout, and pitch circle runout of the flexible flywheel need to be inspected. However, existing inspection methods often separate these parameters and use multiple sets of inspection equipment. Furthermore, existing inspection methods do not apply axial pressure to the flexible flywheel during inspection, and therefore cannot simulate the subtle deformation changes of the flexible flywheel under axial pressure, thus failing to capture the values of the aforementioned test data. Summary of the Invention
[0003] This invention provides an automatic testing device for flexible flywheels to solve the problem in the prior art that data measurement cannot be performed when the flexible flywheel is subjected to axial pressure.
[0004] To solve the above-mentioned technical problems, the present invention provides an automatic testing device for flexible flywheels, including a rotating mechanism, a clamping mechanism, an end face and tooth tip measuring mechanism, a meshing measuring mechanism, and an inner diameter measuring mechanism; the end face and tooth tip measuring mechanism and the meshing measuring mechanism are installed on both sides of the rotating mechanism;
[0005] The rotating mechanism includes an inner fixed seat and an outer rotating body. The outer rotating body is rotatably sleeved on the inner fixed seat. The inner fixed seat is fixedly installed on the first-stage base plate. An inner diameter measuring mechanism is installed on the upper end of the inner fixed seat.
[0006] The clamping mechanism includes a bracket mounted on a primary base plate, on which a servo electric cylinder is mounted. The pressure rod of the servo electric cylinder is rotatably connected to the pressure plate, and the pressure plate is located above the external rotating body.
[0007] The end face and tooth tip measuring mechanism includes a first sliding plate that moves horizontally. Two "U"-shaped blocks are mounted on the first sliding plate. Each "U"-shaped block includes a first fixed block and a first elastic block that are parallel to each other. A first distance sensor and a needle-type cylinder are mounted on the first fixed block. A first spring is also connected between the first fixed block and the first elastic block. A tooth tip measuring block is mounted on the first elastic block of one of the "U"-shaped blocks. A groove is formed on the working plane of the tooth tip measuring block. A rolling first ball is mounted in the groove. An end face measuring block and an end face measuring column are mounted on the first elastic block of the other "U"-shaped block. A cylinder is mounted on the end face measuring block. A second ball is mounted on the end face measuring column.
[0008] The meshing measuring mechanism includes a second sliding plate, a second base, and a standard gear. The second sliding plate moves horizontally on the second base, and the standard gear is rotatably mounted on the second sliding plate. A second spring connects the second sliding plate and the second base.
[0009] A gear ring is fixed to the outer periphery of the outer rotating body, and a rotary motor is also installed on the first-stage base plate. The gear on the rotating shaft of the rotary motor meshes with the gear ring for transmission.
[0010] A first guide block is fixedly installed on the first elastic block, and the first guide block is slidably engaged with the first fixed block. A top block is fixed on both the first fixed block and the first elastic block.
[0011] The first sliding plate is slidably mounted on the end face and tooth tip measuring bracket via the first slider mechanism. The end face and tooth tip measuring bracket is fixedly mounted on the first-stage base plate. A first cylinder is fixed on the first sliding plate, and the piston rod of the first cylinder is fixedly connected to the end face and tooth tip measuring bracket.
[0012] A second distance sensor is fixedly mounted on the second sliding plate, and an extension block and a second cylinder are fixed on the second base. The extension block extends to the detection head of the second distance sensor, and the piston rod of the second cylinder is fixedly connected to the second sliding plate.
[0013] The inner diameter measuring mechanism includes an inner hole positioning column and a pair of inner diameter measuring modules. The inner diameter measuring block of the inner diameter measuring module is placed in a cavity opened inside the inner hole positioning column. The inner diameter measuring block is a long strip. The inner diameter measuring module also includes a second fixed block and a second elastic block that are perpendicularly connected to the inner diameter measuring block. A third distance sensor is fixedly installed on the second fixed block. A third spring is connected between the second fixed block and the second elastic block. A second guide block is fixed on the second elastic block. The second guide block and the second fixed block are in sliding cooperation.
[0014] The primary base plate is fixed on the secondary base plate. The secondary base plate is also equipped with a feeding mechanism and a standard flywheel feeding mechanism. The feeding mechanism includes a feeding bracket, on which a vertically movable feeding tray is installed. The feeding bracket is slidably mounted on the secondary base plate via a second slider mechanism.
[0015] A third cylinder is fixedly installed on the feeding bracket, and the piston rod of the third cylinder is fixedly connected to the feeding tray. A fourth cylinder is fixedly installed on the lower surface of the secondary base plate, and the piston rod of the fourth cylinder is fixedly connected to the feeding bracket.
[0016] The beneficial effects of this invention are as follows: The flexible flywheel automatic detection device of this invention applies axial pressure to the flexible flywheel placed on the rotating mechanism by the clamping mechanism. The rotating mechanism causes the flexible flywheel to rotate and measures and detects its end face runout, tooth tip circle runout, and pitch circle runout, thereby detecting the above data of the flexible flywheel after the axial pressure is applied. Attached Figure Description
[0017] Figure 1 This is a schematic diagram of the overall structure of the flexible flywheel automatic detection device of the present invention;
[0018] Figure 2 This is a schematic diagram of the pressing mechanism of the present invention;
[0019] Figure 3 This is a schematic diagram of the rotating mechanism, end face and tooth tip measuring mechanism, and meshing measuring mechanism of the present invention;
[0020] Figure 4 This is a schematic diagram of the rotating mechanism of the present invention;
[0021] Figure 5 This is a schematic diagram showing the disassembly of the rotating mechanism of the present invention;
[0022] Figure 6 This is a schematic diagram of the inner diameter measuring mechanism of the present invention;
[0023] Figure 7 This is a schematic diagram of the inner diameter measuring module of the present invention;
[0024] Figure 8 This is a schematic diagram of the end face and tooth tip measuring mechanism of the present invention;
[0025] Figure 9 This is a schematic diagram of the end face and tooth tip measuring mechanism of the present invention.
[0026] Figure 10 This is a schematic diagram of the "U"-shaped block of the present invention;
[0027] Figure 11 This is a schematic diagram of the meshing measurement mechanism of the present invention;
[0028] Figure 12 This is a schematic diagram of the feeding mechanism of the present invention;
[0029] Among them, 1-rotation mechanism, 2-pressing mechanism, 3-end face and tooth tip measuring mechanism, 4-meshing measuring mechanism, 5-inner diameter measuring mechanism, 6-first-stage base plate, 7-second-stage base plate, 8-feeding mechanism, 9-standard flywheel feeding mechanism, 101-internal fixed seat, 102-external rotating body, 103-gear ring, 104-rotary motor, 105-gear, 201-bracket, 202-servo electric cylinder, 203-pressure plate, 301-first sliding plate, 302-first guide block, 303-“U”-shaped block, 304-first fixed block, 305-first elastic block, 306-first distance sensor, 307-needle cylinder, 308-first spring, 309-tooth tip measuring block, 310-groove, 311-first sphere, 312-end face measuring block, 3 13-End face measuring column, 314-Cylinder, 315-Second sphere, 316-Top block, 317-First slider mechanism, 318-End face and tooth top measuring bracket, 319-First cylinder, 401-Second sliding plate, 402-Second base, 403-Standard gear, 404-Second spring, 405-Second distance sensor, 406-Extension block, 407-Second cylinder, 501-Inner hole positioning column, 502-Inner diameter measuring module, 503-Second guide block, 504-Inner diameter measuring block, 505-Second fixing block, 506-Second elastic block, 507-Third distance sensor, 508-Third spring, 801-Feeding bracket, 802-Feeding tray, 803-Second slider mechanism, 804-Third cylinder, 805-Fourth cylinder. Detailed Implementation
[0030] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0031] An automatic testing device for flexible flywheels, such as Figure 1 It includes a rotating mechanism 1, an inner diameter measuring mechanism 5, a clamping mechanism 2 installed above the rotating mechanism 1, an end face and tooth tip measuring mechanism 3 set around the rotating mechanism 1, a meshing measuring mechanism 4, a feeding mechanism 8, and a standard flywheel feeding mechanism 9.
[0032] like Figure 4-5 The rotating mechanism 1 includes an inner fixed seat 101 and an outer rotating body 102. The inner fixed seat 101 is fixedly installed on the first-stage base plate 6, and the outer rotating body 102 is sleeved on the inner fixed seat 101. The outer rotating body 102 and the inner fixed seat 101 are rotatably engaged. An inner diameter measuring mechanism 5 is installed at the middle of the upper end of the inner fixed seat 101. A gear ring 103 is fixed on the outer periphery of the outer rotating body 102. A rotary motor 104 is also installed on the first-stage base plate 6. The gear 105 on the rotating shaft of the rotary motor 104 meshes with the gear ring 103 for transmission.
[0033] like Figure 1-2 The clamping mechanism 2 includes a bracket 201 fixedly installed on the first-stage base plate 6. A servo electric cylinder 202 is installed on the bracket 201. The pressure rod of the servo electric cylinder 202 moves in a vertical direction. The pressure rod of the servo electric cylinder 202 is rotatably connected to the pressure plate 203. The pressure plate 203 rotates on the horizontal plane and is located above the external rotating body 102.
[0034] like Figure 3 , 8 -10, the end face and tooth tip measuring mechanism 3 includes a first sliding plate 301 that moves horizontally. The first sliding plate 301 is slidably mounted on the end face and tooth tip measuring bracket 318 via a first slider mechanism 317. The end face and tooth tip measuring bracket 318 is fixedly mounted on a primary base plate 6. A first cylinder 319 is fixedly mounted on the first sliding plate 301. The piston rod of the first cylinder 319 is fixedly connected to the end face and tooth tip measuring bracket 318. The extension and retraction direction of the piston rod of the first cylinder 319 is the same as the movement direction of the first sliding plate 301. Two "U"-shaped blocks 303 are mounted on the first sliding plate 301.
[0035] like Figure 10 The "U"-shaped block 303 includes a first fixed block 304 and a first elastic block 305 that are parallel to each other. The first fixed block 304 and the first elastic block 305 are connected at the right end. A first distance sensor 306 and a needle cylinder 307 are installed on the first fixed block 304. The needle cylinder 307 is located to the right of the first distance sensor 306. A first spring 308 is also connected between the first fixed block 304 and the first elastic block 305. A first guide block 302 is fixedly installed on the first elastic block 305. The first guide block 302 is slidably engaged with the first fixed block 304 and serves as a guide. A top block 316 is fixed on each of the first fixed block 304 and the first elastic block 305. The top blocks 316 are located to the right of the first distance sensor 306, the first spring 308, the needle cylinder 307, and the first guide block 302. The two top blocks 316 are installed correspondingly.
[0036] like Figure 9The two "U"-shaped blocks 303 are a first "U"-shaped block and a second "U"-shaped block, respectively. The first "U"-shaped block is horizontally positioned, meaning that the first fixing block 304 and the first elastic block 305 of the first "U"-shaped block are on the same horizontal plane. The first elastic block 305 of the first "U"-shaped block is elastic in the horizontal direction. A tooth tip measuring block 309 is installed on the first elastic block 305 of the first "U"-shaped block. The tooth tip measuring block 309 has a vertical working plane with a groove 310 on it. A rolling first ball 311 is installed in the groove 310. The first fixing block 304 and the first elastic block 305 of the second "U"-shaped block are on the same vertical plane. An end face measuring block 312 and an end face measuring column 313 are installed on the first elastic block 305 of the second "U"-shaped block. A cylinder 314 is installed on the end face measuring block 312, with its central axis horizontally positioned. A second ball 315 is installed on the end face measuring column 313.
[0037] like Figure 11 The meshing measuring mechanism 4 includes a second sliding plate 401, a second base 402, and a standard gear 403. The second sliding plate 401 moves horizontally on the second base 402. The standard gear 403 is rotatably mounted on the second sliding plate 401. A second spring 404 connects the second sliding plate 401 and the second base 402. Figure 3 The second spring 404 pulls the second sliding plate 401 to move in the direction of the rotating mechanism 1; an extension block 406 and a second cylinder 407 are fixed on the second base 402, and the piston rod of the second cylinder 407 is fixedly connected to the second sliding plate 401; a second distance sensor 405 is fixedly installed on the second sliding plate 401, and the extension block 406 extends to the detection head of the second distance sensor 405. When the second sliding plate 401 moves, the second distance sensor 405 moves accordingly, while the extension block 406 and the second base 402 are fixed, thus the second distance sensor 405 measures the amount of movement change between the second sliding plate 401 and the second base 402.
[0038] like Figure 6-7 The inner diameter measuring mechanism 5 includes an inner hole positioning post 501 and a pair of inner diameter measuring modules 502. The inner hole positioning post 501 is cylindrical in shape with a chamfered edge at the top. The inner diameter measuring block 504 of the inner diameter measuring module 502 is placed in a cavity opened inside the inner hole positioning post 501. The inner diameter measuring block 504 is a long strip. The inner diameter measuring module 502 also includes a second fixed block 505 and a second elastic block 506 that are perpendicularly connected to the inner diameter measuring block 504. A third distance sensor 507 is fixedly installed on the second fixed block 505. A third spring 508 is connected between the second fixed block 505 and the second elastic block 506. A second guide block 503 is fixed on the second elastic block 506. The second guide block 503 slides with the second fixed block 505.
[0039] like Figure 1 The primary base plate 6 is fixed on the secondary base plate 7. The secondary base plate 7 is also equipped with a feeding mechanism 8 and a standard flywheel feeding mechanism 9. Figure 12 The feeding mechanism 8 includes a feeding bracket 801, on which a vertically movable feeding tray 802 is mounted. The feeding bracket 801 is slidably mounted on the secondary base plate 7 via a second slider mechanism 803. A third cylinder 804 is fixedly mounted on the feeding bracket 801, and the piston rod of the third cylinder 804 is fixedly connected to the feeding tray 802. A fourth cylinder 805 is fixedly mounted on the lower surface of the secondary base plate 7, and the piston rod of the fourth cylinder 805 is fixedly connected to the feeding bracket 801.
[0040] During operation, the external robotic arm places the flexible flywheel to be tested onto the loading tray 802 of the loading mechanism 8. At this time, the loading tray 802 is at the uppermost point of its working stroke in the vertical direction. The pressure plate 203 of the clamping mechanism 2 also moves to its uppermost point. The loading bracket 801 moves along the second slider mechanism 803 towards the rotating mechanism 1, so that the loading tray 802 moves above the external rotating body 102. Then, the loading tray 802 descends, causing the external rotating body 102 to hold the flexible flywheel. The loading tray 802 has a hollow center, and the loading tray 802 and the external rotating body 102 do not interfere with each other. At this time, the inner hole positioning post 501 is inserted into the inner diameter hole of the flexible flywheel. The measuring heads at the ends of the inner diameter measuring blocks 504 of the two inner diameter measuring modules 502 abut against the inner diameter hole of the flexible flywheel, thereby changing the initial distance between the second elastic block 506 and the second fixed block 505. The third distance sensor 507 measures the change and thus obtains the inner diameter data of the flexible flywheel.
[0041] Servo cylinder 202 controls pressure plate 203 to press down on flexible flywheel and maintain pressure, and the first sliding plate 301 of end face and tooth tip measuring mechanism 3 moves towards flexible flywheel. Tooth tip measuring block 309 on the first "U"-shaped block moves to the side of flexible flywheel tooth tip, and end face measuring block 312 and end face measuring column 313 on the second "U"-shaped block move to above the end face of flexible flywheel. The piston rod of needle cylinder 307 on the first "U"-shaped block extends and abuts against its first elastic block 305, and the first elastic block 305 deforms, so that the first ball 311 on the first elastic block 305 abuts against the tooth tip of flexible flywheel. The first distance sensor 306 on the first "U"-shaped block measures the distance between itself and the first elastic block 305. Rotary motor 104 controls external rotating body 102 to rotate, driving flexible flywheel to rotate. During this rotation, the first distance sensor 306 obtains tooth tip circular runout data of flexible flywheel. After the measurement is completed, the piston rod of the needle cylinder 307 retracts, and the first elastic block 305 returns to its original state under the pull of the first spring 308.
[0042] Similarly, the first distance sensor 306 on the second "U"-shaped block measures the relevant data on the runout of the flexible flywheel end face. After the data measurement of the end face and tooth tip is completed, the first sliding plate 301 moves away from the flexible flywheel.
[0043] The second sliding plate 401 of the control meshing measuring mechanism 4, driven by the tension of the second spring 404, moves towards the flexible flywheel being measured, causing the standard gear 403 to mesh with the flexible flywheel being measured. Figure 11 , 3 The extension direction of the second sliding plate 401 passes through the center of the outer rotating body 102, and the extension direction of the distance measurement by the second distance sensor 405 also passes through the center of the outer rotating body 102. During the rotation of the flexible flywheel, the standard gear 403 maintains meshing transmission with the flexible flywheel. During this process, the radial runout change of the standard gear 403 caused by the flexible flywheel is converted into the movement of the second sliding plate 401 on the second base 402, which is then measured by the second distance sensor 405 to obtain the indexing circle runout data. After the measurement is completed, the piston rod of the second cylinder 407 retracts, pulling the second sliding plate 401 away from the measured flexible flywheel.
[0044] After all the above measurements are completed, the pressure plate 203 moves upward and the feeding tray 802 moves upward to lift the flexible flywheel. Then, the feeding bracket 801 moves away from the rotating mechanism 1 and the external robot arm removes the flexible flywheel.
[0045] In summary, the flexible flywheel automatic detection device of the present invention applies axial pressure to the flexible flywheel placed on the rotating mechanism by the clamping mechanism. The rotating mechanism causes the flexible flywheel to rotate, and measures and detects its end face runout, tooth tip circle runout, and pitch circle runout, thereby detecting the above data of the flexible flywheel after the axial pressure is applied.
[0046] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of the claims of the present invention.
Claims
1. An automatic testing device for flexible flywheels, characterized in that: It includes a rotating mechanism (1), a pressing mechanism (2), an end face and tooth tip measuring mechanism (3), a meshing measuring mechanism (4), and an inner diameter measuring mechanism (5); the end face and tooth tip measuring mechanism (3) and the meshing measuring mechanism (4) are installed on both sides of the rotating mechanism (1); The rotating mechanism (1) includes an inner fixed seat (101) and an outer rotating body (102). The outer rotating body (102) is rotatably sleeved on the inner fixed seat (101). The inner fixed seat (101) is fixedly installed on the first-level base plate (6). An inner diameter measuring mechanism (5) is installed on the upper end of the inner fixed seat (101). The pressing mechanism (2) includes a bracket (201) mounted on a primary base plate (6), a servo electric cylinder (202) mounted on the bracket (201), the pressure rod of the servo electric cylinder (202) being rotatably connected to the pressure plate (203), and the pressure plate (203) being located above the external rotating body (102); The end face and tooth tip measuring mechanism (3) includes a first sliding plate (301) that moves horizontally. Two "U"-shaped blocks (303) are mounted on the first sliding plate (301). Each "U"-shaped block (303) includes a first fixed block (304) and a first elastic block (305) that are parallel to each other. A first distance sensor (306) and a needle cylinder (307) are mounted on the first fixed block (304). A first spring (308) is also connected between the first fixed block (304) and the first elastic block (305). A tooth tip measuring block (309) is installed on the first elastic block (305) of the U-shaped block (303). A groove (310) is provided on the working plane of the tooth tip measuring block (309). A first rolling ball (311) is installed in the groove (310). An end face measuring block (312) and an end face measuring column (313) are installed on the first elastic block (305) of the other U-shaped block (303). A cylinder (314) is installed on the end face measuring block (312), and a second ball (315) is installed on the end face measuring column (313). The meshing measuring mechanism (4) includes a second sliding plate (401), a second base (402), and a standard gear (403). The second sliding plate (401) moves horizontally on the second base (402). The standard gear (403) is rotatably mounted on the second sliding plate (401). A second spring (404) is connected between the second sliding plate (401) and the second base (402).
2. The automatic testing equipment for flexible flywheels as described in claim 1, characterized in that, The outer circumference of the external rotating body (102) is fixed with a gear ring (103), and a rotary motor (104) is also installed on the first-stage base plate (6). The gear (105) on the rotating shaft of the rotary motor (104) meshes with the gear ring (103) for transmission.
3. The automatic testing equipment for flexible flywheels as described in claim 1, characterized in that, A first guide block (302) is fixedly installed on the first elastic block (305). The first guide block (302) is slidably engaged with the first fixed block (304). A top block (316) is fixed on the first fixed block (304) and the first elastic block (305).
4. The automatic testing equipment for flexible flywheels as described in claim 1, characterized in that, The first sliding plate (301) is slidably mounted on the end face and tooth tip measuring bracket (318) via the first slider mechanism (317). The end face and tooth tip measuring bracket (318) is fixedly mounted on the first-level base plate (6). A first cylinder (319) is fixed on the first sliding plate (301). The piston rod of the first cylinder (319) is fixedly connected to the end face and tooth tip measuring bracket (318).
5. The automatic testing equipment for flexible flywheels as described in claim 1, characterized in that, A second distance sensor (405) is fixedly installed on the second sliding plate (401), and an extension block (406) and a second cylinder (407) are fixed on the second base (402). The extension block (406) extends to the detection head of the second distance sensor (405), and the piston rod of the second cylinder (407) is fixedly connected to the second sliding plate (401).
6. The automatic testing equipment for flexible flywheels as described in claim 1, characterized in that, The inner diameter measuring mechanism (5) includes an inner hole positioning column (501) and a pair of inner diameter measuring modules (502). The inner diameter measuring block (504) of the inner diameter measuring module (502) is placed in a cavity opened inside the inner hole positioning column (501). The inner diameter measuring block (504) is a long strip block. The inner diameter measuring module (502) also includes a second fixed block (505) and a second elastic block (506) that are perpendicularly connected to the inner diameter measuring block (504). A third distance sensor (507) is fixedly installed on the second fixed block (505). A third spring (508) is connected between the second fixed block (505) and the second elastic block (506). A second guide block (503) is fixed on the second elastic block (506). The second guide block (503) slides with the second fixed block (505).
7. The automatic testing equipment for flexible flywheels as described in claim 1, characterized in that, The primary base plate (6) is fixed on the secondary base plate (7). The secondary base plate (7) is also equipped with a feeding mechanism (8) and a standard flywheel feeding mechanism (9). The feeding mechanism (8) includes a feeding bracket (801). The feeding bracket (801) is equipped with a vertically movable feeding tray (802). The feeding bracket (801) is slidably mounted on the secondary base plate (7) through a second slider mechanism (803).
8. The automatic testing equipment for flexible flywheels as described in claim 7, characterized in that, A third cylinder (804) is fixedly installed on the feeding bracket (801). The piston rod of the third cylinder (804) is fixedly connected to the feeding tray (802). A fourth cylinder (805) is fixedly installed on the lower surface of the secondary base plate (7). The piston rod of the fourth cylinder (805) is fixedly connected to the feeding bracket (801).