Backward pushing type taper machining equipment for steering knuckle

Abstract

The utility model discloses a steering knuckle backward pushing type taper machining device which comprises a fixing bottom plate and a backward pushing plate, a first fixing plate is fixedly installed on one side of the top face of the fixing bottom plate, a second fixing plate is fixedly installed on the other side of the top face of the fixing bottom plate, and a driving lead screw is installed between the first fixing plate and the second fixing plate. One end of the driving lead screw is connected with the output end of a second motor, guide sliding rods are symmetrically and fixedly installed between the first fixing plate and the second fixing plate, a first lead screw sleeve is fixedly installed on the reverse pushing plate, guide sliding sleeves are symmetrically and fixedly installed on the reverse pushing plate, and a rotating shaft is installed in the center of the reverse pushing plate. A mounting cylinder is fixedly mounted at the other end of the rotating shaft. The steering knuckle grinding device has the advantages that the two grinding heads can be synchronously and symmetrically adjusted so as to improve the machining quality of workpieces, the mode that the workpieces are reversely pushed to the grinding heads is adopted, the use stability of the grinding heads in the machining process is improved, the machining quality of steering knuckles is further improved, and practicability is higher.

Description

Technical Field

[0001] The utility model relates to the technical field of taper processing equipment, in particular to a steering knuckle push-back type taper processing equipment. Background Art

[0002] The steering knuckle, also known as the "ram's horn", is one of the important parts in the automobile steering axle. It can make the car run stably and sensitively transmit the driving direction. The function of the steering knuckle is to transmit and bear the front load of the car, support and drive the front wheel to rotate around the kingpin to steer the car. Since the shape of the steering knuckle is similar to the ram's horn cone, it is necessary to use taper processing equipment to mill it during processing to obtain a workpiece product with the corresponding taper. For this purpose, steering knuckle taper processing equipment is required.

[0003] The prior art discloses a drill processing device with controllable taper, which is convenient for processing the drill into drills of different tapers and has a low scrap rate, including a workbench, a top plate fixedly connected to the workbench through a plurality of support columns, a through slot being provided on the top plate, a threaded ring being fixedly connected at the through slot, a screw being provided on the threaded sleeve of the threaded ring, the top and bottom ends of the screw being rotatably connected to an upper connecting plate and a lower connecting plate respectively, a plurality of limit rods being fixedly connected to the bottom end of the upper connecting plate, the limit rods extending through the top plate to the outside and being fixedly connected to the lower connecting plate, a driving assembly being provided on the screw, the bottom end of the lower connecting plate being fixedly connected to two first rotating seats, a rotating plate being rotatably connected to the first rotating seat, a grinding head being fixedly connected to the rotating plate, a rotating assembly being provided on the rotating plate, a placement slot being provided on the top of the workbench, a placement cylinder being connected in the placement slot, and a driving assembly being provided on the placement cylinder.

[0004] The above-mentioned utility model adjusts the angle of the grinding head to achieve different taper processing of the workpiece when in use. However, it is difficult to ensure that the adjustment angles of the two grinding heads are consistent when two electric push rods are used independently, which will affect the taper processing quality of the workpiece, and the grinding head with adjusted angles needs to be raised and lowered with the upper connecting plate and the lower connecting plate. It is difficult to ensure the stability of the grinding head when it moves in a forward push, which will have a certain impact on the taper processing quality of the workpiece, and its practicality is relatively general. Utility Model Content

[0005] 1. Technical issues to be resolved

[0006] In view of the shortcomings of the prior art, the utility model provides a steering knuckle push-back taper processing equipment, which can realize synchronous and symmetrical adjustment of two grinding heads to improve the workpiece processing quality, and adopts the method of pushing the workpiece back to the grinding head to improve the stability of the grinding head during processing, further improve the steering knuckle processing quality, and has the advantages of greater practicality, thereby solving the problems in the above-mentioned background technology.

[0007] (II) Technical solution

[0008] In order to achieve the above-mentioned advantages, the two grinding heads can be adjusted synchronously and symmetrically to improve the processing quality of the workpiece, and the method of pushing the workpiece back to the grinding head is adopted to improve the stability of the use of the grinding head during processing, further improve the processing quality of the steering knuckle, and have the advantage of greater practicality. The specific technical scheme adopted by the utility model is as follows: A steering knuckle push-back taper processing equipment, comprising a fixed base plate and a push-back plate, a first fixed plate is fixedly installed on one side of the top surface of the fixed base plate, and a second fixed plate is fixedly installed on the other side of the top surface of the fixed base plate, a driving screw is installed between the first fixed plate and the second fixed plate, and one end of the driving screw is connected to the output end of the second motor, a guide slide rod is symmetrically fixedly installed between the first fixed plate and the second fixed plate, a first screw sleeve is fixedly installed on the push-back plate, and A guide sleeve is installed, a rotating shaft is installed in the center of the push plate, and one end of the rotating shaft is connected to the output end of the first motor, and a mounting cylinder is fixedly installed on the other end of the rotating shaft, a fixed seat is fixedly installed on one side of the second fixed plate, and a guide slot is opened in the center of the fixed seat, and a bidirectional lead screw is installed in the guide slot, one end of the bidirectional lead screw is connected to the output end of the third motor, a guide slider is symmetrically embedded in the guide slot, and a second lead screw sleeve is fixedly installed in the guide slider, and a second connecting seat is fixedly installed on one side of the guide slider, a rotating seat is symmetrically fixedly installed on one side of the fixed seat, and a rotating plate is installed on the rotating seat, and a grinding head is installed on the rotating plate, and the first connecting seat is fixedly installed on the outer side walls of the two rotating plates, and a connecting rod is connected between the first connecting seat and the second connecting seat.

[0009] Furthermore, the first screw sleeve cooperates with the driving screw, the second screw sleeve cooperates with the bidirectional screw, and the guide slide rod is sleeved in the guide slide sleeve.

[0010] Furthermore, a protective cover is fixedly installed on one side of the second fixed plate, and a liquid homogenizing box is fixedly installed on the inner wall of the protective cover, and a number of spray heads are evenly installed on the bottom surface of the liquid homogenizing box, a waste box is fixedly installed on one side of the top surface of the fixed bottom plate, and the waste box is located below the grinding head, one side of the bottom of the inner cavity of the waste box is connected to one end of a liquid extraction pipe, and the other end of the liquid extraction pipe is connected to the inner cavity of the liquid homogenizing box, and a small pump is installed on the liquid extraction pipe.

[0011] Furthermore, a control panel is fixedly mounted on the side wall of the first fixed plate, and the control panel is electrically connected to the first motor, the second motor, the third motor and the small pump.

[0012] Furthermore, a support seat is fixedly installed on the inner wall of the waste box, and a filter screen is placed on the support seat.

[0013] Furthermore, the central axis of the push back plate, the central axis of the mounting tube and the central axis of the fixing seat are on the same straight line.

[0014] Furthermore, the cross-section of the protective cover is in the shape of an inverted concave letter "Q".

[0015] (III) Beneficial effects

[0016] Compared with the prior art, the utility model provides a steering knuckle push-back taper processing device, which has the following beneficial effects:

[0017] (1) The utility model is provided with an installation cylinder, a push plate and a grinding head. When in use, a worker can place the steering knuckle workpiece to be processed in the center of the installation cylinder and fix it, and then start the third motor to rotate through the control panel. A second fixed plate is welded on one side of the top surface of the fixed bottom plate, and a fixed seat is fixedly installed on the side wall of the second fixed plate, and a guide slide groove is opened in the center of the fixed seat, a two-way screw is installed in the guide slide groove, and one end of the two-way screw is connected to the output end of the third motor, and a rotating seat is symmetrically fixedly installed on one side of the fixed seat, and a rotating plate is installed on the rotating seat, and a grinding head is fixedly installed on the rotating plate, and a first connecting seat is fixedly installed on one side of the two rotating plates, and a guide slider is symmetrically embedded in the guide slide groove, and a second screw sleeve is fixedly installed in the guide slider, and the second screw sleeve cooperates with the two-way screw, in addition, a second connecting seat is fixedly installed on one side of the guide slider, and a connecting rod is connected between the first connecting seat and the second connecting seat, so when the third motor drives the two-way screw to rotate, it can drive the two guide sliders to slide relative to each other, thereby The two rotating plates are pushed together with the two grinding heads to adjust the angles synchronously and symmetrically to realize the adjustment of the machining taper of the steering knuckle to be processed. After the two grinding heads are adjusted, the worker can drive the rotating shaft to rotate through the first motor, so that the mounting cylinder and the steering knuckle workpiece to be processed rotate, and then start the second motor to drive the driving screw installed between the first fixed plate and the second fixed plate to rotate. The set back push plate is fixedly installed with a first screw sleeve, and the first screw sleeve cooperates with the driving screw, and a guide slide rod is sleeved in the guide slide sleeve symmetrically fixed on the back push plate, so as to drive the back push plate to move along the direction of the guide slide rod with the rotation of the driving screw, thereby realizing the back push installation cylinder and the steering knuckle workpiece to be processed moving toward the grinding head position to realize the taper processing of the steering knuckle. The steering knuckle back push taper processing equipment can realize synchronous and symmetrical adjustment of the two grinding heads to improve the workpiece processing quality, and adopts the method of back pushing the workpiece to the grinding head to improve the use stability of the grinding head during processing, further improve the steering knuckle processing quality, and is more practical.

[0018] (2) The utility model is provided with a waste box, a protective cover and a spray head. As mentioned above, the push plate can drive the steering knuckle workpiece to move to the grinding head for taper processing. A protective cover is fixedly installed on one side of the second fixed plate. During processing, the steering knuckle workpiece and the grinding head are both located on the inner side of the protective cover to prevent the worker from accidentally touching the workpiece and causing danger. It can also prevent metal debris generated during the processing from splashing to the outside and causing danger. In addition, a waste box installed on the top surface of the fixed bottom plate is provided below the two grinding heads, and cutting fluid is stored in the waste box. When the taper processing is performed, Workers can start the small pump installed on the liquid extraction pipe, and use the small pump to transport the cutting fluid in the inner cavity of the waste box through the liquid extraction pipe to the liquid mixing box fixedly installed on the inner wall of the protective cover, and finally spray it out through several spray heads installed on the bottom of the liquid mixing box. The sprayed cutting fluid is used to spray the steering knuckle workpiece in processing to improve the processing quality and cool it down. A support seat is fixedly installed on the inner wall of the waste box, and a filter net is placed on the support seat, which can filter the metal waste in the cutting fluid to realize the recycling of the cutting fluid, which is more practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 It is a structural schematic diagram of a steering knuckle push-back taper processing device according to an embodiment of the utility model;

[0021] Figure 2 According to the embodiment of the utility model Figure 1 A magnified image of point A;

[0022] Figure 3 According to the embodiment of the utility model Figure 1 The enlarged view of point B;

[0023] Figure 4 It is a stereoscopic view of a push back plate of a steering knuckle push back taper processing device according to an embodiment of the utility model.

[0024] In the figure:

[0025] 1. Fixed bottom plate; 2. Control panel; 3. First motor; 4. Second motor; 5. Push back plate; 6. First fixed plate; 7. Guide sleeve; 8. Guide slide rod; 9. Waste box; 10. Second fixed plate; 11. Small pump; 12. Liquid extraction pipe; 13. Fixed seat; 14. First lead screw sleeve; 15. Mounting cylinder; 16. Driving lead screw; 17. Protective cover; 18. Liquid homogenizing box; 19. Spray head; 20. Rotating seat; 21. Rotating plate; 22. Grinding head; 23. First connecting seat; 24. Connecting rod; 25. Second connecting seat; 26. Guide slide groove; 27. Bidirectional lead screw; 28. Second lead screw sleeve; 29. ​​Guide slide block; 30. Third motor; 31. Support seat; 32. Filter; 33. Rotating axis. DETAILED DESCRIPTION

[0026] To further illustrate each embodiment, the present invention provides drawings, which are part of the disclosure of the present invention and are mainly used to illustrate the embodiments. They can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these contents, ordinary technicians in the field should be able to understand other possible implementation methods and advantages of the present invention. The components in the figures are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0027] According to an embodiment of the utility model, a steering knuckle push-back taper processing device is provided.

[0028] The present invention is now further described in conjunction with the accompanying drawings and specific implementation methods. Figure 1-4As shown, the steering knuckle push-back taper processing equipment according to the embodiment of the utility model comprises a fixed base plate 1 and a push-back plate 5, a first fixed plate 6 is fixedly installed on one side of the top surface of the fixed base plate 1, and a second fixed plate 10 is fixedly installed on the other side of the top surface of the fixed base plate 1, a driving screw 16 is installed between the first fixed plate 6 and the second fixed plate 10, and one end of the driving screw 16 is connected to the output end of the second motor 4, a guide slide bar 8 is symmetrically fixedly installed between the first fixed plate 6 and the second fixed plate 10, a first screw sleeve 14 is fixedly installed on the push-back plate 5, and a guide sleeve 7 is symmetrically fixedly installed on the push-back plate 5, a rotating shaft 33 is installed in the center of the push-back plate 5, and one end of the rotating shaft 33 is connected to the output end of the first motor 3, and a mounting tube 15 is fixedly installed on the other end of the rotating shaft 33, a fixed seat 13 is fixedly installed on one side of the second fixed plate 10, and a guide slide groove 26 is opened in the center of the fixed seat 13, and A bidirectional lead screw 27 is installed in the guide slot 26, one end of the bidirectional lead screw 27 is connected to the output end of the third motor 30, a guide slider 29 is symmetrically embedded in the guide slot 26, and a second lead screw sleeve 28 is fixedly installed in the guide slider 29, and a second connecting seat 25 is fixedly installed on one side of the guide slider 29, a rotating seat 20 is symmetrically fixedly installed on one side of the fixed seat 13, and a rotating plate 21 is installed on the rotating seat 20, and a grinding head 22 is installed on the rotating plate 21, and a first connecting seat 23 is fixedly installed on the outer side walls of the two rotating plates 21, and a connecting rod 24 is connected between the first connecting seat 23 and the second connecting seat 25, so as to realize synchronous and symmetrical adjustment of the two grinding heads 22 to improve the processing quality of the workpiece, and the workpiece is pushed back to the grinding head 22 to improve the stability of the grinding head 22 during processing, further improve the processing quality of the steering knuckle, and have stronger practicality.

[0029] In one embodiment, the first screw sleeve 14 cooperates with the driving screw 16 , the second screw sleeve 28 cooperates with the bidirectional screw 27 , and the guide slide rod 8 is sleeved in the guide slide sleeve 7 .

[0030] In one embodiment, a protective cover 17 is fixedly installed on one side of the second fixed plate 10, and a liquid equalizing box 18 is fixedly installed on the inner wall of the protective cover 17, and a plurality of spray heads 19 are evenly installed on the bottom surface of the liquid equalizing box 18, a waste box 9 is fixedly installed on one side of the top surface of the fixed base plate 1, and the waste box 9 is located below the grinding head 22, one side of the bottom of the inner cavity of the waste box 9 is connected to one end of a liquid extraction pipe 12, and the other end of the liquid extraction pipe 12 is connected to the inner cavity of the liquid equalizing box 18, and a small pump 11 is installed on the liquid extraction pipe 12, which plays a role in spraying the steering knuckle workpiece being processed with the sprayed cutting fluid to improve the processing quality and reduce the temperature.

[0031] In one embodiment, a control panel 2 is fixedly mounted on the side wall of the first fixed plate 6, and the control panel 2 is electrically connected to the first motor 3, the second motor 4, the third motor 30 and the small pump 11, so as to control the normal operation of the equipment.

[0032] In one embodiment, a support seat 31 is fixedly mounted on the inner wall of the waste box 9, and a filter screen 32 is placed on the support seat 31 to filter metal debris in the cutting fluid to achieve recycling of the cutting fluid.

[0033] In one embodiment, the central axis of the push back plate 5, the central axis of the mounting tube 15 and the central axis of the fixing seat 13 are on the same straight line.

[0034] In one embodiment, the cross-section of the protective cover 17 is an inverted concave shape.

[0035] Working principle: The utility model is provided with a mounting tube 15, a push plate 5 and a grinding head 22. When in use, a worker can place the steering knuckle workpiece to be processed in the center of the mounting tube 15 and fix it, and then start the third motor 30 to rotate through the control panel 2. A second fixed plate 10 is welded to one side of the top surface of the fixed bottom plate 1, and a fixed seat 13 is fixedly installed on the side wall of the second fixed plate 10, and a guide groove 26 is opened in the center of the fixed seat 13, a bidirectional lead screw 27 is installed in the provided guide groove 26, and one end of the bidirectional lead screw 27 is connected to the output end of the third motor 30, and a rotating seat 20 is symmetrically fixedly installed on one side of the fixed seat 13, and a rotating plate 21 is installed on the rotating seat 20, and a grinding head 22 is fixedly installed on the rotating plate 21, and two rotating plates 21 are provided. A first connecting seat 23 is fixedly installed on one side of the rotating plate 21, a guide slide block 29 is symmetrically embedded in the guide slide groove 26, and a second screw sleeve 28 is fixedly installed in the guide slide block 29, and the second screw sleeve 28 cooperates with the bidirectional screw 27. In addition, a second connecting seat 25 is fixedly installed on one side of the guide slide block 29, and a connecting rod 24 is connected between the first connecting seat 23 and the second connecting seat 25. Therefore, when the third motor 30 drives the bidirectional screw 27 to rotate, the two guide slide blocks 29 can be driven to slide relative to each other, thereby pushing the two rotating plates 21 together with the two grinding heads 22 to synchronously and symmetrically adjust the angle, so as to adjust the machining taper of the steering knuckle to be processed. After the two grinding heads 22 are adjusted, the worker can drive the first motor 3 to drive the second grinding heads 22 to adjust the machining taper of the steering knuckle to be processed. The movable rotating shaft 33 rotates, thereby rotating the installation cylinder 15 and the steering knuckle workpiece to be processed, and then the second motor 4 is started to drive the driving screw 16 installed between the first fixed plate 6 and the second fixed plate 10 to rotate. The first screw sleeve 14 is fixedly installed on the set push plate 5, and the first screw sleeve 14 cooperates with the driving screw 16, and the guide slide sleeve 7 symmetrically fixedly installed on the push plate 5 is sleeved with a guide slide rod 8, so as to drive the push plate 5 to move along the direction of the guide slide rod 8 with the rotation of the driving screw 16, so as to realize the push installation cylinder 15 and the steering knuckle workpiece to be processed to move to the position of the grinding head 22, so as to realize the taper processing of the steering knuckle. The steering knuckle push-type taper processing equipment can realize the synchronization of the two grinding heads 22 Symmetrical adjustment is performed to improve the processing quality of the workpiece, and the workpiece is pushed back to the grinding head 22 to improve the stability of the grinding head 22 during processing, further improve the processing quality of the steering knuckle, and have stronger practicality. In addition, the utility model is provided with a waste box 9, a protective cover 17 and a spray head 19. As mentioned above, the push-back plate 5 can drive the steering knuckle workpiece to move to the grinding head 22 for taper processing. A protective cover 17 is fixedly installed on one side of the second fixed plate 10. During processing, the steering knuckle workpiece and the grinding head 22 are both located on the inner side of the protective cover 17 to prevent workers from accidentally touching them and causing danger, and to prevent metal debris generated during the processing from splashing to the outside and causing danger. In addition, a waste box 9 installed on the top surface of the fixed bottom plate 1 is provided below the two grinding heads 22.The waste box 9 stores cutting fluid. When performing taper processing, the worker can start the small pump 11 installed on the liquid extraction pipe 12, and use the small pump 11 to transport the cutting fluid in the inner cavity of the waste box 9 through the liquid extraction pipe 12 to the liquid mixing box 18 fixedly installed on the inner wall of the protective cover 17, and finally spray it out through a number of spray heads 19 installed on the bottom of the liquid mixing box 18. The sprayed cutting fluid is used to spray the steering knuckle workpiece in processing to improve the processing quality and cool it down. The inner wall of the waste box 9 is fixedly installed with a support seat 31, and a filter screen 32 is placed on the support seat 31, which can filter the metal waste in the cutting fluid to achieve the recycling of the cutting fluid, which is more practical.

[0036] In the present utility model, unless otherwise clearly stipulated and limited, the terms such as "installation", "setting", "connection", "fixation" and "screw-on" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. Unless otherwise clearly defined, ordinary technicians in this field can understand the specific meanings of the above terms in the utility model according to the specific circumstances.

[0037] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A steering knuckle push-back taper processing device, comprising a fixed base plate (1) and a push-back plate (5), characterized in that: A first fixed plate (6) is fixedly installed on one side of the top surface of the fixed base plate (1), and a second fixed plate (10) is fixedly installed on the other side of the top surface of the fixed base plate (1); a driving screw (16) is installed between the first fixed plate (6) and the second fixed plate (10), and one end of the driving screw (16) is connected to the output end of the second motor (4); a guide slide bar (8) is symmetrically fixedly installed between the first fixed plate (6) and the second fixed plate (10); a first screw sleeve (14) is fixedly installed on the push back plate (5), and a guide slide sleeve (7) is symmetrically fixedly installed on the push back plate (5); a rotating shaft (33) is installed in the center of the push back plate (5), and one end of the rotating shaft (33) is connected to the output end of the first motor (3), and the other end of the rotating shaft (33) is fixedly installed with a mounting tube (15); a fixed A seat (13) is provided with a guide slot (26) in the center of the fixed seat (13), and a bidirectional lead screw (27) is installed in the guide slot (26), one end of the bidirectional lead screw (27) is connected to the output end of the third motor (30), a guide slider (29) is symmetrically embedded in the guide slot (26), and a second lead screw sleeve (28) is fixedly installed in the guide slider (29), and a second connecting seat (25) is fixedly installed on one side of the guide slider (29), a rotating seat (20) is symmetrically fixedly installed on one side of the fixed seat (13), a rotating plate (21) is installed on the rotating seat (20), and a grinding head (22) is installed on the rotating plate (21), and a first connecting seat (23) is fixedly installed on the outer side walls of the two rotating plates (21), and a connecting rod (24) is connected between the first connecting seat (23) and the second connecting seat (25).

2. The knuckle reverse push taper processing equipment according to claim 1, characterized in that: The first screw sleeve (14) cooperates with the driving screw (16), the second screw sleeve (28) cooperates with the bidirectional screw (27), and the guide slide rod (8) is sleeved in the guide slide sleeve (7).

3. The knuckle reverse push taper processing equipment according to claim 1, characterized in that: A protective cover (17) is fixedly mounted on one side of the second fixed plate (10), and a liquid homogenizing box (18) is fixedly mounted on the inner wall of the protective cover (17), and a plurality of spray heads (19) are evenly mounted on the bottom surface of the liquid homogenizing box (18); a waste box (9) is fixedly mounted on one side of the top surface of the fixed bottom plate (1), and the waste box (9) is located below the grinding head (22); one side of the bottom of the inner cavity of the waste box (9) is connected to one end of a liquid extraction pipe (12), and the other end of the liquid extraction pipe (12) is connected to the inner cavity of the liquid homogenizing box (18), and a small pump (11) is mounted on the liquid extraction pipe (12).

4. The knuckle reverse push taper processing equipment according to claim 1, characterized in that: A control panel (2) is fixedly mounted on the side wall of the first fixed plate (6), and the control panel (2) is electrically connected to the first motor (3), the second motor (4), the third motor (30) and the small pump (11).

5. The steering knuckle push-back taper processing equipment according to claim 3, characterized in that: A support seat (31) is fixedly mounted on the inner wall of the waste box (9), and a filter screen (32) is placed on the support seat (31).

6. The steering knuckle push-back taper processing equipment according to claim 1, characterized in that: The central axis of the push back plate (5), the central axis of the mounting tube (15) and the central axis of the fixing seat (13) are located on the same straight line.

7. The steering knuckle push-back taper processing equipment according to claim 3, characterized in that: The cross-section of the protective cover (17) is in the shape of an inverted concave letter "Q".

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