Diamond drill bit surface polishing device

Abstract

The diamond drill bit surface polishing device comprises a shell, a notch with an upward opening and penetrating leftwards is formed in the shell, a material containing groove is formed in the lower side face of the notch, an inner groove is formed in the left side face of the material containing groove, and a push rod driven by a pneumatic mechanism is arranged in the inner groove; the polishing belt is used for polishing the diamond drill bit, rigid collision caused by the mode that a grinding wheel and the like are adopted in a traditional polishing machine is avoided, the service life of consumables needed by polishing work is prolonged, and the polishing effect is guaranteed; the self-adaptive adjusting device can be used for diamond drill bits of various specifications in a self-adaptive adjusting mode and has the advantages of being wide in application range and easy to operate. The polishing work is carried out in the working cavity, the working cavity in the polishing machine is in a semi-closed state, and the feeding groove and the discharging opening which are communicated with the outside are shielded by the cover plate or the water curtain, so that outward scattering of chippings in the polishing process is effectively reduced.

Description

Technical Field

[0001] The invention relates to the technical field of polishing, and in particular to a diamond drill bit surface polishing device. Background Art

[0002] The diamond drill bit is an integrated drill bit. The entire drill bit has no moving parts and a relatively simple structure. It has high strength, high wear resistance and impact resistance. It was one of the three major new drilling technologies in the world in the 1980s.

[0003] At present, the equipment used for grinding diamond drill bits on the market is generally open, which can easily cause the grinding debris to float in the air, which has an adverse effect on the life and health of the workers. In addition, the current method for grinding diamond drill bits is generally to use materials such as grinding wheels to make rigid contact with the diamond drill bits. Due to the extremely high hardness of the diamond drill bits, the grinding wheels are easily damaged during the grinding process, and the diamond drill bits are easily damaged. Summary of the invention

[0004] In order to overcome the above-mentioned defects in the prior art, the object of the present invention is to provide a diamond drill bit surface polishing device, and the technical solution adopted is:

[0005] A diamond drill bit surface polishing device according to the present invention comprises a shell, a notch is provided in the shell, the notch is provided with a material placement groove in the lower side surface of the notch, an inner groove is provided in the left side surface of the material placement groove, and a push rod driven by a pneumatic mechanism is provided in the inner groove, a processing cavity is provided in the shell, a feeding groove which passes through the processing cavity is provided in the right side surface of the material placement groove, an internal thread ring is fixed in the annular surface of the processing cavity, and a threaded disk is connected to the internal thread of the internal thread ring, a material passage which passes through the left and right in the threaded disk, and a clamping mechanism capable of clamping the drill bit is provided in the material passage, an annular groove is provided in the left side surface of the threaded disk, a gear ring is fixed on the inner annular surface of the annular groove, and a driving mechanism capable of driving the gear ring to rotate is provided in the processing cavity, a through hole which passes through to the right is provided in the right side surface of the processing cavity, and the right side surface of the shell A suspension motor is fixedly arranged on the side, and a main shaft extending into the processing chamber after passing through the through hole is installed on the left side of the suspension motor, and two slide grooves are arranged in the right side of the processing chamber, and the two slide grooves are respectively located at the front and rear sides of the main shaft, and a supporting block is slidably connected in each of the slide grooves, and a bearing shaft is rotatably connected in the left side of the supporting block, and the two bearing shafts are connected by a polishing belt, and a polishing mechanism is arranged in the processing chamber, and the polishing mechanism can make the main shaft drive the polishing belt to move, and polish the drill bit surface through the polishing belt, and a discharge port that passes through the outer shell outward is arranged in the inner side surface of the inner thread ring, and a water storage chamber is arranged in the outer shell, and a discharge groove connected to the water storage chamber is arranged in the lower side surface of the processing chamber, water is stored in the water storage chamber, and a water curtain mechanism is arranged in the outer shell, and the water curtain mechanism can form a water curtain at the discharge port to prevent debris from being discharged.

[0006] Furthermore, a cover plate is hinged on the left side of the processing chamber, and the cover plate can close the feed trough.

[0007] Furthermore, the clamping mechanism includes an electromagnetic slot arranged in the upper and lower sides of the material passing port, the outer side of the electromagnetic slot is connected to a clamping block via a No. 1 spring, and an electromagnet is arranged on the outer side of the electromagnetic slot.

[0008] Further, the driving mechanism includes a motor groove arranged in the left side surface of the processing chamber, a driving motor is fixedly provided on the left side surface of the motor groove, and a driving shaft is installed on the right side surface of the driving motor, a left side groove is provided in the right side surface of the driving shaft, a fixing frame is slidably connected in the side surface of the annular groove, a mating shaft is rotatably connected in the fixing frame, a gear meshing with the gear ring is installed at the right end of the mating shaft, the mating shaft extends to the left into the left side groove, and a sliding block is provided at the left end of the mating shaft.

[0009] Furthermore, the polishing mechanism includes a spring groove arranged in the right side surface of the processing chamber, the upper side surface of the spring groove is connected to a spring block through a No. 2 spring, and the left side surface of the spring block is rotatably connected to a connecting shaft, and the main shaft, the connecting shaft and one of the bearing shafts are connected by a synchronous belt.

[0010] Furthermore, a driving groove connected to the upper side of the slide groove is provided in the outer shell, a positioning motor is provided on the front side of the driving groove, and a rotating shaft is installed on the rear side of the positioning motor, and a threaded shaft rotatably connected to the lower side of each slide groove and threadedly connected to the support block is provided, and the threaded shaft is connected to the rotating shaft through a No. 1 bevel gear set.

[0011] Furthermore, a thermal sensor, a light transmitter and a light receiver are provided in the side of the processing chamber.

[0012] Furthermore, the water curtain mechanism includes an arcuate groove arranged in the annular surface of the through hole and connected to the water storage chamber, a support frame is provided in the arcuate groove, a water-drawing shaft extending into the water storage chamber is rotatably connected in the support frame, and a spiral disk is provided on the annular surface of the water-drawing shaft, and the water-drawing shaft is connected to the main shaft through a No. 2 bevel gear set.

[0013] Furthermore, the lower side surface of the discharge port is inclined toward the rear and downward, and a reflux groove connected to the water storage chamber is provided in the lower side surface of the discharge port, a water curtain groove is provided in the upper side surface of the arc groove, and a water outlet connected to the upper side surface of the water curtain groove is provided in the side surface of the arc groove.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] The present invention uses a polishing belt to polish the diamond drill bit, thereby avoiding the rigid collision that would occur in a conventional polishing machine using a grinding wheel or the like, prolonging the working life of the consumables required for the polishing work, and ensuring the polishing effect;

[0016] Since the present invention uses a polishing belt for polishing, the present invention can be adaptively adjusted to be used for diamond drill bits of various specifications, and has the advantages of wide application range and simple operation;

[0017] The polishing work is carried out in the working chamber, and the working chamber in the present invention is in a semi-closed state. The feed trough and discharge port connected to the outside are shielded by a cover plate or a water curtain, which effectively reduces the dispersion of debris during the polishing process and protects the environment and the life and health of the workers. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the structure of the present invention;

[0019] Figure 2 yes Figure 1 Schematic diagram of the structure of the middle suspension motor;

[0020] Figure 3 yes Figure 1 The right side view of the middle discharge port;

[0021] Figure 4 yes Figure 1 A schematic diagram of the left side of the processing chamber;

[0022] Figure 5 yes Figure 1 Schematic diagram of the structure at the middle motor slot;

[0023] Figure 6 yes Figure 5 Schematic diagram of the structure of the middle clamping block;

[0024] In the figure:

[0025] 11. Shell; 12. Notch; 13. Feeding trough; 14. Inner groove; 15. Push rod; 16. Processing cavity; 17. Feeding trough; 18. Inner thread ring; 19. Threaded disk; 20. Feeding port; 21. Annular groove; 22. Gear ring; 23. Through hole; 24. Suspension motor; 25. Spindle; 26. Light emitter; 27. Slide; 28. Support block; 29. ​​Bearing shaft; 30. Polishing belt; 31. Discharge port; 32. Water storage cavity; 33. Cover plate; 34. Electromagnetic slot; 35. Clamping block; 36. Electromagnet; 37. Motor slot; 38. Drive motor; 39. Drive Moving shaft; 40, left groove; 41, fixing frame; 42, matching shaft; 43, spring groove; 44, spring block; 45, connecting shaft; 46, synchronous belt; 47, driving groove; 48, positioning motor; 49, rotating shaft; 50, threaded shaft; 51, No. 1 bevel gear set; 52, arc groove; 53, water-drawing shaft; 54, spiral disk; 55, reflux groove; 56, water curtain groove; 57, water outlet; 58, No. 2 bevel gear set; 59, sliding block; 60, discharge groove; 61, thermal sensor; 62, clamping mechanism; 63, driving mechanism; 64, polishing mechanism; 65, water curtain mechanism. DETAILED DESCRIPTION

[0026] The present invention is further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention. All other embodiments obtained by ordinary technicians in the field without making creative work belong to the protection scope of the present invention:

[0027] Reference Figure 1-Figure 6According to an embodiment of the present invention, a diamond drill bit surface polishing device comprises a shell 11, wherein a notch 12 opening upward and penetrating to the left is provided in the shell 11, a material placement groove 13 is provided in the lower side of the notch 12, an inner groove 14 is provided in the left side of the material placement groove 13, and a push rod 15 driven by a pneumatic mechanism is provided in the inner groove 14, a processing cavity 16 is provided in the shell 11, a feed groove 17 penetrating into the processing cavity 16 is provided in the right side of the material placement groove 13, an inner thread ring 18 is fixed in the annular surface of the processing cavity 16, and The inner thread ring 18 is connected with a threaded disk 19 through the inner thread, and a feeding port 20 is provided in the threaded disk 19, and a clamping mechanism 62 capable of clamping a drill bit is provided in the feeding port 20, and an annular groove 21 is provided in the left side of the threaded disk 19, and a gear ring 22 is fixed on the inner ring surface of the annular groove 21, and a driving mechanism 63 capable of driving the threaded disk 19 to rotate by driving the gear ring 22 to rotate is provided in the processing cavity 16, and a through hole 23 is provided in the right side of the processing cavity 16, and the outer shell 11 is provided with a through hole 23 through to the right. A suspension motor 24 is fixedly arranged on the right side, and a spindle 25 is installed on the left side of the suspension motor 24 after passing through the through hole 23 and extending into the processing chamber 16. Two slide grooves 27 are arranged on the right side of the processing chamber 16, and the two slide grooves 27 are respectively located on the front and rear sides of the spindle 25, and a support block 28 is slidably connected in each of the slide grooves 27. A bearing shaft 29 is rotatably connected in the left side of the support block 28, and the two bearing shafts 29 are connected by a polishing belt 30. A polishing mechanism 64 is arranged in the processing chamber 16. The polishing mechanism 64 enables the spindle 25 to drive the polishing belt 30 to move, and polishes the drill surface through the polishing belt 30. The inner side surface of the internal thread ring 18 is provided with a discharge port 31 that penetrates the outer shell 11 outward, and the outer shell 11 is provided with a water storage chamber 32, and the lower side surface of the processing chamber 16 is provided with a discharge groove 60 that is connected to the water storage chamber 32. Water is stored in the water storage chamber 32, and the outer shell 11 is provided with a water curtain mechanism 65. The water curtain mechanism 65 can form a water curtain at the discharge port 31 to prevent debris from being discharged.

[0028] Furthermore, a cover plate 33 is hinged on the left side of the processing chamber 16 , and the cover plate 33 can close the feed trough 17 .

[0029] Furthermore, the clamping mechanism 62 includes an electromagnetic slot 34 provided in the upper and lower sides of the feed port 20, the outer side of the electromagnetic slot 34 is connected to a clamping block 35 via a No. 1 spring, and an electromagnet 36 is provided on the outer side of the electromagnetic slot 34. When the electromagnet 36 is in a power-off state, the two clamping blocks 35 do not contact each other, and when the electromagnet 36 is energized, the clamping blocks 35 will be repelled, at which time the two clamping blocks 35 are close to each other and can clamp the drill bit.

[0030] Furthermore, the driving mechanism 63 includes a motor slot 37 arranged in the left side surface of the processing chamber 16, a driving motor 38 is fixedly arranged on the left side surface of the motor slot 37, and a driving shaft 39 is installed on the right side surface of the driving motor 38, a left side slot 40 is arranged in the right side surface of the driving shaft 39, a fixing frame 41 is slidably connected in the side surface of the annular groove 21, a matching shaft 42 is rotatably connected in the fixing frame 41, a gear meshing with the gear ring 22 is installed at the right end of the matching shaft 42, the matching shaft 42 extends to the left into the left side slot 40, and a sliding block 59 is arranged at the left end of the matching shaft 42, The sliding block 59 will not disengage from the left groove 40. When the driving shaft 39 rotates, it will drive the sliding block 59 to rotate the matching shaft 42. When the matching shaft 42 rotates, it will drive the gear ring 22 and the threaded disk 19 to rotate. Due to the threaded connection relationship between the threaded disk 19 and the internal thread ring 18, the threaded disk 19 will move left and right while rotating. When the threaded disk 19 moves left and right, due to the relationship of the fixing frame 41, the matching shaft 42 will maintain the left and right position relationship with the threaded disk 19, and the sliding block 59 will slide left and right in the left groove 40.

[0031] Furthermore, the polishing mechanism 64 includes a spring groove 43 arranged in the right side surface of the processing chamber 16, the upper side surface of the spring groove 43 is connected to the spring block 44 through the No. 2 spring, and the left side surface of the spring block 44 is rotatably connected to the connecting shaft 45, the main shaft 25, the connecting shaft 45 and one of the bearing shafts 29 are connected through a synchronous belt 46, when the main shaft 25 rotates, the bearing shaft 29 is driven to rotate through the synchronous belt 46, when the support block 28 moves up and down, the No. 2 spring will drive the spring block 44 to move up and down, thereby keeping the synchronous belt 46 taut and preventing it from falling off.

[0032] Furthermore, the housing 11 is provided with a driving groove 47 connected to the upper side of the slide groove 27, the front side of the driving groove 47 is provided with a positioning motor 48, and the rear side of the positioning motor 48 is installed with a rotating shaft 49, and the lower side of each of the slide grooves 27 is rotatably connected with a threaded shaft 50 threadedly connected to the support block 28, and the threaded shaft 50 is connected to the rotating shaft 49 through a No. 1 bevel gear set 51. When the positioning motor 48 is energized, it will drive the rotating shaft 49 to rotate the threaded shaft 50, and when the threaded shaft 50 rotates, it will drive the support block 28 to move up and down, thereby adjusting the upper and lower positions of the polishing belt 30.

[0033] Furthermore, a thermal sensor 61 , a light emitter 26 and a light receiver are disposed in the side of the processing chamber 16 .

[0034] Furthermore, the water curtain mechanism 65 includes an arcuate groove 52 provided in the annular surface of the through hole 23 and connected to the water storage chamber 32, a support frame is provided in the arcuate groove 52, a water-drawing shaft 53 extending into the water storage chamber 32 is rotatably connected in the support frame, and a spiral disk 54 is provided on the annular surface of the water-drawing shaft 53, and the water-drawing shaft 53 is connected to the main shaft 25 through a No. 2 bevel gear set 58.

[0035] Furthermore, the lower side surface of the discharge port 31 is inclined toward the rear and lower side, and a reflux groove 55 connected to the water storage chamber 32 is provided in the lower side surface of the discharge port 31, a water curtain groove 56 is provided in the upper side surface of the arc groove 52, and a water outlet 57 connected to the upper side surface of the water curtain groove 56 is provided in the side surface of the arc groove 52. When the through hole 23 rotates, the water pumping shaft 53 will be driven to rotate through the second bevel gear set 58. When the water pumping shaft 53 rotates, it will drive the spiral disk 54 to make the water in the water storage chamber 32 move upward along the arc groove 52. At this time, the water will flow into the water curtain groove 56 through the water outlet 57, form a water curtain and fall into the discharge port 31, and then the water flowing along the lower side surface of the discharge port 31 will flow back to the water storage chamber 32 through the reflux groove 55.

[0036] A diamond drill bit surface polishing device of the present invention has the following working process:

[0037] When the diamond drill bit needs to be polished, the staff energizes the suspension motor 24, which drives the water curtain mechanism 65 to work. At this time, there is a water curtain in the discharge port 31, and the polishing belt 30 moves when the main shaft 25 rotates.

[0038] At this time, the staff will place the drill bit that needs to be sharpened in the material trough 13, and then the pneumatic mechanism drives the push rod 15 to move to the right. At this time, the drill bit in the material trough 13 will be pushed by the push rod 15 and move into the processing chamber 16. At this time, the cover plate 33 is opened and the drill bit is located in the material port 20. When the push rod 15 moves to the right limit, the electromagnet 36 is energized and the drill bit is clamped by the clamping block 35.

[0039] Then the driving motor 38 is energized and drives the driving shaft 39 to rotate. At this time, the threaded disk 19 drives the drill bit to rotate while moving to the right. At the same time, the push rod 15 is reset to the left. At this time, the cover plate 33 is reset and blocks the feed trough 17. When the light receiver cannot receive the light emitted by the light transmitter 26, it indicates that the right end of the diamond drill bit has moved to the right to the predetermined position. At this time, the driving shaft 39 stops moving. Then the positioning motor 48 is energized and the support block 28 and the moving polishing belt 30 move upward. When the thermal sensor 61 senses a high temperature area in the processing chamber 16, it indicates that the polishing belt 30 is in contact with the surface of the drill bit. At this time, the positioning motor 48 is powered off, and then the driving shaft 39 continues to rotate. At this time, the surface of the drill bit is polished by the polishing belt 30 during the process of moving to the right.

[0040] When the threaded disk 19 moves to the right limit, the polishing work on the surface of the diamond drill bit is completed, and the debris will fall into the water in the water storage chamber 32 through the discharge groove 60 during the polishing process to prevent it from spreading. Then the chute 27 is energized and the polishing belt 30 moves to the lower limit. Then the drive shaft 39 reverses, and the threaded disk 19 starts to move to the left. After the threaded disk 19 moves for a certain period of time, the rotation speed of the drive shaft 39 is slowed down, and the electromagnet 36 is powered off. Then, as the threaded disk 19 continues to move to the left, the diamond on the left side of the threaded disk 19 The drill bit will abut against the cover plate 33, and the diamond drill bit will move rightward relative to the threaded disk 19, and the diamond drill bit will detach from the threaded disk 19 and fall down. When the threaded disk 19 moves to the left limit, the drive shaft 39 will rotate forward again for a certain period of time until it is a certain distance away from the left side of the processing chamber 16. At this time, the drive motor 38 is powered off, and the diamond drill bit that has fallen down and completed the polishing work will be discharged through the discharge port 31, and most of the debris on it will be washed away by water when passing through the discharge port 31, and the polishing work of a diamond drill bit is completed.

[0041] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A diamond drill bit surface polishing device, comprising a housing (11), characterized in that: The outer shell (11) is provided with a notch (12) which opens upward and passes through to the left, a material placement groove (13) is provided in the lower side of the notch (12), an inner groove (14) is provided in the left side of the material placement groove (13), and a push rod (15) driven by a pneumatic mechanism is provided in the inner groove (14), a processing cavity (16) is provided in the outer shell (11), a feeding groove (17) which passes through the processing cavity (16) is provided in the right side of the material placement groove (13), an internal thread ring (18) is fixed in the annular surface of the processing cavity (16), and the internal thread of the internal thread ring (18) is connected to a threaded disk (19), and the thread The threaded disc (19) is provided with a material passage (20) which passes through the left and right sides, and the material passage (20) is provided with a clamping mechanism (62) capable of clamping a drill bit. The left side surface of the threaded disc (19) is provided with an annular groove (21), and a gear ring (22) is fixedly provided on the inner ring surface of the annular groove (21). The processing chamber (16) is provided with a driving mechanism (63) which can drive the threaded disc (19) to rotate by driving the gear ring (22). The right side surface of the processing chamber (16) is provided with a through hole (23) which passes through to the right. The right side surface of the housing (11) is provided with a suspension motor (24). A main shaft (25) is installed on the left side of the hanging motor (24) and extends into the processing chamber (16) after passing through the through hole (23). Two slide grooves (27) are arranged in the right side of the processing chamber (16). The two slide grooves (27) are respectively located at the front and rear sides of the main shaft (25), and a supporting block (28) is slidably connected in each of the slide grooves (27). A bearing shaft (29) is rotatably connected in the left side of the supporting block (28), and the two bearing shafts (29) are connected by a polishing belt (30). A polishing mechanism (64) is arranged in the processing chamber (16). The polishing mechanism (64) The spindle (25) can drive the polishing belt (30) to move, and the surface of the drill bit can be polished by the polishing belt (30); the inner side surface of the internal thread ring (18) is provided with a discharge port (31) that penetrates the outer shell (11) outward; the outer shell (11) is provided with a water storage chamber (32); and the lower side surface of the processing chamber (16) is provided with a discharge groove (60) that is connected to the water storage chamber (32); water is stored in the water storage chamber (32); and the outer shell (11) is provided with a water curtain mechanism (65); the water curtain mechanism (65) can form a water curtain at the discharge port (31) to prevent debris from being discharged.

2. A diamond drill bit surface polishing device according to claim 1, characterized in that: A cover plate (33) is hingedly connected to the left side of the processing chamber (16), and the cover plate (33) can close the feed trough (17).

3. A diamond drill bit surface polishing device according to claim 1, characterized in that: The clamping mechanism (62) comprises an electromagnetic slot (34) arranged in the upper and lower sides of the material passing port (20), the outer side of the electromagnetic slot (34) is connected to a clamping block (35) via a No. 1 spring, and an electromagnet (36) is arranged on the outer side of the electromagnetic slot (34).

4. A diamond drill bit surface polishing device according to claim 1, characterized in that: The driving mechanism (63) comprises a motor slot (37) arranged in the left side surface of the processing chamber (16), a driving motor (38) is fixedly arranged on the left side surface of the motor slot (37), and a driving shaft (39) is installed on the right side surface of the driving motor (38), a left side slot (40) is arranged in the right side surface of the driving shaft (39), a fixing frame (41) is slidably connected in the side surface of the annular slot (21), a matching shaft (42) is rotatably connected in the fixing frame (41), a gear meshing with the gear ring (22) is installed at the right end of the matching shaft (42), the matching shaft (42) extends leftward into the left side slot (40), and a sliding block (59) is arranged at the left end of the matching shaft (42).

5. The diamond drill bit surface polishing device according to claim 1, characterized in that: The polishing mechanism (64) comprises a spring groove (43) arranged in the right side surface of the processing chamber (16); the upper side surface of the spring groove (43) is connected to a spring block (44) via a No. 2 spring; and the left side surface of the spring block (44) is rotatably connected to a connecting shaft (45); the main shaft (25), the connecting shaft (45) and one of the bearing shafts (29) are connected via a synchronous belt (46).

6. A diamond drill bit surface polishing device according to claim 5, characterized in that: The housing (11) is provided with a driving groove (47) connected to the upper side of the slide groove (27); the front side of the driving groove (47) is provided with a positioning motor (48), and the rear side of the positioning motor (48) is installed with a rotating shaft (49); the lower side of each slide groove (27) is rotatably connected with a threaded shaft (50) threadedly connected to the support block (28); the threaded shaft (50) is connected to the rotating shaft (49) through a number one bevel gear set (51).

7. A diamond drill bit surface polishing device according to claim 1, characterized in that: A thermal sensor (61), a light emitter (26) and a light receiver are arranged in the side of the processing chamber (16).

8. The diamond drill bit surface polishing device according to claim 1, characterized in that: The water curtain mechanism (65) comprises an arcuate groove (52) arranged in the annular surface of the through hole (23) and connected to the water storage chamber (32); a support frame is arranged in the arcuate groove (52); a water-drawing shaft (53) extending into the water storage chamber (32) is rotatably connected in the support frame; a spiral disk (54) is arranged on the annular surface of the water-drawing shaft (53); and the water-drawing shaft (53) is connected to the main shaft (25) via a second bevel gear set (58).

9. A diamond drill bit surface polishing device according to claim 8, characterized in that: The lower side surface of the discharge port (31) is inclined toward the rear and downward, and a reflux groove (55) communicating with the water storage chamber (32) is provided in the lower side surface of the discharge port (31), a water curtain groove (56) is provided in the upper side surface of the arc surface groove (52), and a water outlet (57) communicating with the upper side surface of the water curtain groove (56) is provided in the side surface of the arc surface groove (52).

Images