A drilling device for a pilot-operated overflow valve core casting blank

Abstract

This invention belongs to the field of valve core processing technology, and specifically discloses a drilling device for a pilot-operated overflow valve core casting blank, including a base and a fixed sleeve. The fixed sleeve is located above the base near the rear edge. A support plate is connected between the rear side of the base and the rear side of the fixed sleeve. A clamping device is provided on the base. A reciprocating cavity is opened inside the fixed sleeve. In this invention, before processing, the top of the plunger valve core blank needs to be pre-drilled. Then, the plunger valve core blank with the pre-drilled top is placed in the clamping device and fixed by the clamping device. Then, the drilling device driven by the drive assembly first enlarges the pre-drilled plunger valve core blank. After enlargement, the constraint mechanism is triggered, which causes the inner drill bit of the drilling device to work for a second drilling. The whole process does not require equipment switching, thus avoiding the problem of the axis of the two hole diameters being misaligned and improving production efficiency.

Description

Technical Field

[0001] This invention relates to the field of valve core processing technology, and in particular to a drilling device for a pilot-operated overflow valve core casting blank. Background Technology

[0002] The pilot-operated relief valve consists of a main valve that drains excess oil from the circuit and a pilot valve that controls the operation of the main valve. Compared with the direct-acting relief valve, the pilot-operated relief valve has a slower response but a smaller pressure regulation deviation and is easier to achieve unloading control and remote control. The device acts on the pressure measuring surfaces of the main valve core and the pilot valve core and consists of a pilot valve and a main valve.

[0003] Currently, the main valve core of pilot-operated relief valves mostly uses a pendant-shaped valve core. During processing, it needs to be drilled twice. The first drilling is to enlarge the hole connected to the spring. The second drilling is to open a hole at the bottom of the hole connected to the spring and penetrate to the bottom of the valve core to form an oil inlet channel. These two drilling steps need to be performed in separate steps. The equipment switching between the first and second drilling requires action, which can easily cause the axis of the two holes to shift, resulting in a deviation in the position of the two holes. This will generate lateral impact force during subsequent oil intake, thus causing vibration and affecting the stability of the pilot-operated relief valve. Summary of the Invention

[0004] In order to solve the problems existing in the prior art, the present invention provides a drilling device for a pilot-operated overflow valve core casting blank.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a drilling device for a pilot-operated overflow valve core casting blank, comprising a base and a fixed sleeve, the fixed sleeve being located above the base near the rear edge, a support plate being connected between the rear side of the base and the rear side of the fixed sleeve, a clamping device being provided on the base, a reciprocating cavity being provided inside the fixed sleeve, a driving assembly being provided inside the reciprocating cavity, and a drilling device being provided inside the reciprocating cavity;

[0006] The drilling device includes a reaming sleeve and an inner drill bit. The inner drill bit is located inside the reaming sleeve, which is located inside the reciprocating cavity. The bottom of the reaming sleeve slides through to the bottom of the fixed sleeve. A receiving cavity is provided at the bottom of the reaming sleeve, and the bottom of the inner drill bit is located inside the receiving cavity. A constraint mechanism is provided between the reaming sleeve and the inner drill bit.

[0007] Preferably, the clamping device includes two arc-shaped clamping plates, and a processing groove is provided at the middle of the top of the base. A pre-positioning groove is provided at the middle of the bottom surface of the processing groove. A plumb bob valve core blank is provided inside the pre-positioning groove, and the plumb bob valve core blank is located directly below the fixed sleeve.

[0008] Preferably, guide grooves are provided on both sides of the bottom surface of the processing groove near the prepositioning groove. Two arc-shaped clamps are slidably disposed on the bottom surface of the processing groove and near the sides of the prepositioning groove. The bottom of the two arc-shaped clamps is slidably engaged in the inside of the guide groove. Adjusting screws are threadedly connected to both sides of the base. One end of each of the two adjusting screws is rotatably engaged in one side of the arc-shaped clamp.

[0009] Preferably, the drive assembly includes a cylinder mounted on the top of the fixed sleeve. The output end of the cylinder slides through the interior of the reciprocating cavity. A transmission cavity is formed on the outer surface of the fixed sleeve near the top edge. A drive gear is rotatably arranged inside the transmission cavity, and the outer side of the drive gear extends to the outer side of the fixed sleeve.

[0010] Preferably, a driven gear is rotatably arranged inside the transmission cavity, and the driving gear meshes with the driven gear. A long gear rack is rotatably arranged near one edge of the inner top surface of the transmission cavity. The top of the long gear rack extends into the interior of the transmission cavity and is fixed to the bottom end of the driven gear.

[0011] Preferably, the output end of the cylinder is rotatably provided with a drive shaft, and a gear ring is fixed on the outer surface of the drive shaft near the top edge. The gear ring meshes with a long gear rack, and the gear ring and the long gear rack can slide axially. The bottom of the drive shaft is fixed to the top of the inner drill bit.

[0012] Preferably, the constraint mechanism includes multiple constraint rods, an annular sleeve is fixed on the outer surface of the reaming drill sleeve near the top edge, the outer surface of the annular sleeve is in contact with the inner wall of the reciprocating cavity, multiple limiting slides are equidistantly provided on the outer surface of the inner drill bit near the top edge along the circumferential direction, the top of the multiple limiting slides all penetrates to the top of the inner drill bit, and an oblique guide opening is provided on one side of the inner wall of the multiple limiting slides near the top edge.

[0013] Preferably, an annular ring is provided between the inner walls of the annular sleeve, the inner wall of the annular ring is in contact with the outer surface of the inner drill bit, multiple limiting sliders are fixed to the inner wall of the annular ring, the multiple limiting sliders are slidably engaged inside the limiting slide, and tension springs are fixed to the bottom of the annular ring, the bottom of the tension springs is fixed to the inner bottom surface of the annular sleeve, and the bottom of the annular ring is in contact with the top of the reaming drill sleeve.

[0014] Preferably, the reaming bushing has multiple internal cavities, and multiple constraint rods are located inside the corresponding internal cavities. A conical ring is fixed to the outer surface of the constraint rod, and the conical ring is located inside the internal cavity. A cylindrical groove is opened at one end of the constraint rod. A guide rod is fixed to one side of the internal cavity, and one end of the guide rod slides through into the constraint rod. A constraint spring is fixed to the bottom surface of the cylindrical groove, and one end of the constraint spring is fixed to the inner wall of one side of the internal cavity. A through-hole is opened on the top surface of the internal cavity, and the top of the through-hole extends to the top of the reaming bushing. A lifting plate is slidably arranged inside the through-hole. The top of the lifting plate is fixed to the bottom of the annular ring, and the bottom of the lifting plate extends into the internal cavity. The bottom side of the lifting plate is in contact with the outer surface of the conical ring.

[0015] Preferably, the outer surface of the inner drill bit is provided with an annular groove, the inner top surface of the annular groove is inclined, and the outer surface of the inner drill bit is provided with an inner ring groove located at the inner bottom surface of the annular groove. The inner top and bottom surfaces of the inner ring groove are both inclined, and one end of the constraint rod passes through the interior of the annular groove and extends into the interior of the inner ring groove.

[0016] Compared with the prior art, the beneficial effects of the present invention are:

[0017] 1. In this invention, before processing, the top of the droop valve core blank needs to be pre-drilled. Then, the droop valve core blank with the pre-drilled top is placed in a clamping device and fixed by the clamping device. Then, the drilling device of the drive assembly first enlarges the hole of the droop valve core blank. After the hole is enlarged, the constraint mechanism is triggered, which causes the inner drill bit of the drilling device to work for a second drilling. The whole process does not require the equipment to switch working actions, which can avoid the problem of the axis of the two hole diameters being offset and improve production efficiency.

[0018] 2. When the clamping device of the present invention is working, the blank of the drooping valve core after the top hole is first placed inside the prepositioning groove, and then the drooping valve core blank is clamped by rotating the adjusting screw and the arc-shaped clamping plate. When the arc-shaped clamping plate slides, the guide groove and the bottom of the arc-shaped clamping plate restrain each other, so that the arc-shaped clamping plate can slide smoothly.

[0019] 3. When the drive component of the present invention is working, the extension and retraction of the cylinder can drive the drilling device to move vertically. During vertical movement, the drive gear is connected to the external power equipment, and the power can be transmitted to the driven gear. When the driven gear rotates, it can drive the long gear rack to rotate. When the long gear rack rotates, it can drive the gear ring to rotate, which in turn drives the drive shaft to rotate. The drive shaft drives the inner drill bit to rotate. Since a constraint mechanism is set between the inner drill bit and the reaming drill sleeve, the rotation of the inner drill bit can drive the reaming drill sleeve to rotate together.

[0020] 4. In this invention, when the constraint mechanism is working, the inner drill bit and the reaming sleeve are first constrained and engaged with each other through the limiting slide and the limiting slider, allowing them to move synchronously. During the first reaming, the cylinder extends and retracts, driving the drilling device to slide down. When the drilling device slides down, the inner drill bit and the reaming sleeve drill synchronously. The reaming sleeve reams the pre-drilled hole at the top of the pre-drilled valve core blank. When the reaming sleeve slides down to a certain depth, the bottom of the annular sleeve contacts the inner bottom surface of the reciprocating cavity, thus limiting the annular sleeve. At this time, the reaming sleeve continues to slide down reciprocally, while the cylinder continues to drive the shaft. As the drill bit is pushed downwards, the reciprocating motion of the reaming bushing during the pushing process causes the constraint rod to be pushed out from the inner ring groove into the annular groove under the downward pressure. After being pushed out, the constraint rod slides into the inner cavity. During the sliding, the lifting plate is pushed upwards by the inclined outer surface of the conical ring, which in turn causes the annular ring to slide upwards. As the annular ring slides upwards, multiple limiting sliders slide out from the limiting slide rail to the outer surface of the drive shaft, thereby releasing the constraint between the inner drill bit and the reaming bushing. At this point, the inner drill bit can be driven to slide downwards into the receiving cavity to perform secondary drilling on the plumb valve core blank. Attached Figure Description

[0021] Figure 1 A side-view three-dimensional structural schematic diagram of a drilling device for a pilot-operated overflow valve core casting blank is provided for this invention.

[0022] Figure 2 A top-view three-dimensional structural diagram of a drilling device for a pilot-operated overflow valve core casting blank is provided for this invention.

[0023] Figure 3 This invention provides a cross-sectional three-dimensional structural schematic diagram of a drilling device for a pilot-operated overflow valve core casting blank.

[0024] Figure 4 This invention provides a cross-sectional three-dimensional structural diagram of the fixing sleeve in a drilling device for a pilot-operated overflow valve core casting blank.

[0025] Figure 5 A cross-sectional three-dimensional structural diagram of the base in a drilling device for a pilot-operated overflow valve core casting blank is provided for this invention.

[0026] Figure 6 A top-view three-dimensional structural diagram of the reaming drill bushing in a drilling device for a pilot-operated overflow valve core casting blank is provided for this invention.

[0027] Figure 7 This invention provides a cross-sectional three-dimensional structural diagram of the reaming drill bushing in a drilling device for a pilot-operated overflow valve core casting blank.

[0028] Figure 8 For the present invention Figure 3 A magnified view of a portion of point A in the middle.

[0029] In the diagram: 1. Base; 2. Support plate; 3. Fixing sleeve; 4. Cylinder; 5. Machining groove; 6. Adjusting screw; 7. Arc-shaped clamping plate; 8. Guide groove; 9. Pre-positioning groove; 10. Piercing valve core blank; 11. Transmission cavity; 12. Driving gear; 13. Driven gear; 14. Long gear rack; 15. Reaming drill sleeve; 16. Annular sleeve; 17. Receiving cavity; 18. Internal drill bit; 19. Gear ring; 20. Annular ring; 21. Tension spring; 22. Reciprocating cavity; 23. Through port; 24. Lifting plate; 25. Annular groove; 26. Inner ring groove; 27. Drive shaft; 28. Limiting slide; 29. ​​Inclined guide port; 30. Limiting slider; 31. Inner cavity; 32. Constraint rod; 33. Cylindrical groove; 34. Guide rod; 35. Constraint spring; 36. Conical ring. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Please see Figure 1-8 The present invention provides a technical solution: a drilling device for a pilot-operated overflow valve core casting blank, including a base 1 and a fixing sleeve 3. The fixing sleeve 3 is located above the base 1 near the rear edge. A support plate 2 is connected between the rear side of the base 1 and the rear side of the fixing sleeve 3. A clamping device is provided on the base 1. A reciprocating cavity 22 is opened inside the fixing sleeve 3. A driving component is provided inside the reciprocating cavity 22. A drilling device is provided inside the reciprocating cavity 22.

[0032] The drilling device includes a reaming sleeve 15 and an inner drill bit 18. The inner drill bit 18 is disposed inside the reaming sleeve 15. The reaming sleeve 15 is located inside the reciprocating cavity 22. The bottom of the reaming sleeve 15 slides through to the bottom of the fixed sleeve 3. A receiving cavity 17 is provided at the bottom of the reaming sleeve 15. The bottom of the inner drill bit 18 is located inside the receiving cavity 17. A constraint mechanism is provided between the reaming sleeve 15 and the inner drill bit 18.

[0033] The effect achieved is that, before processing, the top of the droop valve core blank 10 needs to be pre-drilled. Then, the droop valve core blank 10 with the pre-drilled top is placed in the clamping device and fixed by the clamping device. Then, the drilling device of the drive assembly is used to pre-expand the hole of the droop valve core blank 10. After the hole is expanded, the constraint mechanism is triggered, which causes the inner drill bit 18 of the drilling device to work for a second drilling. The whole process does not require the equipment to switch working actions, which can avoid the problem of the axis of the two hole diameters being misaligned and improve production efficiency.

[0034] like Figure 1 , Figure 2 , Figure 3 and Figure 5 As shown, the clamping device includes two arc-shaped clamping plates 7. A processing groove 5 is provided at the middle of the top of the base 1. A pre-positioning groove 9 is provided at the middle of the inner bottom surface of the processing groove 5. A plumb bob valve core blank 10 is provided inside the pre-positioning groove 9. The plumb bob valve core blank 10 is located directly below the fixing sleeve 3. Guide grooves 8 are provided at both sides of the inner bottom surface of the processing groove 5 near the two edges of the pre-positioning groove 9. The two arc-shaped clamping plates 7 are slidably disposed on the inner bottom surface of the processing groove 5 and close to both sides of the pre-positioning groove 9. The bottom of the two arc-shaped clamping plates 7 are slidably engaged inside the guide grooves 8. Adjusting screws 6 are threadedly connected to both sides of the base 1. One end of each of the two adjusting screws 6 is rotatably engaged on one side of the arc-shaped clamping plate 7.

[0035] The effect achieved is that, firstly, the drooping valve core blank 10 with the top hole is placed inside the prepositioning groove 9, and then the drooping valve core blank 10 is clamped by rotating the arc-shaped clamping plate 7 of the adjusting screw 6. When the arc-shaped clamping plate 7 slides, the guide groove 8 and the bottom of the arc-shaped clamping plate 7 are mutually constrained, so that the arc-shaped clamping plate 7 can slide smoothly.

[0036] like Figure 3 , Figure 4 and Figure 7As shown, the drive assembly includes a cylinder 4, which is mounted on the top of the fixed sleeve 3. The output end of the cylinder 4 slides through the reciprocating cavity 22. A transmission cavity 11 is provided on the outer surface of the fixed sleeve 3 near the top edge. A drive gear 12 is rotatably arranged inside the transmission cavity 11, and the outer side of the drive gear 12 extends to the outer side of the fixed sleeve 3. A driven gear 13 is rotatably arranged inside the transmission cavity 11, and the drive gear 12 and the driven gear 13 mesh with each other. A long gear rack 14 is rotatably arranged on the top surface of the transmission cavity 11 near one side edge. The top of the long gear rack 14 extends into the transmission cavity 11 and is fixed to the bottom end of the driven gear 13. A drive shaft 27 is rotatably arranged on the output end of the cylinder 4. A gear ring 19 is fixed on the outer surface of the drive shaft 27 near the top edge. The gear ring 19 meshes with the long gear rack 14, and the gear ring 19 and the long gear rack 14 can slide axially. The bottom of the drive shaft 27 is fixed to the top of the inner drill bit 18.

[0037] The effect achieved is that the extension and retraction of cylinder 4 can drive the drilling device to move vertically. During vertical movement, the drive gear 12 is connected to the external power equipment, which can then transmit power to the driven gear 13. When the driven gear 13 rotates, it can drive the long gear rack 14 to rotate. When the long gear rack 14 rotates, it can drive the gear ring 19 to rotate, which in turn drives the drive shaft 27 to rotate. The drive shaft 27 drives the inner drill bit 18 to rotate. Since a constraint mechanism is set between the inner drill bit 18 and the reaming drill sleeve 15, the rotation of the inner drill bit 18 can drive the reaming drill sleeve 15 to rotate together.

[0038] like Figure 3 Figure 7 and Figure 8As shown, the constraint mechanism includes multiple constraint rods 32. An annular sleeve 16 is fixed to the outer surface of the reaming sleeve 15 near its top edge. The outer surface of the annular sleeve 16 fits against the inner wall of the reciprocating cavity 22. Multiple limiting slides 28 are equidistantly spaced along the circumferential direction on the outer surface of the inner drill bit 18 near its top edge. The tops of the multiple limiting slides 28 extend to the top of the inner drill bit 18. An inclined guide opening 29 is provided on one side of the inner wall of each of the multiple limiting slides 28 near its top edge. An annular ring 20 is provided between the inner walls of the annular sleeve 16. The inner wall of the ring 20 is in contact with the outer surface of the inner drill bit 18. Multiple limiting sliders 30 are fixed to the inner wall of the ring 20, and these sliders 30 are slidably engaged inside the limiting slide 28. A tension spring 21 is fixed to the bottom of each ring 20, and the bottom of the tension spring 21 is fixed to the inner bottom surface of the ring sleeve 16. The bottom of the ring 20 is in contact with the top of the reaming drill sleeve 15. Multiple inner cavities 31 are opened inside the reaming drill sleeve 15, and multiple constraint rods 32 are correspondingly located inside the inner cavities 31. The outer surface of the constraint rods 32 is fixed with... A conical ring 36 is located inside the inner cavity 31. A cylindrical groove 33 is formed at one end of the constraint rod 32. A guide rod 34 is fixed to one side of the inner cavity 31, and one end of the guide rod 34 slides through the constraint rod 32. A constraint spring 35 is fixed to the bottom surface of the cylindrical groove 33, and one end of the constraint spring 35 is fixed to the inner wall of one side of the inner cavity 31. A through-hole 23 is formed on the top surface of the inner cavity 31, and the top of the through-hole 23 extends to the top of the reaming drill sleeve 15. A lifting plate 24 is slidably arranged inside the through-hole 23. The top of the ring is fixed to the bottom of the ring 20. The bottom of the lifting plate 24 extends into the interior of the inner cavity 31, and one side of the bottom of the lifting plate 24 is in contact with the outer surface of the conical ring 36. The outer surface of the inner drill bit 18 is provided with an annular groove 25. The inner top surface of the annular groove 25 is inclined. The outer surface of the inner drill bit 18 is provided with an inner ring groove 26 located on the inner bottom surface of the annular groove 25. The inner top and bottom surfaces of the inner ring groove 26 are inclined. One end of the constraint rod 32 passes through the interior of the annular groove 25 and extends into the interior of the inner ring groove 26.

[0039] The effect achieved is as follows: First, the inner drill bit 18 and the reaming sleeve 15 are mutually constrained and engaged by the limiting slide 28 and the limiting slider 30, allowing them to move synchronously. During the first reaming, the cylinder 4 extends and retracts, driving the drilling device to slide down. When the drilling device slides down, the inner drill bit 18 and the reaming sleeve 15 drill synchronously. The reaming sleeve 15 reams the pre-drilled hole at the top of the pre-drilled hole of the drooping valve core blank 10. When the reaming sleeve slides down to a certain depth, the bottom of the annular sleeve 16 contacts the inner bottom surface of the reciprocating cavity 22, thereby limiting the annular sleeve 16. At this time, the reaming sleeve 15 continues to slide down reciprocally, while the cylinder 4 continues to push the drive shaft 27 down. During the operation, the reciprocating motion of the reaming sleeve 15 is limited, so under the action of downward pressure, one end of the constraint rod 32 will be pushed out from the inner ring groove 26 to the inner ring groove 25. After being pushed out, the constraint rod 32 will slide into the inner cavity 31. When sliding, the lifting plate 24 will be pushed upward by the inclined outer surface of the conical ring 36, which will then cause the annular ring 20 to slide upward. When the annular ring 20 slides upward, multiple limiting sliders 30 will slide out from the limiting slide 28 to the outer surface of the drive shaft 27, thereby releasing the constraint between the inner drill bit 18 and the reaming sleeve 15. At this time, the inner drill bit 18 can be driven to slide downward into the receiving cavity 17 to perform secondary drilling on the plumb valve core blank 10.

[0040] Working principle: When using this device, first place the top-hole-drilled valve core blank 10 inside the pre-positioning groove 9. Then, clamp the valve core blank 10 by rotating the arc-shaped clamping plate 7 on the adjusting screw 6. When the arc-shaped clamping plate 7 slides, the guide groove 8 and the bottom of the arc-shaped clamping plate 7 mutually restrain each other, allowing the arc-shaped clamping plate 7 to slide smoothly. The extension and retraction of the cylinder 4 can drive the drilling device to move vertically. During vertical movement, the drive gear 12 connects with the external power equipment, thereby transmitting power to the driven gear 13. When the driven gear 13 rotates... The long gear rack 14 can rotate, which drives the gear ring 19 to rotate, thereby driving the drive shaft 27 to rotate. The drive shaft 27 drives the inner drill bit 18 to rotate. Because a constraint mechanism is set between the inner drill bit 18 and the reaming sleeve 15, the rotation of the inner drill bit 18 can drive the reaming sleeve 15 to rotate together. First, the inner drill bit 18 and the reaming sleeve 15 are mutually constrained and engaged by the limiting slide 28 and the limiting slider 30, so that they can move synchronously. During the first reaming, the cylinder 4 extends and retracts, driving the drilling device to slide down. During the downward movement, the inner drill bit 18 and the reaming sleeve 15 drill synchronously. The reaming sleeve 15 enlarges the pre-drilled hole at the top of the pre-drilled hole of the plunger valve core blank 10. When the reaming sleeve slides downward to a certain depth, the bottom of the annular sleeve 16 contacts the inner bottom surface of the reciprocating cavity 22, thereby limiting the annular sleeve 16. At this time, the reaming sleeve 15 continues to slide downward reciprocally, while the cylinder 4 continues to push the drive shaft 27 downward. During the pushing process, because the reaming sleeve 15 is limited and reciprocates, under the action of downward pressure, one end of the constraint rod 32 will be pulled from the inner ring. The card slot 26 is pushed out into the annular groove 25. After being pushed out, the constraint rod 32 slides into the inner cavity 31. During the sliding, the lifting plate 24 is pushed upward by the inclined outer surface of the conical ring 36, which in turn causes the annular ring 20 to slide upward. When the annular ring 20 slides upward, multiple limiting sliders 30 slide out from the limiting slide 28 to the outer surface of the drive shaft 27, thereby releasing the constraint between the inner drill bit 18 and the reaming drill sleeve 15. At this time, the inner drill bit 18 can be driven to slide downward into the receiving cavity 17 to perform secondary drilling on the plumb valve core blank 10.

[0041] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A drilling apparatus for a pilot relief valve spool casting blank, characterized by, The utility model relates to a base (1) and fixed sleeve (3), fixed sleeve (3) is located the upper side of base (1) near rear side edge, the rear side of base (1) and the rear side of fixed sleeve (3) are connected with support plate (2), be provided with clamping device on base (1), the inside of fixed sleeve (3) is set up with reciprocating cavity (22), the inside of reciprocating cavity (22) is provided with drive assembly, the inside of reciprocating cavity (22) is provided with drilling device, The drilling device includes a counterbore drill sleeve (15) and an inner drill bit (18), the inner drill bit (18) is disposed inside the counterbore drill sleeve (15), the counterbore drill sleeve (15) is located inside the reciprocating cavity (22), the bottom of the counterbore drill sleeve (15) slides through to the lower side of the fixed sleeve (3), the bottom of the counterbore drill sleeve (15) is provided with a receiving cavity (17), the bottom of the inner drill bit (18) is located inside the receiving cavity (17), a constraint mechanism is provided between the counterbore drill sleeve (15) and the inner drill bit (18), the constraint mechanism includes a plurality of constraint rods (32), the outer surface of the counterbore drill sleeve (15) is fixed with an annular sleeve (16) near the top edge, the outer surface of the annular sleeve (16) is in close contact with the inner wall of the reciprocating cavity (22), a plurality of limit sliding grooves (28) are equidistantly provided on the outer surface of the inner drill bit (18) near the top edge in the circumferential direction, the top of each limit sliding groove (28) penetrates through the top of the inner drill bit (18), and a slanting guide opening (29) is provided on the inner wall of one side of each limit sliding groove (28) near the top edge. The inner wall of the annular ring (20) is fixed with a plurality of limiting sliding blocks (30), a plurality of the limiting sliding blocks (30) are all slidingly clamped in the inside of the limiting sliding way (28), the bottom of the annular ring (20) is fixed with a tension spring (21), the bottom of the tension spring (21) is fixed in the inside bottom surface of the annular sleeve (16), the bottom of the annular ring (20) is mutually attached with the top of the reaming sleeve (15), a plurality of inner cavities (31) are formed in the inside of the reaming sleeve (15), a plurality of constraint rods (32) are all correspondingly located in the inside of the inner cavity (31), the outer surface of the constraint rod (32) is fixed with a conical ring (36), the conical ring (36) is located in the inside of the inner cavity (31), one end of the constraint rod (32) is provided with a cylindrical groove (33), one side of the inner cavity (31) is fixed with a guide rod (34), one end of the guide rod (34) is slidingly penetrated into the inside of the constraint rod (32), the inside bottom surface of the cylindrical groove (33) is fixed with a constraint spring (35), one end of the constraint spring (35) is fixed on the inner wall of one side of the inner cavity (31), the inside top surface of the inner cavity (31) is provided with a through hole (23), the top of the through hole (23) is penetrated to the top of the reaming sleeve (15), the inside of the through hole (23) is slidingly provided with a jacking plate (24), the top of the jacking plate (24) is fixed on the bottom of the annular ring (20), the bottom of the jacking plate (24) extends to the inside of the inner cavity (31), and the bottom side of the jacking plate (24) is mutually attached with the outer surface of the conical ring (36), the outer surface of the inner drill bit (18) is provided with an annular groove (25), the inside top surface of the annular groove (25) is inclined, the outer surface of the inner drill bit (18) is provided with an inner ring clamping groove (26) on the inside bottom surface of the annular groove (25), the inside top surface and the bottom surface of the inner ring clamping groove (26) all have an inclined angle, one end of the constraint rod (32) is penetrated to the inside of the annular groove (25) and extends to the inside of the inner ring clamping groove (26).

2. A drilling apparatus for a pilot relief valve spool casting blank according to claim 1, wherein: The clamping device comprises two arc-shaped clamping plates (7), the top of the base (1) is provided with a machining groove (5) at the middle, the inside bottom surface of the machining groove (5) is provided with a predetermined positioning groove (9) at the middle, the predetermined positioning groove (9) is provided with a vertical head valve core blank (10), and the vertical head valve core blank (10) is located directly below the fixing sleeve (3).

3. A drilling apparatus for a pilot relief valve spool casting blank according to claim 2, wherein: The inside bottom surface of the processing groove (5) is provided with a guide groove (8) near the two side edges of the pre-positioning groove (9), the two arc-shaped clamping plates (7) are correspondingly and slidingly arranged on the inside bottom surface of the processing groove (5) near the two sides of the pre-positioning groove (9), the bottom of the two arc-shaped clamping plates (7) is correspondingly and slidingly clamped in the inside of the guide groove (8), and the two sides of the base (1) are threadedly connected with adjusting screws (6), one end of the two adjusting screws (6) is rotatably clamped on one side of the arc-shaped clamping plate (7).

4. A drilling apparatus for a pilot relief valve spool casting blank according to claim 3, wherein: The driving assembly comprises a cylinder (4), the cylinder (4) is installed at the top of the fixed sleeve (3), the output end of the cylinder (4) is slidingly penetrated into the inside of the reciprocating cavity (22), the outer surface of the fixed sleeve (3) is provided with a transmission cavity (11) near the top edge, the inside of the transmission cavity (11) is rotatably provided with a driving gear (12), and the outer side of the driving gear (12) extends to the outside of the fixed sleeve (3).

5. A drilling apparatus for a pilot relief valve spool casting blank according to claim 4, wherein: The inside of the transmission cavity (11) is rotatably provided with a driven gear (13), the driving gear (12) and the driven gear (13) are in mesh with each other, the inside top surface of the transmission cavity (11) is rotatably provided with a long gear strip (14) near one side edge, the top of the long gear strip (14) extends to the inside of the transmission cavity (11) and is fixed to the bottom end of the driven gear (13).

6. A drill for a pilot relief valve spool casting blank according to claim 5 wherein: The output end of the cylinder (4) is rotatably provided with a driving shaft (27), the outer surface of the driving shaft (27) is fixedly provided with a gear ring (19) near the top edge, the gear ring (19) is in mesh with the long gear strip (14) and can axially slide between the gear ring (19) and the long gear strip (14), and the bottom of the driving shaft (27) is fixed to the top of the inner drill bit (18).

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