Expansion pin assembly for split type reamer bit, split type reamer bit and assembling method

Abstract

The invention discloses an expansion pin assembly for a split reamer bit, the split reamer bit and an assembling method. The expansion pin assembly for the split type reamer bit comprises an expansion pin shaft sleeve, an expansion pin bolt and an expansion pin nut. An expansion head is arranged at one end of the expansion pin shaft sleeve, a first circular truncated cone through hole is formed in the expansion head, and the hole wall surface of the first circular truncated cone through hole is a first circular truncated cone surface; a locking head is arranged at one end of the expansion pin bolt, and the outer surface of the locking head is a second circular truncated cone face matched with the first circular truncated cone face. And when the expansion pin bolt is completely inserted into the expansion pin shaft sleeve, the second circular truncated cone surface is tightly attached to the first circular truncated cone surface. According to the expansion pin assembly, through the self-locking effect between the first circular truncated cone face and the second circular truncated cone face, the loosening phenomenon in the construction process can be effectively prevented, mechanical self-locking is achieved, an anti-loosening device such as a locking nut or a cotter pin does not need to be additionally arranged, and the connection reliability is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of reaming bit technology. Specifically, it relates to an expansion pin assembly for a split-type reaming bit, a split-type reaming bit, and an assembly method thereof. Background Technology

[0002] The raise boring process involves first installing the raise boring rig in the upper horizontal roadway (or on the surface), then drilling a pilot hole from top to bottom using a small-diameter pilot hole bit (mostly a tricone bit), and using clean water or mud as the circulating well washing fluid. Once the pilot hole is drilled through, the pilot hole bit is removed in the lower horizontal roadway, and a reaming bit is installed. Then, the hole is reamed from bottom to top along the pilot hole. The broken drill cuttings fall freely from the working face to the lower horizontal roadway by their own weight, and then the cuttings are transported out from the lower horizontal roadway by the loading equipment.

[0003] Reamer bits are key components of raise boring machines for breaking large volumes of rock; they are large in diameter and heavy. To facilitate transport through narrow shafts or tunnels and allow for flexible diameter changes, reamer bits generally adopt a split design, consisting of the main bit body and the split bit itself. Currently, these two parts are almost entirely connected and secured on-site using high-strength bolt assemblies.

[0004] However, this traditional bolted connection method reveals several insurmountable drawbacks under the specific conditions of raise boring:

[0005] 1. On-site assembly efficiency is extremely low. In the dimly lit, damp, and confined space of the lower level tunnel, workers need to manually align the drill bit body, which weighs several tons, with the reamer blades, and use heavy torque wrenches to tighten dozens of circumferentially distributed high-strength bolts one by one in a strict diagonal sequence. The entire process is tedious and time-consuming, usually taking 3-5 hours or even longer, which greatly consumes valuable effective drilling time and becomes a key bottleneck affecting the overall construction progress.

[0006] 2. Connection reliability is greatly affected by human factors. The reliable strength of bolted connections depends on the skill level and sense of responsibility of the installers. If the preload is uneven or does not meet design requirements, the bolts are prone to loosening under the continuous and severe vibration, impact, and alternating loads faced by the reaming drill bit. The failure of a single bolt can trigger load redistribution, potentially leading to a chain reaction of breakage of adjacent bolts, posing a significant safety hazard of the entire split drill bit loosening or even falling.

[0007] 3. Difficult disassembly and replacement, high maintenance costs. After long-term high-intensity work, bolt threads often "seize" due to vibration and corrosion, making disassembly extremely difficult. It often requires destructive methods such as gas cutting, which is not only time-consuming and labor-intensive, but also easily causes damage to bolts and connecting parts, increasing spare parts costs and material consumption. Summary of the Invention

[0008] Therefore, the technical problem to be solved by the present invention is to provide an expansion pin assembly for a split-type reamer, a split-type reamer, and an assembly method. The assembly method uses the expansion pin assembly to assemble the split-type reamer, making the reamer not only reliably connected and with strong load-bearing capacity, but also enabling truly rapid assembly and disassembly, reducing reliance on manual skills, and effectively resisting vibration and impact under harsh working conditions. It not only has good adaptability to working conditions but also higher durability.

[0009] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0010] A split-type expanding pin assembly for reaming drill bits includes an expanding pin bushing, an expanding pin bolt coaxially inserted into the expanding pin bushing, and an expanding pin nut threadedly engaged with the expanding pin bolt.

[0011] An expansion head is provided at one end of the expansion pin bushing, and a first frustum through hole is provided inside the expansion head. The first frustum through hole is connected to the central through hole of the expansion pin bushing. The hole wall surface of the first frustum through hole is a first frustum surface, and the first frustum surface expands outward in a direction away from the expansion pin bushing.

[0012] One end of the expansion bolt is provided with a locking head, and the outer surface of the locking head is a second frustum adapted to the first frustum surface;

[0013] During the process of inserting the expansion bolt into the expansion bolt sleeve, it passes through the first frustum through hole and the center through hole of the expansion bolt sleeve in sequence. When the expansion bolt is fully inserted into the expansion bolt sleeve, the second frustum surface and the first frustum surface are in close contact.

[0014] The expansion pin assembly for the split-type reaming drill bit described above has at least two dividing grooves on the expansion head, so that at least two expansion flaps with the same structure are formed on the expansion head. After the expansion pin bolt is fully inserted into the expansion pin bushing, during the process of tightening the expansion pin nut, the locking head applies a radial expansion force to the expansion head, causing the expansion flaps to undergo elastic deformation under the action of the radial expansion force, thereby making the outer surface of the expansion head tightly adhere to the split-type reaming drill bit.

[0015] In the above-mentioned split-type reaming drill bit expansion pin assembly, the expansion head is a frustum cylinder, the outer surface of the frustum cylinder is a third frustum surface, the end of the frustum cylinder connected to the expansion pin bushing has the smallest diameter, and the dividing groove extends from the end of the frustum cylinder with the larger diameter to the end with the smaller diameter.

[0016] The expansion pin assembly for the aforementioned split-type reaming drill bit has a taper of 1:10 for both the first and second frustum surfaces.

[0017] The aforementioned split-type reaming drill bit expansion pin assembly further includes an expansion pin cap coaxially sleeved at the other end of the expansion pin bushing. One end of the expansion pin cap is provided with a receiving plate, and the receiving plate is provided with a through hole. The diameter of the through hole is larger than the diameter of the expansion pin bolt and smaller than the outer diameter of the expansion pin bushing, so that the expansion pin bolt passes through the through hole and the expansion pin bushing is supported by the receiving plate.

[0018] A spring washer and a flat washer are provided between the receiving plate of the expansion pin nut and the expansion pin cap to prevent the nut from loosening.

[0019] The aforementioned split-type reaming drill bit expansion pin assembly has a locking head with an internal hexagonal groove, and the central axis of the internal hexagonal groove is collinear with the central axis of the locking head.

[0020] A split-type reaming drill bit includes a main drill bit and a split drill bit. The split drill bit is connected to the main drill bit via an expansion pin assembly, which is the expansion pin assembly for the split-type reaming drill bit described above.

[0021] The aforementioned split-type reaming drill bit, the main drill bit includes a first drill bit body and a first connecting component disposed on the first drill bit body, the split drill bit includes a second drill bit body and a second connecting component disposed on the second drill bit body, the second connecting component and the first connecting component are tightly connected by at least two sets of expansion pin components, the two sets of expansion pin components being the first expansion pin component and the second expansion pin component, respectively.

[0022] The first connecting assembly includes at least a first connecting plate and a second connecting plate spaced apart, with an installation gap between the first connecting plate and the second connecting plate; the first connecting plate has at least two first connecting holes spaced apart vertically, and the second connecting plate has at least two second connecting holes spaced apart vertically.

[0023] The second connecting component includes at least an insertion plate, which has insertion holes corresponding to the first connecting hole and the second connecting hole. During assembly, the insertion plate is inserted into the installation gap, and the first connecting plate, the insertion plate, and the second connecting plate are tightly connected by the first expansion pin component and the second expansion pin component. The first expansion pin component and the second expansion pin component have opposite through-direction directions.

[0024] In the aforementioned split-type reaming drill bit, at least one of the two first connecting holes on the first connecting plate is configured as a second frustum through hole, and at least one of the two second connecting holes on the second connecting plate is configured as a third frustum through hole. When there is only one second frustum through hole on the first connecting plate and only one third frustum through hole on the second connecting plate, the second frustum through hole and the third frustum through hole are located on different horizontal planes.

[0025] The wall surface of the second frustum through hole is the fourth frustum surface corresponding to the third frustum surface, and the wall surface of the third frustum through hole is the fifth frustum surface corresponding to the third frustum surface, and the large diameter end and small diameter end of the fourth frustum surface and the fifth frustum surface are in opposite positions.

[0026] The taper of the third, fourth, and fifth frustums is 1:10.

[0027] The assembly method of the split-type reamer, wherein the split-type reamer is the aforementioned split-type reamer, includes the following steps:

[0028] Step P1: Insert the insert plate of the split drill bit into the installation gap so that the first connecting hole, the insertion hole and the second connecting hole are on the same horizontal plane;

[0029] Step P2: Insert the first expansion pin assembly and the second expansion pin assembly in sequence, so that the expansion pin bushing of the first expansion pin assembly passes through the second frustum through hole, the insertion hole and the second connecting hole in sequence, and the expansion pin bushing of the second expansion pin assembly passes through the third frustum through hole, the insertion hole and the first connecting hole in sequence. When the expansion pin bushing of the first expansion pin assembly is fully inserted, the third frustum surface of the first expansion pin assembly is in close contact with the fourth frustum surface; when the expansion pin bushing of the second expansion pin assembly is fully inserted, the third frustum surface of the second expansion pin assembly is in close contact with the fifth frustum surface.

[0030] Step P3: Insert the expansion bolt into the expansion bolt sleeve. When the expansion bolt is fully inserted, the second frustum surface is in close contact with the first frustum surface.

[0031] Step P4: Insert the expansion pin cap, flat washer, and spring washer sequentially onto the end of the expansion pin bolt, and ensure that the receiving plate of the expansion pin cap is tightly against the end face of the expansion pin bushing; then tighten the expansion pin nut on the expansion pin bolt. During the tightening process of the expansion pin nut, the locking head of the expansion pin bolt applies a radial expansion force to the expansion head of the expansion pin bushing. The expansion head deforms under the action of the radial expansion force, making the third and fourth frustum surfaces of the first expansion pin assembly and the third and fifth frustum surfaces of the second expansion pin assembly fit more tightly.

[0032] Step P5: Repeat steps P1-P4 until all the split drill bits are installed on the main drill bit, completing the assembly of the split reaming drill bit.

[0033] The technical solution of the present invention achieves the following beneficial technical effects:

[0034] The expansion pin assembly of this application can effectively prevent loosening during construction through the self-locking effect between the first and second frustum surfaces. Furthermore, when the frustum surfaces are pressed under axial force, the resulting huge frictional force will prevent the connector from loosening on its own under vibration and impact loads, thus achieving mechanical self-locking. This greatly improves the reliability of the connection without the need for additional anti-loosening devices such as lock nuts or cotter pins.

[0035] When the split-type reaming drill bit of this application is connected using the expansion pin assembly, it not only has the reinforcement effect of the first and second frustum surfaces, but also further strengthens the connection between the expansion pin assembly and the main drill bit by setting a frustum surface corresponding to the third frustum surface on the main drill bit. The two reinforcement effects can greatly improve the installation tightness of the split-type reaming drill bit.

[0036] The assembly method of the split-type reamer of this application uses expansion pin assemblies to install the split-type drill bits one by one onto the main drill bit. Each split-type drill bit only requires two sets of expansion pin assemblies to meet the installation tightness requirements of the split-type reamer, which greatly improves the installation efficiency. Furthermore, by setting the special frustum surface and corresponding taper of the expansion pin assembly, the problem of existing bolts or expansion pins easily seizing is solved, making the split-type reamer not only highly efficient to assemble, but also easy to disassemble and thus reusable, which greatly reduces spare parts costs and material consumption. Attached Figure Description

[0037] Figure 1 A schematic diagram of the structure of the expansion pin assembly of the present invention;

[0038] Figure 2 Figure 1 Exploded view;

[0039] Figure 3 A schematic diagram of the structure of the expansion pin bushing of the expansion pin assembly of the present invention;

[0040] Figure 4 A schematic diagram of the expansion head of the expansion pin bushing of the expansion pin assembly of the present invention;

[0041] Figure 5 A schematic diagram of the structure of the expansion pin bolt and locking head of the expansion pin assembly of the present invention;

[0042] Figure 6 A schematic diagram of the assembly structure of the expansion head and locking head of the present invention;

[0043] Figure 7 A schematic diagram of the structure of the expansion pin cap of the expansion pin assembly of the present invention;

[0044] Figure 8 A schematic diagram of the structure of the split-type reaming drill bit of the present invention;

[0045] Figure 9 A schematic diagram of the main body of the split-type reaming drill bit in Embodiment 2 of the present invention;

[0046] Figure 10 A schematic diagram of the structure of the first connecting assembly of the main drill bit in Embodiment 2 of the present invention;

[0047] Figure 11 A schematic diagram of the split-type reaming drill bit in Embodiment 2 of the present invention;

[0048] Figure 12 A schematic diagram of the structure of the second connecting component of the split drill bit in Embodiment 2 of the present invention;

[0049] Figure 13 A schematic diagram of the main body of the split-type reaming drill bit in Embodiment 3 of the present invention;

[0050] Figure 14 A schematic diagram of the structure of the first connecting assembly of the main drill bit in Embodiment 3 of the present invention;

[0051] Figure 15 A schematic diagram of the structure of the second frustum-shaped through hole in the first connecting component in Embodiment 3 of the present invention;

[0052] Figure 16 A schematic diagram of the third frustum-shaped through hole of the first connecting component in Embodiment 3 of the present invention;

[0053] Figure 17 A schematic diagram of the split drill bit structure of the split reaming drill bit in Embodiment 3 of the present invention;

[0054] Figure 18 A schematic diagram of the structure of the second connecting component of the split drill bit in Embodiment 3 of the present invention;

[0055] Figure 19 A schematic diagram of the installation of the split-type reaming drill bit in Embodiment 3 of the present invention.

[0056] The reference numerals in the figure are as follows: 1-Expansion pin bushing; 11-Central through hole; 12-Expansion head; 121-First frustum through hole; 1211-First frustum surface; 122-Dividing groove; 123-Expansion flap; 124-Third frustum surface; 2-Expansion pin bolt; 21-Locking head; 211-Second frustum surface; 212-Hexagonal recess; 3-Expansion pin nut; 4-Expansion pin cap; 41-Receiving plate; 411-Through hole; 5-Spring washer; 6-Flat washer; 7-Main drill bit; 71-First drill bit body; 72-First connecting assembly; 721-First connecting plate; 7211-First connecting hole; 7212-Second frustum through hole; 7213-Fourth frustum surface; 722-Second connecting plate; 7221-Second connecting hole; 7222-Third frustum through hole; 7223-Fifth frustum surface; 723-Third connecting plate; 7231-Third connecting hole; 724-Fourth connecting plate; 7241-Fourth connecting hole; 725-First gap; 726-Second gap; 727-Third gap; 728-Installation gap; 8-Split drill bit; 81-Second drill bit body; 82-Second connecting assembly; 821-First insertion plate; 8211-First insertion hole; 822-Second insertion plate; 8221-Second insertion hole; 823-Third insertion plate; 8231-Third insertion hole; 824-Installation plate; 8241-Installation hole; 9-First expansion pin assembly; 10-Second expansion pin assembly. Detailed Implementation

[0057] Example 1, such as Figure 1 and Figure 2 As shown, the split-type reaming drill bit expansion pin assembly of this embodiment includes an expansion pin bushing 1, an expansion pin bolt 2 coaxially inserted in the expansion pin bushing 1, and an expansion pin nut 3 threadedly engaged with the expansion pin bolt 2. An expansion pin cap 4 is coaxially sleeved on one end of the expansion pin bushing 1, and a spring washer 5 and a flat washer 6 are provided between the expansion pin nut 3 and the expansion pin cap 4 to prevent loosening.

[0058] like Figure 3 As shown, the other end of the expansion pin sleeve 1 is provided with an expansion head 12. The expansion head 12 is provided with a first frustum through hole 121. The first frustum through hole 121 communicates with the central through hole 11 of the expansion pin sleeve 1. The central through hole 11 is a through hole arranged along the axial direction of the expansion pin sleeve 1. The expansion pin bolt 2 is inserted into the expansion pin sleeve 1 through the central through hole 11. The hole wall surface of the first frustum through hole 121 is a first frustum surface 1211. The first frustum surface 1211 expands outward in the direction away from the expansion pin sleeve 1. That is, the end of the first frustum surface 1211 near the expansion pin sleeve 1 is a small diameter circle, and the end of the first frustum surface 1211 away from the expansion pin sleeve 1 is a large diameter circle. When the expansion pin bolt 2 is inserted into the expansion pin sleeve 1, it is inserted from the end of the large diameter circle of the expansion head 12 to the end of the small diameter circle.

[0059] Furthermore, the expansion head 12 is provided with at least two dividing grooves 122, so that at least two expansion lobes 123 with identical structures are formed on the expansion head 12. In this example, such as Figure 4 As shown, the expansion head 12 is provided with four dividing grooves 122, and the four dividing grooves 122 are arranged opposite each other in pairs, so that four expansion petals 123 with the same structure are formed on the expansion head 12. In specific processing, the expansion pin bushing 1 is cut with a "cross-shaped" dividing groove by wire cutting process, so that four expansion petals 123 with the same structure and a certain degree of elasticity are formed on the expansion head 12.

[0060] Furthermore, the expansion head 123 is a frustum cylinder, the outer surface of which is a third frustum surface 124. The end of the frustum cylinder connected to the expansion pin bushing 1 has the smallest diameter, and the dividing groove 122 extends from the end with the larger diameter to the end with the smaller diameter of the frustum cylinder.

[0061] like Figure 5 As shown, one end of the expansion bolt 2 is provided with a locking head 21. The outer surface of the locking head 21 is a second frustum 211 adapted to the first frustum 1211. During the tightening of the expansion nut 3, the first frustum 1211 of the locking head 21 interacts with the second frustum 211 of the expansion head 12. The locking head 21 applies a radially expanding force to the expansion head 12, forcing the expansion flap 123 to elastically deform outward, so that its outer surface fits tightly against the split-type reaming drill bit, achieving the first tightening effect. As the expansion nut 3 continues to tighten, the expansion flap 123 continues to expand, generating greater contact pressure and friction with the split-type reaming drill bit, further improving the tightening effect, achieving the second tightening effect, and achieving extremely high shear bearing capacity and anti-loosening effect.

[0062] Furthermore, the taper of both the first frustum 1211 and the second frustum 211 is 1:10. A 1:10 taper provides a consistent guiding angle with excellent self-centering and alignment capabilities. The frustum effectively guides the expansion bolt 2 to the correct assembly position, easily correcting even minor initial alignment errors. Moreover, the tapered frustum has a self-locking effect, effectively preventing loosening during construction. Once the frustum is pressed under axial force, the resulting friction prevents the connector from loosening under vibration and impact loads. This achieves mechanical self-locking, eliminating the need for additional anti-loosening devices such as lock nuts or cotter pins, significantly improving connection reliability. Furthermore, the frustum-shaped connection efficiently converts the strong axial preload into radial clamping force and normal pressure on the contact surface. The small taper of the frustum-shaped surface makes this conversion process very smooth, achieving effective force transmission efficiency and stress distribution. The 1:10 ratio achieves the best balance between providing sufficient clamping force and avoiding excessive contact stress, so that the load is evenly distributed across the entire contact frustum-shaped surface, reducing stress concentration and improving fatigue life.

[0063] The locking head 21 is provided with an internal hexagonal groove 212, and the central axis of the internal hexagonal groove 212 is collinear with the central axis of the locking head 21.

[0064] During the insertion of the expansion bolt 2 into the expansion bushing 1, the expansion bolt 2 passes sequentially through the first frustum through hole 121 and the central through hole 11 of the expansion bushing 1. When the expansion bolt 2 is fully inserted into the expansion bushing 1, the second frustum surface 211 and the first frustum surface 1211 are tightly fitted together. Figure 6 As shown, after the expansion bolt 2 is fully inserted into the expansion bushing 1, during the tightening of the expansion nut 3, the locking head 21 applies a radial expansion force to the expansion head 12, causing the expansion flap 123 to undergo elastic deformation under the action of the radial expansion force, thereby making the outer surface of the expansion head 12 tightly adhere to the split-type reaming drill bit.

[0065] The secondary tightening mechanism of the expansion flap 123 achieves connection rigidity and anti-loosening capability far exceeding that of a single bolt pre-tightening, making it particularly suitable for the high-vibration conditions of raise boring machines. The elastic deformation of the expansion flap 123 can compensate for minor tolerances and damage during hole machining, exhibiting strong adaptability to on-site conditions. During installation, the entire tightening process can be completed simply by using an Allen wrench in conjunction with the appropriate wrench to tighten the expansion bolt 2 and expansion nut 3, making the operation simple and highly efficient. Similarly, during disassembly, simply using an Allen wrench in conjunction with the appropriate wrench to loosen the expansion bolt 2 and expansion nut 3 allows the expansion flap 123 to essentially return to its original shape under its own elasticity, enabling easy removal and avoiding the "locking" phenomenon.

[0066] like Figure 7 As shown, one end of the expansion pin cap 4 is provided with a receiving plate 41, and the receiving plate 41 is provided with a through hole 411. The diameter of the through hole 411 is larger than the diameter of the expansion pin bolt 2 and smaller than the outer diameter of the expansion pin bushing 1, so that the expansion pin bolt 2 passes through the through hole 411 and the expansion pin bushing 1 is supported by the receiving plate 41.

[0067] The expansion pin assembly of this application features a simple connection, convenient disassembly, and reusability. Because its self-locking characteristic is predictable and manageable, when disassembly is required, a controllable hydraulic device can easily separate the frustum-shaped connection by applying a reverse pulling force. This solves the core pain points of traditional expansion pins: "difficult disassembly" and "disposable consumables." Furthermore, the expansion pin assembly of this application suffers minimal damage during disassembly, and each component can be reused multiple times, significantly reducing maintenance costs and spare parts inventory.

[0068] Example 2, as Figure 8 As shown, the split-type reaming drill bit includes a main drill bit 7 and a split drill bit 8. The split drill bit 8 is connected to the main drill bit 7 through an expansion pin assembly, which is the expansion pin assembly for the split-type reaming drill bit described in Example 1.

[0069] like Figure 9 As shown, the main drill bit 7 includes a first drill bit body 71 and a first connecting assembly 72 disposed on the first drill bit body 71. Figure 10 As shown, the first connecting component 72 includes a first connecting plate 721 and a second connecting plate 722 spaced apart, with an installation gap 728 formed between the first connecting plate 721 and the second connecting plate 722; the first connecting plate 721 is provided with two first connecting holes 7211 spaced apart vertically, and the second connecting plate 722 is provided with two second connecting holes 7221 spaced apart vertically.

[0070] like Figure 11 As shown, the split drill bit 8 includes a second drill bit body 81 and a second connecting assembly 82 disposed on the second drill bit body 81. The second connecting assembly 82 is tightly connected to the first connecting assembly 72 via the expansion pin assembly. The two sets of expansion pin assemblies are the first expansion pin assembly 9 and the second expansion pin assembly 10, respectively. Figure 12 As shown, the second connecting component 82 includes an insertion plate 824, which has an insertion hole 8241 corresponding to the first connecting hole 7211 and the second connecting hole 7221. During assembly, the insertion plate 8241 is inserted into the installation gap 728, and the first connecting plate 721, the insertion plate 824, and the second connecting plate 722 are tightly connected by the first expansion pin component 9 and the second expansion pin component 10. The penetration directions of the first expansion pin component 9 and the second expansion pin component 10 are opposite.

[0071] Example 3, a split-type reaming drill bit, differs from Example 2 in that, in this example, as... Figure 13 As shown, the main drill bit 7 includes a first drill bit body 71 and a first connecting assembly 72 disposed on the first drill bit body 71, as... Figure 14 As shown, the first connecting assembly 72 includes a first connecting plate 721, a second connecting plate 722, a third connecting plate 723, and a fourth connecting plate 724; the third connecting plate 723 and the fourth connecting plate 724 are spaced apart between the first connecting plate 721 and the second connecting plate 722, such that a first gap 725 is formed between the first connecting plate 721 and the fourth connecting plate 724, a second gap 726 is formed between the fourth connecting plate 724 and the third connecting plate 723, and a third gap 727 is formed between the third connecting plate 723 and the second connecting plate 722;

[0072] like Figure 15 and Figure 16 As shown, the first connecting plate 721 is provided with two vertically spaced first connecting holes 7211, the second connecting plate 722 is provided with two vertically spaced second connecting holes 7221, the third connecting plate 723 is provided with two vertically spaced third connecting holes 7231, and the fourth connecting plate 724 is provided with two vertically spaced fourth connecting holes 7241.

[0073] Further, at least one of the two first connecting holes 7211 on the first connecting plate 721 is configured as a second frustum-shaped through hole 7212, and at least one of the two second connecting holes 7221 on the second connecting plate 722 is configured as a third frustum-shaped through hole 7222. When there is only one second frustum-shaped through hole 7212 on the first connecting plate 721 and only one third frustum-shaped through hole 7222 on the second connecting plate 722, the second frustum-shaped through hole 7221 and the third frustum-shaped through hole 7222 are located on different planes; specifically, as shown... Figure 15 As shown, the upper first connecting hole 7211 on the first connecting plate 721 is configured as a second frustum through hole 7212, while the lower first connecting hole 7211 is a normal cylindrical through hole; as Figure 16 As shown, the lower second connecting hole 7221 on the second connecting plate 722 is configured as a third frustum through hole 7222, while the upper second connecting hole 7221 is a normal cylindrical through hole.

[0074] In this example, such as Figure 17 As shown, the split drill bit 8 includes a second drill bit body 81 and a second connecting assembly 82 disposed on the second drill bit body 81, as... Figure 18As shown, the second connecting assembly 82 includes a first insertion plate 821, a second insertion plate 822, and a third insertion plate 823. The first insertion plate 821 has a first insertion hole 8211 corresponding to the first connecting hole 7211 and the fourth connecting hole 7241; the second insertion plate 822 has a second insertion hole 8221 corresponding to the third connecting hole 7231 and the fourth connecting hole 7241; and the third insertion plate 823 has a third insertion hole 8231 corresponding to the second connecting hole 7221 and the third connecting hole 7231. During assembly, the first insertion plate 821 is inserted into the first gap 725, the second insertion plate 822 is inserted into the second gap 726, and the third insertion plate 823 is inserted into the third gap 727. Then, the first connecting plate 721, the first insertion plate 821, the fourth connecting plate 724, the second insertion plate 822, the third connecting plate 723, the third insertion plate 823, and the second connecting plate 722 are tightly connected by the first expansion pin assembly 9 and the second expansion pin assembly 10.

[0075] The wall surface of the second frustum through hole 7212 is the fourth frustum surface 7213 corresponding to the third frustum surface 124, and the wall surface of the third frustum through hole 7222 is the fifth frustum surface 7223 corresponding to the third frustum surface 124. The large diameter end and small diameter end of the fourth frustum surface 7213 and the fifth frustum surface 7223 are in opposite positions. The taper of the third frustum surface 124, the fourth frustum surface 7213 and the fifth frustum surface 7223 is 1:10. The 1:10 taper setting achieves the same effect as the taper setting of the first frustum 1211 and the second frustum 211. During the assembly of the split drill bit, the expansion pin bolt 2 and the expansion pin bushing 1 have a self-locking reinforcement effect of 1:10 taper, and the expansion pin bushing 1 and the main drill bit 7 also have a self-locking reinforcement effect of 1:10 taper. The two reinforcement effects can effectively ensure the tightness of the split reaming drill bit.

[0076] Example 4: Assembly method of a split-type reamer, wherein the split-type reamer is the split-type reamer described in Example 3, comprising the following steps:

[0077] Step P1, as follows Figure 19As shown, the split-type reaming drill bit includes a main drill bit 7 and four split drill bits 8. During assembly, one of the split drill bits 8 is installed first. The first insertion plate 821, the second insertion plate 822, and the third insertion plate 823 of the split drill bit 8 are inserted into the first gap 725, the second gap 726, and the third gap 727 respectively. The first connecting hole 7211, the first insertion hole 8211, the fourth connecting hole 7241, the second insertion hole 8221, the third connecting hole 7231, the third insertion hole 8231, and the second connecting hole 7221 are located on the same horizontal plane, and the upper holes are on the same horizontal plane as the upper holes, and the lower holes are on the same horizontal plane as the lower holes.

[0078] Step P2: Insert the first expansion pin assembly 9 and the second expansion pin assembly 10 in sequence, so that the expansion pin bushing 1 of the first expansion pin assembly 9 passes through the second frustum through hole 7212, the first insertion hole 8211, the fourth connecting hole 7241, the second insertion hole 8221, the third connecting hole 7231, the third insertion hole 8231 and the second connecting hole 7221 in sequence, so that the expansion pin bushing 1 of the second expansion pin assembly 10 passes through the third frustum through hole 7222, the third insertion hole 8231, the third connecting hole 7231, the second insertion hole 8221, the fourth connecting hole 7241, the first insertion hole 8211 and the first connecting hole 7211 in sequence. When the expansion pin bushing 1 of the first expansion pin assembly 9 is fully inserted, the third frustum surface 124 of the first expansion pin assembly 9 is in close contact with the fourth frustum surface 7213. When the expansion pin shaft of the second expansion pin assembly 10 is fully inserted, the third frustum surface 124 of the second expansion pin assembly 10 is in close contact with the fifth frustum surface 7223.

[0079] Step P3: Insert the expansion bolt 2 into the expansion bolt sleeve 1. When the expansion bolt 2 is fully inserted, the second frustum surface 211 is in close contact with the first frustum surface 1211. Specifically, first insert the expansion bolt 2 into the expansion bolt sleeve 1 of the first expansion bolt assembly 9, and then insert the corresponding expansion bolt 2 into the expansion bolt sleeve 1 of the second expansion bolt assembly 10.

[0080] Step P4: Insert the expansion pin cap 4, flat washer 6, and spring washer 5 sequentially onto the end of the expansion pin bolt 2, ensuring the receiving plate 41 of the expansion pin cap 4 is tightly against the end face of the expansion pin bushing 1. Then, tighten the expansion pin nut 3 onto the expansion pin bolt 2. During the tightening process, the locking head 21 of the expansion pin bolt 2 applies a radial expansion force to the expansion head 12 of the expansion pin bushing 1. Under the action of the radial expansion force, the expansion head 12 undergoes elastic deformation, causing the third frustum surface 124 of the first expansion pin assembly 9 and the fourth frustum surface 7213, and the third frustum surface 124 of the second expansion pin assembly 10 and the fifth frustum surface 7213 to... 223. The fit is tighter; specifically, firstly, the expansion pin cap 4, flat washer 6 and spring washer 5 are sequentially inserted into the end of the expansion pin bolt 2 of the first expansion pin assembly 9. Then, the expansion pin nut 3 is tightened on the expansion pin bolt 2 of the first expansion pin assembly 9. During the tightening process, an appropriate Allen wrench can be used in conjunction with a nut wrench to tighten the expansion pin nut 3, thereby improving the connection reliability of the first expansion pin assembly 9. Then, the expansion pin cap 4, flat washer 6 and spring washer 5 are sequentially inserted into the end of the expansion pin bolt 2 of the second expansion pin assembly 10. Then, the expansion pin nut 3 is tightened on the expansion pin bolt 2 of the second expansion pin assembly 10, thus completing the installation of a split drill bit.

[0081] Step P5: Repeat steps P1-P4 until all the split drill bits 8 are installed on the main drill bit 7, completing the assembly of the split reaming drill bit.

[0082] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of the claims of this patent application.

Claims

1. An expansion pin assembly for a split-type reaming drill bit, characterized in that, It includes an expansion pin bushing (1), an expansion pin bolt (2) coaxially inserted into the expansion pin bushing (1) through a central through hole (11), and an expansion pin nut (3) threadedly engaged with the expansion pin bolt (2). One end of the expansion pin bushing (1) is provided with an expansion head (12), and the expansion head (12) is provided with a first frustum through hole (121). The first frustum through hole (121) is connected to the central through hole (11) of the expansion pin bushing (1). The hole wall surface of the first frustum through hole (121) is a first frustum surface (1211), and the first frustum surface (1211) expands outward in a direction away from the expansion pin bushing (1). One end of the expansion bolt (2) is provided with a locking head (21), and the outer surface of the locking head (21) is a second frustum (211) adapted to the first frustum (1211). During the process of inserting the expansion bolt (2) into the expansion bushing (1), it passes through the first frustum through hole (121) and the center through hole (11) of the expansion bushing (1) in sequence. When the expansion bolt (2) is fully inserted into the expansion bushing (1), the second frustum surface (211) and the first frustum surface (1211) are tightly fitted together.

2. The expansion pin assembly for a split-type reaming drill bit according to claim 1, characterized in that, The expansion head (12) is provided with at least two dividing grooves (122), so that at least two expansion petals (123) with the same structure are formed on the expansion head (12). After the expansion pin bolt (2) is fully inserted into the expansion pin bushing (1), during the process of tightening the expansion pin nut (3), the locking head (21) applies a radial expansion force to the expansion head (12), so that the expansion petals (123) undergo elastic deformation under the action of the radial expansion force, thereby making the outer surface of the expansion head (12) fit tightly against the split-type reaming drill bit.

3. The expansion pin assembly for a split-type reaming drill bit according to claim 2, characterized in that, The expansion head (12) is a frustum cylinder, and the outer surface of the frustum cylinder is a third frustum surface (124). The diameter of the end of the frustum cylinder connected to the expansion pin sleeve (1) is the smallest, and the dividing groove (122) extends from the end with the larger diameter to the end with the smaller diameter along the frustum cylinder.

4. The expansion pin assembly for a split-type reaming drill bit according to claim 3, characterized in that, The taper of the first frustum (1211) and the taper of the second frustum (211) are both 1:

10.

5. The expansion pin assembly for a split-type reaming drill bit according to claim 3, characterized in that, It also includes an expansion pin cap (4) coaxially sleeved at the other end of the expansion pin bushing (1). One end of the expansion pin cap (4) is provided with a support plate (41). The support plate (41) is provided with a through hole (411). The diameter of the through hole (411) is larger than the diameter of the expansion pin bolt (2) and smaller than the outer diameter of the expansion pin bushing (1), so that the expansion pin bolt (2) passes through the through hole (411) and the expansion pin bushing (1) is supported by the support plate (41). A spring washer (5) and a flat washer (6) are provided between the expansion pin nut (3) and the expansion pin cap (4) to prevent the nut from loosening.

6. The expansion pin assembly for a split-type reaming drill bit according to claim 3, characterized in that, The locking head (21) is provided with an internal hexagonal groove (212), and the central axis of the internal hexagonal groove (212) is collinear with the central axis of the locking head (21).

7. A split-type reaming drill bit, characterized in that, It includes a main drill bit (7) and a split drill bit (8), wherein the split drill bit (8) is connected to the main drill bit (7) by an expansion pin assembly, wherein the expansion pin assembly is an expansion pin assembly for a split-type reaming drill bit as described in any of claims 3-6.

8. The split-type reaming drill bit according to claim 7, characterized in that, The main drill bit (7) includes a first drill bit body (71) and a first connecting component (72) disposed on the first drill bit body (71). The split drill bit (8) includes a second drill bit body (81) and a second connecting component (82) disposed on the second drill bit body (81). The second connecting component (82) and the first connecting component (72) are tightly connected by at least two sets of expansion pin components, which are a first expansion pin component (9) and a second expansion pin component (10). The first connecting component (72) includes at least a first connecting plate (721) and a second connecting plate (722) spaced apart, with an installation gap (728) formed between the first connecting plate (721) and the second connecting plate (722); the first connecting plate (721) is provided with at least two vertically spaced first connecting holes (7211), and the second connecting plate (722) is provided with at least two vertically spaced second connecting holes (7221); The second connecting component (82) includes at least an insert plate (824), on which an insert hole (8241) corresponding to the first connecting hole (7211) and the second connecting hole (7221) is provided. During assembly, the insert plate (824) is inserted into the installation gap (728), and the first connecting plate (721), the insert plate (824), and the second connecting plate (722) are tightly connected by the first expansion pin component (9) and the second expansion pin component (10). The first expansion pin component (9) and the second expansion pin component (10) have opposite penetration directions.

9. The split-type reaming drill bit according to claim 8, characterized in that, At least one of the two first connecting holes (7211) on the first connecting plate (721) is configured as a second frustum through hole (7212), and at least one of the two second connecting holes (7221) on the second connecting plate (722) is configured as a third frustum through hole (7222). When there is only one second frustum through hole (7212) on the first connecting plate (721) and only one third frustum through hole (7222) on the second connecting plate (722), the second frustum through hole (7212) and the third frustum through hole (7222) are located on different horizontal planes. The wall surface of the second frustum through hole (7212) is the fourth frustum surface (7213) corresponding to the third frustum surface (124), and the wall surface of the third frustum through hole (7222) is the fifth frustum surface (7223) corresponding to the third frustum surface (124). The large diameter end and small diameter end of the fourth frustum surface (7213) and the fifth frustum surface (7223) are in opposite positions. The taper of the third frustum (124), the fourth frustum (7213), and the fifth frustum (7223) is 1:

10.

10. A method for assembling a split-type reaming drill bit, characterized in that, The split-type reaming drill bit is the split-type reaming drill bit as described in claim 9, comprising the following steps: Step P1: Insert the insertion plate (824) of the split drill bit (8) into the installation gap (728) so that the first connecting hole (7211), the insertion hole (8241) and the second connecting hole (7221) are on the same horizontal plane; Step P2: Insert the first expansion pin assembly (9) and the second expansion pin assembly (10) in sequence, so that the expansion pin sleeve (1) of the first expansion pin assembly (9) passes through the second frustum through hole (7212), the insertion hole (8241) and the second connecting hole (7222) in sequence, and the expansion pin sleeve (1) of the second expansion pin assembly (10) passes through the third frustum through hole (7222), the insertion hole (8241) and the first connecting hole (7211) in sequence. When the expansion pin sleeve (1) of the first expansion pin assembly (9) is fully inserted, the third frustum surface (124) of the first expansion pin assembly (9) is in close contact with the fourth frustum surface (7213); when the expansion pin sleeve (1) of the second expansion pin assembly (10) is fully inserted, the third frustum surface (124) of the second expansion pin assembly (10) is in close contact with the fifth frustum surface (7223). Step P3: Insert the expansion bolt (2) into the expansion bolt sleeve (1). When the expansion bolt (2) is fully inserted, the second frustum (211) is in close contact with the first frustum (1211). Step P4: Insert the expansion pin cap (4), flat washer (6) and spring washer (5) into the end of the expansion pin bolt (2) in sequence, and make the receiving plate (41) of the expansion pin cap (4) tightly against the end face of the expansion pin bushing (1); then tighten the expansion pin nut (3) on the expansion pin bolt (2). During the tightening of the expansion pin nut (3), the locking head (21) of the expansion pin bolt (2) applies a radial expansion force to the expansion head (12) of the expansion pin bushing (1). The expansion head (12) undergoes elastic deformation under the action of the radial expansion force, so that the third frustum surface (124) of the first expansion pin assembly (9) and the fourth frustum surface (7213) and the third frustum surface (124) of the second expansion pin assembly (10) and the fifth frustum surface (7223) fit more closely. Step P5, repeat steps P1-P4 until all the split drill bits (8) are installed on the main drill bit (7) to complete the assembly of the split reaming drill bit.

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