A thread milling cutter for machining small diameter threaded holes

Abstract

This utility model belongs to the technical field of milling tools and discloses a thread milling cutter for machining small-diameter threaded holes. It aims to solve the problems of poor adaptability and high cost of traditional milling cutters. The cutter includes a cutter head with milling teeth and a helical chip removal groove, a first tool holder coaxially connected to the cutter head, and multiple sets of second tool holders of different lengths. Modular assembly is achieved through a connection and locking structure. During assembly, the second tool holder is selected according to the machining depth, and it is connected to the insertion slot via a connecting rod. An anti-rotation structure prevents relative rotation between the two and aligns the fixing holes. A fixing member containing a fixing rod and a screw passes through the fixing holes for locking. A recessed groove hides the operating head to prevent collisions. During machining, power is transmitted to the cutter head via the second and first tool holders to mill the threads, and the helical chip removal groove removes chips. The second tool holders are made of carbon steel, and damage to them occurs first, requiring only replacement. This milling cutter flexibly adapts to different machining depths, reducing costs and resource waste, and improving machining efficiency and quality.

Description

Technical Field

[0001] This utility model relates to the field of milling tools, specifically a thread milling cutter for machining small-diameter threaded holes. Background Technology

[0002] In the machining industry, internal thread machining is a crucial process for ensuring the stability and functionality of component connections. Especially in the field of precision component manufacturing, the machining quality of small-diameter internal threads directly determines the overall performance of the product. With the increasing market demand for product miniaturization and integration, more and more workpieces need to be machined with internal threads within limited space. Due to structural design requirements, some workpieces require machining hole depths far exceeding the conventional range. Machining these ultra-deep small-diameter internal threads has become a challenge in the industry.

[0003] Currently, thread milling has gradually replaced traditional tapping due to its high machining accuracy, excellent surface roughness, and strong adaptability to difficult-to-cut materials, becoming the preferred solution for machining ultra-deep small-diameter internal threads. However, in actual machining, interference between the lathe spindle head and the workpiece consistently restricts machining efficiency and economy. Because the workpiece itself is small and the hole depth is significant when machining ultra-deep small-diameter holes, thread milling cutters with conventional length shanks cannot reach the bottom of the hole to complete the machining. To ensure the cutter can reach the bottom of the hole, a specially designed thread milling cutter with an extended shank must be used. This extends the shank length to avoid spatial conflict between the spindle head and the workpiece, preventing the spindle head from directly pressing against the workpiece. Once interference occurs, it can cause scratches and deformation on the workpiece surface, and may also damage the spindle head, leading to equipment failure and production stoppage.

[0004] However, the use of specialized thread end mills with extended shanks has introduced new problems of cost and resource waste. On the one hand, different workpieces require different hole depths, ranging from standard to ultra-deep. To accommodate these varying depth requirements, companies need to purchase multiple sets of specialized thread end mills with different lengths. For example, in automotive parts manufacturing, a single production line might require 5-8 different types of thread end mills with varying shank lengths.

[0005] On the other hand, the utilization rate of individual custom thread end mills is extremely low. Since each end mill is only suitable for machining at a specific depth, when the production line switches to machining workpieces of different depths, the corresponding end mill is left idle. If the end mill develops problems such as corrosion or decreased accuracy due to prolonged inactivity, additional costs must be incurred for repair or replacement. This "one hole, one cutter" adaptation model results in inefficient use of tool resources, causing serious resource waste and increasing the company's production costs and capital tied up in inventory.

[0006] Furthermore, most existing custom thread end mills are one-piece structures. If the cutter shank is worn, bent, or damaged, the entire cutter needs to be replaced. However, the core components such as the cutter head and milling teeth may still be in good condition, further increasing costs. In summary, the current solution of using multi-specification custom thread end mills to solve the problem of interference between the spindle head and the workpiece suffers from high costs, low utilization rates, and significant resource waste. There is an urgent need for a thread end mill structure that allows for flexible adjustment of the shank length and accommodates multiple depth machining needs, in order to optimize tool configuration, reduce production costs, and improve machining economy and efficiency. Utility Model Content

[0007] To address the shortcomings of existing technologies, this utility model provides a thread milling cutter for machining small-diameter threaded holes, thereby solving the problems of inconvenience and high cost of existing cutting tools mentioned in the background art.

[0008] To achieve the above-mentioned objectives, this utility model provides the following technical solution: a thread milling cutter for machining small-diameter threaded holes, comprising:

[0009] The cutter head has milling teeth on its outer peripheral surface and multiple sets of spiral chip removal grooves on its edge, which penetrate the milling teeth.

[0010] The first tool holder is coaxially and fixedly connected to the tool head, and the first tool holder is a slender cylinder made of tungsten steel.

[0011] Multiple sets of second tool holders, each a cylindrical carbon steel bar, with varying lengths;

[0012] The assembly structure includes a plug rod and a plug slot. The plug rod is fixedly disposed on the side of the first cutter bar away from the cutter head, and the plug slot is disposed in the second cutter bar. The first cutter bar and the second cutter bar are connected by plugging in the plug rod and the plug slot.

[0013] The locking structure includes a fixing hole and a fixing member. The fixing hole passes through the second tool bar and the insertion rod, and the fixing member is disposed in the fixing hole.

[0014] Preferably, an expansion platform is provided at the junction of the first tool bar and the plug rod, and the diameter of the expansion platform is opposite to the diameter of the second tool bar.

[0015] Preferably, the plug rod has two sets of parallel anti-rotation flat openings, and the plug groove has a mating shape corresponding to the anti-rotation flat openings.

[0016] Preferably, the fixing component includes two sets of operating heads, a fixing rod, and an internal threaded hole. One set of operating heads is provided with a fixing rod corresponding to the fixing hole, and the other set of operating heads is provided with a screw. The fixing rod is provided with an internal threaded hole corresponding to the screw, and the fixing rod is threadedly connected to the screw.

[0017] Preferably, the second tool holder has two sets of structural notches at the corresponding fixing holes, and the structural notches have grooves corresponding to the operating head.

[0018] Compared with the prior art, this utility model provides a thread milling cutter for machining small-diameter threaded holes, which has the following features:

[0019] Beneficial effects:

[0020] This thread end mill for machining small-diameter threaded holes features a cutter head, milling teeth, helical chip removal grooves, a first tool holder, multiple sets of second tool holders, an assembly structure, and a locking structure. The tool holders are detachable and replaceable, allowing adaptation to different workpieces by changing the length of the tool holders. It is particularly suitable for machining internal threads in ultra-deep small holes, preventing the spindle head from pressing against the workpiece. When machining ordinary depths, a tool holder of a normal length can be used, avoiding the impact of an excessively long tool holder on machining. It allows for flexible switching, effectively improving tool utilization. Furthermore, the material used for the second tool holders is weaker than that of the first tool holder, so if a tool holder fails, it will only occur at the second tool holder. The use of low-value components results in low cost of damage and strong practicality. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0022] Figure 2 This is a schematic diagram of the cutter head and the first cutter bar structure of this utility model;

[0023] Figure 3 This is a schematic diagram of the second tool holder structure of this utility model;

[0024] Figure 4 This is a schematic diagram of the second tool holder and the fixing component of this utility model.

[0025] In the diagram: 1. Cutting head; 2. Milling thread; 3. Spiral chip removal groove; 4. First cutter bar; 5. Second cutter bar; 6. Connecting rod; 7. Connecting groove; 8. Structural notch; 9. Fixing hole; 10. Fixing component; 11. Anti-rotation flat end; 12. Mating shape; 13. Operating head; 14. Fixing rod; 15. Screw; 16. Internal threaded hole; 17. Groove. Detailed Implementation

[0026] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0027] Please see Figure 1-4 This utility model provides a technical solution:

[0028] A thread milling cutter for machining small-diameter threaded holes, comprising:

[0029] The cutter head 1 has milling teeth 2 on its outer peripheral surface and multiple sets of spiral chip removal grooves 3 on its edge, with the spiral chip removal grooves 3 penetrating the milling teeth 2.

[0030] The first tool holder 4 is coaxially and fixedly connected to the tool head 1. The first tool holder 4 is a slender cylinder made of tungsten steel. The tool head 1 is usually made of tungsten steel or diamond. If the tool head 1 is made of tungsten steel, the tool head 1 and the first tool holder 4 are integrally formed.

[0031] Multiple sets of second tool holders 5, each a cylindrical carbon steel body, with varying lengths; the use of carbon steel significantly reduces costs. The diameter of the second tool holder 5 matches the tool holder fixture, and the different lengths of the multiple sets of second tool holders 5 allow for replacement as needed. Changing the second tool holder 5 alters the tool holder length, making it particularly suitable for machining deep, small-diameter internal threads. The longer tool holder allows the cutting head 1 to penetrate deeper, preventing the spindle head from squeezing the workpiece.

[0032] The assembly structure includes a plug rod 6 and a plug slot 7. The plug rod 6 is fixedly installed on the side of the first cutter bar 4 away from the cutter head 1, and the plug slot 7 is installed in the second cutter bar 5. The first cutter bar 4 and the second cutter bar 5 are connected by plugging in the plug rod 6 and the plug slot 7.

[0033] The locking structure includes a fixing hole 9 and a fixing member 10. The fixing hole 9 passes through the second tool bar 5 and the insertion rod 6, and the fixing member 10 is disposed in the fixing hole 9.

[0034] Furthermore, an expansion platform is provided at the joint between the first tool bar 4 and the insertion rod 6, and the diameter of the expansion platform is opposite to the diameter of the second tool bar 5.

[0035] Furthermore, the insertion rod 6 has two sets of parallel anti-rotation flat openings 11, and the insertion groove 7 has a mating shape 12 corresponding to the anti-rotation flat opening 11. The anti-rotation flat opening 11 and the mating shape 12 are similar to flat keys, which can prevent the first tool bar 4 and the second tool bar 5 from rotating relative to each other, and facilitate insertion. After insertion, the fixing holes 9 on the first tool bar 4 and the second tool bar 5 automatically align, making it easy to lock them using the fixing member 10.

[0036] Furthermore, the fixing component 10 includes two sets of operating heads 13, fixing rods 14, and internal threaded holes 16. One set of operating heads 13 is provided with fixing rods 14 corresponding to fixing holes 9, and the other set of operating heads 13 is provided with screws 15. The fixing rods 14 have internal threaded holes 16 corresponding to screws 15, and the fixing rods 14 and screws 15 are threadedly connected. The operating heads 13 have internal hexagonal holes, slotted holes, and star-shaped holes, etc., to facilitate the use of tools to operate their rotation.

[0037] Furthermore, two sets of structural notches 8 are provided on the second tool holder 5 corresponding to the fixing hole 9, and grooves 17 corresponding to the operating head 13 are provided on the structural notches 8. The grooves 17 are used to hide the operating head 13 and prevent it from protruding.

[0038] Structural Description:

[0039] Cutter head 1: The core cutting component of the thread milling cutter. The outer peripheral surface is provided with milling teeth 2 and the edge has multiple sets of spiral chip removal grooves 3 that penetrate the milling teeth 2. It is usually made of tungsten steel or diamond and is coaxially fixedly connected to the first cutter 4.

[0040] Milling thread 2: Located on the outer peripheral surface of the cutter head 1, it has a helical cutting edge. During machining, it contacts the hole wall of the workpiece and mills the hole wall to form an internal thread.

[0041] Spiral chip removal groove 3: A groove-shaped structure formed on the edge of the cutter head 1 and penetrating the milling tooth 2. It is spiral in shape and is used to guide the metal chips generated during milling out of the hole along the spiral trajectory to avoid chip accumulation affecting the machining.

[0042] First tool holder 4: A slender cylinder coaxially fixedly connected to the tool head 1, made of tungsten steel. If the tool head 1 is made of tungsten steel, the two are integrally formed. It can transmit power and connect the tool head 1 and the second tool holder 5.

[0043] Second tool holder 5: Multiple sets of carbon steel cylinders of different lengths, with diameters adapted to the tool holders. They are connected to the first tool holder 4 through assembly and locking structures and can be replaced to adjust the total length of the tool holder.

[0044] Insertion rod 6: A rod-shaped structure fixed on the side of the first tool bar 4 away from the tool head 1, with two sets of parallel anti-rotation flat openings 11, which cooperate with the insertion slot 7 to realize the insertion of the first tool bar 4 and the second tool bar 5;

[0045] Insertion slot 7: A groove structure formed inside the second tool bar 5, with a mating shape 12 inside that corresponds to the anti-rotation flat opening 11, used to accommodate the insertion rod 6 and realize the docking of the first tool bar 4 and the second tool bar 5;

[0046] Structural notch 8: A notch structure is provided at the corresponding fixing hole 9 of the second tool holder 5, and a groove 17 is provided on it to provide space for the installation and operation of the fixing member 10;

[0047] Fixing hole 9: A hole-like structure that passes through the second tool bar 5 and the insertion rod 6, used to accommodate the fixing member 10, and to lock the first tool bar 4 and the second tool bar 5 through the fixing member 10;

[0048] Fixing component 10: includes two sets of operating heads 13, fixing rods 14, screws 15 and internal threaded holes 16, and is a locking component that is set in the fixing hole 9, which can rigidly lock the first tool bar 4 and the second tool bar 5.

[0049] Anti-rotation flat opening 11: Two sets of parallel plane structures are opened on the plug rod 6, which cooperate with the fitting shape 12 to prevent the first tool bar 4 and the second tool bar 5 from rotating relative to each other and to align the fixing hole 9.

[0050] Matching shape 12: A structure set in the insertion slot 7 and corresponding to the anti-rotation flat opening 11, similar to a flat key, which can fit into the anti-rotation flat opening 11 to restrict the relative rotation of the first tool bar 4 and the second tool bar 5;

[0051] Operating head 13: A component of the fixing part 10, consisting of two sets, one set connecting the fixing rod 14 and the other set connecting the screw 15, which has internal hexagonal holes and other structures to facilitate tool operation and rotation;

[0052] Fixed rod 14: A rod-shaped structure connected to a set of operating heads 13, with a diameter corresponding to the fixed hole 9, and an internal threaded hole 16, which can be threadedly connected to the screw 15 to achieve locking;

[0053] Screw 15: A rod-shaped structure connected to another set of operating heads 13, which can be screwed into the inner threaded hole 16 of the fixing rod 14, and the fixing member 10 locks the first tool bar 4 and the second tool bar 5 through the threaded connection;

[0054] Internal threaded hole 16: A threaded hole structure opened in the fixing rod 14, corresponding to the screw 15, which can realize the assembly and locking function of the fixing part 10 through the thread engagement with the screw 15;

[0055] Slot 17: A groove structure formed on the structural notch 8, corresponding to the operating head 13, used to hide the operating head 13 and prevent it from protruding from the surface of the second tool holder 5.

[0056] Working principle: During the tool holder adaptation and assembly stage before machining, the second tool holder 5 of corresponding length needs to be selected according to the depth of the small-diameter threaded hole of the workpiece to be machined. If machining a small-diameter internal thread that is too deep, a longer second tool holder 5 is selected to ensure that the tool head 1 can penetrate to the bottom of the hole; if machining a threaded hole of ordinary depth, a second tool holder 5 of conventional length is selected to avoid tool holder redundancy that could cause vibration. During assembly, the insertion rod 6 on the side of the first tool holder 4 away from the tool head 1 is aligned with the insertion groove 7 at the end of the selected second tool holder 5. At this time, the two sets of parallel anti-rotation flat edges 11 on the insertion rod 6 and the mating shape 12 in the insertion groove 7 form a guide structure similar to a flat key, pushing the first tool holder 4 and the second tool holder 5 axially so that the anti-rotation flat edges 11 are fully embedded in the mating shape 12. This process can not only quickly complete the coaxial positioning of the two, but also prevent the first tool holder 4 and the second tool holder 5 from rotating relative to each other due to high-speed rotation during subsequent machining by limiting the fit between the anti-rotation flat edges 11 and the mating shape 12. At the same time, when the anti-rotation flat end 11 is fully engaged with the mating shape 12, the fixing holes 9 on the first tool bar 4 and the second tool bar 5 will automatically align, providing precise positioning for subsequent locking operations.

[0057] After the assembly and positioning are completed, the locking and fixing process begins. The operator disassembles the fixing component 10 in the locking structure and removes two sets of components with operating heads 13—one set of operating heads 13 connects to the fixing rod 14, and the other set connects to the screw 15. First, the operating head 13 with the fixing rod 14 is inserted into the fixing hole 9 through the structural notch 8 on one side of the second cutter bar 5, so that the fixing rod 14 passes through the insertion rod 6 between the second cutter bar 5 and the first cutter bar 4, until the operating head 13 is embedded in the groove 17 of the structural notch 8; then, the operating head 13 with the screw 15 is inserted into the structural notch 8 on the other side of the second cutter bar 5, so that the screw 15 is aligned with the internal threaded hole 16 in the fixing rod 14, and the screw 15 is screwed into the internal threaded hole 16 by rotating the operating head 13, until both sets of operating heads 13 are fully engaged in the groove 17, and the fixing rod 14 and the screw 15 are tightly fitted together. At this point, the fixing member 10 rigidly locks the first tool holder 4 and the second tool holder 5 through the fixing hole 9. Simultaneously, the recessed groove 17 conceals the operating head 13, preventing it from protruding from the surface of the second tool holder 5 and thus avoiding collisions with the workpiece hole wall or lathe fixture during machining. Furthermore, the enlarged diameter at the junction of the first tool holder 4 and the connecting rod 6 matches the diameter of the second tool holder 5, ensuring the consistency of the overall tool holder structure's outer diameter and further enhancing stability during high-speed rotation.

[0058] In the actual machining stage, the assembled thread milling cutter is connected to the lathe tool holder via the second tool holder 5. Utilizing the carbon steel material of the second tool holder 5, costs are controlled while ensuring stable fit with the fixture. After the lathe is started, power is transmitted to the second tool holder 5 through the tool holder. Then, with the dual protection of a locking structure and an anti-rotation structure, torque is stably transmitted to the first tool holder 4, ultimately driving the cutter head 1 to rotate coaxially at a set speed. When the cutter head 1 extends into the small-diameter hole of the workpiece, the milling teeth 2 on the outer periphery of the cutter head 1 contact the hole wall, and the helical cutting edges of the milling teeth 2 mill the hole wall to form an internal thread conforming to specifications. In this process, the multiple sets of spiral chip removal grooves 3 on the edge of the cutter head 1 play a key role: the metal chips generated during milling are discharged outward along the spiral trajectory of the spiral chip removal grooves 3. Since the spiral chip removal grooves 3 penetrate the milling tooth 2, the chips can be directly guided from the milling area to the outside of the hole, avoiding the accumulation of chips in the hole and affecting the cutting accuracy of the milling tooth 2. At the same time, it reduces the scratches on the cutter head 1 and the workpiece surface caused by the chips, ensuring the quality of thread processing. If the cutter head 1 is made of tungsten carbide, it and the first tool holder 4, which is also made of tungsten carbide, are integrally formed, which can further improve the connection strength between the cutter head 1 and the first tool holder 4, ensuring rigidity transmission during high-speed milling. If the cutter head 1 is made of diamond, it can be fixed to the first tool holder 4 by welding or other methods, adapting to the processing requirements of harder workpieces.

[0059] After machining, if it is necessary to change to machine threaded holes of different depths, the two sets of operating heads 13 of the fixing part 10 can be rotated in the opposite direction to unscrew the screw 15 from the internal threaded hole 16 of the fixing rod 14. After removing the fixing part 10, the first tool holder 4 and the second tool holder 5 can be separated axially. The second tool holder 5 of the corresponding length can be replaced and reassembled for use. In addition, since the second tool holder 5 is made of carbon steel, its strength is weaker than that of the first tool holder 4 made of tungsten steel. If the tool holder is damaged due to accidental force during machining, the damage will first occur at the low-value second tool holder 5. In this case, only the second tool holder 5 needs to be replaced, without scrapping the entire tool, which greatly reduces maintenance costs and resource waste.

[0060] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A thread milling cutter for machining small diameter threaded holes, characterized by, include: The cutter head (1) has milling teeth (2) on its outer peripheral surface. The edge of the cutter head (1) is provided with multiple sets of spiral chip removal grooves (3), and the spiral chip removal grooves (3) penetrate the milling teeth (2). The first tool holder (4) is coaxially fixedly connected to the tool head (1), and the first tool holder (4) is a slender cylinder made of tungsten steel. Multiple sets of second tool holders (5), each set of the second tool holders (5) is a cylinder made of carbon steel, and the lengths of the multiple sets of second tool holders (5) are different; The assembly structure includes a plug rod (6) and a plug groove (7). The plug rod (6) is fixedly disposed on the side of the first cutter bar (4) away from the cutter head (1). The plug groove (7) is disposed in the second cutter bar (5). The first cutter bar (4) and the second cutter bar (5) are connected by plugging in the plug rod (6) and the plug groove (7). The locking structure includes a fixing hole (9) and a fixing member (10). The fixing hole (9) passes through the second tool bar (5) and the plug rod (6), and the fixing member (10) is disposed in the fixing hole (9).

2. The thread milling cutter for machining small diameter threaded holes according to claim 1, characterized in that, An expansion platform is provided at the joint between the first tool bar (4) and the plug rod (6), and the diameter of the expansion platform is opposite to the diameter of the second tool bar (5).

3. The thread milling cutter for machining small diameter threaded holes according to claim 2, characterized in that, The plug rod (6) has two sets of parallel anti-rotation flat openings (11), and the plug groove (7) has a matching shape (12) corresponding to the anti-rotation flat openings (11).

4. The thread milling cutter for machining small diameter threaded holes according to claim 3, wherein The fixing member (10) includes two sets of operating heads (13), a fixing rod (14) and an internal threaded hole (16). One set of operating heads (13) is provided with a fixing rod (14) corresponding to the fixing hole (9), and the other set of operating heads (13) is provided with a screw (15). The fixing rod (14) is provided with an internal threaded hole (16) corresponding to the screw (15), and the fixing rod (14) and the screw (15) are threadedly connected.

5. The thread milling cutter for machining small diameter threaded holes according to claim 4, wherein The second cutter bar (5) has two sets of structural notches (8) at the corresponding fixing hole (9), and the structural notches (8) have grooves (17) corresponding to the operating head (13).

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