Hard tip for PCD / PCBN cutting tool having a coolant through-hole and its manufacturing process

Abstract

To address wear issues and improve performance, we manufacture hard tips for PCD / PCBN cutting tools that have coolant through-holes. [Solution] The hard tip for PCD / PCBN cutting tools having coolant through holes according to the present invention is made from PCD or PCBN and has 1 to 3 coolant holes. The manufacturing process begins with creating a part A made of PCD or PCBN. To enhance conductivity, part A is joined to part B, which is a conductive material such as carbide or steel, by brazing with silver brazing paste. Next, coolant through holes are formed in the brazed joint of parts A and B using a high-voltage electrical discharge machine (EDM). After drilling, parts A and B are separated by heating to a temperature of 650°C or higher. In the final step, part A is brazed to a carbide shank that already has holes that fit part A, ensuring that the coolant paths are properly aligned.

Description

Technical Field

[0001] It relates to mechanical engineering and electrical engineering, particularly to a hard tip for a PCD / PCBN cutting tool having coolant through holes and its manufacturing process.

Background Art

[0002] Cutting tools are widely used in the manufacturing industry for cutting operations on materials that require both high precision and durability. Cutting tools made of cutting tips of synthetic diamonds such as polycrystalline diamond (PCD) or polycrystalline cubic boron nitride (PCBN) effectively control dimensional accuracy and positioning when cutting or drilling a wide range of materials. PCD cutting tools are particularly suitable for cutting non-ferrous metals such as aluminum, copper, and brass, as well as non-metallic materials such as plastics, wood, and composite materials. On the other hand, PCBN cutting tools are suitable for cutting high-hardness steels such as hardened steel exceeding 50 HRc (Rockwell hardness c), cast iron, and sintered materials. PCD / PCBN cutting tools are ideal for high-precision applications, such as when producing mechanical components, electronic parts, and ceramics. Compared with conventional tools, PCD / PCBN cutting tools are more durable because the synthetic diamond used at the cutting edge is extremely hard, thereby providing resistance to deformation, wear, and scratching. Chip removal is also effectively achieved with these tools, thereby reliably extending the tool life and reducing damage to the workpiece.

[0003] Currently, hard-tipped PCD / PCBN cutting tools are typically made by brazing a hard piece of PCD / PCBN to a carbide shank and then grinding it into a shape suitable for cutting. Despite being stronger and more durable than other types of cutting tools, hard-tipped PCD / PCBN cutting tools tend to wear out faster than expected when used to cut equally hard and wear-resistant materials. This reduces tool life and cutting accuracy, and can even cause damage to the workpiece. [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] One of the key factors causing wear in hard-tipped PCD / PCBN cutting tools is the heat generated by friction during cutting. Injecting a coolant is effective in reducing heat during cutting and also contributes to chip evacuation. Currently, coolant delivery in hard-tipped PCD / PCBN cutting tools is achieved through internal through-holes in the carbide shank, releasing the coolant from the side of the shank. However, the most effective cooling occurs when the coolant is delivered directly to the tool tip. To date, there are no available methods for drilling through-holes in hard synthetic diamond material. Therefore, the inventors have developed a novel method and tool design for manufacturing hard tips for PCD / PCBN cutting tools with coolant through-holes to address the wear problem and improve performance. [Means for solving the problem]

[0005] The present invention aims to solve the above problems by drilling through-holes for coolant within a hard synthetic diamond material shaped to fit the grooves of a carbide shank. The through-holes extend continuously from the carbide shank into the PCD / PCBN tip, allowing the coolant to be delivered directly to the cutting edge during machining. This reduces heat during cutting, reduces wear, and extends tool life. It also reduces heat within the drilled holes, resulting in less material shrinkage and better control of dimensional accuracy.

[0006] Drilling through holes in synthetic diamond material requires advanced mechanical and electrical engineering techniques to precisely align the hole in the diamond with the hole in the carbide shank while avoiding cracking. This alignment ensures effective coolant delivery and maintains the strength and durability of the cutting tip despite the presence of the hole. This also brings significant convenience and efficiency to cutting applications.

[0007] The objective of this invention is to design and manufacture a hard tip for PCD / PCBN cutting tools having a coolant through-hole in order to extend the tool life of the cutting tool by reducing wear during machining, and to improve product quality and dimensional accuracy by reducing material shrinkage due to heat. This also allows for increased machining speed, thereby reducing production time and lowering production costs. [Brief explanation of the drawing]

[0008] [Figure 1] Front and side views of a hard-tipped PCD / PCBN cutting tool having 1 to 3 grooves and a coolant through-hole. [Figure 2] These are front and side views of a carbide rod having 1 to 3 coolant through-holes. [Figure 3] These are front and side views of a cylindrical carbide rod ground into a straight or stepped shape. [Figure 4]These are front and side views of a carbide rod ground to a shank having a spiral groove. [Figure 5] These are front and side views of the PCD / PCBN hard tip material (part A) and conductive material (part B) before brazing. [Figure 6a] This diagram shows the brazing of parts A and B using silver brazing paste, where the thickness of part A is less than or equal to its diameter. [Figure 6b] This diagram shows the brazing of parts A and B using silver brazing paste, where the thickness of part A is greater than its diameter. [Figure 7] These are front and side views of part A after the coolant through-holes have been drilled and it has been separated from part B. [Figure 8] This diagram shows the brazing of part A to a carbide shank having a through-hole for the coolant. [Figure 9] This is a diagram illustrating the grinding of the cutting edge of a tool. [Modes for carrying out the invention]

[0009] A PCD / PCBN cutting tool with a hard tip and a coolant through-hole comprises two main components: a cutting tip (1) and a carbide shank (2). Three variations include single-hole, double-hole, and triple-hole configurations (see Figure 1).

[0010] The manufacturing steps are as follows:

[0011] Step 1: Cut a cylindrical carbide rod with 1 to 3 coolant through holes to the desired length and grind it into a straight or stepped cylindrical shape with a diameter of 2 to 25 mm (see Figures 2 and 3).

[0012] Step 2: Grind grooves into the carbide shank with a diameter greater than 3 mm (see Figure 4). This step can be skipped if the diameter is 3 mm or less.

[0013] Step 3: A cylindrical, non-conductive synthetic diamond cutting tip (part A), made of PCD or PCBN, is brazed to a conductive material (part B), made of carbide or steel, using silver brazing paste at a temperature of 650°C or higher. Part A must have a thickness of 1 to 12 mm and a diameter of 2 to 25 mm, depending on the diameter of the carbide shank. The outer diameter of part B must be ground to match the diameter of part A, and the thickness of part B must be at least 0.5 mm (see Figure 5).

[0014] - If the thickness of part A is less than or equal to the diameter, use one part B (see Figure 6a).

[0015] - If the thickness of part A is greater than its diameter, use two parts B at both ends (see Figure 6b).

[0016] Step 4: On the surfaces of parts A and B ("workpiece"), which were brazed together in Step 3, determine the position of the coolant through-holes by referring to the size of the position, and determine the angle of the coolant through-holes from the center point of the carbide rod. This ensures that the position, size, and angle of the holes to be drilled in the workpiece are correct. Next, mount the workpiece in the fixture of the electrical discharge machine (EDM). Set up the EDM by making contact between the electrodes and four points on the workpiece surface to calculate the position of the workpiece's center. Adjust the workpiece so that its center aligns with the position of the electrodes. Then, tilt the fixture according to the required angle and move the workpiece to the specific drilling position.

[0017] Drilling is initiated using a high-voltage discharge of 200-440 volts and 0.3-50 amperes. The EDM discharges current through electrodes with internal coolant passages ranging in diameter from 0.1 to 3 mm. The electrodes function like drill bits, discharging current from the positive electrode in the EDM head to the negative electrode in the fixed workpiece. The resulting hole diameter will be 0.1 to 3 mm, depending on the size of the electrode tube used.

[0018] After drilling the first hole, if the second hole and / or the third hole are required, tilt the fixture and return the workpiece to the centered position. Then, tilt the fixture according to a specific angle and move the workpiece to the designated position for the second hole and / or the third hole as required.

[0019] Step 5: Separate Component A from Component B by heating at a temperature of 650°C or higher, and then wash and remove the brazing residue (see Figure 7). Re-braze Component A to the carbide shank having the coolant through holes from Step 2 with a silver brazing paste at a temperature of 650°C or higher (see Figure 8).

[0020] Step 6: Grind the cutting end and the groove to the desired dimensions (see Figure 9).

[0021] Best Mode As disclosed in detail in the above preferred embodiments.

Claims

1. A hard tip for a polycrystalline diamond (PCD) / polycrystalline cubic boron nitride (PCBN) cutting tool having a through-hole for a coolant, wherein the PCD / PCBN cutting tool hard tip is The through-holes in the coolant have a thickness of 1 to 12 mm and a diameter of 2 to 25 mm. A hard tip for PCD / PCBN cutting tools, characterized by comprising one to three through holes in the coolant, and a ground cutting end and groove.

2. A method for manufacturing a hard tip for a PCD / PCBN cutting tool having a through-hole for a coolant, wherein the manufacturing method is: The invention relates to the manufacture of a component A, wherein the component A is made from a synthetic diamond consisting of polycrystalline diamond (PCD) or polycrystalline cubic boron nitride (PCBN), and has a thickness of 1 to 12 mm and a diameter of 2 to 25 mm. A method for manufacturing hard tips for PCD / PCBN cutting tools, including the following.

3. When the thickness of part A is less than or equal to the diameter of part A, the conductivity is increased by brazing part A to part B, which is a piece of conductive material made of carbide or steel, wherein the brazing is The component B has a diameter of 2 to 25 mm and a thickness of 0.5 mm or more that matches the diameter of the component A, and the conductivity of the component A is enhanced by brazing the component A to component B, which is a piece of conductive material made of carbide or steel, including brazing at a temperature of 650°C or higher using silver brazing paste. The manufacturing method according to claim 2, further comprising:

4. The manufacturing method according to claim 3, wherein, if the thickness of part A is greater than the diameter of part A, the two pieces of part B are brazed to part A at a temperature of 650°C or higher using silver brazing paste.

5. The method involves drilling through holes for a coolant within a workpiece consisting of bonded parts A and B, wherein the position, size, and angle of the through holes for the coolant are determined relative to the center of the carbide shank, the workpiece is fixed to an electrical discharge machine, and the electrodes of the electrical discharge machine are placed at four points on the surface of the workpiece to calculate the center of the workpiece. After adjusting the angle and position of the workpiece, a through-hole for the coolant is created in the workpiece, wherein a high-voltage current is discharged at 200 to 440 V and 0.3 to 50 A through an electrode tube having an inner bore of 0.1 to 3 mm, and the through-hole for the coolant is created in the workpiece with a diameter of 0.1 to 3 mm according to the size of the electrode tube. The manufacturing method according to claim 4, including

6. The manufacturing method according to claim 5, wherein, if a second coolant through-hole and / or a third coolant through-hole is required, the workpiece is tilted, repositioned to its original center, and then adjusted to the specified positions of the second and / or third through-hole.

7. The manufacturing method according to claim 6, comprising heating the perforated workpiece to a temperature of 650°C or higher to separate part A and part B, and then cleaning part A to remove any brazing residue.

8. The brazing of the aforementioned part A to a carbide shank having a through hole for the coolant is performed by Aligning the hole in part A with the through-hole for the coolant in the carbide shank, and Brazing at a temperature of 650°C or higher using silver brazing paste. The process involves brazing the aforementioned part A to a carbide shank having a through-hole for the coolant. The manufacturing method according to claim 7, including

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