An impact-resistant and fracture-resistant resin drill and its preparation method
By modifying the resin binder and using a gradient curing process, the problem of abrasive shedding and breakage in resin drills under heavy loads and high impact conditions has been solved, resulting in improved efficiency, durability, and precision of the tool.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG YINPAI NEW MATERIALS CO LTD
- Filing Date
- 2026-03-18
- Publication Date
- 2026-06-02
AI Technical Summary
Existing resin drills lack sufficient impact toughness under heavy loads and high impact conditions, the abrasive is prone to falling off and breaking, the bonding force is weak, and the heat resistance is poor, resulting in a shortened tool life.
Modified resin binders, containing micron or nano ceramic particles and thermotropic liquid crystal polymers, are used to enhance the holding power and impact toughness of the abrasive and improve its heat resistance through premixing, cold pressing and gradient curing processes.
It significantly improves the impact toughness of resin drills and the abrasive's resistance to breakage, extends service life, and improves processing accuracy and efficiency.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of superhard material tool technology, and in particular to an impact-resistant and fracture-resistant resin drill and its preparation method. Background Technology
[0002] In precision machining, medical device manufacturing (such as dental and orthopedic surgery), jewelry carving, and model making, resin drills and grinding heads made of diamond or cubic boron nitride (CBN) abrasives and binders are commonly used for cutting, grinding, and polishing materials. Current resin drills mostly use phenolic resin or polyimide resin as a binder to adhere diamond abrasive particles to a metal substrate. The manufacturing process typically includes mixing, molding, curing, and subsequent processing.
[0003] Conventional resin-bonded diamond drill bits have a working layer consisting of a mixture of diamond abrasive and phenolic resin binder, which is then hot-pressed and cured onto a steel substrate. The drill bit relies on the cutting edge of the diamond abrasive, rotating at high speed, to remove material.
[0004] However, the existing technology has the following problems: (1) Insufficient impact toughness: Phenolic resin binder is brittle. When processing high-hardness materials (such as zirconia ceramics, quenched steel) or performing intermittent cutting, the working layer of the drill bit is prone to micro-cracks due to instantaneous impact force, resulting in premature abrasive particle detachment (abnormal wear) and shortening the drill bit life. (2) Weak bonding force and easy abrasive breakage: The holding force of the resin binder on diamond abrasive is limited. Under heavy-load grinding conditions, the friction and cutting forces increase sharply, and the heat generated easily softens the resin binder, further reducing the holding force on the abrasive, causing the diamond particles to fall off as a whole or, although the particles do not fall off, they break off themselves and lose their cutting ability. (3) Poor heat resistance: The high temperature generated by high-speed grinding will accelerate the thermal decomposition and carbonization of the resin binder, resulting in a decrease in the strength of the working layer, and the problem of "burning" the workpiece and tool failure.
[0005] Therefore, how to significantly improve the impact toughness and abrasive breakage resistance of resin drills under heavy load and high impact conditions while maintaining good cutting efficiency, and extend tool life, is a technical problem that urgently needs to be solved in this field. Summary of the Invention
[0006] In view of the defects of existing resin drills, such as easy abrasive detachment and breakage due to poor impact toughness and weak bonding force under heavy load, the purpose of this invention is to provide an impact-resistant and breakage-resistant resin drill and its preparation method, thereby solving the problems mentioned in the background art.
[0007] This invention is achieved through the following technical solution: an impact-resistant and fracture-resistant resin drill, comprising a metal substrate and a working layer attached to the working part of the metal substrate, wherein the working layer comprises diamond abrasive and resin binder; The resin binder is a modified resin binder, which comprises a resin binder matrix, a first modifier, and a second modifier. The first modifier is micron- or nano-sized ceramic particles, used to enhance the holding force of the abrasive and the strength of the binder body; The second modifier is a thermotropic liquid crystal polymer, used to improve the impact toughness of the binder.
[0008] In a preferred embodiment, the first modifier is one or more of nano-silicon carbide, nano-alumina, micron-silicon carbide, and micron-alumina.
[0009] In a preferred embodiment, the resin binder matrix is one of phenolic resin and polyimide resin.
[0010] A method for preparing the impact-resistant and shatter-resistant resin drill includes the following steps: a) Matrix pretreatment: Roughening the working parts of the metal matrix; b) Preparation of mixed powder: The diamond abrasive is premixed with the first modifier to allow the first modifier to adhere to the surface of the diamond abrasive; then the resin binder matrix and the second modifier are added and mixed to obtain the mixed powder. c) Cold pressing: The mixed powder is filled into the mold, placed in the working part of the metal substrate, and cold pressed at room temperature to obtain a green body; d) Gradient curing: The green body is cured by gradient heating and then cooled in the furnace to obtain the finished product.
[0011] In a preferred embodiment, the gradient curing in step d) includes a low-temperature wax removal stage, a medium-temperature curing stage, and a high-temperature heat treatment stage performed sequentially.
[0012] In a preferred embodiment, the temperature of the low-temperature wax removal stage is 120-160℃, the temperature of the medium-temperature curing stage is 200-250℃, and the temperature of the high-temperature heat treatment stage is 260-300℃.
[0013] In step b), the premixing time is 10-20 minutes, and the mixing time after adding the resin binder matrix and the second modifier is 15-30 minutes.
[0014] As a preferred embodiment, the roughening treatment in step a) is sandblasting or knurling, so that the surface roughness of the working part of the metal substrate reaches Ra 3.2-6.3μm.
[0015] In a preferred embodiment, the cold pressing pressure in step c) is 150-250 MPa, and the holding time is 20-40 s.
[0016] After adopting the above technical solution, the beneficial effects of the present invention are: (1) Improved impact toughness: The microfiber network structure formed by TLCP can effectively absorb and disperse impact energy and prevent crack propagation. According to the test, the impact toughness of the resin drill working layer of the present invention is improved by about 40%-60%. When processing zirconia ceramics containing micropores (resulting in intermittent cutting), no working layer chipping phenomenon occurred.
[0017] (2) Enhanced abrasive holding force and improved anti-breakage ability: The addition of nano-SiC particles, on the one hand, refines the resin matrix and improves its hardness and modulus; on the other hand, they fill the microscopic defects on the surface of diamond abrasive and generate chemical or physical adsorption with diamond, significantly enhancing the holding force of the binder on the abrasive. In heavy-duty grinding tests, the abrasive shedding rate was reduced by more than 70%, and most of the abrasive particles were normal grinding wear, rather than overall shedding or breakage.
[0018] (3) Improved heat resistance and wear resistance: The high thermal conductivity of nano-SiC particles helps to dissipate grinding heat quickly and reduces the thermal softening of the resin binder. The composite modified resin matrix itself is more wear-resistant, resulting in better shape retention of the drill bit working layer, higher processing accuracy, and an overall service life that is extended by 2-3 times. Detailed Implementation
[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0020] This invention provides a technical solution: an impact-resistant and fracture-resistant resin drill, comprising a metal substrate and a working layer attached to the working part of the metal substrate, wherein the working layer comprises diamond abrasive and resin binder; The resin binder is a modified resin binder, which includes a resin binder matrix, a first modifier, and a second modifier; the resin binder matrix is one of phenolic resin and polyimide resin.
[0021] The first modifier is micron- or nano-sized ceramic particles, used to enhance the holding force of the abrasive and the strength of the binder; the first modifier is one or more of nano-silicon carbide, nano-alumina, micron-sized silicon carbide, and micron-sized alumina. The second modifier is a thermotropic liquid crystal polymer, used to improve the impact toughness of the binder.
[0022] A method for preparing impact-resistant and shatter-resistant resin drills includes the following steps: a) Substrate pretreatment: The working part of the metal substrate is roughened by sandblasting or knurling to achieve a surface roughness of Ra 3.2-6.3μm. b) Preparation of mixed powder: Premix the diamond abrasive with the first modifier for 10-20 minutes to allow the first modifier to adhere to the surface of the diamond abrasive; then add the resin binder matrix and the second modifier and mix for 15-30 minutes to obtain the mixed powder. c) Cold pressing: The mixed powder is filled into the mold, placed in the working part of the metal substrate, and cold pressed at room temperature to obtain a green body. The cold pressing pressure is 150-250MPa and the holding time is 20-40s. d) Gradient curing: The green body is cured by gradient heating and then cooled in the furnace to obtain the finished product. Gradient curing includes a low-temperature wax removal stage, a medium-temperature curing stage and a high-temperature heat treatment stage performed in sequence. The temperature of the low-temperature wax removal stage is 120-160℃, the temperature of the medium-temperature curing stage is 200-250℃, and the temperature of the high-temperature heat treatment stage is 260-300℃.
[0023] Example 1: The preparation method of impact-resistant and shatter-resistant resin drill is as follows: Step 1: Substrate Pretreatment: Select a cemented carbide substrate with a diameter of 3mm and sandblast its front working part to achieve a surface roughness of Ra 3.2-6.3μm. The purpose of this step is to increase the mechanical bonding force between the substrate and the subsequent working layer.
[0024] Step 2: Prepare the mixed powder: Raw material preparation: Prepare diamond abrasive with a particle size of 325 / 400 mesh and a concentration of 75%.
[0025] The resin binder matrix is polyimide resin powder, accounting for 60% of the total mass of the binder.
[0026] The first modifier is nano-silicon carbide (SiC) particles with an average particle size of 80 nm, accounting for 20% of the total mass of the binder. Its function is to disperse and strengthen the resin matrix and anchor it to the diamond surface, thereby improving the wettability and holding power of the binder on the abrasive.
[0027] The second modifier is a thermotropic liquid crystal polymer (TLCP) powder, model Vectra A950, accounting for 20% of the total mass of the binder. TLCP can spontaneously form a microfiber structure in the molten state, playing a role similar to "fiber reinforcement", which greatly improves the toughness and impact resistance of the resin matrix.
[0028] Mixing process: First, dry mix the diamond abrasive and nano-SiC particles in a high-speed mixer for 15 minutes to ensure the SiC particles adhere evenly to the diamond surface. Then, add polyimide resin powder and TLCP powder, and continue mixing for 20 minutes. Finally, add a small amount (0.5% of the total mass) of liquid paraffin as a wetting agent, mix for another 5 minutes, and then discharge for later use.
[0029] Step 3, Cold Pressing: The mixed powder is filled into a specially designed ring mold, which has a pre-treated cemented carbide substrate placed inside. At room temperature, a pressure of 200 MPa is applied for 30 seconds to press the powder into a green layer that adheres tightly to the working part of the substrate.
[0030] Step 4, Gradient curing: Place the pressed semi-finished product into a vacuum curing oven.
[0031] First stage (low-temperature dewaxing): The temperature is increased from room temperature to 150°C at a rate of 1°C / min and held for 60 minutes. The purpose is to slowly remove the wetting agent and the moisture and gases adsorbed in the raw materials.
[0032] Second stage (medium-temperature curing): The temperature is increased to 230℃ at a rate of 0.5℃ / min and held for 120 minutes. During this stage, the polyimide resin undergoes a cross-linking reaction, and TLCP begins to melt and form a microfiber structure.
[0033] The third stage (high-temperature heat treatment): the temperature is increased to 280℃ at a rate of 1℃ / min and held for 240 minutes. During this stage, the resin is completely cured, the TLCP microfiber structure is fixed, and an interpenetrating network structure is formed with the resin matrix, while nano-SiC particles are uniformly distributed within it.
[0034] Cooling: After curing, allow the oven to cool naturally to room temperature, then remove the finished product.
[0035] Example 2: This example is basically the same as Example 1, except that the first modifier in step two is replaced with micron-sized alumina (Al2O3) powder (average particle size 2μm), while the second modifier remains TLCP. Although replacing nano-SiC with micron-sized Al2O3 slightly reduces the toughening effect on the resin matrix compared to nanomaterials, Al2O3 is cheaper and effectively improves the wear resistance of the resin binder. This method is suitable for processing materials with slightly lower hardness but stricter requirements for tool cost control, such as ordinary glass or stone. The gradient curing process parameters need to be adjusted accordingly: the temperature of the second stage (medium-temperature curing) is increased to 250℃, and the holding time is shortened to 90 minutes to ensure sufficient bonding between the micron-sized particles and the resin.
[0036] Comparative Example The same matrix and diamond abrasive as in Example 1 were used, but the binder was pure polyimide resin powder (without the first and second modifiers), and the preparation process adopted conventional hot pressing curing (heating to 230°C once and holding for 120 minutes).
[0037] The performance of the resin-coated abrasives prepared in Examples 1, 2, and the comparative example was tested. The test methods are as follows: 1. Impact toughness: The impact toughness of the working layer material was tested using a pendulum impact testing machine.
[0038] 2. Abrasive shedding rate: Zirconia ceramic test blocks were processed under the same conditions. After a certain processing time, the surface of the working layer was observed with a microscope, and the amount of abrasive shedding was counted.
[0039] 3. Service life: Under standard working conditions, continuous processing is performed until the drill bit fails, and the processing time is recorded.
[0040] Table 1, Performance Test Table As can be seen from the table, the resin drills of Examples 1 and 2 of this invention are significantly superior to the comparative examples in terms of impact toughness, abrasive holding power, and service life. Example 1 uses nano-SiC as the first modifier, resulting in better performance; Example 2 uses micron-sized Al2O3, which is lower in cost and also significantly improves performance.
[0041] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. An impact-resistant and fracture-resistant resin drill, characterized in that, It includes a metal substrate and a working layer attached to the working part of the metal substrate, wherein the working layer contains diamond abrasive and a resin binder; The resin binder is a modified resin binder, which comprises a resin binder matrix, a first modifier, and a second modifier. The first modifier is micron- or nano-sized ceramic particles, used to enhance the holding force of the abrasive and the strength of the binder body; The second modifier is a thermotropic liquid crystal polymer, used to improve the impact toughness of the binder.
2. The impact-resistant and shatter-resistant resin drill as described in claim 1, characterized in that: The first modifier is one or more of nano silicon carbide, nano alumina, micro silicon carbide, and micro alumina.
3. The impact-resistant and shatter-resistant resin drill as described in claim 1 or 2, characterized in that: The resin binder matrix is one of phenolic resin and polyimide resin.
4. A method for preparing the impact-resistant and fracture-resistant resin drill as described in any one of claims 1 to 3, characterized in that, Includes the following steps: a) Matrix pretreatment: Roughening the working parts of the metal matrix; b) Preparation of mixed powder: The diamond abrasive is premixed with the first modifier to allow the first modifier to adhere to the surface of the diamond abrasive; then the resin binder matrix and the second modifier are added and mixed to obtain the mixed powder. c) Cold pressing: The mixed powder is filled into the mold, placed in the working part of the metal substrate, and cold pressed at room temperature to obtain a green body; d) Gradient curing: The green body is cured by gradient heating and then cooled in the furnace to obtain the finished product.
5. The method for preparing the impact-resistant and shatter-resistant resin drill as described in claim 4, characterized in that: The gradient curing in step d) includes a low-temperature wax removal stage, a medium-temperature curing stage, and a high-temperature heat treatment stage performed sequentially.
6. The method for preparing the impact-resistant and shatter-resistant resin drill as described in claim 5, characterized in that: The temperature of the low-temperature wax removal stage is 120-160℃, the temperature of the medium-temperature curing stage is 200-250℃, and the temperature of the high-temperature heat treatment stage is 260-300℃.
7. The method for preparing the impact-resistant and shatter-resistant resin drill as described in claim 4, characterized in that: In step b), the premixing time is 10-20 minutes, and the mixing time after adding the resin binder matrix and the second modifier is 15-30 minutes.
8. The method for preparing the impact-resistant and shatter-resistant resin drill as described in claim 4, characterized in that: The roughening treatment in step a) is sandblasting or knurling, so that the surface roughness of the working part of the metal substrate reaches Ra 3.2-6.3μm.
9. A method for preparing the impact-resistant and shatter-resistant resin drill as described in claim 4, characterized in that: The cold pressing pressure in step c) is 150-250MPa, and the holding time is 20-40s.