A grinding wheel for grinding orthopedic Kirschner wires

Abstract

The invention discloses a grinding wheel for grinding orthopedic Kirschner wires. The preparation method comprises the following steps: preparing a composite ceramic metal bond by mixing ceramic bond powder and metal cobalt powder according to a mass ratio; putting cubic boron nitride abrasive grains and the composite ceramic metal bond powder into a three-dimensional mixer to prepare a premix; performing a molding process on the prepared premix on a hydraulic press; performing a blank drying process; sintering to obtain a composite ceramic metal bond grinding wheel block; and performing a gluing process with a steel body. The grinding wheel provided by the invention has good stability, high hardness and strong grinding ability.

Description

Technical Field

[0001] The invention belongs to the field of grinding wheels and manufacturing methods thereof, and in particular relates to a CBN grinding wheel for medical use. Background Art

[0002] In 1909, German scholar Martin Kirschner first applied Kirschner wires to clinical practice. It has a history of more than 100 years and is known as the first of the "Four Great Inventions" of orthopedics. Although bone plate systems and intramedullary nail systems have made great breakthroughs in trauma orthopedic implants, simple and practical Kirschner wires still dominate for fractures in special parts. Currently, the most widely used treatment is for children's fractures. Kirschner wires have the advantages of little effect on epiphyseal growth, easy operation, and percutaneous insertion.

[0003] At present, there is no professional standard in my country for the processing and grinding of Kirschner wires. The traditional grinding wheels used in the medical device industry have unstable grinding accuracy, poor surface roughness, serious chip sticking, and low grinding efficiency. Since the Kirschner wire itself is small in size and is mostly made of stainless steel and titanium alloy, the grinding process requires good grinding wheel stability, high processing accuracy, and long dressing cycle to ensure grinding efficiency. Summary of the invention

[0004] The purpose of the present invention is to solve the defects of the conventional grinding wheel in the prior art of processing Kirschner wires, such as poor stability, low processing accuracy, insufficient hardness and grinding ability, and difficulty in application on high-speed CNC grinding machines, and to provide a medical Kirschner wire grinding wheel with good stability, high hardness and strong grinding ability and a manufacturing method thereof.

[0005] The present invention is achieved through the following technical solutions:

[0006] A grinding wheel for grinding orthopedic Kirschner wires, the preparation method is as follows:

[0007] 1) preparing a composite ceramic metal binder by mixing ceramic binder powder and metal cobalt powder in a mass ratio of 9-9.5:1; the ceramic binder powder comprises the following mass fractions: 58-64% quartz sand, 18-21% micro powder ceramic corundum, 8-12% boron ore, 5-15% sodium carbonate, and 4-6% lithium carbonate; uniformly mixing the cobalt powder and the ceramic binder powder in a mortar according to a proportion, and setting aside;

[0008] 2) Screening the cubic boron nitride abrasive particles to obtain a particle size of 200-220 mesh;

[0009] 3) putting the cubic boron nitride abrasive and the composite ceramic metal binder powder into a three-dimensional mixer and mixing for 3-3.5 hours to prepare a premix;

[0010] 4) weighing the premix prepared in 3) according to the designed unit weight, putting it into the mold, and performing molding on a hydraulic press;

[0011] 5) placing the blank obtained in step 4) in a box-type desiccant for 5-5.5 hours for drying;

[0012] 6) placing the dried formed blank into a box-type resistance furnace, burying it in quartz sand and sintering it in an air atmosphere at a sintering temperature of 780°C-785°C, and keeping it warm for 1-2 hours to obtain a composite ceramic metal bond grinding wheel block;

[0013] 7) gluing the composite ceramic metal bond grinding wheel block prepared in 6) to the steel body, and then placing it in a box-type dryer for curing;

[0014] 8) The grinding wheel processed in 7) is machined to ensure precise shape and good appearance.

[0015] The particle size of the ceramic binder powder is 390-400 mesh.

[0016] The cobalt powder is 400 mesh particles with a purity of not less than 99.7%.

[0017] In step 3), carboxymethyl cellulose is added to the cubic boron nitride for wetting treatment, and the composite ceramic metal binder is premixed with a dextrin solution with a concentration of 30%.

[0018] In step 4), the molding pressure is 20 MPa.

[0019] In step 5), the drying temperature is 150°C-160°C.

[0020] The present invention has the following advantages:

[0021] 1) Metal cobalt belongs to the iron group metal component and has good affinity to abrasive cubic boron nitride particles. It can improve the interface bonding between the binder and the abrasive and play a good role in strengthening and toughening the grinding wheel.

[0022] 2) During the grinding process, the composite ceramic metal bond has a strong grip on the abrasive, reducing the phenomenon of premature abrasive shedding during the process, and has good self-sharpening and high removal rate. DETAILED DESCRIPTION

[0023] Example 1

[0024] The manufacturing process steps of this embodiment are as follows:

[0025] 1) Prepare a composite ceramic metal binder by mixing ceramic binder powder (particle size 400 mesh) and metal cobalt in a mass ratio of 9:1. The ceramic binder powder is composed of 58% quartz sand, 21% micro-powder ceramic corundum, 8% boron ore, 15% sodium carbonate, and 4% lithium carbonate; the cobalt powder is 400 mesh particles with a purity of not less than 99.7%. Mix the cobalt powder and the ceramic binder powder in a mortar in a certain proportion and set aside.

[0026] 2) The cubic boron nitride abrasive is sieved, and the particle size after sieving is 200 mesh.

[0027] 3) Put the cubic boron nitride abrasive and the composite ceramic metal binder powder into a three-dimensional mixer and mix for 3 hours to make a premix. A wetting agent such as carboxymethyl cellulose should be added to the cubic boron nitride for wetting treatment, and the composite ceramic metal binder should be premixed with a temporary binder, which can be a dextrin liquid with a concentration of 30-40%.

[0028] 4) The premix prepared in 3) is weighed according to the designed unit weight, put into the mold, and molded on a hydraulic press with a molding pressure of 20 MPa.

[0029] 5) Place the molded blank in a box-type desiccant for 5.5 hours for drying at a drying temperature of 160°C.

[0030] 6) The dried molded blank is placed in a box-type resistance furnace and buried in quartz sand for sintering in an air atmosphere at a sintering temperature of 780° C. for 1 hour to obtain a composite ceramic metal bond grinding wheel block.

[0031] 7) The grinding wheel block prepared in 6) is glued to the steel body, and then placed in a box-type dryer for curing.

[0032] 8) The grinding wheel processed in 7) is machined to ensure precise shape and good appearance.

[0033] Example 2

[0034] 1) Prepare a composite ceramic metal binder by mixing ceramic binder powder (particle size 400 mesh) and metal cobalt in a mass ratio of 9.5:1. The ceramic binder powder is composed of 64% quartz sand, 20% micro-powder ceramic corundum, 10% boron ore, 10% sodium carbonate, and 5% lithium carbonate by mass fraction; the cobalt powder is 450 mesh particles with a purity of not less than 99.7%. Mix the cobalt powder and the ceramic binder powder in a mortar in proportion and set aside.

[0035] 2) The cubic boron nitride abrasive is sieved, and the particle size after sieving is 200 mesh.

[0036] 3) Put the cubic boron nitride abrasive and the composite ceramic metal binder powder into a three-dimensional mixer and mix for 3.5 hours to prepare a premix. The cubic boron nitride should be wetted by adding a wetting agent, and the composite ceramic metal binder should be premixed with a temporary binder.

[0037] 4) The premix prepared in 3) is weighed according to the designed unit weight, put into the mold, and molded on a hydraulic press with a molding pressure of 20 MPa.

[0038] 5) Place the preform in a box-type desiccant for 5 hours for drying at a drying temperature of 150°C.

[0039] 6) The dried molded blank is placed in a box-type resistance furnace and buried in quartz sand for sintering in an air atmosphere at a sintering temperature of 785° C. The temperature is kept for 1 hour to obtain a composite ceramic metal bond grinding wheel block.

[0040] 7) The grinding wheel block prepared in 6) is glued to the steel body, and then placed in a box-type dryer for curing.

[0041] 8) The grinding wheel processed in 7) is machined to ensure precise shape and good appearance.

[0042] Example 3

[0043] 1) Prepare a composite ceramic metal binder by mixing ceramic binder powder (particle size 400 mesh) and metal cobalt in a mass ratio of 9.2:1. The ceramic binder powder is composed of 62% quartz sand, 18% micro-powder ceramic corundum, 12% boron ore, 5% sodium carbonate, and 6% lithium carbonate; the cobalt powder is 500 mesh particles with a purity of not less than 99.7%. Mix the cobalt powder and the ceramic binder powder in a mortar in a certain proportion and set aside.

[0044] 2) The cubic boron nitride abrasive is sieved, and the particle size after sieving is 200 mesh.

[0045] 3) Put the cubic boron nitride abrasive and the composite ceramic metal binder powder into a three-dimensional mixer and mix for 3 hours to prepare a premix. The cubic boron nitride should be wetted by adding a wetting agent, and the composite ceramic metal binder should be premixed with a temporary binder.

[0046] 4) The premix prepared in 3) is weighed according to the designed unit weight, put into the mold, and molded on a hydraulic press with a molding pressure of 20 MPa.

[0047] 5) Place the molded blank in a box-type desiccant for 5 hours and dry it at a drying temperature of 155°C.

[0048] 6) The dried molded blank is placed in a box-type resistance furnace and buried in quartz sand for sintering in an air atmosphere at a sintering temperature of 780° C. for 1.5 hours to obtain a composite ceramic metal bond grinding wheel block.

[0049] 7) The grinding wheel block prepared in 6) is glued to the steel body, and then placed in a box-type dryer for curing.

[0050] 8) The grinding wheel processed in 7) is machined to ensure precise shape and good appearance.

[0051] The following table compares the service life, dressing cycle and grinding efficiency of the grinding wheels for grinding Kirschner pins made in the three embodiments of the present invention with those of the traditional grinding wheels imported from Japan.

[0052]

[0053]

[0054] It can be seen from the above table that when grinding Kirschner wires, the performance of the grinding wheel of the present invention exceeds that of the imported grinding wheel.

[0055] Principle of the present invention:

[0056] Cubic boron nitride abrasive is used. After sieving, cubic boron nitride particles with a particle size of 200 mesh are selected. By reducing the abrasive particle size, the smoothness of the Kirschner wire is improved, the grinding scratches are reduced, and the roughness of the needle tip is reduced.

[0057] The present invention uses cobalt powder with a purity of not less than 99.7%, and then mixes the cobalt powder and the basic ceramic binder powder in a bowl according to a ratio, combines the advantages of the metal binder and the ceramic binder, enhances the binder's ability to hold the abrasive grains, improves the interface bonding between the binder and cubic boron nitride, and plays a good role in strengthening and toughening the abrasive grains. At the same time, the surface quality of the grinding is better than that of the traditional grinding wheel, and the processing efficiency is higher. The composite ceramic metal binder grinding wheel of the present invention has a high material removal rate.

[0058] The present invention adds sodium carbonate and lithium carbonate as fillers to reduce grinding heat and improve the chip sticking phenomenon when grinding stainless steel.

Claims

1. A grinding wheel for orthopedic Kirschner wire grinding, characterized in that The preparation method is as follows: 1) preparing a composite ceramic metal binder by mixing ceramic binder powder and metal cobalt powder in a mass ratio of 9-9.5:1; the ceramic binder powder comprises the following mass fractions: 58-64% quartz sand, 18-21% micro powder ceramic corundum, 8-12% boron ore, 5-15% sodium carbonate, and 4-6% lithium carbonate; uniformly mixing the cobalt powder and the ceramic binder powder in a mortar according to a proportion, and setting aside; 2) Screening the cubic boron nitride abrasive particles to obtain a particle size of 200-220 mesh; 3) Putting the cubic boron nitride abrasive and the composite ceramic metal binder powder into a three-dimensional mixer and mixing for 3-3.5 hours to prepare a premix; 4) weighing the premix prepared in 3) according to the designed unit weight, putting it into the mold, and performing molding on a hydraulic press; 5) placing the blank obtained in step 4) in a box-type desiccant for 5-5.5 hours for drying; 6) placing the dried formed blank into a box-type resistance furnace, burying it in quartz sand and sintering it in an air atmosphere at a sintering temperature of 780°C-785°C, and keeping it warm for 1-2 hours to obtain a composite ceramic metal bond grinding wheel block; 7) gluing the composite ceramic metal bond grinding wheel block prepared in 6) to the steel body, and then placing it in a box-type dryer for curing; 8) The grinding wheel processed in 7) is machined to ensure precise shape and good appearance.

2. The grinding wheel for orthopedic Kirschner wire grinding according to claim 1, characterized in that: The particle size of the ceramic binder powder is 390-400 mesh.

3. The grinding wheel for orthopedic Kirschner wire grinding according to claim 1, characterized in that: The cobalt powder is 400-500 mesh particles with a purity of not less than 99.7%.

4. The grinding wheel for orthopedic Kirschner wire grinding according to claim 1, characterized in that: In step 3), carboxymethyl cellulose is added to the cubic boron nitride for wetting treatment, and the composite ceramic metal binder is premixed with 30% dextrin solution.

5. The grinding wheel for orthopedic Kirschner wire grinding according to claim 1, characterized in that: In step 4), the molding pressure is 20 MPa.

6. The grinding wheel for orthopedic Kirschner wire grinding according to claim 1, characterized in that: In step 5), the drying temperature is 150°C-160°C.

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