CN115284187B - A method for rapidly preparing structured forming grinding wheels - Google Patents

Abstract

The present invention belongs to the technical field of abrasive tool manufacturing, and discloses a method for rapidly preparing a structured forming grinding wheel, comprising the following steps: uniformly mixing abrasive particles, a binder, a pore-forming agent, and an additive powder; drying the powder; establishing a structured grinding wheel geometric model; slicing and layering the grinding wheel geometric model; filling the mixed powder into a selective laser sintering device; sintering and molding the powder layer by layer through a laser molding system; designing the distribution distance of the glass fiber mesh along the thickness direction of the grinding wheel according to calculation, and laying a layer of glass fiber mesh on the upper part of the sintered layer after the molding system is sintered, and repeating the above molding procedure on this basis; after the structured grinding wheel is sintered, the molding cylinder of the selective laser sintering device is cooled to room temperature and taken out, and the excess powder bonded to the surface of the grinding wheel is cleaned; and finally fully solidified in a microwave heating furnace. The present invention solves the problems of slow molding speed and poor flexibility of the existing grinding wheel structuralization method, and is suitable for rapid structural processing of grinding wheels.

Description

A method for rapidly preparing structured forming grinding wheels

Technical Field

The invention relates to the technical field of abrasive material and tool manufacturing, and in particular to a method for quickly preparing a structured forming grinding wheel.

Background technique

During form grinding, the contact area between the grinding wheel and the workpiece is large, the grinding heat transfer conditions are poor, and there is a common problem of grinding damage to the workpiece due to excessive grinding temperature. Structuring the forming grinding wheel is an effective way to solve the problem of form grinding burns. However, the working surface of the forming grinding wheel is usually a curved surface, and it is very difficult to machine structured features on the curved surface.

At present, there are several main methods for structuring grinding wheels: mechanical processing structuring, abrasive water jet structuring, laser structuring, etc. Mechanical processing structuring is to use diamond or carbide tools to structure the surface of the grinding wheel by using their high hardness to produce the required structural features. Mechanical processing structuring is currently the most widely used method for structuring grinding wheels. Its advantages are mature technology, simple equipment, and low cost, but its disadvantages are also obvious. The processing is not flexible and it is difficult to process complex structural features. The types of structuring are usually only spiral grooves, parallel grooves, bevel grooves and other structures. Due to the limitations of the processing tools, the geometric dimensions of the structured grooves are large, resulting in a large surface roughness of the workpiece ground by the grinding wheel. Abrasive water jet processing structuring uses high-speed moving liquid or abrasive particles to collide with the surface of the grinding wheel to remove the binder and abrasive particles. Abrasive water jet structuring has the advantages of no heat affected zone, strong processing capability, wide processing range, and good incision quality. However, during the abrasive water jet erosion process, certain damage will be caused to the eroded section of the material, and with the increase of erosion depth, the tail angle and roughness of the eroded section will also increase, seriously affecting the processing quality. In addition, the geometric flexibility of abrasive water jet processing is not high, and it is difficult to process complex structural features. Laser structuring is a processing method that uses a focused laser beam as a heat source to bombard the workpiece and melt the material to form small holes, incisions, connections, and cladding. Compared with mechanical processing structuring and abrasive water jet structuring, laser structuring has the characteristics of high processing accuracy, good processing quality, fast processing speed, and high geometric flexibility. It can process various types of structural features on the surface of the grinding wheel with extremely high accuracy. However, laser processing equipment is expensive, the cost is high, and it is more troublesome to control laser parameters, which is easy to cause graphitization of diamond abrasive grains.

In response to the above problems, a Chinese patent (patent application number: CN202010201595.2) discloses a tool and a grooving method for mechanically processing grinding wheel grooves. First, the working end of the grinding wheel dresser is trimmed according to the required groove size of the grinding wheel using a laser, and then the grinding wheel dresser, connecting block, disc milling cutter handle, etc. are combined into a grinding wheel grooving tool, which can be connected to the machine tool to groove the grinding wheel. This solution can efficiently process circumferential grid grooves on the grinding wheel with good grooving quality and high efficiency. However, this solution uses laser to trim the grinding wheel dresser according to the size of the grinding wheel groove. When different groove sizes need to be made, multiple dressers need to be prepared, and the grinding wheel dresser needs to be replaced frequently. In addition, this solution is limited to the structural processing of the grinding wheel only for the groove structure, and it is difficult to process other types of structural features.

The Chinese patent (patent application number: CN201711265610.4) discloses a CVD diamond grinding wheel with ordered microstructure on the surface and its preparation method, and proposes a method of first using chemical vapor deposition to produce a 1.5mm thick diamond film on the outer circumference of the titanium alloy grinding wheel hub, then using ion beam polishing technology to grind and polish the outer circumference of the diamond film, and finally using a pulsed laser beam to ablate the microgroove structure on the outer circumference of the diamond film circle by circle. The structured diamond grinding wheel prepared by this scheme has the advantages of long service life, high grinding efficiency, and good grinding quality, but the process of preparing the diamond structured grinding wheel by this scheme is cumbersome, the deposition rate of the chemical vapor deposition method is not high, the forming speed is slow, and the grinding wheel production cycle is long, which greatly reduces the forming efficiency of the grinding wheel.

The Chinese patent (patent application number: CN201310455451.X) discloses a method for manufacturing a microstructured large-grain diamond grinding wheel, and proposes to use a pulsed laser beam to trim the protruding part of the abrasive grain on the working surface of the large-grain diamond grinding wheel, and to process a three-dimensional micro-groove matrix structure on the working surface of the grinding wheel, thereby improving the grinding performance of the large-grain diamond grinding wheel and improving its grinding processing accuracy. However, the structural processing of micro-grooves on a single abrasive grain of the grinding wheel requires frequent adjustment of the position of the pulsed laser beam, and the processing process is inevitably cumbersome, resulting in a long molding cycle of the grinding wheel.

Although the prior art such as the above-mentioned grinding wheel structuring scheme has realized the structured processing of the grinding wheel, these methods all realize the structuring of the grinding wheel by performing dressing processing on the grinding wheel after the grinding wheel preparation is completed. In addition, due to the limitation of the motion function of the processing equipment and the fact that only a single structural feature can be processed at a time, there are still problems such as the inevitable cumbersome processing process, slow forming speed, poor flexibility, and narrow scope of application. Even if multiple structural features can be set for simultaneous processing, there will still be problems such as complex equipment motion functions and high preparation costs. If the structural features of the grinding wheel are more complex, these problems will be more serious. The selective laser sintering technology is based on a digital model. It uses a laser beam to sinter discrete powder materials and manufacture parts layer by layer. It can simultaneously form the grinding wheel and prepare structural features. And because the selective laser sintering technology uses a laser beam to sinter the powder in the target area according to the model contour data, it can simultaneously complete the forming of all structural features of the grinding wheel on a cross section. Therefore, the processing process is only related to the thickness of the structured grinding wheel model, and will not be affected by the complexity of the structural features. It greatly increases the forming speed, flexibility, and scope of application of the grinding wheel, and has a very broad prospect for the rapid preparation of structured forming grinding wheels.

Summary of the invention

The present invention aims to provide a method for quickly preparing a structured shaped grinding wheel, so as to solve the problems of slow forming speed and poor flexibility of the existing grinding wheel structuring method.

In order to achieve the above object, the present invention provides the following technical solutions:

A method for rapidly preparing a structured forming grinding wheel comprises the following steps:

S1. Pour appropriate amount of abrasive, binder, pore-forming agent and additive powder into a three-dimensional mixer and mix evenly;

S2, placing the evenly mixed powder into a vacuum heating machine for drying;

S3. Establish a structured forming grinding wheel geometric model in a computer three-dimensional modeling software, modify the grinding wheel geometric model file format to STL and import it into the supporting software of the selected area laser sintering equipment;

S4, slicing and layering the imported structured forming grinding wheel geometric model in the supporting software of the selective laser sintering equipment;

S5, filling the mixed and heated mixed powder into the powder cylinder of the selective laser sintering equipment, and adjusting the height of the mixed powder in the powder cylinder to be consistent with the height of the substrate in the forming cylinder through the control system in the selective laser sintering equipment;

S6. Set reasonable parameters in the control system of the selective laser sintering equipment, and sinter the powder layer by layer through the laser forming system;

S7, according to the calculation, the distribution distance of the glass fiber mesh along the thickness direction of the grinding wheel is designed. After the molding system sintered the powder of a given thickness, a layer of glass fiber mesh was laid on the top of the sintered layer, and the molding procedure of step S6 was repeated on this basis, so as to quickly prepare a formed grinding wheel with structural characteristics;

S8. After the structured grinding wheel is sintered, the molding cylinder of the laser sintering equipment is cooled to room temperature and taken out, and the excess powder bonded to the surface of the grinding wheel is cleaned with a high-pressure blower to obtain a sintered product;

Preferably, the abrasive in step S1 is aluminum oxide, the binder is thermosetting phenolic resin, the pore-forming agent is aluminum oxide ceramic hollow spheres, the particle size of the abrasive is 100 mesh to 60 mesh, the average particle size of the binder is 90 um, and the average pore size of the pore-forming agent is 200 um.

Through the above settings, the average particle sizes of the abrasive and the pore-forming agent are similar, which is conducive to achieving uniform distribution of the pore-forming agent in the grinding wheel. The average particle size of the binder is about 1/2 times the particle size of the abrasive, which is conducive to the full combination of the resin powder and the abrasive and improves the bonding strength of the grinding wheel.

Preferably, in step S2, the heating temperature of the vacuum heating machine is 50° C. and the heating time is 30 min.

Through the above settings, preheating the mixed powder can effectively reduce the shrinkage deformation and thermal stress of the resin during the sintering process, and improve the forming accuracy and mechanical properties of the grinding wheel.

Preferably, the layer thickness of the slice is selected according to the abrasive particle size and the pore size of the pore former, and the single layer thickness of the slice is selected to be 0.2 mm-0.5 mm according to the abrasive particle size.

Through the above settings, the single-layer sintering thickness is selected to be 1-2 times the average particle size of the abrasive and the pore-forming agent, which can effectively avoid problems such as repeated sintering of the resin due to insufficient single-layer sintering thickness and insufficient sintering due to excessive single-layer sintering thickness, thereby causing insufficient grinding wheel strength and stratification.

Preferably, the power of the laser is set to 18 W, the diameter of the light spot is set to 0.15 mm, the scanning interval is set to 0.1 mm, the scanning speed is set to 1200 mm/s, and the scanning mode is set to offset scanning.

Through the above settings, the selected sintering parameters are the best results of multiple experiments. The powder material can be fully sintered at a higher sintering rate and without overburning of the resin, thereby improving the bonding strength of the grinding wheel.

Preferably, the preparation method further comprises: S9, to ensure that the resin powder is fully cured, placing the structured formed grinding wheel formed by selective laser sintering into a microwave curing furnace for post-processing.

Through the above arrangement, it can be ensured that the resin powder in the structured grinding wheel is fully solidified.

Preferably, in step S9, the temperature of microwave curing is set to 200° C., and the curing time is set to 10 min.

Through the above arrangement, it is possible to ensure that the resin powder in the structured grinding wheel is fully solidified, thereby avoiding the situation where the grinding wheel strength is insufficient due to insufficient resin sintering.

Compared with the prior art, the present invention has the following beneficial effects:

1. This scheme provides a new method for preparing structured grinding wheels with the help of SLS printing technology, so that surface structured grinding wheels can be prepared.

2. This solution avoids the problem of damage to the grinding wheel surface.

3. This scheme obtains a variety of different surface structured grooves by controlling the laser melting area.

4. The single-layer molding time of the structured grinding wheel of this scheme only takes tens of seconds, and the molding time of the entire grinding wheel only takes tens of minutes, which greatly improves the molding speed of the structured grinding wheel and shortens the preparation cycle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic structural diagram of a selective laser sintering system in this embodiment;

FIG2 is a schematic diagram of a grinding wheel structure reinforced with a glass fiber mesh in this embodiment;

FIG3 is a schematic diagram of the structure of the glass fiber mesh in this embodiment;

FIG. 4 is a schematic diagram of the structure of the formed structured grinding wheel in this embodiment.

The names of the corresponding marks in the drawings are: laser sintering equipment 1, powder cylinder 2, forming cylinder 3, scanning system 4, sintered layer 5, glass fiber mesh 6, upper mesh 7, middle mesh 8, lower mesh 9.

Detailed ways

The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments:

As shown in FIGS. 1 to 4 , a method for rapidly preparing a structured forming grinding wheel comprises the following steps:

S1. Pour abrasive grains, binders, pore formers, and additive powders of basically the same particle size into a three-dimensional mixer and mix them evenly according to a certain proportion; the volume fraction of the binder is 40.5%, the volume fraction of the abrasive grains is 40%, the volume fraction of the pore former is 15%, and the volume fraction of the additive is 4.5%. The abrasive grains of the structured grinding wheel are aluminum oxide, the binder is thermosetting phenolic resin, the pore former is aluminum oxide ceramic hollow spheres, the additive is SiO2 micropowder, the average particle size of the additive is 1μm, the particle size of the abrasive grains is 100 mesh to 60 mesh, the average particle size of the binder is 90um, and the average pore size of the pore former is 200um.

S2. Put the evenly mixed powder into a vacuum heating machine for drying. The heating temperature of the vacuum heating machine is 50°C and the heating time is 30 minutes.

S3. Establish a structured forming grinding wheel geometry model in a computer three-dimensional modeling software, modify the grinding wheel geometry model file format to STL and import it into the supporting software of the selected area laser sintering equipment 1.

S4. In the supporting software of the selective laser sintering equipment 1, the imported structured forming grinding wheel geometric model is sliced and layered reasonably; the layer thickness of the slice is reasonably selected according to the abrasive grain size and the pore size of the pore former, and the single layer thickness of the slice is preferably selected to be 0.2mm-0.5mm according to the size of the abrasive grain size.

S5, filling the mixed and heated mixed powder into the powder cylinder 2 of the selective laser sintering equipment 1, and adjusting the height of the mixed powder in the powder cylinder 2 to be consistent with the height of the substrate in the forming cylinder 3 through the control system in the selective laser sintering equipment 1;

S6. Set reasonable laser power, spot diameter, and scanning spacing, scanning speed, scanning mode and other parameters in the scanning system 4 in the control system of the selective laser sintering equipment 1, and sinter the powder layer by layer through the laser forming system; the laser power is set to 18W, the spot diameter is set to 0.15mm, the scanning spacing is set to 0.1mm, the scanning speed is set to 1200mm/s, and the scanning mode is set to offset scanning.

S7. According to the calculation, the distribution distance of the glass fiber mesh 6 along the thickness direction of the grinding wheel is designed. After the molding system sintered the powder of a given thickness, a layer of glass fiber mesh 6 was laid on the upper part of the sintered layer 5. The glass fiber mesh 6 consists of an upper mesh 7, a middle mesh 8 and a lower mesh 9. The diameter of the middle mesh 8 is the largest, and the diameters of the upper mesh 7 and the lower mesh 9 are equal and smaller than the diameter of the middle mesh 8. On this basis, the molding procedure of step 6 is repeated to quickly prepare a formed grinding wheel with structural characteristics.

S8. After the structured grinding wheel is sintered, the forming cylinder 3 of the selective laser sintering equipment 1 is cooled to room temperature and taken out, and the excess powder adhered to the surface of the grinding wheel is cleaned with a high-pressure blower to obtain a sintered product.

S9. To ensure that the resin powder is fully cured, the structured formed grinding wheel formed by selective laser sintering is placed in a microwave curing furnace for post-processing. The microwave curing temperature is set to 200°C and the curing time is set to 10 minutes.

This scheme adopts the selective laser sintering 3D printing technology to quickly prepare the structured forming grinding wheel. The geometric model of the structured grinding wheel is established by computer software. The powder material in the target area is sintered according to the contour data of the structured grinding wheel model through the thermal action of the laser beam, and the structured grinding wheel is quickly prepared in a layer-by-layer stacking manner. After the structured grinding wheel is formed, it is reinforced by microwave curing to ensure that the grinding wheel meets the required strength requirements.

The above is only an embodiment of the present invention, and common knowledge such as specific technical solutions or characteristics known in the implementation scheme is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several modifications and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims (7)

1. A method for rapidly preparing a structured forming grinding wheel, characterized in that it comprises the following steps: S1. Pour appropriate amount of abrasive, binder, pore-forming agent and additive powder into a three-dimensional mixer and mix evenly; S2, placing the evenly mixed powder into a vacuum heating machine for drying; S3. Establish a structured forming grinding wheel geometric model in a computer three-dimensional modeling software, modify the grinding wheel geometric model file format to STL and import it into the supporting software of the selected area laser sintering equipment; S4, slicing and layering the imported structured forming grinding wheel geometric model in the supporting software of the selective laser sintering equipment; S5, filling the mixed and heated mixed powder into the powder cylinder of the selective laser sintering equipment, and adjusting the height of the mixed powder in the powder cylinder to be consistent with the height of the substrate in the forming cylinder through the control system in the selective laser sintering equipment; S6. Set reasonable parameters in the control system of the selective laser sintering equipment, and sinter the powder layer by layer through the laser forming system; S7, according to the calculation, the distribution distance of the glass fiber mesh along the thickness direction of the grinding wheel is designed. After the molding system sintered the powder of a given thickness, a layer of glass fiber mesh was laid on the top of the sintered layer, and the molding procedure of step S6 was repeated on this basis, so as to quickly prepare a formed grinding wheel with structural characteristics; S8. After the structured grinding wheel is sintered, the molding cylinder of the selected area laser sintering equipment is cooled to room temperature and taken out, and the excess powder adhered to the surface of the grinding wheel is cleaned with a high-pressure blower to obtain a sintered product. 2. A method for rapidly preparing a structured formed grinding wheel according to claim 1, characterized in that: the abrasive in step S1 is aluminum oxide, the binder is a thermosetting phenolic resin, the pore-forming agent is alumina ceramic hollow balls, the particle size of the abrasive is 100 mesh to 60 mesh, the average particle size of the binder is 90 um, and the average pore size of the pore-forming agent is 200 um. 3. A method for rapidly preparing a structured forming grinding wheel according to claim 1, characterized in that: in step S2, the heating temperature of the vacuum heating machine is 50°C and the heating time is 30 minutes. 4. A method for rapidly preparing a structured formed grinding wheel according to claim 1, characterized in that the layer thickness of the slice is selected according to the abrasive particle size and the pore size of the pore former, and the single layer thickness of the slice is selected from 0.2 mm to 0.5 mm according to the size of the abrasive particle size. 5. A method for rapid preparation of a structured formed grinding wheel according to claim 1, characterized in that: the laser power is set to 18W, the diameter of the spot is set to 0.15mm, the scanning interval is set to 0.1mm, the scanning speed is set to 1200mm/s, and the scanning mode is set to offset scanning. 6. A method for rapidly preparing a structured forming grinding wheel according to any one of claims 1-5, characterized in that: the preparation method further comprises: S9, in order to ensure that the resin powder is fully cured, placing the structured forming grinding wheel formed by selective laser sintering into a microwave curing furnace for post-processing. 7 . The method for rapidly preparing a structured formed grinding wheel according to claim 6 , wherein the temperature of microwave curing in step S9 is set to 200° C. and the curing time is set to 10 min.