KR20070116333A - Abrasive blasting machine for cutting tool - Google Patents

Abstract

A magnetic abrasive polishing machine for a cutting tool is provided to perform precise polishing of 3-dimensional compound shapes and to polish a workpiece having complex shape, since a magnetic abrasive arranged linearly to a line of magnetic force compresses and polishes the workpiece by magnetic force. A magnetic abrasive polishing machine for a cutting tool comprises a driving motor(10), a multi-head(12), a vessel(16), and a magnet(14). The driving motor generates a predetermined driving force. The multi-head receives driving force from the driving motor for up/down reciprocating movement while rotating, and is provided with a chuck(12a) for clamping the cutting tool. The container is disposed below the multi-head and charged with a magnetic abrasive(18) mixed with magnetic fluid and abrasive media. The magnet is respectively disposed on opposite sides of the vessel, having a predetermined space therebetween, and forms a magnetic field.

Description

Abrasive blasting machine for cutting tool for improving performance of cutting tools

1 is a view schematically showing a process in which a workpiece is polished by a magnetic abrasive material in which magnetic fluid and abrasive particles are mixed under a constant magnetic field according to the present invention.

FIG. 2 is a diagram schematically showing a force acting on the magnetic abrasive shown in FIG. 1; FIG.

Figure 3 (a) is a view showing the arrangement of the magnetic abrasive material when there is no magnetic field according to the present invention.

Figure 3 (b) is a view showing the arrangement of the simple mixed magnetic abrasive material under the magnetic field according to the present invention.

Figure 4 is a side view showing the configuration of a magnetic polishing device for improving the performance of the cutting tool according to an embodiment of the present invention.

FIG. 5 is a front view showing the self-polishing apparatus shown in FIG. 4. FIG.

FIG. 6 is a view showing an essential part of the self-polishing apparatus shown in FIG. 4. FIG.

Figure 7a is a graph showing the change in the polishing force according to the intensity of the magnetic flux density in the magnetic polishing device of the present invention.

Figure 7b is a graph showing the change in the polishing force according to the size of the abrasive grains in the self-polishing apparatus of the present invention.

Figure 7c is a graph showing the change in the polishing force according to the blending ratio in the self-polishing apparatus of the present invention.

8 is a view showing the position of the scanning electron microscope photographing surface of the end mill for presenting an example for examining the surface change of the workpiece polished by the self-polishing apparatus of the present invention.

FIG. 9A is a view showing the surface of an end mill not self-polishing in FIG. 8; FIG.

FIG. 9B is a view showing the surface of the end mill self-polishing in the reverse direction while moving up and down in FIG.

9C is a view showing the surface of the end mill self-polishing only in the reverse direction without the vertical movement in FIG.

FIG. 9D is a view showing the surface of the end mill self-polishing in the forward direction while moving up and down in FIG. 8.

FIG. 9E is a view showing the surface of the end mill self-polishing only in the forward direction without vertical movement in FIG. 8.

10 is a graph showing the tool life (finishing conditions) for each type of tool according to the present invention.

<Description of the symbols for the main parts of the drawings>

10: drive motor 12: multihead

12a: chuck 14: magnet

16: Courage 18: Magnetic Abrasive

100: self-polishing device A: workpiece

The present invention relates to a surface polishing apparatus of a cutting tool, and more particularly, to a magnetic polishing apparatus that can improve the performance of a cutting tool by improving the surface of the cutting tool using a magnetic polishing technique.

As is well known, in order to manufacture various industrial parts, mechanical processing of molds (forging, extrusion, drawing, injection), which directly process (for example, cutting, cutting, grinding, drilling, etc.) or forming the shape You have to shave. Therefore, the precision of the part depends on the precision at the time of the direct machining or the mold machining, and the machining precision depends on the performance of the tool used.

In order to improve the performance of cutting tools, research has been conducted to improve the performance of tools in various directions, such as the development of tool materials, the development of tool shapes, and the development of coating methods. Currently, a new technology for improving the performance of cutting tools is related to the improvement of surface roughness of the tool, and there is a research report that the tool life is improved by 100% only by improving the surface roughness of the tool without changing the material and shape of the tool.

On the other hand, the method of improving the surface roughness of the cutting tool should add the final polishing process when machining the tool, and due to the three-dimensional complex shape of the cutting tool, the machining by the grinding wheel (fixed particles) has a limitation in improving the surface roughness, and the glass particles Polishing is a difficult process due to the shape of the cutting tool. Therefore, a new machining technology that can improve the surface roughness of the cutting tool is required.

Currently, research related to cutting tools is mainly focused on end mill performance evaluation for preparing basic data and manufacturing guidelines for high speed machining. Study on the shape of the end mill during cutting, that is, the tool inclination angle and clearance angle, the effect of the cutting edge length and cutting speed on the cutting behavior of the tool, and the change of the tool shape by measuring the cutting force and tool wear in high speed machining (Helix angle, Tool shape and tool grades, such as the study of the change of tool wear according to the number of blades and the inclination angle, the measurement of cutting force and tool wear during cutting using the end mill of ultrafine cemented carbide material, and the surface roughness according to the tool wear. The research on the tool performance by the tool coating is actively conducted. Therefore, it is necessary to identify the relationship between the surface roughness of the cutting tool and the tool performance, and further improve the tool performance by improving the surface roughness of the cutting tool.

On the other hand, cutting tools such as end mills consist of three-dimensional curved surfaces, making it difficult to mirror the surface by conventional grinding or polishing processes. Therefore, it is necessary to develop new polishing techniques for mirror polishing of complex three-dimensional shapes.

Referring to the above points, the conventional surface polishing method of the cutting tool is no longer a method for improving the performance of the cutting tool, a more direct and efficient surface polishing method is urgently required.

In order to satisfy the requirements as described above, the present invention improves the surface of a cutting tool by using a magnetic polishing technology to provide a magnetic fluid movement condition setting and magnetic polishing device for improving cutting tool performance.

In addition, the present invention provides a magnetic polishing apparatus in which magnetic abrasive materials arranged linearly along a magnetic force line are pressed while polishing a workpiece by magnetic force.

In addition, the present invention provides a self-polishing apparatus for improving the performance of the cutting tool that can grind the workpiece of severe irregularities and complex shape.

The present invention also provides a self-polishing device for improving the performance of the cutting tool that can improve the life of the tool compared to the conventional cutting tool.

In view of achieving the above, the present invention is a drive motor for generating a predetermined driving force, a multi-head is installed to the chuck that the cutting tools bite up and down while rotating and receiving the driving force of the drive motor, Located at the bottom of the multi-head is a container filled with a magnetic abrasive material mixed with magnetic fluid and abrasive particles, and the cutting tool consisting of a magnet which is installed on both sides while maintaining a constant interval with the container to form a magnetic field to improve the performance A self-polishing device is proposed.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. In the following description will be presented a representative embodiment in the present invention to achieve the above technical problem. And other embodiments that can be presented with the present invention replace the description in the configuration of the present invention.

Meanwhile, the term 'workpiece' used in the present invention is not only a conventional cutting tool (or tool) but also a cutting tool having a three-dimensional complex shape such as an end mill, and an ultra-precision field of a three-dimensional complex shape (for example, Friction material, injection mold, etc.). Therefore, the terms such as a workpiece or cutting tool, a tool, an end mill, a cutting tool having a three-dimensional complex shape to be used (marked) below will all be understood to mean "workpiece (A)".

In the present invention, the magnetic fluid (for example, Ferrofluid) and abrasive media (for example, diamond, etc.) mixed in a specific ratio of the flow type magnetic abrasive material is arranged in a magnetic flux direction in a magnetic flux density It is intended to improve the performance of cutting tools by grinding the surface of cutting tools by self-polishing method that rotates and reciprocates the workpiece.

To this end, the present invention designed and manufactured a self-polishing device, and studied the polishing characteristics of the cemented carbide round bar used as a material of the cutting tool with the developed self-polishing device, and also the tool performance by self-polishing the cutting tool based on the result Was evaluated.

On the other hand, in the magnetic polishing to be implemented in the present invention using a magnetic abrasive comprising a magnetic fluid and abrasive particles as a component, the magnetic abrasive material arranged in a linear line along the lines of magnetic force, while polishing the workpiece (cutting tool) by the magnetic force It is a processing method. In this way, the magnetic polishing method is different from the conventional method using a grinding tool, so that the magnetic abrasive material is pressed while processing the unevenness of the workpiece, it is effective to remove or burr the three-dimensional free-form surface, cylindrical workpiece, pipe inner pipe, etc. to be. At this time, the magnetic abrasive material has a form in which the magnetic fluid and the abrasive particles are simply mixed with the metallized form, and in the present invention, a simple mixed magnetic abrasive material is used.

In addition, the magnetic polishing device proposed in the present invention, as shown in Figure 1, by placing two magnets of different polarities on both sides of the workpiece to generate a magnetic force, the magnetic force generated at this time is transmitted to the magnetic abrasive material to compress the workpiece do. The workpiece is then rotated and vibrated up and down to polish the magnetic abrasive material and the workpiece relative to each other.

In this case, a force acting on the magnetic abrasive is shown schematically in FIG. 2. In FIG. 2, the magnetic force plays a role in polishing. Under the magnetic field, one magnetic particle receives a force Pa of the magnetic force Px in the direction of the magnetic field line and the magnetic force Py in the direction of the isotropic line. At this time, the force that the magnetic particles compress the abrasive particles is Pb which is the component force of the force Pa of the magnetic force. The main component force Ph and the distribution force Pv which are components of the said Pb should just be able to adjust a magnetic force for grinding | polishing. However, the magnetic force is expressed by the polishing pressure through the magnetic abrasive material. Since the magnitude of the magnetic force that the particles receive under the magnetic field varies depending on the type of magnetic abrasive material, that is, the magnetic particles, how much force the actual magnetic particles receive under the magnetic field. It is necessary to control the appropriate amount of polishing pressure.

As seen above, the particles are not ground simply by pressing the workpiece. In the compressed state, the abrasive particles must have relative motion between the workpieces. In addition, if the relative motion is monotonous, polishing traces may be left, and the efficiency of polishing may be reduced, and thus, the movement should be as complex as possible. To this end, in the present invention, first, the workpiece is rotated so as to be continuously polished, and second, the workpiece is moved up and down to have a complicated polishing trajectory.

In addition, Figure 3 (b) is a view showing the arrangement of the simple mixed magnetic abrasive material under the magnetic field, the magnetic particles are arranged in the direction of the magnetic field while the abrasive particles are arranged in the same direction. This is significantly different from that in which magnetic particles and abrasive particles are simply mixed in the absence of a magnetic field as shown in FIG. 3 (a), and the workpiece is subjected to polishing force and surface polishing is performed by this arrangement.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

4 to 6 is a view showing the configuration of the surface polishing apparatus for improving the performance of the cutting tool according to an embodiment of the present invention. The polishing apparatus of the present invention is a magnetic polishing apparatus 100 for polishing a surface of a cutting tool by using a magnetic abrasive material 18, including a drive motor 10, a multihead 12, a magnet 14, and a container 16. And a magnetic abrasive material 18 composed of a magnetic fluid and abrasive particles.

Referring to the drawings, the drive motor 10 is rotated to 1800rpm using a servo motor to adjust the speed by installing an inverter to derive the experimental results according to the rotation speed. In addition, a limit switch (not shown) was installed to enable automatic up / down reciprocation. At this time, the rotation speed of the drive motor 10 can be adjusted at any time according to the type of the workpiece (A).

The multihead 12 is a conventional device that constitutes a chuck 12a capable of biting the work A (ie, a cutting tool such as an end mill), and fixes the work A to the multihead 12. In order to simultaneously perform the polishing process, the container 16 is designed in consideration of the flow distance of the apparatus and the polishing depth of the work piece A, which is intended to achieve the maximum polishing effect with the minimum volume. At this time, the multi-head 12 is made to perform the up / down reciprocating motion while rotating in the state in which the workpiece (A) is fixed. That is, the multihead 12 is installed in the screw guide 22 by the bracket 20, the motor 24 is assembled to the screw guide 22, the screw in accordance with the driving force of the motor 24 When the guide 22 is operated, the multihead 12 reciprocates up and down. At this time, the multihead 12 rotates at a constant speed by the driving force of the driving motor 12.

The magnets 14 forming the magnetic field are provided with two types of permanent magnets or electromagnets, each centered around the work piece A, so that the N poles and the S poles face each other. At this time, the electromagnet was made to be able to adjust the distance, it was possible to determine the strength of the magnetic field by adjusting the amount of current. In addition, the permanent magnet is installed to guide the number of permanent magnets can be adjusted by installing a guide, it is manufactured to be removable when not applied. That is, each of the magnets 14 is fixed to the bracket 26, the bracket 26 is installed in the screw guide 28, the handle 30 is installed at one end of the screw guide 28 If the handle 30 is selectively rotated in the left / right direction, the bracket 26 is moved left / right along the screw guide 28, so that the distance between the magnets 14 can be adjusted. do.

The vessel 16 contains a mixed solution (i.e., magnetic abrasive 18) in which magnetic fluid and abrasive grains are mixed, and is installed between the magnet 14 and the magnet 14 to provide a workpiece A. Polish. At this time, the container 16 has a connecting shaft 32 is attached to the bottom surface, as shown in Figures 5 and 6, the connecting shaft 32 is provided with a link 34, the end of the link 34 A bracket 36 is attached to the portion, and the bracket 36 is assembled to the motor 38. The container 16 configured as described above moves in the front / rear direction by the driving force of the motor 38.

That is, when the workpiece A, which is held by the chuck 12a of the multihead 12, enters the container 16, a magnetic force is generated in each magnet 14 installed on both sides of the container 16. Magnetic particles arranged along the lines of magnetic force arrange the abrasive particles as a chain, and the arranged abrasive particles compress the work A to perform the rotation of the multihead 12 and the up / down reciprocating motion. The work piece A is polished. At this time, the magnetic flux density acting inside the container 16 is uniformly formed, and the magnetic fluid and the array of abrasive particles are uniformly formed.

Magnetic abrasive material 18 is composed of a magnetic fluid and abrasive particles, as seen above, in the present invention, a simple mixed magnetic abrasive material was used. The magnetic fluid 18 is a colloidal dispersion in which several micro-sized particles that are sensitive to magnetism such as iron (iron) are dispersed in a liquid solution. When the magnetic field is applied from the outside, the dispersion is in the direction of the magnetic field. Along the flow. At this time, Ferrofluid is generally used as the magnetic fluid, and the abrasive particles are mainly used as diamond powder or Green Silicon Carbide Powder (hereinafter referred to as "GC particles").

For reference, the GC particles are particles having green color due to impurities of colorless hexagonal plate crystals, and have a melting point of 2700 ° C. or more, sublimation at 2200 ° C., and a solidity between ruby and diamond. It is extremely stable and hardly soluble in water or acid.

In the above description, the physical characteristics of the magnetic abrasive material, the general conditions for self-polishing the surface of the cutting tool using the magnetic abrasive material, the method of self-polishing the surface of the cutting tool and the magnetic polishing apparatus used in the method The configuration has been described. In the following, the change of the most important factor (i.e., the polishing force acting between the abrasive grain and the workpiece) that is directly related to the polishing performance is examined according to the movement conditions of the magnetic abrasive, and then the surface of the workpiece is magnetized using the magnetic polishing apparatus of the present invention. The surface change of the workpiece and the performance evaluation of the self-polished workpiece should be described in detail.

One. Variation of Abrasive Force by Kinetic Conditions of Self-polishing Materials

7A to 7C are graphs illustrating a change in polishing force according to polishing conditions in the self-polishing apparatus 100 of the present invention described above.

That is, in Figure 7a shows the relationship between the magnetic flux density and the polishing force according to the number of rotations, the larger the magnetic flux density, the higher the polishing force, which means that as the magnetic flux density increases, the chain coupling of the magnetic fluid becomes harder, This is because the viscosity of the abrasive particles fixed between the chain bonds increases.

In addition, Figure 7b shows the relationship between the size of the abrasive particles and the polishing force according to the number of revolutions. As shown in FIG. 7B, the smaller the size of the abrasive particles, the higher the polishing force tends to be. This means that the smaller the size of the abrasive particles, the greater the number of abrasive particles acting on the polishing surface.

And in Figure 7c shows the relationship between the blending ratio and the polishing force according to the rotation speed. As shown in FIG. 7C, the smaller the blending ratio, the greater the polishing force. As the amount of abrasive grains, which is an element that interferes with the chain bonding of the magnetic fluid, is reduced, the bonding force between the magnetic fluids becomes stronger, and this force becomes a work ( This is because it acts as the friction force of A). When the blending ratio is large, impurities (polishing particles) which interfere with the chain bonding between the magnetic fluids are increased, thereby decreasing the bonding strength between the magnetic fluids, which in turn leads to a decrease in the indentation force of the abrasive particles, thereby reducing the actual polishing power.

2. Surface change of end mill (workpiece) by self-polishing

The surface change of the flank plane and the crater plane of the end mill is scanned when the workpiece A (hereinafter referred to as "end mill") is self-polished using the self-polishing apparatus 100 of the present invention. Each was observed with an electron microscope. The position of the flank and crate surface of the end mill is shown in Figure 8, the observation results are shown in Figures 9a to 9e.

That is, Figure 9a is a surface photograph of the end mill not self-polishing, Figures 9b to 9e are end mills which are self-polishing for 30 minutes, respectively, and self-polishing was carried out with a difference depending on the rotation direction and the vertical movement in the self-polishing conditions. In addition, Figure 9b shows the end mill surface when the vertical motion in the reverse rotation, Figure 9c shows the surface of the end mill does not move up and down in the reverse rotation. 9D illustrates the surface of the end mill when vertical movement is performed in the forward rotation, and FIG. 9E illustrates the surface of the end mill without vertical movement in the forward rotation.

As seen above, the surface of the polished end mill was better than that of the unmilled end mill, and the polished surface was different according to the polishing method. In the case of self-polishing in the reverse direction as shown in Figs. 9b and c, the flank was well polished, and the crate was hardly polished. In addition, in the case of self-polishing in the forward direction as shown in FIGS. 9D and 9E, the flank and crate surfaces were polished at the same time, but the polishing effect of the flank surface was inferior.

3. Performance Evaluation of Self-polishing Tool

As a result of evaluating the performance of the tool self-polishing by the self-polishing apparatus 100 of the present invention according to the cutting conditions and polishing conditions, the performance of the tool polished for 30 minutes while rotating in the forward direction and vertical movement was good, and finished rather than roughing conditions It was confirmed that the performance of the tool is excellent when cutting under the conditions. And quantitatively evaluate the degree of performance improvement as shown in FIG.

10 is a graph showing the cutting period until the tool wear reaches 0.1 mm and 0.2 mm, respectively, when the flat end mill is cut under the finishing conditions. The tool life is improved compared to unpolished tools. Therefore, it is possible to improve the tool performance by improving the surface of the cutting tool by self-polishing technology.

As described above, in the present invention, by using the self-polishing technique, the three-dimensional composite shape can be polished precisely, and the tool life can be improved by merely improving the tool surface without changing the shape and coating of the cutting tool. There is an advantage. In addition, the surface shape of the cutting tool can be improved, and it is effective to be applied to ultra-precision fields (friction surfaces and injection molds of various machines) of three-dimensional complex shape.

Claims (6)

In the apparatus for polishing the surface of the cutting tool, A drive motor 10 generating a predetermined driving force; A multihead 12 having a reciprocating up and down movement while receiving and receiving a driving force of the driving motor 10, and having a chuck 12a biting the cutting tools; A container 16 positioned below the multihead 12 and filled with a magnetic abrasive material 18 in which magnetic fluid and abrasive particles are mixed; Self-polishing apparatus for improving the performance of the cutting tool, characterized in that it is installed on both sides while maintaining a predetermined interval with the container (16), and comprises a magnet (14) to form a magnetic field. The method of claim 1, The magnetic fluid is a magnetic polishing device for improving the performance of the cutting tool, characterized in that the Ferrofluid. The method of claim 1, The abrasive particles are self-polishing apparatus for improving the performance of the cutting tool, characterized in that the diamond powder or Green Silicon Carbide Powder. The method according to any one of claims 1 to 3, The multihead 12 is installed in the screw guide 22 by the bracket 20, the motor 24 is assembled to the screw guide 22, the screw guide 22 in accordance with the driving force of the motor 24 The multi-head 12 according to the operation of the magnetic polishing device for improving the performance of the cutting tool, characterized in that the up / down reciprocating motion. The method according to any one of claims 1 to 3, Each of the magnets 14 is fixed to the bracket 26, the bracket 26 is installed in the screw guide 28, the handle 30 is installed at one end of the screw guide 28 is Magnetic polishing apparatus for improving the performance of the cutting tool, characterized in that for moving the magnet 14 in the left / right direction. The method according to any one of claims 1 to 3, A connecting shaft 32 is attached to the bottom of the container 16, a link 34 is installed on the connecting shaft 32, and a bracket 36 is attached to an end of the link 34. Bracket (36) is a self-polishing device for improving the performance of the cutting tool, characterized in that assembled to the motor (38) to move the container (16) in the forward / rearward direction.

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