JP6006959B2 - Method for forming recess, corner corner finishing method and mold manufacturing method - Google Patents

Description

The present invention relates to a corner corner processing method, and more particularly, to a corner corner processing method included in a closed three-dimensional recess like a mold.

Even in the machining of molds and even general products, it is often necessary to create corners in closed three-dimensional recesses as shown in FIG.
In such a case, conventionally, as shown in FIG. 2, the opposite shape is made by cutting, and the shape is transferred by, for example, electric discharge machining to produce a target rough shape, and further polished. For this reason, the accuracy is not high, and it takes time and effort, and not only the processing efficiency is low, but also the cost is high.

In addition, as an example of a product having a fine and complicated shape, there is a reflector called a reflex reflector. When the reflex reflector is attached to an automobile, etc., the light emitted from the other vehicle is reflected back in the direction of the other vehicle. The car can be informed.
Although this reflex reflector is a molded product produced by an inversion type, it cannot be accurately handled by a mold produced by the above-described electric discharge machining, and as shown in Patent Document 1, many arrow-shaped pins are bundled. In this way, a mold was used which was made into a matrix and subjected to electroforming plating treatment.
However, this method is also prone to manufacturing errors and takes more time than the above-described electric discharge machining.

JP 2005-125649 A

Even when producing the corners, but troublesome if cutting machining efficiency increases not Kakekara can not produce corners below the rotation radius at the cutting by the rotary tool such as an end mill, higher the corners If you want to produce it with precision, you have been reluctantly using the method described above.
The present invention has been made paying attention to the above-mentioned conventional problems, and provides a novel and useful method that can solve the above-mentioned problems by creating a high-precision corner corner while being a cutting method. Is the purpose.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the invention of claim 1 is formed by cutting a closed concave portion constituted by three triangular faces orthogonal to each other and having a ridge line as a corner corner. In the method, using a cutting tool having a cutting edge portion having a V-shaped cutting edge ridge portion, a one-pass relatively continuous with respect to the work material while applying elliptical vibration so as to have a motion component in the cutting direction . Cutting is performed with a bent tool path, one of the three surfaces is formed by the linear cutting edge ridge portion on one side, and two of the three surfaces are formed by the linear cutting edge ridge portion on the other side. In the method of forming a recess, the three surfaces are simultaneously finished by transferring the sweep shape of the contour of the V-shaped cutting edge ridge line by cutting while adjusting to form .
The invention of claim 2 is the method for forming a concave portion according to claim 1, which is the method of forming the recess and forming side by side a plurality of recesses on a plane or a curved surface.

According to a third aspect of the present invention, there is provided a method for finishing a corner portion included in a concave portion closed by cutting, and a work material formed coarsely in advance while applying elliptical vibration so that the cutting tool has a motion component in the cutting direction. towards the corners, by relatively cutting movement, when finishing the angle corner tool paths successively changing the direction of the cutting movement the angle corner, an elliptical vibration plane, cutting direction wherein a plane including the direction of the cut thickness of the workpiece, finishing method of corners, characterized in that the surface between the plane including the ridge line direction of the cutting edge of the cutting direction said cutting tool and It is.
A fourth aspect of the present invention, the finishing method of the corner portion according to claim 3, a finishing method of corners, characterized in that finishing the corners orthogonal.

A fifth aspect of the present invention, the finishing method of the corner portion according to claim 3 or 4, to simultaneously finish the two faces to the ridge line of the corner portion by the feed movement also added feed movement This is a characteristic corner corner finishing method.

The invention of claim 6 is characterized in that, in the corner corner finishing processing method according to any one of claims 3 to 5, the cutting motion is performed while applying an elliptical motion in a direction in which the flank faces away from the cut surface. This is a method for finishing corners .

A seventh aspect of the present invention is a method of manufacturing a mold having a closed concave portion, wherein the method includes the step of forming or finishing the concave portion using the method according to any one of the first to sixth aspects. Is the method.

According to the method of the present invention, it is possible to create a corner portion with high accuracy by cutting, which is not troublesome.

It is an example of the three-dimensional structure manufactured using the finishing method of the corner part of this invention. It is explanatory drawing in the case of manufacturing the three-dimensional structure of FIG. 1 by the conventional method (electric discharge machining). It is explanatory drawing in the case of producing a corner part using the finishing method of a corner part of this invention. It is explanatory drawing of the tool path of the cutting tool in the case of manufacturing the three-dimensional structure of FIG. 1 using the finishing method of the corner part of this invention. It is a perspective view which shows the state immediately after manufacture of one recessed part by the formation method of the recessed part which concerns on embodiment of this invention. FIG. 6 is a five-side view of a cutting edge portion of the cutting tool used in FIG. 5. It is the upper side figure and sectional drawing of the recessed part manufactured in FIG. It is a side view which shows the contact attitude | position of the blade edge | tip part of the cutting tool in manufacture in FIG. 5, and the locus | trajectory of elliptical vibration. It is a perspective view which shows the movement locus | trajectory of the blade edge | tip part of the cutting tool in manufacture in FIG. It is a top view of the metal mold | die of the reflex reflector produced by arranging many recessed parts of FIG. 5 on a plane. FIG. 6 is a side view showing a stage in the middle of manufacturing a mold for a reflex reflector by arranging a large number of recesses in FIG. 5 on a curved surface.

A. As shown in the processing method of a general corners Figure 3 (1), toward the corner portion of the workpiece which has previously been coarsely formed, the cutting processing is given only cutting movement with a cutting tool, the corner At the corner , the cutting speed becomes zero, and at least in the vicinity thereof, the cutting speed is extremely low.
At such a low cutting speed, the friction force generated between the chip and the tool rake face or between the finished surface and the tool flank face has a drooping characteristic (characteristic that the friction force decreases as the speed increases). Therefore, it is known that frictional vibration (including stick-slip) that is one of self-excited vibrations is likely to occur. When this vibration occurs, the corners cannot be created with high accuracy. However, in the present invention, cutting is performed while applying minute high-frequency elliptical vibration (including circular vibration) indicated by a curve in the drawing so that the cutting tool A has a motion component in the cutting direction, so that the cutting edge always has a vibration speed. Therefore, the actual cutting speed does not become zero or extremely small. Therefore, the problem of frictional vibration does not occur.

  Also, at such a low cutting speed, the new surface of the work material that has just separated and the tool surface tend to adhere due to the combination of the work material and the tool material, and the finished surface may peel off or the tool surface may peel off. Cause problems. However, in the present invention, since the cutting edge always has a vibration speed as described above, the adhesion phenomenon hardly occurs. In addition, by increasing the maximum vibration speed in the cutting direction from the cutting speed (apparent average speed), the tool is detached from the work material at each vibration cycle, so the new surface of the work material becomes dirty with air or cutting oil. It is considered that the chemical activity is reduced and adhesion is suppressed.

In addition, by making the vibration trajectory not an straight line but an ellipse, in the plane including the cutting direction and the cutting thickness direction, at the moment of cutting, the tool has a speed in the chip discharge direction relative to the tool, The frictional force that prevents the chip from flowing out is not generated, and the chip outflow can be promoted. In addition, in the plane including the cutting direction and the ridge line direction of the cutting edge, at the moment of cutting, the speed of the so-called cutting direction is given, so that the chip can be generated and cut easily so that it is easy to cut while pulling with a knife. Emission can be promoted. In practical (that is, three-dimensional) corner corner processing, by setting the elliptical vibration surface between the two surfaces, an intermediate effect between them can be obtained. Compared to the case where vibration is not added, chip generation and discharge are greatly facilitated.

  Note that the phase relationship between the vibration in the cutting direction and the vibration in the cutting thickness direction is not the direction in which the finished surface is crushed by the flank, but the flank (not necessarily a single plane, but two in practical cutting). The above-mentioned plane or curved surface (all these surfaces) can be mirror-finished by adjusting so that the elliptical motion of all these surfaces always away from the finished finished surface.

Further, as shown in FIG. 3B, the corners can be finished with a continuous tool path by changing the direction of the cutting motion.
Before and after the cutting direction suddenly changes at the corners , the rake angle and clearance angle of the tool with respect to the cutting direction change greatly. In front of the corner, the rake angle is large (on the positive side) (the blade is sharp), so that the cutting resistance is small, and chip generation and discharge are easy. On the other hand, after the corner , the rake angle is small (absolute value on the negative side is large and the blade is dull), so the cutting resistance is large and it becomes difficult to generate and discharge chips. Depending on the material and the shape of the tool, it may be impossible to generate and discharge chips.
In addition, the back component force (the direction of the cutting thickness, the component in the direction of cutting and the direction perpendicular to the cutting edge) increases especially after the corners , so deformation of the work material and tools, the mechanical structure that supports them, etc. It becomes impossible to realize a desired cut-out, resulting in problems that a desired shape cannot be created and a tool is lost. In difficult-to-cut materials such as mold steel, it is practically impossible, and even if it is not possible, the finished surface properties after the corners deteriorate (problems such as swell and whip).
However, in the present invention, since elliptical vibration is given, even if the cutting direction changes, the relative vibration trajectory relative to the vibration direction hardly changes, and the vibration effect with respect to the cutting direction can be enjoyed as it is. By promoting this, the back force is reduced, machining errors and flash problems due to deformation are greatly reduced, and highly accurate corners can be created.
In addition, when the tool is detached from the work material with the tool posture immediately after the corner corner, there may be a problem that the so-called exit beam becomes large. The back force is reduced, and machining errors and flash problems due to deformation are greatly reduced.

When a part of the locus of elliptical vibration is transferred to the machining shape and remains, a slight roundness remains at the corner, but unlike when rotating an end mill tool or the like with a radius of (sub) millimeter order. Thus, the amplitude of the elliptical vibration can be set to a minute dimension on the order of micrometers, and does not become a problem as a corner of a general product (including a mold).
In addition, since the frequency of elliptical vibration generally uses the high frequency in the ultrasonic region, a relatively large mechanical structure cannot respond, and as a result, hardly deforms, so that the machining accuracy is not adversely affected. .

As described above, if the finishing method of the present invention is used, by using this elliptical vibration, it has succeeded in producing a corner corner with high accuracy by cutting a plurality of tool paths or a continuous tool path. . The elliptical vibration is described in Japanese Patent No. 3500344, and is generated on the micron order using ultrasonic waves.

In the machining according to the present invention, if a feeding motion is added to the above-described cutting motion, two surfaces having corners as ridge lines can be simultaneously finished .
For example, as shown in FIG. 4, the three-dimensional shape shown in FIG. 1 is fed with a feed motion (a plurality of tool paths along contour lines or a tool path connected in a spiral shape) in addition to the cutting motion. By giving, the surface of the shape along the feed movement can be finished . In FIG. 4, when each tool path is viewed in the ridge line direction, cutting is performed as shown in FIG. Since the finished surface is formed by transferring the shape of the cutting edge of the tool in the feed movement direction, as shown in FIG. If a plane can be created and the feeding motion is curved using an R bite, a curved surface can be created as shown in FIG. This is the same as in the case of open three-dimensional cutting.

B. Reflex reflector mold manufacturing example
According to the method for forming a recess according to the present invention, it is possible to create a highly accurate corner portion as the sweep shape by transferring the shape of the tool edge as it is.
Therefore, as an example, a manufacturing example of a reflex reflector mold manufactured by finishing three surfaces simultaneously with one continuous tool path will be described below.

FIG. 5 shows a state immediately after the formation of one closed recess 3 in the metal body 1 having a flat block-like upper surface. In this recess 3, three triangular surfaces 5, 7, 9 that are orthogonal to each other are configured as mirror surfaces, and the ridges between adjacent surfaces of the three surfaces 5, 7, 9 become corner corners 11, 13, 15. ing.
The recess 3 is formed by cutting with a cutting tool 21.

As shown in FIG. 6, a rake face 23 is formed at the cutting edge of the tip of the cutting tool 21. The rake face 23 is a flat surface in which main cutting edge ridge lines 27 and 29 extending in a V shape from the tip 25 are present on both sides, and a flank face sandwiching the inclined ridge line 31 on the lower surface of the tool. 33 and 35 are formed.
The shape of the cutting edge portion of the cutting tool 21 corresponds to the concave portion 3 formed in the metal body 1 shown in FIG. 7, and the cutting edge where the main cutting edge ridge line portions 27 and 29 intersect as shown in a partial cross-sectional view thereof. The angle α corresponds to the groove angle θ (0), the inclination angle β of the main cutting edge ridge line portion 27 corresponds to the inclination angle θ (1) of the surface 5 on one side, and the inclination angle of the main cutting edge ridge line portion 29. γ corresponds to the inclination angle θ (2) of the other surfaces 7 and 9.

  As shown in FIG. 8, the cutting tool 21 is held in a posture with respect to the metal body 1. In this posture, a clearance angle ε is formed on the rear side in the traveling direction. In the posture described above, ultrasonic elliptical vibration as shown by an arrow is given to the cutting tool 21. This elliptical vibration surface is a surface between a surface including the cutting direction and the direction of the cutting thickness and a surface including the cutting direction and the ridge line direction of the cutting edge. Further, the elliptical vibration surface has a direction in which the flank surfaces 33 and 35 are separated from the cut new surface.

When the tip 25 of the cutting edge of the cutting tool 21 is fed into the metal body 1 and advanced while maintaining the above posture, the main cutting edge ridge line 27, the leading edge 25, and the main cutting edge ridge line 29 are continuous. The finished contour is transferred to the metal body 1.
The tool path P indicated by the arrows in FIGS. 5 and 7 is capable of continuous one-pass (one-stroke writing). When the cutting tool 21 is advanced along the tool path P, as shown in FIG. The sweep shape which is the movement trajectory of the contour is created as the concave portion 3.

A ridge line portion is created by the movement trajectory of the contours of the leading edge portion 25 of the blade edge portion and the main cutting edge ridge line portions 27 and 29 sandwiching it. This ridge portion becomes the corner portions 11 and 13 of the recess 3.
Since the main cutting edge ridge line portion 27 is set to exist on the surface including the tool path P, one surface 5 is created by the movement trajectory of the contour. Further, since the main cutting edge ridge line portion 29 intersects the surface including the tool path P and the tool path P is bent, two surfaces 7 and 9 are created by the movement trajectory of the contour. A corner 15 is created at the ridge between 7 and 9.
Therefore, in the recessed part 3, the triangular three surfaces 5, 7, and 9 orthogonal to each other are created, and each ridgeline is a corner part. The created three surfaces 5, 7, and 9 are mirror surfaces, and no “polishing” that causes errors is required.

In addition, although the recessed part 3 is manufactured by one cutting in the above, the frequency | count is not limited. Therefore, when it is desired to deepen the concave portion 3, the tool may be fed little by little in the depth direction of the concave portion 3 and processed by a plurality of times of cutting (a plurality of tool paths).
Further, even if the three surfaces are not finished at the same time, as shown in FIG. 3 (1), the surfaces may be divided into three times, and after the two surfaces are finished as shown in FIG. Only the second side may be finished.

When a large number of the recesses 3 are arranged, a reflex reflector mold 37 as shown in FIG. 10 is obtained.
The mold 37 shown in FIG. 10 above is one in which a retroreflective shape of an orthogonal trihedron is created on the plane of the metal body 1, but the tool posture of the cutting tool 21 is tilted as shown in FIG. It is possible to create a free-form surface by proceeding to.

The embodiment of the present invention has been described in detail above. However, the specific configuration is not limited to this embodiment, and the present invention can be changed even if there is a design change without departing from the gist of the present invention. included.
For example, in the above-described embodiment, the workpiece is not limited to a metal body and may be any material that can be cut, such as an amorphous Ni-based coating layer or glass, and further, a cemented carbide or SiC. Ceramics are also included.

The method of the present invention is particularly suitable for implementation in the mold manufacturing industry where a high degree of accuracy is required.

DESCRIPTION OF SYMBOLS 1 ... Metal body 3 ... Recessed 5, 7, 9 ... Surface 11, 13, 15 ... Corner corner 21 ... Cutting tool 23 ... Rake face 25 ... Tip part 27, 29 ... Main cutting edge ridgeline part 31 ... Ridge line part 33, 35 ... Flank α ... Cutting edge angle β, γ ... Tilt angle ε ... Flank angle θ (0) ... Groove angle θ (1), θ (2) ... Tilt angle

Claims (7)

In the method of forming a closed recess by cutting, which is composed of three triangular faces orthogonal to each other and the ridge line is a corner ,
Using a cutting tool having a cutting edge portion provided with a V-shaped cutting edge ridge line portion ,
While applying elliptical vibration so as to have a motion component in the cutting direction, the cutting motion is performed with a continuous one-pass bent tool path relative to the work material,
Cut while adjusting so that one of the three surfaces is formed by the linear cutting edge ridge portion on one side and two of the three surfaces are formed by the linear cutting edge ridge portion on the other side With that
A method of forming a recess , wherein the three surfaces are simultaneously finished by transferring the sweep shape of the contour of the V-shaped cutting edge ridge line portion. In the formation method of the recessed part described in Claim 1,
A method for forming a recess, wherein a plurality of recesses are formed side by side on a plane or curved surface. In the finishing method for corners included in the recesses closed by cutting,
While applying elliptical vibration so that the cutting tool has a motion component in the cutting direction, the cutting tool is relatively moved toward the corners of the work material that is formed roughly in advance.
When finishing the angle corner tool paths successively changing the direction of the cutting movement the angle corner,
The elliptical vibration surface is a surface between a surface including a cutting direction and a cutting thickness direction of the work material, and a surface including a cutting direction and a ridge line direction of a cutting edge of the cutting tool. Corner corner finishing method. In the corner corner finishing processing method according to claim 3,
A corner corner finishing method characterized by finishing corner corners orthogonal to each other. In the corner corner finishing method according to claim 3 or 4,
A corner corner finishing method characterized in that, in addition to a feed motion, two surfaces having a corner corner as a ridge line are simultaneously finished by the feed motion. In the corner corner finishing processing method according to any one of claims 3 to 5,
A corner corner finishing method, characterized in that a cutting motion is performed while an elliptical motion is applied in a direction in which the flank faces away from the cut surface. In a method for manufacturing a mold having a closed recess,
The manufacturing method of a metal mold | die provided with the process of forming or finishing the said recessed part using the method as described in any one of Claim 1 to 6.