JPH11509899A - Rotating bit for cutting and its cutting method - Google Patents

Abstract

(57) Abstract: A cutting self-rotating and self-polishing tool has a substantially circular rotary cutting element (2). It is mounted and arranged such that the angle of attack of the cutting element (2) is between 90 ° and 120 ° and the skew angle is between 5 ° and 40 °. The cutting element (2) is convex on the front side and has a clearance angle and a rake angle that vary along the periphery of the cutting edge.

Description

Detailed Description of the Invention Rotary Bit for Cutting and Cutting Method Thereof The present invention relates to a structure of a rotary cutting bit that can be used for processing and that can be installed in a device intended for cutting and pulverizing the above-mentioned materials, and a cutting method therefor. BACKGROUND ART In general, the mechanism of the cutting process is as shown in FIG. A material such as rock is cut by the thrust force T and the normal component C _n of the cutting force generated when the device is driven. Under the action of these forces, the tool moves horizontally and vertically simultaneously, creating complex stresses that are greater than the resistance of the rock.

Compressive stresses occur inside the rock when the force C _n acts distributed on the front face of the bit.

This compressive stress is insufficient to fracture the rock, but the preload causes the rock to It won't distort any more.

High level of load density produced by the bit cutting edge when force T is applied Therefore, shear stress occurs inside the rock. Such shear stress can cause brittle materials to A crushing crack occurs and spreads.

At the same time, forces C _n and T create a stressed area in the over-pressurized rock adjacent to the bit cutting edge. This is the so-called core pressure accumulation, and this pressure accumulation is released in the form of an explosion when the maximum resistance of the rock is exceeded.

Fragmentation cracks, as previously mentioned, tend to initially go to the open face of the rock, since they progress from the cutting edge to the point of least resistance. However, these cracks cannot circumvent the portion of the rock that has been compressed by C _n and has increased resistance. Thus, a crushing crack passes around the compressed portion of the rock and reaches an open face at a distance L from the front face of the bit, separating the stressed portion of the rock and dropping this fragment from the entire rock mass. .

Covers insufficient cracks under continuous simultaneous action of compressive stress and shear stress. Once enough energy has been accumulated to Fragments of the whole rock or almost the whole rock are removed from the bedrock one after another by the explosion.

An efficient rock cutting process therefore concentrates a large amount of load on the cutting edge of the bit. You have to keep it in the middle. The normal force T is the narrow force between the rock and the bit cutting edge. Only the contact line is acted on, so a large concentrated load results in a positive relief angle of the bit. obtained by δ. Even relatively small wear in the area of line contact Line contact is very important as the cutting capacity drops off sharply. This contact area If the width of the The occurrence of cracks is also greatly restricted.

Efficient cutting edges require high cutting power and high durability of the cutting element, resistance to excessive loads Reliable protection, maintaining a positive bit clearance angle, and other initial parameters maintaining torque is optimally combined throughout the life of the cutting edge. must be

Several tools have been developed with the aim of achieving some of the qualities mentioned above. is

A first rock breaking tool group consists of cutting bits with non-rotating cutting elements. Become. U.S. Pat. No. 1,174,433 discloses a non-rotating cutter with a convex front face. It is shown. However, the rake angle of this cutter is positive. i.e. long The angle (defined as the angle of attack) between the hand axis and the cutting (worked) surface behind the bit is less than 90°. The cutting edge of this tool is short, with a positive rake angle and a small included angle. Book Compared to the invention, the bit has low durability and wear resistance, soft and abrasive It can only be used to break loose rocks.

U.S. Pat. Nos. 4,538,691 and 4,678,237 disclose that the front The flat rake angle is substantially negative, preventing the bit from over-loading due to the action of lift forces. A non-rotating cutting tool having protected rock breaking elements is disclosed. but However, the bits described here have low cutting power and require large thrusts to penetrate rock. need power. The attack angle of this bit is less than 90°.

U.S. Pat. Nos. 4,538,690, 4,558,753 and 4, No. 593,777 has a concave front face and a bit A large negative rake angle is used for increased durability (including protection from excessive loads). A non-rotating cutting bit is disclosed having rock-breaking elements arranged closely together. there is However, this bit also has poor cutting and penetrating power. This bit It is positioned at an angle of attack of less than 90°.

A second group of patented rock breaking tools has symmetrical cutting elements. , consisting of a round bit rotatable about its longitudinal axis.

In this first subgroup of rotary tools, the rock breaking elements of the bit are e.g. U.S. Pat. Nos. 3,650,656, 3,807,804 and 4 , 804,231 is conical (upward cone) and convex Crush rocks on the back of the Russian Patent No. 1,671,850-A1 describes this and The same so-called conical bit type is disclosed. The contact area depends on the angle of attack. , and can vary between 0 and 90°. explained The bit used is a crush type that works without long crushing cracks. be. These bits are positioned at an angle of attack of less than 90° and are is convex with a zero degree or negative clearance angle and a positive rake angle. the self of these bits Self-rotation is unreliable. Therefore, it is not self-polished. child These bits have significantly higher specific energy requirements for rock breaking than the present invention. .

A second sub-group of rotary tools includes, for example, US Pat. No. 5,078,219 Includes a front rock crushing bit as disclosed in the issue. This bit The dorsal surface is convex with a positive clearance angle and a near-zero angle of attack. Bit cutting edge is sharp , the bit becomes a cutting tool. However, if the bit The design does not prevent it from slowing down in the short term. bit wear Self-sharpening of the bit is not possible because the areas that have been sharpened are not corrected. as mentioned above Moreover, if the width of the contact area with respect to the thrust force T is too wide, the cutting performance is greatly reduced.

A third sub-group of rotary tools is represented by chisel bits as disclosed, for example, in German Offenlegungsschrift 3,336,154 and 3,234,521. These bits are provided with replaceable tubular chisel-shaped cutting sleeves with sharpened front faces. The tip angle of this bit is rather small, the rake angle is large in the positive direction, and the clearance angle is small. Therefore, these bits have low durability and wear resistance and are applicable only when crushing soft, non-abrasive rocks. Compared to the present invention, the angle of attack of these bits is much less than 90°, the front surface is concave and the back surface is convex, and the bits are not self-sharpening. DISCLOSURE OF THE INVENTION Accordingly, it is an object of the present invention to provide a cutting method and rotary cutting bit that do not suffer from the disadvantages of the prior art.

Specifically, it is an object of the present invention to eliminate the wear that normally occurs on bits along the mating surfaces. Regardless, the bit's high To provide a cutting method and a cutting rotary bit capable of maintaining initial cutting ability That's what it is.

In keeping with these and other purposes that will become apparent from the discussion below, , one feature of the present invention is, simply put, a body and a substantially circular cutout connected to the body. Cutting method according to using rotary cutting bit with cutting element or elements and wherein the cutting element has a convex front surface. In the method according to the invention, Rotary cutting bits are arranged so that the angle of attack of the cutting element of the bit exceeds 90°. I'm here. (The angle of attack is the angle between the longitudinal axis of the bit and the cutting surface behind the bit.) degree. ) Implementing the above method and designing a tool according to the present invention has the following advantages: is obtained.

− Significance of the bit, which can break rocks and other similar materials very efficiently cutting power − Longer bit cutting edge length and uniform wear along its back surface Continuous and forced self-rotation of the bit about its longitudinal axis turn − By grinding the interfering cutting element material along its back surface, the bit A continuous and strong drilling of the bit that maintains the initial positive clearance angle along the entire cutting edge of the bit. self-polishing − Increased bit durability resulting in increased bit reliability and longevity and engagement due to very reasonable force transmission through the cutting elements of the bit Increases the range of materials that can be processed. Stresses in brittle cutting elements are almost completely compressive It is powerful.

− The bit must work effectively until most of the cutting elements are lost due to normal wear. , which increases the service life of the bit.

The novel features which may be considered characteristic of the invention are pointed out with particularity in the appended claims. The invention itself, however, both as to organization and method of operation, together with other objects and advantages thereof, may best be understood from the following description of specific embodiments when read in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagram schematically showing the mechanism of rock crushing.

FIG. 2 is a diagram showing a cutting device provided with a rotary bit for cutting according to the present invention; be.

FIG. 3a shows the present invention provided with a cutting element and having a cylindrical front surface and a flat rear surface. FIG. 10 is a diagram showing a bright rotary bit for cutting;

FIG. 3b shows a book provided with a cutting element and having an inverted conical front surface and a flat rear surface; It is a figure which shows the rotary bit for cutting of invention.

FIG. 3c shows the present invention provided with a cutting element and having a conical front surface and a flat rear surface. FIG. 10 is a diagram showing a bright rotary bit for cutting;

FIG. 3d shows the present invention provided with a cutting element and having a cylindrical front surface and a concave rear surface. FIG. 10 is a diagram showing a bright rotary bit for cutting;

FIG. 3e shows the present invention provided with a cutting element and having a cylindrical front surface and a convex rear surface. FIG. 10 is a diagram showing a bright rotary bit for cutting;

FIG. 4a shows a cutting tool according to the invention in which a cylindrical bit body is provided with a simple cutting element. FIG. 4 shows a rotary bit;

FIG. 4b shows a cutting tool according to the invention in which a stepped cylindrical body is provided with a plurality of cutting elements. FIG. 4 shows a rotary bit;

FIG. 4c shows a rotary cutting bit according to the invention having cutting elements of round and smooth shape in cross section. FIG. 10 is a diagram showing a

FIG. 4d shows a rotary cutting bit of the invention having cutting elements of polygonal cross-section; It is a diagram.

FIG. 4e shows a rotary bit for cutting according to the invention having a daisy-shaped cutting element in cross section. It is a figure which shows.

FIG. 5a is a plan view of a rotary cutting bit of the present invention showing the skew angle; FIG.

FIG. 5b shows the main longitudinal portion of a rotary cutting bit according to the invention and all is a diagram showing the vertical plane angle of .

FIG. 5c is a cross-sectional view of the rotary bit for cutting of the present invention.

FIG. 6 is a perspective view showing the cutting operation of the rotating bit for cutting according to the present invention. BEST MODE FOR CARRYING OUT THE INVENTION A cutting tool according to the invention (FIGS. 2, 3 and 4) comprises a body indicated by reference number 1 and a cutting element or insert indicated by reference number 2. have. The body furthermore has a tail 3 which contributes to the rotation of the bit about its longitudinal axis and which can also be used to hold a cutting tool.

As is clear from FIG. 2, the tail of the bit is located inside the tool holder 4, It is held by retainer 5 . Single toolholder or multiple toolholders are aligned with each other and attached to the cutter support 6. Major angles are rotated for cutting Bits are spaced apart from each other, but as described later, the tool Determined by attaching the holder to the cutter support. Bit tail 3 and rotary cutting bit in such a way that it can be rotated about its longitudinal axis. It is held in the tool holder and axially fixed.

Cylindrical or conical bodies are usually alloyed steel with substantial elasticity and strength made in

The insert 2 (Fig. 3) is ring-shaped and can be a one-piece ring or individual segments. can be formed as a composite ring composed of The opening in the center of the ring is cylindrical or or conical, the surface of which is in contact with the body , can be flat or curved. In another embodiment of the invention, the entire bit can be made from only one type of material.

As shown in Figures 3a, 3b and 3c, the top surface of the insert can be flattened. Alternatively, a concave shape as shown in FIG. 3d, or a It may be in the form shown in e. The outer surface of the ring, which is the front surface of the bit, should always to the cylindrical generatrix as shown in FIGS. 3a, 3d and 3e. or an upward circular shape as shown in FIG. 3c A cone, an inverted cone as shown in FIG. 3b.

The outer contour of the cutting element may be straight as shown in Figure 4a, or is stepped as shown in FIG. 4b.

The cross-sectional shape of the cutting element may be round as shown in FIG. polygonal as shown in Figure d, or daisy-shaped as shown in Figure 4e. can

The insert is generally a sintered hard alloy, preferably of the tungsten carbide family. It is made of a hard, wear-resistant material that is gold. The cutting force is applied to the center of the ring, Extremely dangerous tensile stresses in brittle materials such as hard alloys that make up the insert The front face of the insert should be convex because the preferably

Also, if the front face of the bit is convex, the chips will be distributed on both sides of the bit, The crushed rock can be more efficiently removed from the cutting area.

For the connection between the insert and the body, use high temperature braze, especially for composite rings. This can be achieved by brazing using a can be A ring-shaped insert holds the braze material in a semi-sealed state ensure a durable and reliable bond between the body and the insert. can This is especially important during dynamic load conditions. On the other hand, In soldering, residual thermal stress occurs due to the difference in the coefficient of expansion of the elements to be joined. , the use of press-fitting eliminates these residual thermal stresses.

For cutting non-abrasive materials, an inseparable integral body and insert It is recommended to use bits of In this case, e.g. isothermal quenching A special heat treatment must be applied to change the hardness of the bit body and the cutting element. must.

The main new features of the present invention are, as shown in FIGS. 2 and 5b: The rotating bit for cutting is arranged at an angle of attack β with respect to the surface of the rock to be cut. A method according to the invention is implemented.

The skew angle α shown in Figures 5a and 5c is and the angle between the projection of the longitudinal axis of the bit and the direction of motion of the bit is.

Depending on the skew angle, the cutting force C (C = Q cos α) that cuts through the rock and the rotational (crush) force Q _rot that promotes rotation of the bit about its longitudinal axis (Q _rot , = Q sin α) is determined.

The combination of the tool angle of attack b and the tool skew angle α is the main parameter of the tool. parameters (including bit cutting edge rake angle Ψ and clearance angle δ) be a condition.

Due to the spatial arrangement of the tool determined by the angle of attack β and the skew angle α, properties are given.

− The front face of the bit is the _convex surface of the insert, while the back face of the tool is the end face of the insert. (Figs. 5b and 5c) about its longitudinal axis. M _rot is the set of frictional forces generated by force Q _rot (and thrust force) and tangential force Q;

- The direction of linear motion of the tool is defined at each point on the cutting edge of the tool, as shown in Figure 5c. It does not match the cutting (fracture) direction of the rock, which is different every time.

- The instantaneous values of rake angle Ψ _i and clearance angle δ _i vary continuously point by point along the cutting edge of the bit (arc AE in Fig. 5c).

The relief angle _.delta.b has a maximum positive value at point B (FIG. 5c). This angle is assumed to decrease left and right from point B (sin δ _i =sin δ _b cos ε _i ), to be zero at point D and negative at point E. Geometrically correcting the clearance angle of the tool by a positive angle Δδ (Fig. 5b; Δδ = co s β sin α) results in a positive clearance angle along the entire cutting edge of the bit (arc AE in Fig. 5c). become. It therefore maintains this condition, the condition necessary to increase the stress concentration of the rock at the cutting edge.

The clearance angle of the tool at point E becomes zero under the condition |Δδ|=|δ ₀ |. Thus, self-sharpening occurs on the radial line at E as backside material that interferes with maintaining a positive clearance angle along the entire cutting edge is continuously removed. Self-sharpening proceeds around point E of the cutting edge at the same time that wear occurs along locations other than around this point.

The rake angle Ψ _b reaches its maximum negative value at point B in FIG. 5c. This angle increases as we move left and right from point B so that we can assume that at point D the value is zero and at point E the value is positive. Thrust force per unit length is therefore greatest at point E compared to the remaining points on arc AE of FIG. 5c of the cutting edge of the tool.

Therefore, the intensity of wear and friction is maximum at point E, and the value of the clearance angle is zero. Combined with the fact that it is B, a state close to tool sharpening by a machine can be obtained. Figure 5 By introducing a b-positive correction angle ΔΨ, the effect of self-polishing is further enhanced.

The negative rake angle of the tool, which is maximum at the center of the cutting edge, contribute to self-protection. Negative rake angle lifts the tool off the rock occurs. Such excessive loads normally occur as the rocks to be fractured harden. Occur.

Continuous rotation of the tool about its own longitudinal axis is reliable due to the following factors: become highly sensitive.

− There is no substantial resistance to _rotation along the back surface of the tool due to the positive clearance angle − A substantial A cutting force C is used.

The nature of the tool and the fact that wear occurs axially along the back surface and the entire cutting edge of the tool In combination with the fact that the clearance angle continuously returns to the initial value by self-polishing along in cutting mode until the insert is substantially worn away by wear Tools work efficiently.

The angle of attack according to the invention can be in the range of 90° to 120°. Skew angle is 5 ° to 40°. Rake angle ranges from +15° to -15° can be done inside The clearance angle can be in the range of 0-20°. Cutting edge angle is 50°~100° can be within the range of

As described above, the case where the present invention is implemented in the cutting method and rotary bit for cutting has been described. Although described with reference to the drawings, various modifications and changes can be made without departing from the spirit of the invention. and structural changes can be made, so are limited to the details shown here. is not intended to

Claims (17)

[Claims] 1. A rotating cutting element and an angle of attack of the cutting element exceeding 90° and a skew - means for holding said cutting element having an angle; and self-polishing tools. 2. 2. The cutting self of claim 1, wherein said cutting element comprises a convex front surface. Rotating and self-polishing tools. 3. wherein said convex front surface is selected from the group consisting of cylindrical, upturned conical and inverted conical. Self-rotating and self-sharpening for cutting according to claim 2 having a selected shape polishing tool. 4. wherein said cutting element comprises a convex shape, a concave shape, a flat shape and combinations of said shapes. Self-rotating for cutting according to claim 1, having a back surface of a shape selected from: and self-polishing tools. 5. The cutting element has a length selected from the group consisting of a linear profile and a stepped profile. Self-rotating and self-sharpening for cutting according to claim 1, having a hand portion tool. 6. wherein said cutting element has an outer shape selected from the group consisting of round, polygonal and daisy shaped. A self-rotating and self-rotating cutting tool according to claim 1 having a cross-section of a selected shape. self-polishing tool. 7. 2. The method of claim 1, wherein the angle of attack of said cutting element is between 90[deg.] and 120[deg.]. A self-rotating and self-polishing tool for cutting as described. 8. 3. The method of claim 1, wherein the skew angle of said cutting element is between 5[deg.] and 40[deg.]. A self-rotating and self-polishing tool for cutting as described. 9. 3. The method of claim 1, wherein the clearance angle of said cutting element is between -15[deg.] and 15[deg.]. A self-rotating and self-polishing tool for cutting as described. 10. 2. The method of claim 1, wherein the clearance angle of the cutting element is between 0 and 20[deg.]. self-rotating and self-polishing tools for cutting of. 11. Claim 1, wherein the included angle of said cutting element is between 50° and 100°. A self-rotating and self-polishing tool for cutting according to . 12. The clearance angle is positively angle-corrected and the formula Δδ ≤ arcsin (sinαcosβ) (this where α is the skew angle and β is the angle of attack). 12. The cutting, self-rotating and self-polishing tool of claim 11, wherein: 13. providing a rotatable cutting element; and mounting said cutting element by a mounting means. and said cutting element has an angle of attack and skew angle greater than 90°. and displacing the mounting means so as to have. 14. The mounting is such that the angle of attack of the cutting element is between 90° and 120°. 14. The method of claim 13 including mounting said cutting element. 15. The mounting includes a skew of the cutting element of 10° on both inclined planes. 40° to 40°. The method according to item 3. 16. The mounting has a rake angle of the cutting element between -15° and 15° 14. The method of claim 13 including mounting said cutting element in such a manner. 17. Mounting the cutting element such that the clearance angle of the cutting element is between 0 and 20° 3. The method of claim 1, comprising: