JP4644568B2 - Drill - Google Patents

Description

  The present invention relates to a drill suitable for machining with a large drilling depth / hole diameter ratio.

  Currently, the mainstream drills are roughly classified into a blade edge type and a tip exchange type. A general cutting edge grinding drill has a cutting angle of about 110 to 150 ° and has two cutting edges per rotation of the tool. However, the cutting state of the balance cutting, that is, the cutting resistance of both cutting edges cancels each other. Above, the two cutting edges are arranged in the same radial direction. On the other hand, a general tip exchange type drill shares a certain width of the cutting radius in a form in which three or more throwaway tips attached to the cutting head portion along one radial direction partially overlap each other and cooperate. In addition, one cutting blade is configured per one rotation of the tool, and even if the cutting blade is worn, it can be dealt with by exchanging the tip, and the tip itself has a rotationally symmetric shape such as a square, a triangle, a hexagon, etc. By providing a plurality of cutting edge portions, there is an advantage that the cutting edge can be updated twice or three times with the same tip due to the rotational displacement.

  However, in the conventional tip exchange type drill, the size, shape and arrangement of each throw-away tip are set so that the cutting resistances on both sides with the radial center of the tip arrangement as a boundary are balanced. However, it is theoretically difficult to precisely balance the cutting forces of three or more chips, and there is a limit to the processing accuracy of the drill body and the throw-away tip. Therefore, it is unavoidable that the cutting resistance on both sides is somewhat unbalanced in the conventional tip exchange drill, and cutting is performed while absorbing the load due to the unbalance by the rigidity of the shank. It has become.

  However, as the shank portion of the drill becomes longer and thinner, the rigidity naturally decreases. Therefore, in drilling with a deep and small hole diameter, the swing of the drill occurs due to the load that cannot be absorbed, and the machining accuracy deteriorates. For this reason, in the past, it has been considered that machining with a maximum drilling depth (L) / cutting hole diameter (D) ratio L / D of 4 or more is difficult with a tip-exchange drill.

  In view of the above circumstances, an object of the present invention is to provide a drill capable of obtaining high machining accuracy even in machining with a large drilling depth / hole diameter ratio.

In order to achieve the above object, according to claim 1 of the present invention, an outer blade portion 2A for carrying out cutting of the outermost peripheral region C1 of the cutting hole H is provided on the cutting head portion 1a, with reference numerals in the drawings. The outer blade portion 2A is disposed on the substantially opposite side in the radial direction, and the intermediate blade portion 2B responsible for cutting the second region C2 from the outside, and the radial direction Q substantially the same as the outer blade portion 2A and the intermediate blade portion 2B. In the drill in which the chip discharge grooves 4A and 4B are formed on the outer peripheral surface. 2C is located behind the outer blade portion 2A and the intermediate blade portion 2B in the drilling direction F, and the chip removal ratio of the outer blade portion 2A / intermediate blade portion 2B in the entire cutting state is 49/51 to 51/49. The blade arrangement in the entire cutting state of all the blade portions 2A to 2C Yes meridian (radially Q) chip removal amount ratio of one radius region and the other side radial area on the outside of the range, to the site of action of the cutting reaction force by at least an inner edge portion 2C of the cutting head portion 1a periphery, cutting A guide pad 3A that is in sliding contact with the inner periphery of the hole H is attached, and the guide pad 3A is inserted into the annular groove G cut by the outer blade 2A before the cutting by the inner blade 2C is started. It is characterized in that the position is set.

  According to a second aspect of the present invention, in the drill according to the first aspect, the outer blade portion 2A, the intermediate blade portion 2B, and the inner blade portion 2C are constituted by a throw-away tip that can be attached to and detached from the cutting head portion 1a. It is supposed to be.

According to a third aspect of the present invention, in the drill according to the first or second aspect , the ratio of maximum drilling depth L / cutting hole diameter D is 4 or more.

According to a fourth aspect of the present invention, in the drill according to any one of the first to third aspects, the guide pad 3A attached to the site of action of the cutting reaction force by the inner blade portion 2C is rearward in the drill rotation direction from the inner blade portion 2B. It is assumed to be located on the outer periphery of the cutting head portion 1a in an angle range of 60 to 90 °.

The invention according to claim 5 is the drill according to any one of claims 1 to 4 , in addition to the guide pad 3 </ b> A attached to the site of action of the cutting reaction force by the inner blade portion 2 </ b> A, on the substantially opposite side in the radial direction. The guide pad 3B is attached.

The invention of claim 6 is the drill of claim 5 above, in addition to the action site of the cutting reaction force by the inner blade portion 3C and the guide pads 3A and 3B attached to the substantially opposite side in the radial direction, and the cutting on the intermediate blade portion 2B side. A guide pad 3C is also attached to the outer peripheral position of the head portion.

In the drill according to the first aspect of the present invention, at the time of machining, first, the outer blade portion and the intermediate blade portion arranged on both sides in the radial direction of the cutting head portion are cut into the work material, and the annular groove portion is formed by cutting with the two blade portions. Then, after the guide pad attached to the cutting reaction force acting site by the inner blade portion is fitted into the annular groove portion, the guide pad is in sliding contact with the outer periphery of the annular groove portion. The inner blade portion cuts into the remaining circular region and cuts the circular region, and thereafter, the drilling by the cooperation of all the blade portions proceeds in the sliding contact state of the guide pad. More specifically, the initial stage of forming the annular groove portion with the outer blade portion and the intermediate blade portion is performed by a balance cut that balances the cutting resistance in the entire cutting state of both blade portions, and after the next inner blade portion starts to be cut. Cutting is an unbalanced cut. However, the cutting reaction force by the inner blade portion is received by the inner peripheral surface of the cutting hole that is in sliding contact with the guide pad, and the positional relationship between the sliding contact portion and the cutting edge of the inner blade portion is always kept constant by the so-called burnishing action. Be drunk. Thus, according to the present invention, even if the cutting resistance in the both-side radial region on the blade arrangement radial line becomes unbalanced due to the cutting of the inner blade portion, the cutting head portion rotates with a constant axis with no swaying. Thus, high machining accuracy can be obtained even in machining with a large drilling depth / hole diameter ratio.

  According to invention of Claim 2, what can perform a process with a large drilling depth / hole diameter ratio with high precision as a chip | tip exchange type drill is provided.

According to invention of Claim 3 , what can perform the drilling process by which a drilling depth / hole diameter ratio will be 4 or more as said drill can be provided with high precision.

According to the drill of the fourth aspect of the present invention, since the guide pad attached to the site of action of the cutting reaction force by the inner blade portion is at a specific position on the outer periphery of the cutting head portion, the cutting reaction force is applied to the inner peripheral surface of the cutting hole. Since it can be reliably received, machining with a large drilling depth / hole diameter ratio can be performed with higher accuracy.

According to the drill of the fifth aspect of the present invention, the guide pad is also attached to the substantially opposite side in the radial direction in addition to the action part of the cutting reaction force by the inner blade portion. The cutting head portion is held in a rotational state without vibration more strictly, and the processing accuracy is further improved.

According to the drill of the sixth aspect of the present invention, the cutting head portion is held in a more stable rotational state by the burnishing action from the three directions based on the three guide pads in the circumferential direction, and the machining accuracy is further improved.

  Hereinafter, the drill of this invention is demonstrated concretely with reference to drawings. 1 to 3 show a three-chip type oil-holed tip exchange drill according to an embodiment of the present invention, FIG. 4 shows the positional relationship between the cutting edge of the drill and a guide pad, and FIGS. The processing state by a drill is shown.

  1 to FIG. 3 shows a tip exchange drill with an oil hole, the cutting head portion 1a, which is a tip portion of a drill body 1 in which the shank portion 11 and the driver portion 12 are integrated, on the outer side, middle portion, The inner three blade portions 2A to 2C and the three guide pads 3A to 3C are screwed.

  In the drill body 1, two chip discharge grooves 4A and 4B are formed on the outer peripheral surface excluding the base end portion of the shank portion 11 so as to be loosely spiraled while facing each other in the radial direction, and the cutting head portion 1a. A coolant supply hole 5 is formed along the axial direction from the front side to the rear end of the driver portion 12. And in the front end surface 10 of the cutting head part 1a, both the chip discharge grooves 4A and 4B have the one side surfaces 4a and 4b along substantially the same radial direction in one opposing two quadrants (1/4 circle). In this way, each is opened in a substantially V shape, and a coolant discharge port 5a branched from the coolant supply hole 5 is opened in each of the inner and outer portions of the other two opposite quadrants.

  On one side surface 4a of the chip discharge groove 4A facing the front end surface 10 of the cutting head portion 1a, chip seats 6a and 6c are recessed in the head outer peripheral side and the center side, and the tip seat 6a has a throw of the outer blade portion 2A. While the away tip is directly screwed, the throw away tip of the inner blade portion 2C is screwed to the tip seat 6c while being held by the support member 21. Similarly, a chip seat 6b is recessed in one side surface 4b of the chip discharge groove 4B, and a throw-away tip of the intermediate blade portion 2B is directly screwed to the chip seat 6b. And these outer blade part 2A, the intermediate blade part 2B, and the inner blade part 2C are arrange | positioned so that the cutting blade 20 may follow the substantially same radial direction Q, as shown in FIG.

  The front end face 10 of the cutting head part 1a is a recessed part 10a whose center side is lower than the peripheral side, and the tip seat 6c to which the inner blade part 2C is attached is located in the recessed part 10a. Thus, with the drilling direction as the front, the top end of the outer blade 2A is positioned at the foremost end (highest position), and the top end of the intermediate blade 2B is positioned slightly rearward (lower position) than that, and the rear end ( The top end of the inner blade portion 2C is located at the lower position.

  The throwaway tips of the outer blade portion 2A and the intermediate blade portion 2B are both thick plates with a substantially parallelogram when viewed from the front, and the cutting blades 20 are provided on the opposite two sides. By doing so, the same chip can be used twice as a new cutting edge. On the other hand, the throw-away tip of the inner blade portion 2C is a hexagonal shape in which a corner portion of an equilateral triangle is cut obliquely, a cutting blade is provided on the entire periphery, and an installation posture in which an obtuse angle portion is directed in the drilling direction. Therefore, the same tip can be used three times as a new cutting edge by the rotational displacement of 120 degrees.

  Accordingly, the cutting edge 20 on the cutting side of these blade parts 2A to 2C, that is, the side facing the drilling direction, is inclined high inward in the outer blade part 2A, while it is inclined low inward in the intermediate blade part 2B and the inner blade part 2C. is doing. Further, the throwaway tips of these blade portions 2A to 2C are made of cemented carbide, and the size thereof is such that the outer blade portion 2A <intermediate blade portion 2B <inner blade portion 2C as shown in the figure.

  The guide pads 3A to 3C are of the same size and shape with braided pad bodies 32, 32 made of cemented carbide on both sides in the longitudinal direction on a pad support 31 made of steel and substantially strip-shaped. The pad main bodies 32, 32 are fitted to the axially long mounting recess 7 provided on the outer peripheral surface of the cutting head portion 1 a and screwed at the center portion of the pad support 31, so that the pad main bodies 32, 32 are outside blade portions 2 A. The axial center direction O is fixed at the same position in a state of slightly projecting from the peripheral surface of the cutting head portion 1a corresponding to the lateral projection amount. Among them, the guide pad 3A is disposed in an area where the reaction force of the cutting force by the inner blade portion 2C on the outer peripheral surface of the cutting head portion 1a, that is, an angle range of 60 to 90 ° rearward in the drill rotation direction from the inner blade portion 2C. . The guide pad 3B is disposed at a position facing the guide pad 3A in the radial direction, and the guide pad 3C is disposed at the outer peripheral position on the intermediate blade portion 2B side in the radial direction Q along which the blade portions 3A to 3C are aligned.

The front ends 3a of the guide pads 3A to 3C are inclined with the lower end of the cutting blade 20 inclined toward the cutting side of the outer blade 2A and the cutting side of the intermediate blade 2B with the drilling direction F as the front. It is located between the lower ends of the cutting blades 20.

FIG. 4 shows the positional relationship between the blade portions 2A to 2C and the guide pad 3A. However, in this view, along with showing side by side intermediate blade portion 2B and the outer edge portion 2A and an inner blade portion 2C, it illustrates the guide pads 3A on the opposite side sandwiching the center line O from these blade portions 2A-2C. In the figure, F is the drilling direction, φ is the cutting diameter, C1 is the cutting width by the outer blade portion 2A, C2 is the cutting width that only the intermediate blade portion 2B bears, C3 is the cutting width that only the inner blade portion 2C bears, φ = 2 (C1 + C2 + C3), C1 <C2 <C3. Therefore, the outer blade portion 2A and the intermediate blade portion 2B arranged on both sides of the cutting head portion 1a in the radial direction Q have a balance cut with substantially equal cutting resistance, that is, a range of 49/51 to 51/49 as a chip removal amount ratio. Cutting widths C1 and C2 are set so as to be inside.

  S1 to S6 in the figure indicate each cutting stage from the start of drilling according to the positional relationship between the blade portions 3A to 3C. That is, the first stage S1 starts cutting by the outer blade part 2A, the second stage S2 starts cutting by the intermediate blade part 2B, the third stage S3 starts cutting the entire surface of the outer blade part 2A, and the fourth stage S4 is the intermediate blade part. The entire cutting of 2B is started, the fifth step S5 is the cutting start by the inner blade part 2C, and the sixth step S6 is the entire cutting of the inner blade part 2C. The position P of the front end 3a of the guide pad 3A (3B, 3C) is between the third stage S3 and the fourth stage S4. Here, as an example of a specific dimensional relationship, at a cutting diameter φ = 68 mm, C1 = 7.732 mm, C2 = 11.768 mm, C3 = 14.500 mm, S1-S2 = 0.200 mm, S1-S3 = For example, 1.836 mm, S1-S4 = 3.614 mm, S1-S5 = 7.224 mm, S1-S6 = 10.456 mm, S1-P = 2.224 mm.

  With reference to FIGS. 4 and 5 to 7, a description will be given of the drilling process using the oil hole-equipped tip exchange drill having the above configuration. 5 to 7, the guide pad 3A is illustrated on the opposite side in the radial direction of the inner blade portion 2C so that the operation can be easily understood. However, as shown in FIG. It arrange | positions at 60-90 degrees of back sides.

  In the drilling process, first, as shown in FIG. 5, the outer blade 2A of the cutting head portion 1a is cut into the work material W, and then the intermediate blade 2B is cut, but at the rear (low) position. Until the inner cutting edge 2C reaches the work material W, that is, from the first stage S1 to the fifth stage S5, the work material is cut by the outer and intermediate blade parts 2A and 2B. An annular groove portion G is formed on the surface of W. From the third stage S3, the outer peripheral edge of the annular groove G becomes an annular wall surface perpendicular to the surface of the work material W by cutting the entire outer blade 2A. As shown in FIG. The front end 3a of the guide pad 3A is fitted into the annular groove G during the period from the third stage S3 to the fourth stage S4 when the intermediate blade portion 2B starts cutting the entire surface, and the surface of the pad main body 32 is the annular groove portion. Glidably contacts the annular wall surface on the outer periphery of G.

  During the period from the fourth stage S4 to the fifth stage S5, the outer blade part 2A and the intermediate blade part 2B arranged on both sides in the radial direction Q both perform the entire surface cutting, and thus the chip removal amount ratio was set in advance. As described above, stable high-accuracy cutting proceeds in a balanced cut state in which the cutting resistances of the two blade portions 2A and 2B are balanced. Further, since the cutting resistance as a whole is small and proceeds within a very short time from the first stage S1 to the fourth stage S4, the cutting balance is sufficiently maintained by the rigidity of the shank portion 11.

  When the fifth stage S5 is reached, as shown in FIG. 7, the inner blade portion 2C cuts into a circular region M remaining as a convex portion inside the annular groove G of the work material W, and this circular region M is obtusely conical. Along with this, there is a large difference in cutting resistance between the one side radius portion with the outer blade portion 2A and the inner blade portion 2C and the other side radius portion with the intermediate blade portion 2B, and an unbalance cut It becomes the state of. This unbalanced cut state becomes more prominent until the sixth stage S6 where the entire cutting by the inner blade portion 2C starts, and continues from the sixth stage S6 until the end of machining.

  However, before the start of cutting by the inner blade portion 2C, the guide pad 3A is fitted into the annular groove portion G, and the surface of the pad main body 32 is in sliding contact with the annular inner peripheral wall surface, and the sliding contact position is as shown in FIG. Since it becomes an action site of the cutting reaction force by the inner blade portion 2C, an unbalanced force due to the unbalanced cut is received by the annular wall surface of the annular groove portion G via the guide pad 3A, and the sliding of the guide pad 3A by the so-called burnishing action. The positional relationship between the contact portion and the cutting blade 20 of the inner blade portion 2C is always kept constant. Therefore, even in the unbalanced cut state, the cutting head portion 1a is maintained in a rotational state of a constant axis that is strictly free of vibration, and high machining accuracy can be obtained even when the drilling depth / hole diameter ratio is as large as 4 or more. .

  In the present embodiment, during the period from the fourth stage S4 to the fifth stage S5, the guide pad 3A and the guide pad 3B located on the opposite side in the radial direction and the radial direction Q along the blade portions 2A to 2C are provided. As for the guide pad 3C on the intermediate blade portion 2B side, the front end 3a is fitted into the annular groove portion G, and similarly, the surface of the pad main body 32 is in sliding contact with the annular inner peripheral wall surface of the annular groove portion G. By the burnishing action from three directions based on the three guide pads 3A to 3C, the cutting head portion 1a is held in a more stable rotating state, and the processing accuracy is further improved.

  The drill according to the above embodiment has three blade portions of the outer blade portion 2A, the intermediate blade portion 2B, and the inner blade portion 2C, but the drill to which the present invention is applied cuts the outermost peripheral region of the cutting hole H. The outer blade portion that bears, the intermediate blade portion that is disposed on the substantially opposite side in the radial direction and responsible for cutting the second region from the outside, and in the substantially same radial direction as these outer blade portion and the intermediate blade portion As long as it has at least one inner blade portion that is disposed along the inner blade portion and performs cutting of the inner region from the intermediate blade portion, and a chip discharge groove is formed on the outer peripheral surface, and includes a plurality of inner blade portions. May be. That is, when the total number of blade portions arranged along the same radial direction is four, there are two inner blade portions, and when the total number is five, there are three inner blade portions.

  Moreover, in the said embodiment, although each chip | tip part changed the attachment attitude | position and illustrated the tip-exchange-type drill which consists of a throw away tip which can be used 3 times, this invention throws away each blade part once or twice. Needless to say, the present invention can also be applied to a tip exchange drill made of a tip, and can also be applied to a drill in which each blade portion is integrally formed with a cutting head portion.

It is a side view of a drill concerning one embodiment of the present invention. It is a front view of the cutting head part of the drill. It is a side view of the cutting head part of the drill. It is explanatory drawing which shows the positional relationship of the blade part and guide pad of the drill. It is a vertical side view which shows the initial stage of the drilling process by the drill. It is a vertical side view which shows the next step of the said drilling process. It is a vertical side view which shows the unbalance cut state of the said drilling process.

DESCRIPTION OF SYMBOLS 1 Drill 1a Cutting head part 10 Tip surface 11 Shank part 2A Outer blade part 2B Intermediate blade part 2C Inner blade part 20 Cutting blade 3A-3C Guide pad 4A, 4B Chip discharge groove F Drilling direction G Annular groove part H Cutting hole O Axle Q Radial direction W Work material

Claims (6)

An outer blade portion responsible for cutting the outermost peripheral region of the cutting hole in the cutting head portion, an intermediate blade portion responsible for cutting the second region from the outside by disposing the outer blade portion substantially on the opposite side in the radial direction, The outer blade portion and the intermediate blade portion are arranged along substantially the same radial direction and are provided with at least one inner blade portion responsible for cutting the inner region of the intermediate blade portion, and a chip discharge groove is formed on the outer peripheral surface. In the drill,
The inner blade portion is located at the rear of the drilling direction than the outer blade portion and the intermediate blade portion,
The chip removal ratio of the outer cutting edge / intermediate cutting edge in the entire cutting state is in the range of 49/51 to 51/49, and the one-side radius region on the cutting edge arrangement radial line in the entire cutting state of the entire cutting edge and others The chip removal ratio in the side radius region is outside the above range,
A guide pad that is slidably contacted with the inner periphery of the cutting hole is attached to the site of action of the cutting reaction force by at least the inner blade portion of the outer periphery of the cutting head portion
The drill is characterized in that the guide pad is positioned so that the front end portion is inserted into the annular groove portion cut by the outer blade portion before starting the cutting by the inner blade portion.   The drill according to claim 1, wherein the outer blade portion, the intermediate blade portion, and the inner blade portion are constituted by a throw-away tip that can be attached to and detached from the cutting head portion. The drill according to claim 1 or 2 , wherein a ratio of maximum drilling depth / cutting hole diameter is 4 or more. The guide pad attached to the site | part of the reaction force of the cutting reaction force by the said inner blade part is located in the outer periphery of the cutting head part of the angle range of 60-90 degrees of the drill rotation direction back side from the said inner blade part. The drill according to any one of 3 above. The drill according to any one of claims 1 to 4, wherein a guide pad is also attached to a substantially opposite side in the radial direction in addition to the guide pad attached to the site of action of the cutting reaction force by the inner blade portion. In addition to the guide pad is attached to the cutting site of action of the reaction force and its substantially radially opposite by said inner edge portion, formed by the guide pad is attached to the cutting head portion outer peripheral position of the intermediate blade portion side claim 5, wherein Drill.

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