Rotary cutter for hole machining

Abstract

The invention discloses a rotary cutter for hole machining, which comprises a handle part and a cutting part which are coaxial, the cutting part comprises at least two blade sections, a chip groove is formed between the adjacent blade sections, and a first support guide part and a second support guide part which are protruded outwards are arranged on the peripheral side of each blade section. The first supporting guide part and the second supporting guide part are arranged in a front-back spaced mode in the rotating machining direction of the cutting part, the second supporting guide part is a quadric surface, the distance between the front side edge of the second supporting guide part and the axis is minimum, and the distance between the rear side edge of the second supporting guide part and the axis is maximum in the rotating machining direction of the cutting part. A layer of pressure-bearing oil film is formed between the second supporting and guiding part and the hole wall in the hole machining process, and the maximum distance between the second supporting and guiding part and the axis is smaller than the maximum radius of the cutting part. The rotary cutter for hole machining has the advantages that the drilling machining stability can be guaranteed, the second supporting and guiding part can be prevented from being abraded so as to prolong the service life, machining is easy, and the machining difficulty is small.

Description

Technical Field

[0001] The invention relates to the technical field of metal cutting and processing, and in particular to a rotary tool for hole processing. Background Art

[0002] Different from milling, turning and other processing methods, hole processing is a semi-closed processing. Due to poor processing conditions, vibration is easily generated during the processing, resulting in poor straightness, roundness, and surface roughness of the hole. In severe cases, it may even cause the parts to be scrapped. In order to solve such problems, in terms of structural optimization, the existing technology usually designs two pairs of guide parts on the outer peripheral surface of the tool blade to enhance the guiding role of the guide part during the processing. However, the double guide part structure will increase the contact area between the tool and the hole wall during processing, causing the friction between the guide part and the hole wall to increase, resulting in accelerated tool wear and reduced hole wall surface quality.

[0003] The existing Chinese patent document with application number 201710317407.0 discloses a drill bit, specifically disclosing a guide chamfer and a support chamfer formed with a front-to-rear interval on the rear surface in the direction of rotation, the support chamfer includes a leading surface area in the front direction relative to the support edge relative to the direction of rotation, the leading surface area rises toward the support edge in the radial direction, and includes a trailing surface area in the rear direction relative to the support edge, and the trailing surface area decreases in the radial direction. More specifically, at the second guide, the leading surface area and the trailing surface area are ground, and the leading surface area and the trailing surface area form an obtuse angle, the angle is in the range of 130° to 175°, so that the circumferential angle of the support chamfer at this location is less than 1°, which is approximately a linear support, and the support point is blunted, thereby reducing the friction between the support edge and the hole wall during the hole processing process and improving the service life. The drill has the following shortcomings: 1) Although the support edge forms a line contact (direct contact) with the hole wall to reduce friction, the support edge formed by the intersection of the leading surface area and the trailing surface area is easily worn. On the one hand, it is not conducive to extending the service life of the drill bit. On the other hand, it is easy to cause under-support due to the wear of the support edge, affecting the processing stability and processing quality; 2) Processing support chamfers requires three additional steps of grinding the leading surface, grinding the trailing surface, and blunting the support point. The steps are numerous and complicated, resulting in a significant increase in processing costs. In addition, when grinding the trailing surface, the leading surface area may not be accurately reached, resulting in a larger circumferential angle at the support point, and the purpose of approximate linear support cannot be achieved; or a portion of the leading surface area is ground off, resulting in a radius of the support point smaller than the tool diameter, that is, the support chamfering is complex and difficult to process. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a rotary tool for hole machining which can ensure the stability of drilling machining, avoid wear of the second supporting guide part to increase the service life, and has simple machining and low machining difficulty.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions: A rotary tool for hole machining, comprising a coaxial shank and a cutting portion, the cutting portion comprising at least two blade petals, a chip groove formed between adjacent blade petals, a first support guide portion and a second support guide portion both protruding outwardly provided on the circumferential side of the blade petal, the first support guide portion and the second support guide portion being arranged with an interval front and rear arrangement in the rotational machining direction of the cutting portion, the second support guide portion being a quadratic curved surface, the front edge of the second support guide portion in the rotational machining direction of the cutting portion being at a minimum distance from the axis, and the rear edge being at a maximum distance from the axis, so that a layer of pressure-bearing oil film is formed between the second support guide portion and the hole wall during hole machining, the maximum distance of the second support guide portion from the axis being less than the maximum radius of the cutting portion.

[0006] As a further improvement of the above technical solution: The distance between the second support guide portion and the axis in the rotational machining direction of the cutting portion gradually decreases.

[0007] The distance between the front edge of the second support guide portion in the rotational processing direction of the cutting portion and the axis is 0.5D2, the distance between the rear edge of the second support guide portion in the rotational processing direction of the cutting portion and the axis is 0.5D1, and the maximum diameter of the cutting portion is set to D, satisfying 0.006mm≤D-D1≤0.016mm, and D2 = 2D1-D.

[0008] The tangential width of the second support guide portion in the rotational processing direction of the cutting portion is set to w2, and the tangential width of the first support guide portion in the rotational processing direction of the cutting portion is set to w1, satisfying 0.04D ≤ w1 ≤ 0.08D, w1 ≤w2 ≤ 2w1.

[0009] The included angle between the first supporting guide portion and the second supporting guide portion in the rotational processing direction of the cutting portion is set to α, satisfying 20°≤α≤80°.

[0010] The profile of the second support guide portion on a cross section perpendicular to the axis is a quadratic curve, and the equation of the quadratic curve is: , wherein a, b, c, d, and e are constants, and the rectangular coordinate system where the equation of the quadratic curve resides takes the intersection of the cross section and the axis as the origin.

[0011] The first support guide portion is a cylindrical surface, the central axis of the first support guide portion coincides with the axis, and the distance between the first support guide portion and the axis is equal to the maximum radius of the cutting portion.

[0012] The end of the cutting portion away from the shank forms a drill tip, and the blade, the first supporting guide portion and the second supporting guide portion are all extended from the drill tip toward the shank.

[0013] The blade flap, the first support guide portion and the second support guide portion all extend spirally around the axis to the shank portion, and the helix angle β of the blade flap satisfies 0<β≤40°; or, the extension direction of the blade flap, the first support guide portion and the second support guide portion is parallel to the axis.

[0014] The first supporting guide portion and the second supporting guide portion can be detachably fixed on the blade.

[0015] Compared with the prior art, the advantages of the present invention are: In the rotary tool for hole processing of the present invention, since the second support guide part is a quadratic surface, the distance between the front edge of the second support guide part and the axis in the rotation processing direction of the cutting part is the smallest, and the distance between the rear edge and the axis is the largest, and the maximum distance between the second support guide part and the axis is less than the maximum radius of the cutting part, so that a layer of pressure-bearing oil film is formed between the second support guide part and the hole wall during the hole processing. In this way, during the hole processing, the second support guide part does not directly contact the hole wall and there is no direct friction; and the pressure-bearing oil film separates the second support guide part from the hole wall, plays a lubricating role between the second support guide part and the hole wall, avoids the wear of the second support guide part, and improves the service life; at the same time, the second support guide part is supported on the hole wall by the pressure-bearing oil film, and the pressure-bearing oil film plays a flexible supporting role between the second support guide part and the hole wall, avoiding the influence of processing stability and processing quality due to lack of support. That is, during the hole processing of the rotary tool for hole processing, a lubricating and pressure-bearing pressure-bearing oil film is formed between the second support guide part and the hole wall, which can ensure the stability of drilling processing and avoid the wear of the second support guide part to improve the service life. Moreover, the second supporting guide portion is a quadratic curved surface, which is simpler and less difficult to process than the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic structural diagram of the first embodiment of the rotary tool for hole machining of the present invention.

[0017] Figure 2 yes Figure 1 Cross-section of AA.

[0018] Figure 3 It is a cross-sectional view of the second support guide portion of the hole machining rotary tool of the present invention.

[0019] Figure 4 It is a schematic structural diagram of the second embodiment of the rotary tool for hole machining of the present invention.

[0020] Figure 5 yes Figure 4 Cross-sectional view of CC.

[0021] The symbols in the figure represent: 0. Axis; 1. Shank; 10. Pressure oil film; 2. Cutting part; 3. Blade flap; 4. Chip groove; 51. First supporting guide part; 52. Second supporting guide part; 6. Hole wall; 7. Blade; 8. Screw. DETAILED DESCRIPTION

[0022] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0024] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0025] In the present invention, unless otherwise clearly specified and limited, the terms "assemble", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0026] Embodiment 1: Figures 1 to 3An embodiment of a rotary tool for hole machining of the present invention is shown. The rotary tool for hole machining of this embodiment includes a shank 1 and a cutting part 2 with a coaxial line 0. The cutting part 2 includes at least two blade flaps 3. A chip groove 4 is formed between adjacent blade flaps 3. The peripheral side of the blade flap 3 is provided with a first support guide part 51 and a second support guide part 52 both protruding outward. The first support guide part 51 and the second support guide part 52 are arranged in a front-to-back interval in the rotational machining direction of the cutting part 2. The second support guide part 52 is a quadratic surface. The front side edge of the second support guide part 52 in the rotational machining direction of the cutting part 2 is at a minimum distance from the axis 0, and the rear side edge is at a maximum distance from the axis 0, so that a layer of pressure-bearing oil film 10 is formed between the second support guide part 52 and the hole wall 6 during the hole machining process. The maximum distance of the second support guide part 52 from the axis 0 is less than the maximum radius of the cutting part 2.

[0027] The chip groove 4 is a channel for the flow of coolant and the discharge of chips. During the use of the rotary tool for hole machining, the cutting fluid is used for cooling. When the chips are curled and formed, they are discharged from the tail of the groove along the chip groove 4 under the joint "pushing" action of the axial drilling force and the high-pressure coolant. In order to reduce drilling vibration, a first support guide portion 51 and a second support guide portion 52 are provided on the blade 3. The first support guide portion 51 and the second support guide portion 52 are arranged in front and back intervals in the rotation processing direction of the cutting portion 2, that is, the first support guide portion 51 is located in front of the second support guide portion 52 in the rotation processing direction of the cutting portion 2.

[0028] Since the second support guide 52 is a quadratic surface, the distance between the front edge of the second support guide 52 and the axis 0 in the rotation processing direction of the cutting part 2 is the smallest, and the distance between the rear edge and the axis 0 is the largest, and the maximum distance between the second support guide 52 and the axis 0 is less than the maximum radius of the cutting part 2, so that a layer of pressure-bearing oil film 10 is formed between the second support guide 52 and the hole wall 6 during the hole processing. In this way, during the hole processing, the second support guide 52 is not in direct contact with the hole wall 6, and there is no direct friction; and the pressure-bearing oil film 10 separates the second support guide 52 from the hole wall 6, plays a lubricating role between the second support guide 52 and the hole wall 6, avoids the wear of the second support guide 52, and improves the service life; at the same time, the second support guide 52 is supported on the hole wall 6 by the pressure-bearing oil film 10, and the pressure-bearing oil film 10 plays a flexible supporting role between the second support guide 52 and the hole wall 6, avoiding the influence of processing stability and processing quality due to lack of support. That is, during the hole machining process, the rotary tool for hole machining forms a lubricating and pressure-bearing oil film 10 between the second support guide portion 52 and the hole wall 6, which can ensure the stability of the drilling process and avoid the wear of the second support guide portion 52 to increase the service life. Moreover, the second support guide portion 52 is a quadratic surface, which is simpler to machine and less difficult to machine than the prior art.

[0029] like Figure 3 As shown, the second support guide portion 52 is a smooth and continuous quadratic surface convex toward the hole wall 6. It is arranged behind the first support guide portion 51 along the rotation processing direction of the cutting portion 2. Figure 3 Take any point Q on the front side edge in the F direction shown in FIG. 1 , Q is at the smallest distance from the axis 0, and the second support guide 52 rotates in the machining direction of the cutting part 2 (as shown in FIG. 1 ). Figure 3 Take any point P on the rear edge in the F direction shown in the figure, and the distance between P and the axis 0 is the largest. Figure 2 As shown, the distance between Q and the axis line 0 is 0.5D2, and the distance between P and the axis line 0 is 0.5D1. D1 is smaller than the maximum diameter D of the cutting portion 2, so the second supporting guide portion 52 does not directly contact the hole wall 6.

[0030] Furthermore, in this embodiment, the distance between the second supporting guide portion 52 and the axis line O in the rotational machining direction of the cutting portion 2 gradually decreases.

[0031] The second support guide portion 52 is a smooth and continuous secondary curved surface convex toward the hole wall 6. The second support guide portion 52 and the hole wall 6 form a wedge-shaped space with a large front opening and a small rear opening in the rotation processing direction of the cutting portion 2. During the hole processing, when the cutting coolant flows through the second support guide portion 52, a wedge-shaped pressure-bearing oil film 10 with lubrication and pressure-bearing functions will be formed between the second support guide portion 52 and the hole wall 6. The pressure-bearing oil film 10 can both enhance the guiding function and reduce friction, thereby improving the processing quality of the processed hole.

[0032] Furthermore, in this embodiment, the distance between the front edge of the second support guide portion 52 in the rotational processing direction of the cutting portion 2 and the axis line 0 is 0.5D2, and the distance between the rear edge of the second support guide portion 52 in the rotational processing direction of the cutting portion 2 and the axis line 0 is 0.5D1. The maximum diameter of the cutting portion 2 is set to D, satisfying that 0.006mm≤D-D1≤0.016mm, and D2 = 2D1-D.

[0033] like Figure 3 As shown, in this embodiment, in order to ensure that a pressure-bearing oil film 10 can be formed in the wedge-shaped space during the hole machining process, the geometric structure and size of the second support guide portion 52 need to be reasonably designed. According to relevant theories, the second support guide portion 52 is optimally designed as a smooth and continuous quadratic surface structure that bulges toward the hole wall 6, and its cross-sectional profile is a quadratic curve, which can be a part of a circle, parabola, ellipse or hyperbola. At the same time, the minimum gap between the second support guide portion 52 and the hole wall 6 must meet a certain range, such as Figure 2As shown, the maximum diameter of the cutting portion 2 is set to D, satisfying: 0.006mm≤D-D1≤0.016mm, and D2 = 2D1-D. Preferably, the cross-sectional profile of the second support guide portion 52 is a portion of an ellipse. Further preferably, D=10mm, D1=9.99mm, and D2=9.98mm.

[0034] Further, in this embodiment, the tangential width of the second support guide portion 52 in the rotation processing direction of the cutting portion 2 is set to w2, and the tangential width of the first support guide portion 51 in the rotation processing direction of the cutting portion 2 is set to w1, which satisfies 0.04D ≤ w1 ≤ 0.08D, w1 ≤ w2 ≤ 2w1. This is conducive to ensuring good support effects of the first support guide portion 51 and the second support guide portion 52. Preferably, w1=0.6mm, w2=0.9mm.

[0035] Further, in this embodiment, the angle between the first support guide portion 51 and the second support guide portion 52 in the rotation processing direction of the cutting portion 2 is set to α, satisfying 20°≤α≤80°. Specifically, the angle between the first support guide portion 51 and the second support guide portion 52 in the rotation processing direction of the cutting portion 2 is the angle formed by the connection between the front end and the center of the cross-sectional profile of the second support guide portion 52 in the rotation processing direction of the cutting portion 2 and the connection between the front end and the center of the cross-sectional profile of the second support guide portion 52 in the rotation processing direction of the cutting portion 2. 20°≤α≤80° is conducive to ensuring a better guiding effect. α is preferably 30°.

[0036] Further, in this embodiment, the profile of the second support guide portion 52 on the cross section perpendicular to the axis 0 is a quadratic curve, and the equation of the quadratic curve is: , where a, b, c, d, and e are constants, and the rectangular coordinate system containing the equation of the quadratic curve takes the intersection of the cross section and the axis 0 as the origin.

[0037] Further, in this embodiment, the first support guide portion 51 is a cylindrical surface, the central axis of the first support guide portion 51 coincides with the axis 0, and the distance between the first support guide portion 51 and the axis 0 is equal to the maximum radius of the cutting portion 2. Further, the first support guide portion 51 may be provided with an inverted cone on the front side of the cutting portion 2 in the rotation processing direction.

[0038] The first supporting guide portion 51 is a cylindrical surface. During the drilling process, the first supporting guide portion 51 is in direct contact with the hole wall 6 of the processed hole to form a rigid supporting and guiding function.

[0039] Furthermore, in the present embodiment, the end of the cutting portion 2 away from the shank 1 forms a drill tip, and the blade 3, the first supporting guide portion 51 and the second supporting guide portion 52 are all extended from the drill tip toward the shank 1.

[0040] Furthermore, in this embodiment, the blade 3, the first support guide portion 51 and the second support guide portion 52 all spirally extend around the axis 0 to the shank 1, and the helix angle β of the blade 3 satisfies 0<β≤40°. Figure 1 As shown, 0<β≤40°, the rotary tool used for hole processing is an integral twist drill, and β is preferably 30°.

[0041] Embodiment 2: Figure 4 and Figure 5 Another embodiment of the hole machining rotary tool of the present invention is shown, the structure of this embodiment is basically the same as that of the first embodiment, except that the extending direction of the blade 3, the first support guide portion 51 and the second support guide portion 52 is parallel to the axis O. This hole machining rotary tool is a straight groove drill.

[0042] Furthermore, in this embodiment, the processing method is processing with coolant, preferably D=20mm, then D1 and D2 respectively satisfy: 0.006mm ≤ D-D1 ≤ 0.016mm, and D2 = 2D1-D, and the cross-sectional profile of the second support guide portion 52 is preferably a part of an elliptical line, D1=19.99mm, D2=19.98mm.

[0043] Further, in this embodiment, the tangential width w1 of the first support guide portion 51 satisfies: 0.04D ≤ w1 ≤ 0.08D, and the tangential width of the second support guide portion 52 satisfies: w1 ≤ w2 ≤ 2w1. In this embodiment, preferably w1=1.2mm, w2=1.8mm.

[0044] Further, in this embodiment, the angle α between the first support guide portion 51 and the second support guide portion 52 satisfies: 20°≤α≤80°. In this embodiment, α is preferably 40°.

[0045] Furthermore, in this embodiment, the first support guide portion 51 and the second support guide portion 52 can be detachably fixed on the blade 3, which is convenient for replacement. Of course, in other embodiments, the first support guide portion 51 and the second support guide portion 52 can be integrally formed with the blade 3.

[0046] Furthermore, in this embodiment, a cutting blade 7 is provided at one end of the cutting portion 2 away from the shank 1 .

[0047] Furthermore, in the present embodiment, the cutting blade 7, the first supporting guide portion 51 and the second supporting guide portion 52 are detachable structures, which are connected to the cutting portion 2 by screws 8 or other connecting means.

[0048] Embodiment three: Another embodiment of the rotary tool for hole machining of the present invention has a structure that is substantially the same as that of the first embodiment, except that the first support guide portion 51 and the second support guide portion 52 can be detachably fixed to the blade 3, which is convenient for replacement. Of course, in other embodiments, the first support guide portion 51 and the second support guide portion 52 can be integrally formed with the blade 3.

[0049] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention by using the technical content disclosed above without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention should fall within the scope of protection of the technical solution of the present invention.

Claims

1. A rotary tool for hole machining, comprising a shank (1) and a cutting portion (2) coaxially connected to each other, the cutting portion (2) comprising at least two blade lobes (3), a chip removal groove (4) formed between adjacent blade lobes (3), a first supporting guide portion (51) and a second supporting guide portion (52) both protruding outwardly provided on the circumference of the blade lobes (3), the first supporting guide portion (51) and the second supporting guide portion (52) being arranged at intervals in front and back in the rotary machining direction of the cutting portion (2), Features: The second support guide portion (52) is a quadratic curved surface; the distance between the front edge of the second support guide portion (52) and the axis (0) in the rotational processing direction of the cutting portion (2) is the smallest, and the distance between the rear edge and the axis (0) is the largest, so that a layer of pressure-bearing oil film (10) is formed between the second support guide portion (52) and the hole wall (6) during hole processing; and the maximum distance between the second support guide portion (52) and the axis (0) is smaller than the maximum radius of the cutting portion (2).

2. The hole machining rotary tool according to claim 1, Features: The distance between the second support guide portion (52) and the axis (0) in the rotational machining direction of the cutting portion (2) gradually decreases.

3. The hole machining rotary tool according to claim 1, Features: The distance between the front edge of the second supporting guide portion (52) in the rotational processing direction of the cutting portion (2) and the axis (0) is 0.5D2, the distance between the rear edge of the second supporting guide portion (52) in the rotational processing direction of the cutting portion (2) and the axis (0) is 0.5D1, and the maximum diameter of the cutting portion (2) is set to D, satisfying that 0.006mm≤D-D1≤0.016mm, and D2 = 2D1-D.

4. The hole machining rotary tool according to claim 1, Features: The tangential width of the second support guide portion (52) in the rotational processing direction of the cutting portion (2) is set to w2, and the tangential width of the first support guide portion (51) in the rotational processing direction of the cutting portion (2) is set to w1, satisfying 0.04D ≤ w1 ≤ 0.08D, w1 ≤ w2 ≤ 2w1.

5. The hole machining rotary tool according to claim 1, Features: The included angle between the first supporting guide portion (51) and the second supporting guide portion (52) in the rotational processing direction of the cutting portion (2) is set to α, satisfying 20°≤α≤80°.

6. The hole machining rotary tool according to claim 1, Features: The profile of the second supporting guide portion (52) on a cross section perpendicular to the axis (0) is a quadratic curve, and the equation of the quadratic curve is: , wherein a, b, c, d, e are constants, and the rectangular coordinate system where the equation of the quadratic curve is located has the intersection of the cross section and the axis (0) as the origin.

7. The hole machining rotary tool according to claim 1, Features: The first support guide portion (51) is a cylindrical surface, the central axis of the first support guide portion (51) coincides with the axis (0), and the distance between the first support guide portion (51) and the axis (0) is equal to the maximum radius of the cutting portion (2).

8. The hole machining rotary tool according to any one of claims 1 to 7, Features: An end of the cutting portion (2) away from the shank (1) forms a drill tip, and the blade (3), the first support guide portion (51) and the second support guide portion (52) are all arranged to extend from the drill tip in the direction of the shank (1).

9. The hole machining rotary tool according to claim 8, Features: The blade flap (3), the first support guide portion (51) and the second support guide portion (52) all extend helically around the axis (0) to the shank portion (1), and the helix angle β of the blade flap (3) satisfies 0<β≤40°; or, the extension direction of the blade flap (3), the first support guide portion (51) and the second support guide portion (52) is parallel to the axis (0).

10. The hole machining rotary tool according to claim 9, Features: The first supporting guide portion (51) and the second supporting guide portion (52) are both detachably fixed on the blade (3).

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