CN211727631U - Drill bit with replaceable head - Google Patents

Abstract

The application provides a drill bit with a replaceable head, and belongs to the field of cutting tools. The drill bit with the replaceable head comprises a cutter rod and a cutter head. The end part of the cutter bar is provided with a limiting groove. The cutter head is provided with a butting part which is used for enabling the cutter head and the cutter bar to be coaxially arranged after being matched with the limiting groove, and the inner peripheral wall of the limiting groove is matched with the outer peripheral wall of the butting part; the periphery wall of butt joint portion includes first curved surface, and first curved surface includes first gradual change face, and the intersection of first gradual change face and the cross section of butt joint portion is the gradual change line that reduces of distance to the central line of tool bit. The drill bit with the replaceable bit realizes the rotation stopping of the cutter head through the gradual change structure, and the rotation stopping structure is simple. In addition, the first gradual change face of the butt joint part can have a larger contact area with the inner peripheral wall of the limiting groove of the cutter bar, and the torque transmission capacity between the cutter bar and the cutter head can be increased.

Description

Drill bit with replaceable head

Technical Field

The application relates to the field of cutting tools, in particular to a drill bit with a replaceable head.

Background

In recent years, hole machining tools, especially hard alloy drill bits, are developed rapidly, and in order to achieve the purposes of high efficiency, low cost and saving of hard alloy materials, novel structures of drill bits with replaceable heads are continuously appeared. In the interchangeable head drill bit, need set up between tool bit and the cutter arbor and prevent the relative cutter arbor of tool bit and rotate the structure of splining, the structure of splining of current interchangeable head drill bit is comparatively complicated.

SUMMERY OF THE UTILITY MODEL

The embodiment of the application provides a drill bit with a replaceable head, and aims to solve the problem that a rotation stopping structure for preventing a cutter head from rotating relative to a cutter rod in an existing drill bit with a replaceable head is complex.

The embodiment of the application provides a drill bit with a replaceable bit, which comprises a cutter bar and a cutter head;

a limiting groove is formed in the end part of the cutter bar;

the cutter head is provided with an abutting part which is used for enabling the cutter head and the cutter bar to be coaxially arranged after being matched with the limiting groove, and the inner peripheral wall of the limiting groove is matched with the outer peripheral wall of the abutting part;

the peripheral wall of butt joint portion includes first curved surface, first curved surface includes first gradual change face, first gradual change face with the intersection of the cross section of butt joint portion is for reaching the gradual change line that reduces of distance of the central line of tool bit.

In the above technical scheme, the first curved surface of the peripheral wall of the abutting portion includes a first gradually changing surface, and an intersection of the first gradually changing surface and the cross section of the abutting portion is a gradually changing line in which a distance from the first gradually changing surface to a center line of the tool bit gradually decreases, that is, the first gradually changing surface is of a gradually changing structure in the circumferential direction. Since the inner peripheral wall of the stopper groove is matched with the outer peripheral wall of the abutting portion, the inner peripheral wall of the stopper groove has a portion matched with the first gradually changing surface shape. In the process of installing the tool bit, after the abutting part of the tool bit is inserted into the limiting groove, the first gradually-changing surface of the abutting part can be gradually contacted and matched with the corresponding part of the inner peripheral wall of the limiting groove and the first gradually-changing surface by rotating the tool bit, so that the tool bit is prevented from rotating. The drill bit with the replaceable bit realizes the rotation stopping of the cutter head through the gradual change structure, and the rotation stopping structure is simple and stable. In addition, the first gradual change face of the butt joint part has a larger contact area with the inner peripheral wall of the limiting groove of the cutter bar, so that the torque transmission capacity between the cutter bar and the cutter head can be increased. After the first gradually-changing surface of the butt joint part is in contact fit with the corresponding part of the inner peripheral wall of the limiting groove and the first gradually-changing surface, the tool bit and the tool bar can be centered.

In addition, the drill bit with the replaceable head provided by the embodiment of the application also has the following additional technical characteristics:

in some embodiments of the present application, the first curved surface further includes a first connection surface, an intersection line of the first connection surface and the cross section is a first arc line, and a center of the first arc line is located on a center line of the tool bit.

In the above technical solution, an intersection line of the first connecting surface and the cross section is a first arc line, and a center of the first arc line is located on a center line of the cutter head, that is, the center line of the first connecting surface coincides with the center line of the cutter head. Of course, since the inner peripheral wall of the stopper groove matches the outer peripheral wall of the abutting portion, the inner peripheral wall of the stopper groove has a portion matching the shape of the first connecting surface, and also the center line of the matching portion coincides with the center line of the holder. In the process of installing the cutter head, after the butt joint part is inserted into the limiting groove, the cutter head is rotated to enable the first connecting surface to be in contact fit with the part, corresponding to the first connecting surface, of the inner peripheral wall of the limiting groove, the cutter head and the center line of the cutter bar are concentric, meanwhile, the cutter head is enabled to rotate around the center line of the cutter head, and therefore the first gradual change surface is in accurate contact fit with the part, corresponding to the first gradual change surface, of the inner peripheral wall of the limiting groove.

In some embodiments of the present application, the first curved surface further comprises a first transition surface through which the first connection surface smoothly transitions to the first gradual surface.

In the above technical solution, the first curved surface further includes a first transition surface connected between the first connection surface and the first gradual change surface, and the first connection surface can be smoothly transitioned to the first gradual change surface through the first transition surface.

In some embodiments of the present application, the gradual change is a second arc centered off the centerline of the cutter head;

the intersection line of the first transition surface and the cross section is a transition arc line, and the first arc line and the second arc line are both tangent to the transition arc line.

In the above technical scheme, the gradual change line is a second arc line with a circle center deviating from the center line of the tool bit, and the first arc line and the second arc line are both tangent to the transition arc line so as to realize the smooth transition from the first connecting surface to the first gradual change surface. This configuration makes the entire first curved surface easier to mold and manufacture.

In some embodiments of the present application, a direction from the first connection surface to the first gradually-changing surface in a circumferential direction of the abutting portion on the first curved surface is a preset direction;

the distance from the gradual change line to the center line of the cutter head along the preset direction is gradually reduced;

the maximum distance from the gradual change line to the central line of the cutter head is not more than the radius of the first circular arc line.

Among the above-mentioned technical scheme, the distance of the central line of tool bit is reduced gradually along the preset direction to the gradual change line, and the maximum distance of gradual change line to the central line of tool bit is not more than the radius of first circular arc line, and this kind of structure makes at the in-process of installation tool bit, and after butt joint portion inserted and locates spacing recess, it will make first gradual change face get into the corresponding part of interior perisporium and the first connection face of spacing recess earlier to rotate the tool bit, makes the tool bit rotate more easily at the first half section of installation.

In some embodiments of the present application, the first curved surface is a plurality;

a plurality of first chip grooves are formed in the cutter head;

every two adjacent first curved surfaces are separated by a first chip groove.

Among the above-mentioned technical scheme, first chip groove plays the effect of chip removal. Every two adjacent first curved surfaces are separated by a first chip groove, and the structure is reasonable.

In some embodiments of the present application, the first curved surfaces are two;

the two first curved surfaces are distributed symmetrically about the center line of the cutter head.

In the technical scheme, the number of the first curved surfaces is two, the two first curved surfaces are distributed in a central symmetry mode about the center line of the cutter head, and the cutter head is uniformly distributed along the circumferential direction under stress in the cutting process due to the structure.

In some embodiments of the present application, the interchangeable-head drill bit further comprises a first limiting feature for limiting axial downward movement of the cutter head relative to the cutter shaft and a second limiting feature for limiting axial upward movement of the cutter head relative to the cutter shaft.

Among the above-mentioned technical scheme, first limit structure is used for restricting the relative cutter arbor axial downstream of tool bit, and second limit structure is used for restricting the relative cutter arbor axial upstream of tool bit, realizes spacing the axial of tool bit through first limit structure and second limit structure. After the butt joint part is matched with the limiting groove, the cutter head cannot axially move relative to the cutter bar under the limiting action of the first limiting structure and the second limiting structure.

In some embodiments of the present application, the tool bit further comprises a head portion having a bearing surface, the abutment portion extending along the bearing surface in a direction away from the head portion;

the end part of the cutter bar is provided with a bearing surface which is used for abutting against the bearing surface, and the limiting groove is arranged on the bearing surface;

the first limiting structure comprises the supporting surface and the bearing surface.

Among the above-mentioned technical scheme, the butt joint portion extends towards the direction of keeping away from the head along the supporting surface of head, and spacing recess is seted up on the bearing surface of the tip of cutter arbor, and after the butt joint portion inserted and located spacing recess and formed the cooperation, the supporting surface will contact with the bearing surface to reach the mesh that the restriction tool bit axial moves down.

In some embodiments of the present application, the abutment has a bottom surface axially opposite the bearing surface;

the butt joint part is a cone structure which is contracted and extends to the supporting surface from the bottom surface to the direction close to the head part;

the second limit structure comprises an outer peripheral wall of the butt joint part and an inner peripheral wall of the limit groove.

Among the above-mentioned technical scheme, the butt joint portion is the cone structure that extends to the supporting surface from the bottom surface to the direction shrink that is close to the head, and spacing recess then be with butt joint portion assorted cone structure, and the butt joint portion is inserted and is located spacing recess and form the cooperation back, and the periphery wall of butt joint portion will contact with the internal perisporium of spacing recess to reach the mesh of restriction tool bit axial rebound.

In some embodiments of the present application, the first curved surface further includes a first connection surface, an intersection line of the first connection surface and the cross section is a first arc line, and a center of the first arc line is located on a center line of the tool bit;

when the abutting part is positioned in the limiting groove and forms fit, the supporting surface is tightly abutted against the bearing surface, and the first connecting surface is tightly abutted against the part, corresponding to the first connecting surface, of the inner peripheral wall of the limiting groove.

In the technical scheme, when the butt joint part is positioned in the limiting groove and forms fit, the supporting surface is tightly abutted against the bearing surface, and the first connecting surface is tightly abutted against the part, corresponding to the first connecting surface, of the inner peripheral wall of the limiting groove.

In some embodiments of the present application, an axial length of the abutment is less than a depth of the stopper groove.

Among the above-mentioned technical scheme, the axial length of butt joint portion is less than the degree of depth of spacing recess for when the holding surface supported in the holding surface, there is the distance between the bottom surface of butt joint portion and the diapire of spacing recess, avoid forming between tool bit and the cutter arbor and cross the location, guarantee that the holding surface can closely support with the holding surface and lean on.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.

Fig. 1 is an exploded view of a reversible bit provided in accordance with an embodiment of the present application from a first perspective;

FIG. 2 is a cross-sectional view of an abutment portion of a tool tip provided in an embodiment of the present application;

FIG. 3 is a first possible cross-sectional view of an abutment portion of a tool tip provided in accordance with other embodiments of the present application;

FIG. 4 is a second possible cross-sectional view of an abutment portion of a tool tip provided in accordance with other embodiments of the present application;

FIG. 5 is a third possible cross-sectional view of an abutment portion of a tool tip provided in accordance with other embodiments of the present application;

FIG. 6 is an exploded view of a reversible bit provided in accordance with an embodiment of the present application from a second perspective;

fig. 7 is a diagram of an assembly process of a tool bit and a tool bar provided in an embodiment of the present application (an assembly position of the tool bit and the tool bar is in an initial position);

fig. 8 is a diagram of an assembly process of a tool bit and a tool bar provided in an embodiment of the present application (an assembly position of the tool bit and the tool bar is in an intermediate position);

fig. 9 is a view illustrating an assembly process of a tool bit and a tool bar provided in an embodiment of the present application (the assembly position of the tool bit and the tool bar is in a rotation stop position);

FIG. 10 is a schematic view of a configuration of a drill bit with a replaceable bit according to an embodiment of the present disclosure;

fig. 11 is a schematic structural diagram of a drill bit with a replaceable head according to another embodiment of the present disclosure.

Icon: 100-a drill bit; 10-a cutter bar; 11-a limiting groove; 111-a second curved surface; 1111-a second tapered surface; 1112-a second connection face; 1113-a second transition surface; 112-a bottom wall; 113-a clamping groove; 12-a bearing surface; 13-a second flute; 14-bayonet; 20-a cutter head; 21-a docking station; 211-a first curved surface; 2111-first gradual change plane; 2112-first connection face; 2113-first transition surface; 213-a bottom surface; 22-a head; 221-chisel edge; 222-a bearing surface; 223-partial cylindrical surface; 224-land; 225-minor edge; 226-a main edge; 227-card slot; 228-snap; 23-a first flute; a-a gradient; b-a first arc line; c-a transition arc line; d-concave curve; e-a first concave curve; f-a second concave curve; x-a preset direction; y-center line of cutter head; z-the centerline of the tool holder.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

In the description of the embodiments of the present application, it should be noted that the indication of orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship which is usually placed when the product of the application is used, or the orientation or positional relationship which is usually understood by those skilled in the art, or the orientation or positional relationship which is usually placed when the product of the application is used, and is only for the convenience of describing the application and simplifying the description, but does not indicate or imply that the indicated device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the application. Furthermore, the terms "first" and "second" are used to distinguish one description from another, and are not to be construed as indicating or implying relative importance.

Examples

The embodiment of the application provides a drill bit 100 with a replaceable bit, realizes the rotation stopping of a bit 20 through a simple structure, can effectively increase the torque transmission capacity between a cutter bar 10 and the bit 20, can stably realize centering, and is convenient for rapidly assembling and disassembling the bit 20.

As shown in fig. 1, the drill bit 100 includes a tool shank 10 and a tool bit 20. The end of the cutter bar 10 is provided with a limit groove 11. The tool bit 20 is provided with an abutting part 21 which is used for enabling the tool bit 20 to be coaxially arranged with the tool rod 10 after being matched with the limiting groove 11, and the inner peripheral wall of the limiting groove 11 is matched with the outer peripheral wall of the abutting part 21.

Wherein, the peripheral wall of the abutting portion 21 includes a first curved surface 211, and the first curved surface 211 includes a first gradually changing surface 2111. As shown in fig. 2, an intersection of the first gradually-changing surface 2111 and the cross section of the butting portion 21 is a gradually-changing line a in which the distance from the center line Y of the tool bit gradually decreases.

The first curved surface 211 of the outer peripheral wall of the abutting portion 21 includes a first gradually changing surface 2111, and an intersection of the first gradually changing surface 2111 and the cross section of the abutting portion 21 is a gradually changing line a in which a distance from the center line Y of the tool bit gradually decreases, that is, the first gradually changing surface 2111 has a gradually changing structure in the circumferential direction. Since the inner peripheral wall of the stopper groove 11 matches the outer peripheral wall of the abutting portion 21, the inner peripheral wall of the stopper groove 11 has a portion matching the shape of the first curved surface 211. For convenience of description, a portion of the inner circumferential wall of the stopper groove 11 matching the shape of the first curved surface 211 is defined as a second curved surface 111, and a portion of the second curved surface 111 matching the shape of the first gradually-changing surface 2111 is defined as a second gradually-changing surface 1111.

In the process of installing the cutter head 20, after the abutting portion 21 of the cutter head 20 is inserted into the limiting groove 11, the first gradually-changing surface 2111 of the abutting portion 21 can be gradually contacted and matched with the second gradually-changing surface 1111 by rotating the cutter head 20, so that the rotation stop of the cutter head 20 is realized. The drill bit 100 with the replaceable bit realizes the rotation stopping of the bit 20 through the gradual change structure, and has the advantages of simple and stable rotation stopping structure, easy manufacture and low cost. In addition, the first gradually changing surface 2111 of the abutting portion 21 and the second gradually changing surface 1111 of the tool shank 10 can form a larger contact area, and the torque transmission capability between the tool shank 10 and the tool bit 20 can be increased. The first gradually changing surface 2111 of the abutting part 21 and the second gradually changing surface 1111 of the limiting groove 11 are in contact fit, and then the tool bit 20 and the tool bar 10 can be centered.

Further, with reference to fig. 1 and 2, the first curved surface 211 further includes a first connection surface 2112, an intersection line of the first connection surface 2112 and the cross section is a first arc line B, and a center of the first arc line B is located on the center line Y of the tool bit. That is, the centerline of the first connection surface 2112 coincides with the centerline Y of the tool bit.

Of course, since the inner peripheral wall of the stopper recess 11 matches the outer peripheral wall of the abutting portion 21, the second curved surface 111 of the inner peripheral wall of the stopper recess 11 has a portion matching the shape of the first connection surface 2112, which is positioned as the second connection surface 1112 for convenience of description. The centre line of the second connecting surface 1112 coincides with the centre line Z of the tool holder.

In the process of installing the tool bit 20, after the abutting portion 21 is inserted into the limiting recess 11, the tool bit 20 is rotated to make the first connection surface 2112 contact and mate with the second connection surface 1112, so as to ensure that the center line Y of the tool bit coincides with the center line Z of the tool holder, i.e., the tool bit 20 is concentric with the tool holder 10. Meanwhile, the cutter head 20 is ensured to rotate around the central line of the cutter head, so that the first gradually-changing surface 2111 is accurately contacted and matched with the corresponding part of the inner peripheral wall of the limiting groove 11 and the first gradually-changing surface 2111.

Optionally, the first curved surface 211 further includes a first transition surface 2113, and the first connection surface 2112 smoothly transitions to the first gradual surface 2111 through the first transition surface 2113.

Wherein, the gradual change line A is a second arc line with the circle center deviating from the central line Y of the cutter head. The intersection line of the first transition surface 2113 and the cross section is a transition arc line C, and the first arc line B and the second arc line are both tangent to the transition arc line C. This configuration makes the entire first curved surface 211 easier to mold and manufacture.

The gradual change line a is a second arc line whose center deviates from the center line Y of the tool bit, i.e., the center line of the first gradual change surface 2111 is parallel to the center line Y of the tool bit.

It should be noted that the radius of the second circular arc line may be equal to the radius of the first circular arc line B, or the radius of the second circular arc line may be greater than the radius of the first circular arc line B, or the radius of the second circular arc line may be smaller than the radius of the first circular arc line B. In other embodiments, the transition line a may have other shapes, for example, the transition line a may be an involute, a parabola, or the like.

Of course, since the inner peripheral wall of the stopper recess 11 matches the outer peripheral wall of the abutment portion 21, the second curved surface 111 of the inner peripheral wall of the stopper recess 11 has a portion matching the shape of the first transition surface 2113, which is positioned as the second transition surface 1113 for convenience of description. The second connection surface 1112 merges into the second gradual change surface 1111 via a second transition surface 1113.

As can be seen from the above, the first curved surface 211 is formed by sequentially connecting the first connection surface 2112, the first transition surface 2113, and the first gradually-changing surface 2111 in the circumferential direction of the butting portion 21. In other embodiments, the first curved surface 211 may have other structures. For example, as shown in fig. 3, the first curved surface 211 is a first gradually-changing surface 2111; as another example, as shown in fig. 4, the first curved surface 211 includes only a first gradually changing surface 2111 and a first connection surface 2112 directly connected to the first gradually changing surface 2111.

Further, with continued reference to fig. 2, a direction from the first connection surface 2112 to the first gradually-changing surface 2111 in the circumferential direction of the abutting portion 21 on the first curved surface 211 is a preset direction X. The distance from the gradual change line A to the central line Y of the cutter head along the preset direction X is gradually reduced. The maximum distance from the gradual change line A to the central line Y of the cutter head is not more than the radius of the first circular arc line B.

The predetermined direction X is a direction in which the first connection surface 2112, the first transition surface 2113, and the gradient surface are connected in sequence. In fig. 2, the predetermined direction X is clockwise. The distance from the gradual change line a to the center line Y of the tool bit along the preset direction X gradually decreases, and it can be understood that the end of the gradual change line a, which has a larger distance to the center line Y of the tool bit, is connected to the transition circular arc line C.

In the process of installing the tool bit 20, after the abutting portion 21 is inserted into the limiting groove 11, the tool bit 20 is rotated to make the first gradually-changing surface 2111 enter the portion (the second connection surface 1112) of the inner peripheral wall of the limiting groove 11 corresponding to the first connection surface 2112, so that the tool bit 20 is easier to rotate in the first half of the installation process.

In another embodiment, as shown in fig. 5, the direction from the first connection surface 2112 to the first gradually-changing surface 2111 along the circumferential direction of the abutting portion 21 on the first curved surface 211 is a preset direction X, the distance from the gradually-changing line a to the center line Y of the tool bit may gradually decrease along the direction opposite to the preset direction X, and the minimum distance from the gradually-changing line a to the center line Y of the tool bit is not less than the radius of the first circular arc line B. It is understood that the end of the taper line a, which is at a smaller distance from the center line Y of the cutter head, is connected to the transition circular arc line C.

The first curved surface 211 in the outer peripheral wall of the abutting portion 21 may be one or more (two, three, four, etc.).

With continued reference to fig. 1, in the present embodiment, the first curved surface 211 is plural in the outer peripheral wall of the abutting portion 21. The cutting head 20 is provided with a plurality of first flutes 23, and every two adjacent first curved surfaces 211 are separated by one first flute 23.

The first chip groove 23 plays a role of discharging chips, and the chips generated during the drilling process of the cutter head 20 can be discharged through the first chip groove 23. Every two adjacent first curved surfaces 211 are separated by a first chip removal groove 23, the structure is reasonable, and the cutter head 20 is guaranteed to have good chip removal capacity.

Illustratively, the number of the first curved surfaces 211 in the outer peripheral wall of the butting portion 21 is two, and the two first curved surfaces 211 are distributed in a central symmetry manner with respect to the center line Y of the tip. This configuration provides a circumferentially uniform distribution of forces to the cutting tip 20 during cutting.

In the case where there are two first curved surfaces 211, each adjacent two first curved surfaces 211 are separated by one first flute 23, that is, one circumferential end of one first curved surface 211 is separated from one circumferential end of the other first curved surface 211 by one first flute 23, and the other circumferential end of one curved surface is separated from the other circumferential end of the other first curved surface 211 by the other first flute 23, then there are also two first flutes 23. It is also understood that two second flutes 13 divide the outer wall of the abutment 21 into two first curved surfaces 211.

As shown in fig. 2, the intersection of the flute wall of the first flute 23 and the cross-section forms a concave curve D of the cross-section. The section concave curve D, the first arc line B, the transition arc line C, the gradual change line A, the section concave curve D, the first arc line B, the transition arc line C and the gradual change line A are sequentially connected end to form a closed profile.

As shown in fig. 1, the cutting head 20 further includes a head 22 connected to the abutting portion 21, the abutting portion 21 is disposed coaxially with the head 22, and the axes of the abutting portion 21 and the head 22 are the center line Y of the cutting head. An end surface of one axial end of the head 22 is a support surface 222, and the abutting portion 21 extends along the support surface 222 in a direction away from the head 22. An end surface of the abutting portion 21 axially distant from the abutting portion 21 is a bottom surface 213. The bearing surface 222 and the bottom surface 213 are both perpendicular to the centerline Y of the insert.

As shown in fig. 6, a chisel edge 221 is formed at the center of the tip of the head 22. The first flute 23 extends downward from the tip of the head 22 to the bottom surface 213, and the groove wall of the first flute 23 intersects the bottom surface 213 to form a first concave curve E. The two first flutes 23 divide the outer peripheral wall of the head 22 into two coaxial partial cylindrical surfaces 223 which are distributed at intervals, and the partial cylindrical surfaces 223 are blade backs. One end of the circumferential direction of the partial cylindrical surface 223 is formed with a margin 224 protruding radially from the partial cylindrical surface 223, and the diameter of the margin 224 is 0.2-0.5mm larger than the diameter of the partial cylindrical surface 223. The land 224 intersects the groove wall of the first flute 23 to form a secondary edge 225, and the groove wall of the first flute 23 forms a primary edge 226 at the tip of the head 22. The diameter of the margin 224 is the diameter of the bore hole of the drill bit 100. In addition, in order to facilitate the assembly and disassembly of the cutting head 20, two clamping grooves 227 are formed in the head 22, the distance between the two clamping grooves 227 is 180 degrees, and the clamping grooves 227 penetrate through the top end of the head 22 and a part of the cylindrical surface 223 of the head 22 at the same time.

Alternatively, with continued reference to fig. 2, the abutting portion 21 is a cone structure that is contracted and extended from the bottom surface 213 to a direction close to the head portion 22 (axially upward direction) to the supporting surface 222, that is, the radial dimension of the abutting portion 21 is gradually reduced from the bottom surface 213 to the supporting surface 222. The entire abutment 21 can be seen as a convex cone.

Since the intersection lines of the first connection surface 2112, the first transition surface 2113 and the first gradually-changing surface 2111 with the cross section are circular arcs and the butt joint portion 21 has a conical structure, the first connection surface 2112, the first transition surface 2113 and the first gradually-changing surface 2111 are conical surfaces, and the center line of the first connection surface 2112 is parallel to the center line of the first gradually-changing surface 2111.

The bottom surface 213 of the abutment portion 21 contracts during extension in the direction of the support surface 222 by an angle β, which is the cone angle of the cone in which the first connection surface 2112 is located. Illustratively, β is equal to or greater than 5 ° and equal to or less than 25 °.

Of course, since the inner peripheral wall of the limiting recess 11 matches with the outer peripheral wall of the abutting portion 21, the limiting recess 11 is a concave cone matching with the abutting portion 21. Of course, the second connection surface 1112, the second transition surface 1113 and the second gradually changing surface 1111 are also conical surfaces.

The end of the cutter bar 10 is provided with a bearing surface 12, and the limit groove 11 is arranged on the bearing surface 12. The cutter bar 10 is a cylindrical structure, and the radius of the cutter bar 10 is less than or equal to the radius of a part of cylindrical surface 223 (blade back) of the head 22. A plurality of spiral second chip grooves 13 are formed in the peripheral wall of the cutter rod 10, the second chip grooves 13 in the cutter rod 10 correspond to the first chip grooves 23 in the cutter head 20 one by one, and namely the number of the second chip grooves 13 is two. The limiting groove 11 is arranged coaxially with the cutter bar 10, and the central line of the limiting groove 11 is the central line Z of the cutter bar.

The second chip groove 13 extends to the bearing surface 12, and the second chip groove 13 is communicated with the limiting groove 11, so that the end part of the cutter rod 10 forms a bayonet 14 for the butt joint part 21 to enter the limiting groove 11. The bottom wall 112 of the limiting groove 11 and the groove wall of the second chip groove 13 intersect to form a second concave curve F corresponding to the position of the first concave curve E. The two second chip grooves 13 divide the inner wall of the limiting groove 11 into two second curved surfaces 111 which are distributed at intervals.

In the above structure, the bearing surface 222 of the head 22 and the bearing surface 12 of the tool holder 10 constitute a first limit structure for limiting the axial downward movement of the tool bit 20 relative to the tool holder 10; the outer peripheral wall of the head portion 22 and the inner peripheral wall of the retaining recess 11 constitute a second retaining structure (i.e., an anti-loosening function) that limits the axial upward movement of the tool bit 20 relative to the tool holder 10.

After the abutting part 21 of the tool bit 20 is matched with the limiting groove 11 of the tool bar 10, the first gradually-changing surface 2111 of the abutting part 21 is abutted and matched with the second gradually-changing surface 1111 of the limiting groove 11, so that the rotation stopping of the tool bit 20 is realized (namely, a rotation stopping structure); the bearing surface 222 of the head 22 and the bearing surface 12 of the tool holder 10 are mutually abutted and matched, and the first curved surface 211 (conical surface structure) of the outer peripheral wall of the head 22 is abutted and matched with the second curved surface 111 (conical surface structure) of the inner peripheral wall of the limiting groove 11, so that the axial limiting of the tool bit 20 is realized. Namely, the anti-loosening function is realized on the rotation stopping structure, and the cutter head 20 is ensured not to fall off from the cutter bar 10 when the cutter is withdrawn.

Further, when the abutting portion 21 is located in the limiting recess 11 and forms a fit, the supporting surface 222 tightly abuts against the bearing surface 12, and the first connection surface 2112 tightly abuts against a portion (the second connection surface 1112) of the inner peripheral wall of the limiting recess 11 corresponding to the first connection surface 2112. It can be understood that the radial dimension of the first connection surface 2112 of the abutting portion 21 is slightly larger than the radial dimension of the second connection surface 1112 of the limiting recess 11, so that the first connection surface 2112 and the second connection surface 1112 form a relatively close fit. The close fit between first connection face 2112 and second connection face 1112 is similar to an interference fit formed between the outer peripheral wall of the cylindrical body and the bore wall. The structure has good coaxial centering and anti-loosening effects of the cutter bar 10 and the cutter head 20, and ensures that the cutter head 20 cannot fall off from the cutter bar 10 when the cutter is withdrawn. At the same time, this construction enables a quick change of the cutting head 20 without any fasteners between the cutting head 20 and the tool shank 10.

Alternatively, the axial length of the abutment portion 21 is smaller than the depth of the limiting recess 11, i.e. the distance from the support surface 222 to the bottom surface 213 of the abutment portion 21 is smaller than the distance from the bearing surface 12 to the bottom wall 112 of the limiting recess 11. The structure enables a gap to exist between the bottom surface 213 of the abutting part 21 and the bottom wall 112 of the limiting groove 11 when the bearing surface 222 abuts against the bearing surface 12, so that the over-positioning between the tool bit 20 and the tool holder 10 is avoided, and the bearing surface 222 can be ensured to be tightly abutted against the bearing surface 222.

In the present embodiment, when the supporting surface 222 abuts against the bearing surface 12, a gap with a width of 0.05-0.2mm, for example, 0.1mm, is maintained between the bottom surface 213 of the abutting portion 21 and the bottom wall 112 of the limiting recess 11.

When the cutter head 20 and the cutter bar 10 are assembled, the maximum outer diameter position of the abutting part 21 of the cutter head 20 is aligned with the bayonet 14 at the end part of the cutter bar 10, and the abutting part 21 is inserted into the limiting groove 11, so that the bearing surface 222 is contacted with the bearing surface 12; subsequently, as shown in fig. 7, the tool bit 20 is slightly rotated clockwise, so that the first connection surface 2112 of the abutting portion 21 just reaches the position of the second connection surface 1112 of the limiting recess 11, and at this time, the tool bit 20 is assembled with the tool holder 10 at the initial contact position; as shown in fig. 8, since the radial dimension of the first connection surface 2112 is slightly larger than the radial dimension of the second connection surface 1112, the tool bit 20 can be assembled with the tool holder 10 in an intermediate position by forcibly rotating the tool bit 20 with a special wrench (the special wrench is engaged in the engaging slot 227 of the tool bit 20) to gradually contact the first connection surface 2112 with the second connection surface 1112; as shown in fig. 9, since the first gradually changing surface 2111 of the abutting portion 21 and the second gradually changing surface 1111 of the limiting recess 11 are gradually changed, the tool bit 20 is further rotated by force to make the first gradually changing surface 2111 contact and match with the second gradually changing surface 1111, the tool bit 20 and the tool bar 10 are assembled at the rotation stop position, at this time, the abutting portion 21 of the tool bit 20 and the limiting recess 11 of the tool bar 10 are in tight fit, the bearing surface 12 of the abutting portion 21 and the bearing surface 222 of the tool bar 10 are in tight fit, and the first connection surface 2112 of the abutting portion 21 and the second connection surface 1112 of the limiting recess 11 are in tight fit.

When the tool bit needs to be disassembled, the tool bit 20 is only required to be twisted forcefully in the reverse rotation stopping direction (anticlockwise direction) until the initial contact position is reached, the hand feeling is weak and easy, the tool bit 20 is further twisted, and finally the butt joint part 21 of the tool bit 20 is pulled out from the limiting groove 11 of the tool bar 10.

In the assembling process of the tool bit 20 and the tool bar 10, the two first curved surfaces 211 of the abutting portion 21 of the tool bit 20 are respectively matched with the two second curved surfaces 111 of the limiting groove 11 of the tool bar 10, so that the axial and circumferential positioning is realized, the centering is accurate, and the effect is excellent.

As shown in fig. 10, when the abutting portion 21 of the cutting head 20 is engaged with the limiting recess 11 of the tool holder 10, the center line Y of the cutting head coincides with the center line Z of the tool holder (the cutting head 20 is centered with the tool holder 10), and the first chip discharge grooves 23 on the cutting head 20 smoothly penetrate the second chip discharge grooves 13 of the tool holder 10 to form an integral spiral groove.

In the whole tool bit 20, only the first chip grooves 23 penetrate through the supporting surface 222, so that the area of the supporting surface 222 of the tool bit 20 is larger, the contact area between the supporting surface 222 of the tool bit 20 and the bearing surface 12 of the tool bar 10 is larger, the contact is more stable, and the axial force transmission is larger.

In the present embodiment, the abutting portion 21 of the tool bit 20 has a tapered structure, and in other embodiments, the abutting portion 21 may have another structure. For example, as shown in fig. 11, the abutting portion 21 of the cutting head 20 is a cylindrical structure extending from the bottom surface 213 to the direction close to the head 22 with an equal diameter, and the limiting recess 11 is a cylindrical structure matching with the abutting portion 21. In this case, a locking protrusion 228 may be formed on an outer circumferential wall of the abutting portion 21, a locking groove 113 may be formed on an inner circumferential wall of the limiting recess 11, and the axial limitation of the tool bit 20 may be achieved by rotating the tool bit 20 to lock the locking protrusion 228 in the locking groove 113. The bearing surface 222 of the head 22 and the bearing surface 12 of the tool holder 10 form a first limit structure for limiting the axial downward movement of the tool bit 20 relative to the tool holder 10; the upper surface of the locking protrusion 228 and the upper groove wall of the locking groove 113 form a second limit structure for limiting the axial upward movement of the tool bit 20 relative to the tool holder 10.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims (12)

1. A replaceable head drill bit, comprising:

the end part of the cutter bar is provided with a limiting groove; and

the cutter head is provided with an abutting part which is used for enabling the cutter head and the cutter bar to be coaxially arranged after being matched with the limiting groove, and the inner peripheral wall of the limiting groove is matched with the outer peripheral wall of the abutting part;

the peripheral wall of butt joint portion includes first curved surface, first curved surface includes first gradual change face, first gradual change face with the intersection of the cross section of butt joint portion is for reaching the gradual change line that reduces of distance of the central line of tool bit.

2. The bit according to claim 1, wherein the first curved surface further comprises a first connecting surface, an intersection line of the first connecting surface and the cross section is a first circular arc line, and a center of the first circular arc line is located on a center line of the bit.

3. The bit according to claim 2, wherein the first curved surface further comprises a first transition surface, the first connection surface smoothly transitioning from the first gradual surface through the first transition surface.

4. The bit according to claim 3, wherein the taper is a second arc centered off the centerline of the bit;

the intersection line of the first transition surface and the cross section is a transition arc line, and the first arc line and the second arc line are both tangent to the transition arc line.

5. The bit according to any one of claims 2 to 4, wherein a direction from the first connection surface to the first gradually changing surface in a circumferential direction of the abutment portion on the first curved surface is a predetermined direction;

the distance from the gradual change line to the center line of the cutter head along the preset direction is gradually reduced;

the maximum distance from the gradual change line to the central line of the cutter head is not more than the radius of the first circular arc line.

6. The bit according to claim 1, wherein the first curved surface is a plurality of curved surfaces;

a plurality of first chip grooves are formed in the cutter head;

every two adjacent first curved surfaces are separated by a first chip groove.

7. The bit according to claim 6, wherein the first curved surface is two;

the two first curved surfaces are distributed symmetrically about the center line of the cutter head.

8. The bit according to claim 1, further comprising a first stop structure for limiting axial downward movement of the cutter head relative to the cutter shaft and a second stop structure for limiting axial upward movement of the cutter head relative to the cutter shaft.

9. The bit according to claim 8, wherein the cutter head further comprises a head portion having a bearing surface, the abutment portion extending along the bearing surface in a direction away from the head portion;

the end part of the cutter bar is provided with a bearing surface which is used for abutting against the bearing surface, and the limiting groove is arranged on the bearing surface;

the first limiting structure comprises the supporting surface and the bearing surface.

10. The bit according to claim 9, wherein the abutment has a bottom surface axially opposite the bearing surface;

the butt joint part is a cone structure which is contracted and extends to the supporting surface from the bottom surface to the direction close to the head part;

the second limit structure comprises an outer peripheral wall of the butt joint part and an inner peripheral wall of the limit groove.

11. The bit according to claim 10, wherein the first curved surface further comprises a first connecting surface, an intersection of the first connecting surface and the cross section is a first circular arc line, and a center of the first circular arc line is located on a center line of the bit;

when the abutting part is positioned in the limiting groove and forms fit, the supporting surface is tightly abutted against the bearing surface, and the first connecting surface is tightly abutted against the part, corresponding to the first connecting surface, of the inner peripheral wall of the limiting groove.

12. The bit according to claim 11, wherein the axial length of the abutment is less than the depth of the stop recess.

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