CN112828351B

CN112828351B - Step drill with combined cutting edge

Info

Publication number: CN112828351B
Application number: CN202011633693.XA
Authority: CN
Inventors: 朱冬伟; 朱小锋; 卢伟
Original assignee: ZHEJIANG XINXING TOOLS CO Ltd
Current assignee: Zhejiang Xinxing Tools Co.,Ltd.
Priority date: 2020-12-31
Filing date: 2020-12-31
Publication date: 2022-02-22
Anticipated expiration: 2040-12-31
Also published as: CN112828351A

Abstract

The invention provides a combined cutting edge step drill aiming at the defects of low cutting efficiency, large generated cutting heat and low service life of a cutter caused by adopting a single cutting edge in the prior art, the combined cutting edge step drill comprises a cutting part and a clamping cutter handle, wherein the cutting part is provided with at least two pairs of spiral grooves along the axial direction of a drill bit, each pair of spiral grooves are adjacently arranged, each spiral groove penetrates through each step to form a cutting edge with an unequal angle beta, the cutting edges of each pair of spiral grooves are respectively a first cutting edge and a second cutting edge, the conical surface angle beta 1 of the first cutting edge is unequal to the conical surface angle beta 2 of the second cutting edge, the first cutting edge (4a) and the second cutting edge (4b) are combined into chip separation cutting, the combined cutting edge step drill adopting the combined cutting edge step drill has different angles of the cutting edges at two sides of a chip removal channel, and each cutting edge is only contacted with one part of a cut part after the combined cutting edge step drill enters a cutting state, that is, the contact line of each cutting edge and the cut surface is shortened, so that the resistance of the drill bit is reduced, the cutting efficiency can be improved, the friction is reduced when the resistance is reduced, and the cutting heat is reduced.

Description

Step drill with combined cutting edge

Technical Field

The invention relates to the technical field of hole machining tools, in particular to a step drill for machining different hole diameters.

Background

The conventional step drill has the same cutting edges, and when cutting, each cutting edge simultaneously cuts with a cut object, so that the contact area of a cutting part is large, particularly, when the step drilling operation is carried out by adopting handheld equipment, the downward cutting resistance is large, the cutting efficiency is low, and when cutting, the cutting edge and the cut part generate larger friction force to generate higher cutting heat, so that the service life of a drill bit is short.

In addition, the prior art step drill has the advantages that when the handheld device is used for drilling, the handheld device shakes to a certain extent, the gap between the drill bit and the drill hole is gradually increased, the precision of the drilled hole is poor, and the operation is not easy to control.

When a gun drill is used for cutting a thin plate or when large cutting resistance is met, large vibration can be generated, when one step is drilled through to the next step in the cutting process, certain inertia is generated due to downward force, large impact force can be generated, the cutting width of a drill bit is increased suddenly, the drill bit is clamped, in addition, the verticality of the handheld drilling is poor, and the drill bit can generate large torque when being cut into the handheld drilling, so that the cutting failure is caused.

Disclosure of Invention

The invention aims to provide a step drill with a combined cutting edge, aiming at the defects that in the prior art, the cutting efficiency is low, the generated cutting heat is large and the service life of a cutter is short due to the adoption of a single cutting edge.

The purpose of the invention is realized by the following technical scheme:

the step drill with the combined cutting edges comprises a cutting part (1) and a clamping tool handle (2), wherein at least two pairs of spiral grooves are formed in the cutting part along the axis direction of a drill bit, each pair of spiral grooves are adjacently arranged, each spiral groove penetrates through each step to form a cutting edge (4) with an unequal angle beta, the cutting edges of each pair of spiral grooves are respectively a first cutting edge and a second cutting edge, the angle beta 1 of the conical surface of the first cutting edge is unequal to the angle beta 2 of the conical surface of the second cutting edge, and the first cutting edge (4a) and the second cutting edge (4b) are combined to form chip separation cutting;

the conical surface angles of the cutting edge I (4a) and the cutting edge II (4b) are respectively 30 degrees to 65 degrees, and the difference value of the conical surface angle beta 1 of the cutting edge I (4a) and the conical surface angle beta 2 of the cutting edge II (4b) is +/-5 degrees to +/-25 degrees;

the cutting edge I (4a) and the cutting edge II (4b) are respectively provided with a cutting width K which is 1/4-3/4 of the width M of the conical surface, and the conical surface angle of the cutting edge I (4a) or the cutting edge II (4b) is 45 degrees;

the cutting width K is half of the conical surface width M;

the back angle of the cutting edge is a sectional back angle and is formed by intersecting a circle deviated from the center of the drill bit and a step surface of the drill bit, one end of the back angle is intersected with the step surface, and the other end of the back angle is intersected with the cutting edge;

the chord length H of the segmented back angle is 1-8mm, and the fall S of the back angle is 0.05-0.3 mm;

a transition surface is arranged between the vertical surface and the conical surface of the step;

the transition surface is an arc surface;

the radius of the R angle of the arc-shaped surface is 1-4 mm;

the angle beta between the first cutting edge and the second cutting edge formed by each pair of spiral grooves is equal to or unequal to the angle beta between the first cutting edge and the second cutting edge formed by the other pair of spiral grooves.

The angle of each cutting edge of the step drill with the combined cutting edge is different, and after the step drill with the combined cutting edge enters a cutting state, each cutting edge is only contacted with one part of a cut part, namely the contact line of each cutting edge and the cut surface is shortened, so that the resistance of a drill bit is reduced, the cutting efficiency can be improved, and in addition, when the resistance is reduced, the friction force is reduced, and the cutting heat is reduced.

The drill bit adopting the structure of the invention adopts the sectional type relief angle, the clearance between the drilled hole and the drill bit can be controlled to be small, the handheld equipment can be supported by the hole wall of the drilled hole when swinging, and compared with the mode that the clearance angle is adopted completely, the drilling process is kept stable.

By adopting the structure of the invention, the transition surface is arranged between the step and the conical surface to form circular arc transition, when the step drill is used for processing a thin plate, when the step drill penetrates through one step to the next step, the cutting width is gradually increased from the circular arc starting point, thus the impact force can be relieved, and the drill bit is not easy to be clamped due to the generation of over-cutting.

Drawings

FIG. 1 is a schematic front view of a step drill with a combined cutting edge according to the present invention;

FIG. 2 is a left side view of FIG. 1;

FIG. 3 is a view showing a cutting edge developed;

FIGS. 4 and 5 are both cutting edge combination views;

FIG. 6 is a schematic front view of another embodiment of a step drill with a combined cutting edge according to the present invention;

FIG. 7 is a cross-sectional view taken along line A-A of FIG. 6, illustrating the construction of the embodiment of the segmented relief angle of the present invention;

fig. 8 is an enlarged view of B in fig. 7, with the cross-sectional profile of the bit removed.

Description of the reference numerals

1. A cutting portion; 2. clamping a tool shank; 3. a chip removal channel; 4. cutting the cutting edge; 4a, cutting edge I; 4b, cutting edge II; 5. a segmented relief angle; 6. a transition surface; 12. a circular arc surface.

Detailed Description

The invention is further described below with reference to specific examples:

as shown in fig. 1-8, the invention provides a step drill with combined cutting edges. The step drill is integrally divided into two parts, namely a cutting part 1 and a clamping tool handle 2. At least two pairs of spiral grooves are arranged on the cutting part 1 along the height direction of the drill bit, each pair of spiral grooves are adjacently arranged, each spiral groove penetrates through each step to form a cutting edge 4, each spiral groove forms a chip removal channel 3, the cutting edges 4 of each pair of spiral grooves are cutting edges with different angles beta, cutting edges formed by each pair of spiral grooves are respectively a cutting edge I4 a and a cutting edge II 4b, the cutting edges I and the cutting edges II form a pair of cutting edges, the cutting edges I and the cutting edges II can be obtained by secondary processing after the spiral grooves are processed, the conical surface angle of the cutting edge I4 a formed by one spiral groove is beta 1, the conical surface angle of the cutting edge II 4b formed by the other spiral groove matched with the same is beta 2, and as the conical surface angles of the cutting edge I4 a and the cutting edge II 4b are different from the helical angle, therefore, the contact position and the contact angle of the cutting surface are different, and the cutting edge I and the cutting edge II respectively form a cutting surface with the cutting surface, one face is steeper, and one face is gentler, and the cutting part that blade one and blade two formed is different to a blade is responsible for cutting by its step near the excircle lateral part, and another blade is responsible for cutting by its step near the excircle medial part, makes the iron fillings divide the bits, reduces the cutting resistance.

For example, the first edge 4a cuts off the high point part left by the second edge 4b, and the second edge 4b cuts off the high point part left by the first edge 4a, so that the first edge 4a and the second edge 4b are combined into a cutting edge capable of dividing chips, the contact length between the first edge and the cut surface can be reduced, and the cutting resistance can be reduced.

Preferably, the taper angle of one of the cutting edges is 30 ° to 65 °, more preferably 45 °, and the difference between the taper angle β 1 of the first cutting edge 4a and the taper angle β 2 of the second cutting edge 4b is in a range, which should not be too large or too small, and preferably, the difference between the taper angles is 5 ° to 25 °. That is, the taper angle β 2 of the second cutting edge 4b is ═ β 1 ± (5 ° to 25 °).

After the cutting edge I4 a and the cutting edge II 4b are combined to form chip separation cutting, each cutting edge has a cutting width K during cutting, and the cutting width K is 1/4-3/4 of the width of the conical surface as optimization; preferably, the two cutting edges are half of the width M of the corresponding conical surface, so that the cutting lines formed by the two different cutting edges I4 a and II 4b and the processed surface are intersected at the middle position of the conical surface, the cutting forces shared by the two cutting edges are equivalent, the abrasion to the teeth is reduced, the heat generation is reduced, the cutting force of a single tooth is reduced, the heat generation of the teeth is reduced, the service life of the teeth is prolonged, if the width difference of the two cutting edges is too large, the cutting forces are concentrated on one tooth, the stress of the teeth is not reduced, and the chip separation effect is weakened.

When a plurality of pairs of spiral grooves are arranged, the angles of the cutting edges formed by each pair of spiral grooves and the angles of the cutting edges formed by other pairs of spiral grooves can be correspondingly equal and unequal, for example, two pairs of spiral grooves are arranged, the cutting edges of the first pair of spiral grooves are respectively a cutting edge one-to-one and a cutting edge two-to-one, the cutting edges of the other pair of spiral grooves are respectively a cutting edge two-to-two and a cutting edge two-to-two, the cutting edges can be equal to or unequal to the spiral angles of the cutting edges two-to-two, and the spiral angles of the cutting edges two-to-two can be equal or unequal.

In the present invention, the relief angle is set in a stepwise manner in order to further improve stability during drilling operation and to form stable cutting. A sectional back angle 5 is arranged near the cutting edge, the sectional back angle 5 is an arc surface 12 formed by intersecting a circle eccentric to the center O of the drill bit and the surface of the step on the step surface, one end of the arc surface 12 is intersected with the excircle of the step of the drill bit, the other end of the arc surface is intersected with the cutting edge, the arc is called the sectional back angle 5 on the cross section of the step, the arc length is H, and a drill hole R is drilled during drilling_GWith step outer circle R_OThe radial difference between the two is called the back angle drop, the back angle difference is S, the arc length H of the sectional back angle is 1-8mm, and the back angle drop S is 0.05-0.3 mm. The cutting edge is provided with the sectional back angle, the clearance between the RO part of the outer circle of the step and the drill hole RG is controlled to be smaller, and the condition that the clearance between the outer circle of the step and the drill hole is continuously increased by adopting the form of all the back angles in the prior art can be prevented; when the handheld device is used for drilling, the handheld device has certain shaking conditions, and the drilled hole wall can be supported by the small gap, so that a certain supporting effect is realized on the drill bit.

In the invention, in order to reduce the impact force between the drill bit and the thin plate during cutting and avoid causing large vibration and torque, the transition surface 6 is arranged at the intersection of each step and the conical surface, and the transition surface 6 can be an arc-shaped curved surface or a triangular surface and is used for prolonging the line length of the step surface of the step drill and the cut surface to play a role in buffering. The transition surface is preferably an arc surface smoothly connected with the conical surface and the step vertical surface, and the arc radius R is preferably 1-4 mm. An arc transition angle R is arranged between the steps and the conical surface, when the drill bit impacts the thin plate from one step to the next step, the cutting width is gradually increased from the arc starting point in the impact, so that the impact force can be relieved, and the drill bit is not easy to be clamped due to over-cutting.

The clamping tool handle 2 of the step drill can be a triangular handle, a square handle or a hexagonal handle. According to the step drill, the clamping tool handle 2 and the cutting part are respectively positioned at two ends of the step drill, and the clamping tool handle 2 can be a triangular handle; or may be a square shank. The cutting part is clamped and fixed by the clamping cutter handle.

Claims

1. The utility model provides a step drill of modular blade, includes cutting part (1) and clamping handle of a knife (2), its characterized in that, the cutting part be provided with two at least pairs of helicla flutes along the axis direction of drill bit, every pair helicla flute is adjacent to be set up, every the helicla flute runs through each step and forms cutting edge (4) that have the angle beta inequality, and every cutting edge to the helicla flute is blade one and blade two respectively, and the conical surface angle beta 1 of blade one and the conical surface angle beta 2 of blade two are inequality, and blade one (4a) makes up into the branch bits cutting with blade two (4 b).

2. A combined cutting edge step drill according to claim 1, wherein the taper angles of the first cutting edge (4a) and the second cutting edge (4b) are respectively 30 ° to 65 °, and the difference between the taper angle β 1 of the first cutting edge (4a) and the taper angle β 2 of the second cutting edge (4b) is ± 5 ° to ± 25 °.

3. A combined edge step drill according to claim 1 or 2, wherein the first edge (4a) and the second edge (4b) have cutting widths K of 1/4-3/4 of the taper width M, respectively, and the taper angle of the first edge (4a) or the second edge (4b) is 45 °.

4. A combined edge step drill according to claim 3, wherein the cutting width K is half the taper width M.

5. A step drill with a combined cutting edge according to claim 1, wherein the relief angle of the cutting edge is a segmental relief angle formed by intersecting a circle deviated from the center of the drill bit with a step surface of the drill bit, and one end of the segmental relief angle intersects the step surface and the other end intersects the cutting edge.

6. A step drill with combined cutting edge as defined in claim 5, wherein the chord length H of said sectional back angle is 1-8mm, and the fall S of the back angle is 0.05-0.3 mm.

7. A step drill with combined cutting edges as claimed in claim 1 or 2, wherein a transition surface is arranged between the vertical surface and the conical surface of the step.

8. The combination cutting edge step drill according to claim 7, wherein the transition surface is an arc surface.

9. The combination-edge step drill according to claim 8, wherein the radius of the R-angle of the arc-shaped surface is 1-4 mm.

10. A step drill with combined cutting edges according to claim 1, wherein the angle β between the first cutting edge and the second cutting edge formed by each pair of spiral grooves is equal to or different from the angle β between the first cutting edge and the second cutting edge formed by the other pair of spiral grooves.