Stepped drill for machining stepped hole of outer ring

Abstract

The invention discloses a stepped drill for machining an outer ring stepped hole. The bottom of a drill bit is conical, and two main cutting edges, two rear tool faces and two front end negative chamfering areas are symmetrically arranged on the conical surface relative to a drill tip; two water outlet holes are symmetrically formed in the two rear tool faces relative to the drill tip; auxiliary cutting edges symmetrical relative to the central axis are arranged on the drill bit at the upper end of the conical bottom; two chamfering orifice cutting edges which are symmetrical relative to the central axis are arranged at the contact position of the drill bit and the drill handle, and the inclination angle of the two chamfering orifice cutting edges is the same as the inclination angle of the outer ring stepped hole chamfer; a chip groove is formed in the drill handle at the upper end of the drill bit; cold water pipelines are arranged in the drill handle and the drill bit, water outlet holes are also formed in the drill handle, and the water outlet holes are communicated with the cold water pipelines. One-time machining is in place, one tool and tool changing time can be saved, meanwhile, tool maintenance cost and use cost are reduced, the service life of the tool is prolonged, waste of on-site adjustment time is saved, and defective products are reduced.

Description

Technical Field

[0001] This invention belongs to the field of outer ring machining tool technology, and relates to a stepped drill for machining stepped holes in outer rings. Background Technology

[0002] Outer ring shafts are an important type of automotive drive shaft, widely used in rear-wheel drive and four-wheel drive vehicles. In the production of these shafts, stepped holes need to be machined on the outer ring shank. Currently, the stepped holes on outer rings are machined using a combination of two different tools: first, a vertical straight hole is machined using a flat-bottom drill, with a diameter 0.5mm smaller than the required value; then, a compound boring tool is used for finishing, producing the final hole diameter and chamfer. This machining method results in short tool life for both tools and a long machining time, increasing processing costs and the manufacturing cost of the outer ring, especially with large production volumes. Furthermore, incorrect adjustment of the boring tool and flat-bottom drill dimensions can easily lead to tool collisions or incomplete hole machining, resulting in workpiece dimensional defects and severely impacting the machining quality of the automotive drive shaft. Summary of the Invention

[0003] The purpose of this invention is to solve the above-mentioned problems existing in the prior art and provide a step drill for machining outer ring stepped holes. This step drill can complete the machining in one go, which can save a tool and tool change time, reduce tool maintenance costs and usage costs, improve tool life, save time wasted on-site adjustment, and reduce the generation of defective products.

[0004] To achieve the above objectives, the solution of the present invention is: a stepped drill for machining an outer ring stepped hole, comprising a drill shank and a drill bit at the lower end of the drill shank; the bottom of the drill bit is conical, and two main cutting edges, two flank faces, and two front negative chamfer areas are symmetrically arranged on the conical surface relative to the drill tip; the shape formed by rotating the main cutting edge one revolution is the same as the shape of the bottom of the outer ring stepped hole; two water outlet holes are symmetrically arranged on the two flank faces relative to the drill tip; a secondary cutting edge symmetrically arranged relative to the central axis is provided on the upper end of the drill bit at the conical bottom; the position where the drill bit contacts the drill shank is completely matched with the chamfer position of the outer ring stepped hole, and two chamfered hole cutting edges symmetrically arranged relative to the central axis are provided at this position, the inclination angle of the two chamfered hole cutting edges being the same as the inclination angle of the chamfer of the outer ring stepped hole; a chip removal groove is provided on the drill shank at the upper end of the drill bit; a cold water pipe is provided inside the drill shank and the drill bit, and a water outlet hole is also provided on the drill shank, each water outlet hole being connected to the cold water pipe.

[0005] More preferably, a chamfer is provided between the secondary cutting edge and the primary cutting edge. The chamfer reduces tool wear and increases tool life. Preferably, the included angle between the two chamfers is 120°.

[0006] More preferably, the drill bit has a cone apex angle of 140°, which improves the cutting sharpness of the drill bit and increases its lifespan.

[0007] The beneficial effects of this invention are as follows: The drill tip serves as a centering tool; the main cutting edge performs the primary cutting action, removing material from the bottom of the hole; the front-end secondary chamfer increases the sharpness of the drill tip, enhances the chip-breaking ability of the drill bit, reduces drill tip wear, and improves tool life; the flank face determines the sharpness and strength of the drill bit; the secondary cutting tool is a finishing tool, which finishes the hole wall and determines the diameter of the outer ring stepped hole; the water outlet sprays cutting fluid, which cools and flushes away chips; the chamfered hole cutting edge removes material at the chamfer of the outer ring stepped hole to form a chamfer; the chamfering edge reduces tool wear and improves tool life. This invention achieves one-time machining, saving a tool and tool change time, saving overall machining time by at least 10 seconds, meeting the requirements for increased on-site production capacity, while reducing tool maintenance costs and operating costs, and improving tool life by at least 10%. After one tool setting using a tool setter, dimensional adjustments are convenient, ensuring workpiece machining consistency. The same product does not need repeated calculations and adjustments, saving on-site adjustment time and cost of defective products. Attached Figure Description

[0008] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a bottom view of the present invention. Detailed Implementation

[0009] The present invention will be further described below with reference to specific embodiments.

[0010] like Figure 1 and Figure 2As shown, this embodiment includes a drill shank 1 and a drill bit 2 at the lower end of the drill shank 1. The bottom of the drill bit 2 is conical, and two main cutting edges 3, two flank faces 9, and two front negative chamfer areas 10 are symmetrically arranged on the conical surface relative to the drill tip 4. The shape formed by rotating the main cutting edge 3 one revolution is the same as the bottom shape of the outer ring stepped hole. Two water outlet holes 5 are symmetrically arranged on the two flank faces 9 relative to the drill tip 4. A secondary cutting edge 8 symmetrically arranged relative to the central axis is provided on the upper end of the conical bottom of the drill bit 2. The position where the drill bit 2 contacts the drill shank 1 is completely matched with the chamfer position of the outer ring stepped hole. Two chamfered hole cutting edges 6 symmetrically arranged relative to the central axis are provided at this position, and the inclination angle of the two chamfered hole cutting edges 6 is the same as the inclination angle of the chamfer of the outer ring stepped hole. A chip removal groove 11 is provided on the drill shank 1 at the upper end of the drill bit 2. A cold water pipe is provided inside the drill shank 1 and the drill bit 2, and a water outlet hole 5 is also provided on the drill shank 1. Each water outlet hole 5 is connected to the cold water pipe. In this embodiment, a chamfer 7 is provided between the secondary cutting edge 8 and the main cutting edge 3. The chamfer 7 reduces cutting edge wear and improves tool life. In this embodiment, the included angle between the two chamfers 7 is 120°. In this embodiment, the drill bit's cone apex angle is 140°, which improves the drill bit's cutting sharpness and extends its life. In this embodiment, a chisel edge connecting the two main cutting edges 3 is provided at the drill tip, according to actual needs.

[0011] In this embodiment, the drill tip 4 serves a centering function; the main cutting edge 3 performs the primary cutting action, removing material from the bottom of the hole; the front secondary chamfer area 10 increases the sharpness of the drill tip, enhances the drill bit's chip-breaking ability, reduces drill tip wear, and improves tool life; the flank face 9 determines the drill bit's sharpness and strength; the secondary cutting edge 8 is a finishing tool, used to finish the hole wall and determine the hole diameter; the water outlet 5 sprays cutting fluid, serving a cooling and chip-flush function; the chamfered hole cutting edge 6 removes material from the chamfer of the outer ring stepped hole to form a chamfer; the chamfered edge 7 reduces tool wear and improves tool life.

[0012] The above-described embodiments are merely preferred and exemplary, and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A step drill for machining stepped holes in an outer ring, characterized in that: The drill bit includes a drill shank and a drill bit at the lower end of the drill shank. The bottom of the drill bit is conical, and two main cutting edges, two flank faces, and two front negative chamfer areas are symmetrically arranged on the conical surface relative to the drill tip. The shape formed by rotating one revolution of the main cutting edge is the same as the bottom shape of the outer ring stepped hole. Two water outlets are symmetrically arranged on the two flank faces relative to the drill tip. A secondary cutting edge symmetrical relative to the central axis is provided on the upper end of the conical bottom of the drill bit. The position where the drill bit contacts the drill shank is perfectly matched with the chamfer position of the outer ring stepped hole. Two chamfered hole cutting edges symmetrical relative to the central axis are provided at this position, and the inclination angle of the two chamfered hole cutting edges is the same as the inclination angle of the chamfer of the outer ring stepped hole. A chip removal groove is provided on the drill shank at the upper end of the drill bit. A cold water pipe is provided inside the drill shank and the drill bit, and a water outlet is also provided on the drill shank. Each water outlet is connected to the cold water pipe.

2. The step drill for machining outer ring stepped holes according to claim 1, characterized in that: A chamfer is provided between the secondary cutting edge and the main cutting edge.

3. The step drill for machining outer ring stepped holes according to claim 2, characterized in that: The included angle between the two chamfered edges is 120°.

4. The step drill for machining outer ring stepped holes according to claim 1, 2, or 3, characterized in that: The drill bit has a cone apex angle of 140°.

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