Blade edge replaceable drill

Abstract

To provide a blade edge replaceable drill for drilling of a die-casting die which enables an entire length to be larger than 400 mm even when a tool diameter is smaller than or equal to 10 mm.SOLUTION: A blade edge part replaceable drill 1 is a drill for deep hole processing having a replaceable blade edge part 4 and includes: a groove part 2; a guide part 3 which prevents swinging during the processing; a replaceable blade edge part 4; and a joint part 5 which connects these components. A coolant passes through an inner cooling passage 6 of the guide part 3 and passes from the front side of the blade edge part 4 to a spiral external cooling passage 7. The blade edge part replaceable drill 1 has pins 9 which prevent phase shifting between the joint part 5 and the blade edge part 4.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an insert-exchangeable drill.

Background Art

[0002] As an insert-exchangeable drill, for example, Patent Document 1 proposes a technique for enhancing the machining stability of an insert-exchangeable drill that clamps and unclamps a drill head relative to a drill body by relative rotation between a drill head having a cutting edge and the drill body, and fixing the drill head to the drill body at a clamping portion, and enhancing the durability of the drill body.

[0003] The insert-exchangeable drill described in Patent Document 1 is configured such that a support shaft having a taper with a diameter increasing from the base side toward a cylindrical or protruding end fitted into a shaft hole concentric with a rotation center provided in the drill body is provided on the drill head, and a torque receiving surface, a thrust receiving surface, and a clamping portion that generates a clamping force for pressing the drill head against the thrust receiving surface by relative rotation are arranged on the tip side (insert side) of the drill rather than on the support shaft side corresponding to the drill body and the drill head.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in vehicles such as EV vehicles, aluminum is frequently used for weight reduction, and furthermore, in order to integrate the components and reduce the number of components, the components are becoming larger (unified). Although die-cast molds or low-pressure casting molds are used for these components, there are cases where the depth of cooling holes or ejector pin holes is required to be 350 mm or more, which is unprecedented.

[0006] In the drill disclosed in Patent Document 1, it is not possible to efficiently drill holes in a mold that is increasing in size. As another conventional technique, gun drilling exists, but dedicated tools and equipment are required, and the processing efficiency is lower than that of drill processing. When the mold structure is divided or processed using a gun drill during mold design, the processing cost becomes high and the processing time also becomes long. In addition, the hole accuracy of the mold, such as the positional tolerance, hole diameter, and hole processing surface roughness, has a great influence on the mold life and the molding cycle, so the required accuracy is high. For example, a positional tolerance of ±0.1 mm, a hole diameter of ±0.02 mm, and a hole processing surface roughness of Rz 3 μm or less may be required.

[0007] Also, die-cast and low-pressure casting mold materials are called die steels and have a high hardness of Rockwell hardness (HRC) 43 to 50. Therefore, a carbide-coated drill is required for processing such molds. In the production of carbide drill materials, there are cracks during molding and distortion during sintering. If the total length of the drill is long, a stable coating cannot be achieved. Phase shift is likely to occur at the divided part. If a drill is produced on a special order basis, the cost is high and the production lead time is long, and it cannot be applied at the job site.

[0008] It is difficult to produce a replaceable tip drill for hole processing of die-cast molds with a total length exceeding 350 mm when the tool diameter is 10 mm or less, and it may be necessary to compromise on either the production of carbide materials, the processing of drill shapes, or the coating.

[0009] The present invention has been made in view of such problems, and an object thereof is to provide a replaceable tip drill for hole processing of die-cast molds that can exceed a total length of 400 mm even when the tool diameter is 10 mm or less.

Means for Solving the Problems

[0010] The drill bit exchangeable drill according to one aspect of the present invention is a drill with an exchangeable drill bit portion for deep hole machining, and has a groove portion, a guide portion for preventing vibration during machining, an exchangeable drill bit portion, and a joint portion connecting them. The cooling water passes through the internal cooling passage of the guide portion and is led to the spiral external cooling passage from in front of the drill bit portion, and is characterized by having a pin for preventing phase shift between the joint portion and the drill bit portion.

Effects of the Invention

[0011] According to the present invention, since the drill bit portion is made exchangeable and the portion for machining the tip portion and the groove portion for discharging chips are divided, the necessary tool length can be prepared by preparing the number and length of the groove portions according to the overall length. By making the parts other than the drill bit portion reusable, when the drill bit wears, only the drill bit portion is exchanged, thereby suppressing the production lead time and cost. The coolant to the drill bit portion can be supplied by the external cooling passage at the tip portion. A guide portion can be provided to prevent vibration for improving machining quality. It is possible to select the use of pins for preventing phase shift at each fastening portion between the joint portion, the groove portion, the guide portion, and the drill bit portion, and it is possible to provide a drill bit exchangeable drill that can be properly used according to the machining.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6A

Figure 6B

DETAILED DESCRIPTION OF THE INVENTION

[0013] Preferred embodiments of the present invention will be described with reference to the accompanying drawings. In each figure, those denoted by the same reference numerals have the same or similar configurations. Hereinafter, the present invention will be described in detail with reference to the drawings.

[0014] FIG. 1 is a side view showing an example of a cutting-edge replaceable drill 1 according to an embodiment of the present invention. The cutting-edge replaceable drill 1 is a drill in which the cutting edge part 4 is replaceable, and is configured as a drill for deep hole machining that can have a total length exceeding 400 mm even when the tool diameter is 10 mm or less. In the illustrated example, the tool diameter is 8 mm, and the total length excluding the cutting edge part 4 is 415 mm.

[0015] As shown in FIG. 1, the cutting-edge replaceable drill 1 includes a groove part 2, a guide part 3, a cutting edge part 4, and a joint part 5. The groove part 2 is, for example, a cemented carbide such as a WC-Co alloy having excellent mechanical properties, and includes a shank 2' for fixing to a tool holder. In the illustrated example, two groove parts 2 are connected by the joint part 5.

[0016] The guide part 3 is connected to the groove part 2 and prevents vibration during machining. The joint part 5 connects the replaceable cutting edge part 4 and the guide part 3.

[0017] FIG. 2 is a side view schematically showing an example of the cutting-edge replaceable drill 1 shown in FIG. 1. The cutting-edge replaceable drill 1 can be applied to general deep hole machining, and is particularly suitable for high-hardness materials. The workpiece shown in FIG. 2 has, for example, a Rockwell hardness (HRC) of 40 to 60.

[0018] FIG. 3 is a side view schematically showing the internal structure of the guide part 3 shown in FIG. 2, and FIG. 4 is a cross-sectional view showing the internal structure of the guide part 3 cut along the rotation axis. As shown in FIGS. 3 and 4, the cooling water passes through the internal cooling passage 6 of the guide part 3, and is led from the joint part 5 located in front of the cutting edge part 4 (shown in FIG. 2) to the spiral-shaped external cooling passage 7 through the cooling passage 6' that communicates the internal cooling passage 6 and the external cooling passage 7.

[0019] As shown in FIG. 3, a spiral chip discharge groove 8 is formed in the guide part 3. Similarly, spiral chip discharge grooves 8 (not shown) are formed in the joint part 5 and the groove part 2. The chip discharge groove 8 is formed to be continuous from the cutting edge part 4 (shown in FIG. 2) to the shank 2' (shown in FIG. 1).

[0020] The replaceable-tip drill 1 is characterized by having a pin 9 for preventing the phase shift between the joint part 5 and the cutting edge part 4. FIG. 5 is a cross-sectional view showing the internal structure of the joint part 5 cut perpendicular to the rotation axis. The diameter of the pin 9 is preferably 0.3 mm or more. In the illustrated example, two pins 9 are arranged at symmetric positions of 180°. The pin 9 may be one, or three or more.

[0021] FIG. 6A is a cross-sectional view showing an example of the pin for preventing the phase shift between the joint part and the cutting edge part. FIG. 6B is a cross-sectional view showing another example of the pin for preventing the phase shift between the joint part and the cutting edge part. As shown in FIGS. 6A and 6B, the hole into which the pin 9 enters between the cutting edge part 4 and the joint part 5 may be circular if it is larger than the diameter of the pin 9, or may be rectangular or linear.

[0022] According to the tip-exchangeable drill 1 configured as described above, since the tip portion 4 is made exchangeable and the portion for machining the tip end and the groove portion 2 for discharging chips are divided, the necessary tool length can be prepared by preparing the number and length of the groove portions 2 according to the overall length. By making the parts other than the tip portion 4 reusable, when the tip wears, only the tip portion 4 needs to be exchanged, thereby suppressing the production lead time and cost. The coolant for the tip portion 4 can be supplied by the external cooling path 7 at the tip end. A guide portion 3 can be provided to prevent deflection for improving machining quality. It is possible to select the use of phase shift prevention using pins 9 at each fastening portion between the joint portion 5, the groove portion 2, the guide portion 3, and the tip portion 4, etc., and it can be properly used according to the machining. The pin 9 may be used at the fastening portion between the guide portion 3 and the groove portion 2 to prevent phase shift.

[0023] With the increase in the size of products such as EV vehicles, the molds are also becoming larger, and the hole machining for cooling and ejector pins, etc. is becoming deeper. At that time, the length was such that it could not be manufactured with commercially available drills. To solve that problem, in the tip-exchangeable drill 1, hole machining is made possible by making the tip portion 4 exchangeable. Specifically, (1) the portion for machining the tip end and the groove portion 2 for discharging chips are divided to make the length of the cemented carbide that becomes the tool base material manufacturable. Also, when dividing, it enables the discharge of chips and the replenishment of coolant inside the tool. (2) The shape of each fastening portion between the joint portion 5, the groove portion 2, the guide portion 3, and the tip portion 4 is provided with a phase shift structure according to the machining load.

[0024] In the guide portion 3, since frictional heat is generated, it is conceivable that the shrink-fit shrink steel expands due to heat conduction and the gripping force of the tool decreases. Therefore, a chip discharge groove 8 for reducing friction is provided, and a structure is adopted to prevent damage to the guide portion 3 due to chip jamming during machining using this chip discharge groove 8.

[0025] In consideration of the cooling performance during cutting and to provide rigidity to the cutting edge portion 4 of the tool, a structure is adopted where the internal coolant passage 6 switches to the external coolant passage 7 in the vicinity of the cutting edge portion 4. The external coolant passage 7 is provided with a groove in the guide portion 3 that leads toward the cutting edge portion 4 so that the coolant flows toward the cutting edge portion 4, and has a function to prevent reverse flow of the coolant.

[0026] The cemented carbide is shrink-fitted and connected with shrink-fit steel, and a guide is provided in the cemented carbide portion closest to the cutting tool mounting portion. The hole drilled in the pre-processing is used as the guide, and it is arranged to utilize the guide function promptly. The guide length is set to 3.5D.

[0027] The embodiments described above are for facilitating the understanding of the present invention and are not for limiting and interpreting the present invention. Each element included in the embodiments, as well as their arrangements, materials, conditions, shapes, sizes, etc., are not limited to those exemplified and can be changed as appropriate. Also, it is possible to partially substitute or combine the configurations shown in different embodiments.

Description of Reference Numerals

[0028] 1... Exchangeable-tip drill, 2... Groove portion, 2´... Shank, 3... Guide portion, 4... Cutting edge portion, 5... Joint portion, 6... Internal coolant passage, 6´... Internal-to-external coolant passage, 7... External coolant passage, 8... Chip discharge groove, 9... Pin.

Claims

【Claim 1】 A drill with an exchangeable cutting edge for deep hole machining, comprising a groove portion, a guide portion for preventing vibration during machining, an exchangeable cutting edge portion, and a joint portion connecting them, cooling water passes through the internal cooling passage of the guide portion and is led to a spiral external cooling passage in front of the cutting edge portion, characterized by having a pin for preventing phase shift between the joint portion and the cutting edge portion. An exchangeable cutting edge drill.

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