JPH0347782Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a reamer, and particularly to a stepped reamer for machining deep stepped holes.

Prior Art and Problems Conventionally, as shown in FIG. 5, when a stepped reamed hole as shown in the figure is formed in a large workpiece W, and a chamfered portion is formed at the upper end of the hole,
The processing was performed in the following order.

First, a small-diameter hole 15 is drilled from the bottom side of the workpiece W using a small-diameter straight drill, and then a large-diameter hole 16 is similarly drilled to a predetermined depth from the top side of the workpiece W using a large-diameter straight drill. The pilot hole forming process is completed. Then, in the next reaming process, the large diameter hole 16
For the small diameter hole 15, ream it from the top side of the workpiece W using a large diameter reamer, and for the small diameter hole 15, ream it from the bottom side of the workpiece in the direction of arrow A. was going there. Further, the chamfered portion 17 at the entrance of the large-diameter hole 16 was cut out by a biting portion of a reamer having an even larger diameter.

In the conventional hole processing method as described above, several steps are required through the drilling and reaming process, which not only takes time, but also in the reaming process of the small diameter hole 15, the reaming is performed from the opposite direction to the drilling direction. Therefore, there is a drawback that misalignment between the small diameter hole 15 and the large diameter hole 16 tends to occur. Therefore, even if an attempt is made to insert a stepped article having the same external shape as the finished stepped hole into the hole, it may not be possible to insert it, and there is also the problem that the machining time is further increased due to reworking. was.

Conventionally, there has been no stepped reamer that can process such stepped holes at once, because it was predicted that there would be a risk of cutting damage in a stepped reamer.

Purpose of the invention The object of this invention is to eliminate the drawbacks of conventional reaming as described above, and to provide a new reamer capable of reaming a stepped deep hole at one time.

Summary of the invention The reamer according to this invention is formed into a stepped shape that matches the shape of the hole to be machined, and
It is characterized in that only a cutting edge is formed in the small diameter portion of the tip, while a cutting edge and a vanishing land (abutting portion) are formed in the large diameter portion. In the reamer according to this invention, since no vanishing land is formed in the small diameter part of the tip, the machining torque in the small diameter part can be reduced, and there is no risk of cutting damage.
Deep stepped reamed holes can be formed in a single process.

Embodiment of the invention Hereinafter, an embodiment of the invention will be described with reference to FIGS. 1 to 4.

FIG. 1 is a diagram showing the overall shape of a reamer 1 according to the present invention. This reamer 1 has a small diameter tip 2.
It has a first large diameter part 3 connected to the tip part 2, and a second large diameter part 4 connected to the first large diameter part 3, and the second large diameter part 4 is connected to the first large diameter part 3. It is integrated with the shank 5 of the same diameter. Further, the tip portion 2 has a biting portion 6,
Further, a first chamfered portion 7 is provided at the connecting portion between the tip portion 2 and the first large diameter portion 3, while a first chamfered portion 7 is provided at the connecting portion between the first large diameter portion 3 and the second large diameter portion 4. A second chamfer 8 is provided. An even number of 2 to 4 straight blades are formed on the outer periphery from the tip 2 to the second large diameter portion 4.

The feature of the reamer of the present invention is that only the cutting edge 9 is provided at the tip 2, as shown in FIG.
As shown in FIGS. 3 and 4, cutting blades 10 and 11 and burnish lands 12 and 13 are provided. Therefore, during reaming, the only trick applied to the tip portion 2 is the cutting torque, but the large diameter portions 3 and 4
Since the torque applied to the tip portion 2 is the sum of the cutting torque and the torque due to the burnishing action, there is no risk that the torque applied to the tip portion 2 will become excessive.

On the other hand, the reamer of the present invention is designed so that the core thickness t in each of the sections 2 to 4 is 45% or more of the diameter of the tip section 2 to prevent cutting damage. Further, a connecting portion 14 between the tip portion 2 and the first chamfered portion 7
For example, a necking part (necked part) provided in a stepped drill or the like is not provided, but an R joint is used to prevent a decrease in the strength of this part.

Effects of the Invention According to the reamer of the present invention having the above-mentioned structure, a stepped hole as shown in Fig. 5 can be machined at once from the drilling direction, so the number of strokes is reduced by several minutes compared to the conventional machining method. It is possible to form an accurate reamed hole because the reamed hole is reduced to one and no misalignment occurs between the small diameter hole and the large diameter hole. As a result, it is possible to significantly reduce processing costs (including equipment costs), improve processing efficiency, and further improve product quality.

In addition, if the part from the tip of the reamer to the rear end a of the second large diameter part (see Fig. 1) is made of cemented carbide (cemented carbide, ceramic) or high-speed steel, high-speed cutting and strong Cutting becomes possible, and the characteristics of the reamer of the present invention are further enhanced.

[Brief explanation of the drawing]

FIG. 1 is a front view of the reamer according to the present invention, FIG. 2 is a sectional view taken along the - arrow in FIG. 1, FIGS. 3 and 4 are sectional views taken along the - and - arrows in FIG. FIG. 2 is a cross-sectional view of a workpiece having a stepped hole processed by a reamer according to the present invention. 1...Reamer, 2...Tip, 3...First large diameter part, 4...Second large diameter part, 5...Shank, 6
... Biting part, 7... First chamfer part, 8...
Second chamfered portion, 9-11... Cutting edge, 12, 13
...Banitshuland.

Claims (1)

[Scope of utility model registration request] A stepped reamer having a small-diameter tip and at least one large-diameter portion connected to the tip, wherein the tip is provided with only a cutting edge, while the large-diameter portion includes a cutting edge. A reamer characterized by being equipped with a cutting blade and a burnishing land.