JP2572186B2 - Thread machining method using perforated thread cutting coupling tool - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drill and multi-thread thread cutting.
Using a drilling threaded connection tool that is integrated with a milling machine
To cut female threads into plastic
It is.

[0002]

2. Description of the Related Art There is a thread milling tool as a tool for cutting an internal thread. This is provided with a thread cutting blade having a shape corresponding to a thread groove of a female screw to be formed on an outer peripheral portion, and is attached to, for example, an NC milling machine or a machining center, and is driven to rotate around an axis. A female screw is cut on the inner peripheral surface of the prepared hole by being relatively moved in the circumferential direction and the axial direction of the prepared hole in a state where a notch is added to the prepared hole. Thread milling cutters are widely used. When cutting a female screw using such a threading milling cutter, it is necessary to pre-drill a prepared hole having substantially the same diameter as the inner diameter of the female screw to be formed as a pre-process, but in a method using a dedicated drilling tool, Due to the need for equipment and time for tool change, recently, a coupling tool in which a drill is integrally provided at the tip of a thread milling cutter has been proposed.

A tool described in Japanese Patent Application Laid-Open No. 63-200916 is an example of such a tool. A shank portion, a multi-threaded milling machine without a drill and a lead from the axial end side are provided, and a plurality of twist grooves are provided. The formed blade portion is coaxially and integrally provided, and after being drilled by the drill by being relatively moved in the axial direction with respect to the workpiece while being rotationally driven around the axis, the hole is formed around the axis. The internal thread of the prepared hole is cut by the multi-threaded milling cutter by being relatively moved in the prepared hole in the axial direction and the circumferential direction while being rotated.

[0004]

By the way, in the above-mentioned multi-thread thread milling machine, only the groove portion of the female screw to be formed is cut, and the inner peripheral surface of the prepared hole directly forms the crest of the female screw. Is common. That is, the inner peripheral surface of the prepared hole cut by the drill becomes the crest surface of the female screw as it is, and depending on the processing conditions, a sufficiently satisfactory finished surface roughness and accuracy may not always be obtained. For example, when cutting a plastic with a thick drill, plastic is generally a material that is easier to cut than a metal material, so the same machine or cutting tool used for metal materials is used as it is. In many cases, plastics have poor heat conduction, so the heat generated by the cutting process tends to stay locally, and when observing the finished surface, the surface was sometimes cracked and rough or burned . Polycarbonate,
Nylon, acrylic, and the like generate significant heat, and the above problem becomes significant.

[0005] According to the general shape cutting in which the crest of the internal thread is cut at the valley of the thread cutting blade of the multi-thread thread milling machine, the surface cut by the drill is finish-cut by milling. In this case, chips of approximately the same length as the corrugated thread cutting section along the thread cutting edge are generated, impeding their dischargeability, increasing the cutting resistance and shortening the tool life, as well as There are inconveniences such as a decrease in finished surface roughness and accuracy.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a thread forming method capable of cutting a female screw having excellent finish surface roughness and precision of a screw crest.
Is to provide a law .

[0007]

In order to achieve the object, the present invention provides (a) a shank portion, (b) a drill from the axial front end , a reamer having a larger diameter than the drill, and a
A multi-thread thread milling machine with a smaller diameter than the reamer and with no lead is provided, and a threaded cutting tool with coaxially integrated cutting edge with a plurality of twist grooves is used.
Is a method of cutting female threads into plastic.
(C) rotating the perforated threaded connection tool around an axis;
Axial movement relative to the plastic while driving
And drill a pilot hole by the drill
At the same time, finish the inner peripheral surface of the pilot hole with the reamer
Bottom that cuts and forms a pilot hole with approximately the same dimensions as the reamer
The drilling process and (d) the drilling threaded coupling tool
Instead, it is rotated and driven in the pilot hole in the axial and circumferential directions.
Relative to the inner surface of the pilot hole.
The multi-threaded screw so as to constitute the crest of the female screw
The internal thread of the pilot hole is
Having a threading process of cutting only the thread groove
It is characterized by.

[0008]

According to the above-mentioned threading method , when the drilling threaded connection tool is axially moved relative to the plastic while being rotationally driven around the axis, the drill is used. At the same time, the inner peripheral surface of the prepared hole is finish-cut by a reamer having a diameter larger than that of the drill. Therefore, when the female screw is cut on the inner peripheral surface of the prepared hole by the multi-threaded milling cutter by being relatively rotated in the prepared hole while being rotated around the axial center, the female screw is Even when only the thread groove is cut and the inner peripheral surface of the prepared hole forms the crest of the female screw as it is, a female screw crest surface having no burnout and having excellent finished surface roughness and dimensional accuracy can be obtained. Also, the female screw thread groove
Only chips are cut, so chips are broken and chips are discharged
The tool life is improved and the screw life is improved.
The flank and valley of the internal thread obtained by groove cutting
Excellent finished surface roughness and accuracy compared to shape cutting
You. On the other hand, since the finish cutting is performed by the reamer at the same time as the cutting of the prepared hole by the drill, there is an advantage that the female screw having the excellent finished surface and the dimensional accuracy as described above can be processed in the same processing man-hour and processing time as before.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a drilling threaded connection tool (hereinafter simply referred to as a connection tool) 1 suitably used in the method of the present invention .
FIG. 2 is a front view of the apparatus as viewed from a direction perpendicular to the axis. The coupling tool 10 integrally includes a shank portion 12 gripped by an NC milling machine or the like and driven to rotate around an axis, and a blade portion 14 for cutting a workpiece. A pair of torsional grooves 16 twisted clockwise in the rotary cutting direction, that is, clockwise in this embodiment, are formed symmetrically with respect to the axis of the blade portion 14, and the drill 18, the reamer 20, And a multi-threaded milling cutter 22 without leads is provided concentrically.

The cutting edge 24 of the drill 18, the cutting edge 26 of the reamer 20, and the thread cutting edge 28 of the multi-threaded milling cutter 22 are all formed so as to face the twist groove 16, and the chips cut therefrom are formed. Is discharged to the tool base end side through the torsion groove 16. The outer diameter of the thread cutting blade 28 of the multi-thread thread milling cutter 22 is the cutting edge 2 of the drill 18.
4 and the cutting edge 26 of the reamer 20.
The diameter of the reamer 2 is larger than the outer diameter of the thread cutting blade 28.
The diameter of the zero cutting edge 26 is determined to be the same as the inner diameter of the female screw to be machined. The torsion groove 16 reaches the shank portion 12, and a chamfering blade 30 having a larger diameter toward the shank portion 12 is provided continuously to the thread cutting blade 28 of the multi-thread thread milling machine 22.
The maximum diameter of the chamfering blade 30 is the same as the diameter of the shank portion 12 and is larger than the diameter of the cutting blade 26 of the reamer 20.

The coupling tool 10 configured as described above is
For example, it is attached to an NC milling machine or a machining center, and is used for cutting a female screw. First, while being rotated around an axis, it is sent in an axial direction relatively to a workpiece, so that a pilot hole is formed by a drill 18. Is cut, and the inner peripheral surface of the prepared hole is finish-cut by the reamer 20. This is the pilot hole drilling process.
You. By performing the finish cutting by the reamer 20 in this manner, even when processing is performed on a plastic such as polycarbonate or nylon, an inner peripheral surface of a prepared hole having no burnout and excellent finished surface roughness and dimensional accuracy can be obtained. If the joining tool 10 is sent in the axial direction until the tip of the shank 12 reaches the workpiece, the opening of the pilot hole is chamfered by the chamfering blade 30 provided at the tip of the shank 12. be able to.

Thereafter, a screw cutting blade 2 is provided on the inner peripheral surface of the pilot hole.
In a state where the cutting hole 8 is cut, the coupling tool 10 is relatively rotated in the axial direction and the circumferential direction inside the prepared hole while being rotationally driven around the axis, whereby the female screw is cut on the inner peripheral surface of the prepared hole. The cutting depth of the thread cutting blade 28 with respect to the inner peripheral surface of the prepared hole is smaller than the height of the thread of the threaded cutting blade 28, and only the thread groove of the internal thread is cut on the inner peripheral surface of the prepared hole. The inner peripheral surface of the prepared hole other than that forms the crest surface of the female screw as it is. This is the threading process
is there.

Here, since the inner peripheral surface of the prepared hole is finish-cut by the reamer 20, even when the inner peripheral surface of the prepared hole forms the top surface of the female screw as it is, there is no burn and excellent finished surface roughness and dimensions. An internally threaded crest surface with accuracy is obtained. Further, since the cutting only screw groove of the female screw, the chip becomes better discharge of the separated has been cut debris become better surface finish and accuracy with the tool life is improved is obtained, the screw With regard to the flank and valley of the internal thread obtained by groove cutting, excellent finished surface roughness and accuracy can be obtained as compared with the form cutting.

On the other hand, since the finish cutting by the reamer 20 is performed simultaneously with the cutting of the prepared hole by the drill 18, the same man-hour and processing time as those of a conventional tool having only the drill 18 and the multi-thread thread milling cutter 22 are used. As described above, a female screw having an excellent finished surface and excellent dimensional accuracy can be machined.

While the embodiment of the present invention has been described in detail with reference to the drawings, the present invention can be embodied in other forms.

For example, in the above embodiment, the outer diameter of the drill 18 is made smaller than the outer diameter of the multi-threaded milling cutter 22, but it is sufficient that the outer diameter of the drill 18 is at least smaller than the outer diameter of the reamer 20. The diameter may be larger than the outer diameter of the milling cutter 22.

In the above embodiment, a pair of twist grooves 16 are provided.
However, the number of the twist grooves can be changed as appropriate. The chamfering blade 30 may be provided as needed.

Although not specifically exemplified, the present invention can be implemented in various modified and improved modes based on the knowledge of those skilled in the art.

[Brief description of the drawings]

FIG. 1 is a front view of a boring threaded connection tool suitably used in the method of the present invention .

[Explanation of symbols]

 10: Drilling thread cutting coupling tool 12: Shank part 14: Blade part 16: Twist groove 18: Drill 20: Reamer 22: Multi-thread thread milling

Claims (1)

(57) [Claims] 1. A shank portion, a drill from an axial end side , a reamer having a larger diameter than the drill , and a reamer smaller than the reamer.
A multi-threaded milling cutter without a lead with a diameter is provided, and a cutting tool with a plurality of twist grooves is coaxially and integrally provided with a drilling threaded connection tool.
A method for cutting a female screw into a hole , comprising:
The plastic in the axial direction.
With the above, the prepared hole is processed by the drill and
Finish cutting the inner peripheral surface of the pilot hole by the reamer,
A pilot hole forming step for forming a pilot hole having substantially the same size as the reamer
While rotating the perforated threaded coupling tool around the axis.
Axially and circumferentially moving in the pilot hole
As a result, the inner peripheral surface of the pilot hole is
By means of the multi-threaded milling cutter so as to constitute
Cut only the thread of the female screw on the inner peripheral surface of the pilot hole.
Flip drilling threaded formation characterized by having a processing step
Screw processing method using a combination tool.