JPH0440822Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a trapezoidal thread turning tool, and more specifically, a composite tool that has a root cutting part and a flank cutting part independently. Regarding.

[Prior Art] Screws are widely used in functional parts in all fields, and various screw thread shapes are used depending on the purpose of use, such as fastening objects, adjusting distance or tension, or transmitting power. selected. In particular, trapezoidal screws with relatively high yield strength are used for screw shafts used for moving the tool rest in lathes, adjusting the fork width in forklifts, etc. for power transmission.

Trapezoidal threads have a larger pitch and peak height relative to the nominal diameter than the commonly used triangular threads, and therefore, during thread cutting, large cutting resistance proportional to the depth of cut occurs, resulting in high thread accuracy. In order to achieve this, the turning conditions, especially the selection of the cutting tool (bite), are one of the important factors. As for bits that have already been applied, for example, there are known thread-cutting bits with a brazed high tip, as well as thread-cutting bits with a carbide indexable tip.

All of these tools are equipped with trapezoidal cutting edges that match the shape of the threads being cut, so chips flowing from the work surfaces of both the root and flank onto the rake surface interfere with each other and stagnate. This increase in cutting resistance directly leads to higher cutting temperatures, and especially in the case of the former high tip, overall wear is rapidly accelerated and the machining accuracy of the thread decreases. This necessitates very frequent and troublesome shaping and grinding of the chips.

In addition, with the latter type of carbide bits, which are said to be resistant to wear, the load on the bits due to the increase in cutting resistance further acts on the ability to bite into the workpiece, further increasing the resistance, resulting in machining accuracy. In addition to deterioration of the chip, there is also the problem of inducing damage to the chip.

[Problems to be solved by the invention] In order to avoid the increase in resistance due to simultaneous cutting of the valley bottom and flank that intersect with each other as described above,
The inventor of the present invention attempted a processing method in which the cutting of the valley bottom with the groove cutting tool and the cutting of the flank with the trapezoidal cutting tool are made independent of each other at each cutting stage.

However, although the above-mentioned machining method has achieved some results in machining accuracy, it requires replacing the cutting tool at least four times, for example, for two-stage cutting, which hinders the automation of thread cutting and reduces production. They were forced to be sexually recessive.

The present invention aims to solve the technical problems of creating a cutting tool that can sufficiently handle the automation of thread cutting processes, in addition to improving the precision of thread cutting and simplifying tool maintenance.

[Means for solving the problem] In order to solve the above problem, the cutting tool of the present invention has a cutting edge for cutting the root leading in the feed direction and a cutting edge for cutting the flank that follows, arranged side by side at an interval that is an integral multiple of the thread pitch. A new configuration is adopted.

A desirable configuration of the cutting tool of the present invention for a simple structure is to make the above-mentioned spacing between the two cutting edges equal to the thread pitch, and the flanking cutting edge has several cutting edges in the radial direction. The tip is to use a carbide throw-away tip.

The root processing blade portion, which is formed into a plate shape and has a thickness equivalent to the root width, is fastened to each shank together with the flank processing blade portion, and both shanks are further fastened in a composite shape by a holder. be done. The cutting edges of the above-mentioned double-edged portions may be arranged so as to be aligned on the same line parallel to the screw axis, but in order to ensure that the machining of the root and flank is divided into the double-edged portions, the cutting edge of the preceding root-machining blade portion may be slightly aligned. It is desirable that the cutting edge of the flank processing blade part always be opposed to the workpiece with a small gap therebetween.

[Function] Therefore, according to the cutting tool of the present invention, the root machining blade part at each cutting stage and the flank machining blade part which follows with a delay of at least one pitch are responsible for cutting different work surfaces. As a result, chips generated from the valley bottom and flank flow on the independent rake surfaces of each blade, and are removed extremely smoothly without increasing resistance due to interference. Since the relative positional relationship between the two blades does not require any adjustment until the final depth of cut is reached, the operation can easily be carried out in a fully automated process by simply selecting the appropriate depth of cut.

[Example] Hereinafter, an example of the present invention will be described based on the drawings.

Fig. 1 shows an embodiment of the cutting tool A of the present invention applied to right-handed threads, and 1 in the figure indicates the workpiece thread S.
A blade part for processing the bottom of a valley made of high speed steel material, for example, which has a plate thickness corresponding to the bottom width H of and extends in the longitudinal direction (radial direction of the thread S to be cut), and is movable in the same longitudinal direction by the shank 2. It is guided and fastened to the jack 2 by a presser foot 3 and a set screw 4. Reference numeral 5 denotes a flank machining blade part which is arranged in parallel with the root machining blade part 1 and the workpiece screw S with an interval corresponding to the pitch P in the axial direction (anti-feeding direction), for example.
This is a known carbide throw-away chip having three cutting edges in a radial direction of 120 degrees, and only one cutting edge aligned with the root cutting edge 1 is shown in the figure. The flank machining blade part 5 is a shank 6.
It is seated on an acute-angled seat surface (not shown) of the shank 6 and is fastened to the same shank 6 with a presser foot 7 and a set screw 8 in the same way as the root cutting blade 1. Reference numeral 9 denotes a holder for integrally integrating both the shank 2 and 6, and both the shank 2 and 6 fitted in the holder 9 are fastened with bolts 10, respectively.

In addition, Figures 2 and 3 are approximately 1/2 of the height of the mountain.
This figure shows the cutting situation with the final depth of cut and the final depth of cut. The cutting edge of the leading root machining blade part 1 is made to protrude slightly from that of the following flank machining blade part 5, and the cutting edge of the flank machining blade part 5 always maintains a minute gap C with the workpiece screw S. It is adjusted as follows. It is desirable that the amount of protrusion of the cutting edge, that is, the above-mentioned interval C, be approximately 0.05 to 0.1 mm.

The thread cutting operation is started after the positions of the cutting edges of the double-edged parts 1 and 5 are adjusted and the scale of the depth of cut is adjusted in advance. As shown in FIG. 2, by using a predetermined depth of cut and automatic feed, the leading groove cutting blade 1 first performs straight grooving, and the flank cutting blade 5 follows with a delay of one rotation and one pitch. The machined groove is widened, that is, flanked.

At this time, the chips are on the cutting edge surface of the valley bottom machining blade part 1,
In the flank machining blade part 5, the water flows from the trapezoidal slope (both indicated by thin diagonal lines) to the rake surfaces of the blade parts 1 and 5, and is smoothly removed without mutual interference and stagnation. Then, in the final cutting stage shown in Fig. 3, the shallow trapezoidal groove in the previous stage is further cut into a straight groove by the valley bottom processing blade 1, and the valley bottom is rounded.
The cutting surface of the flank F is determined, and the cutting surface of the flank F is also determined by the subsequent widening process of the flank machining blade part 5. During this time, there is no need to replace or adjust the cutting tool A at all, so the thread cutting work is performed in continuous automatic operation from beginning to end.

It should be noted that wear of the root machining blade part 1 can be countered by simple surface grinding of the flank surface, so the required man-hours are so small that they can be virtually ignored.

[Effects of the invention] As explained above, the cutting tool of the present invention has a cutting edge for valley bottom processing leading in the feed direction and a cutting edge for flank processing following it arranged side by side at an interval that is an integral multiple of the thread pitch. , it has the following excellent effects.

(1) Since the root and flank of the thread shape are cut by separate blade parts, the cutting resistance of each blade part is reduced accordingly, and furthermore, mutual interference of chips is a secondary factor that increases resistance. Since the screws are also removed, there is less risk of breakage, especially when a carbide throw-away tip is placed on the flank machining blade, and a sufficiently high screw precision can be ensured.

(2) Since a simple groove cutting board bit can be used as the cutting edge for valley bottom machining, its repair and regeneration is extremely easy, and the troublesome shaping and grinding that was applied to conventional high tips is completely eliminated. Ru.

(3) There is no need to change the cutting tool during thread cutting,
Therefore, there is no need for various adjustment operations associated with this, and complete automation of thread cutting through continuous operation can be easily achieved, so that productivity can be dramatically improved.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the cutting tool of the present invention;
FIG. 2 is a cross-sectional plan view including the screw axis showing the state of cutting at a shallow cutting stage, and FIG. 3 is a similar cross-sectional plan view at the final cutting stage. 1... Blade part for valley bottom processing, 5... Blade part for flank processing, 2, 6... Shank, 3, 7... Presser foot,
9...Holder.

Claims (1)

[Claims for Utility Model Registration] (1) A tool for turning trapezoidal threads, in which a cutting edge for cutting the root leading in the feed direction and a cutting edge for cutting the flank following the cutting are arranged side by side at an interval that is an integral multiple of the thread pitch. (2) The cutting tool according to claim 1, wherein the cutting edge of the root cutting portion is slightly more protruding than that of the flank cutting portion. (3) The cutting tool according to claim 1 or 2, wherein the flank processing blade is a carbide throw-away tip.