JPH04250916A - Broach - Google Patents

Abstract

PURPOSE:To provide a broach which prevents the blade of the broach for shaping a hole and a groove from causing wear due to a small chipping or tooth chip, and a nick angular part from destroying in a short time due to the increase of the cutting resistance of a work piece. CONSTITUTION:A broach is subjected to R workings R1, R2, R3 at the tip 3 and groove bottom or the both of the nick angular part in advance in order to increase the strength of the nick angular part of the broach. Consequently the generation of the chipping and defect of the blade of the broach is prevented compared with those which make the nick angular part in an acute angle like the conventional broach.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a broach, which is a cutting tool for forming holes and grooves.

0002

2. Description of the Related Art The shape of the nick of a conventional broach for machine tools is such that the corners of the tip, bottom, or both are formed into an acute angle T, as shown in FIGS. 4, 5, and 6. Note that 2 indicates the broach rake face, and 3 indicates the nick corner.

0003

[Problems to be Solved by the Invention] As mentioned above, in conventional broaches, the nick shape is formed at an acute angle at the tip, bottom, or both corners, so that the broach wears during broaching. When observed, the wear at the notched part is as shown in Figure 5, and the wear at the corner is greater than the wear at the cutting edge in the vicinity, and it is expected that the wear developed due to the influence of the initial microchipping. As described above, in the conventional broach and nick shapes, the tips, bottoms, or both have acute angles, so there is a problem that the broach blade is likely to chip or break. The present invention aims to eliminate the above-mentioned problems and provide a new broach that prevents chipping and tooth chipping.

0004

[Means for Solving the Problems] Therefore, the broach for machine tools of the present invention is characterized in that the tips of the knick corners and/or the groove bottoms of the broach are rounded in advance in order to increase the strength of the corners. It is said that

[0005]

[Operation] If the radius applied to the tip of the nick corner, the bottom of the groove, or both of the broach is 0.05 or less, minute chipping will occur in several cut workpieces, almost the same as when no radius processing is performed. FIG. 6 shows a case where the knick corner 3 is not rounded. Also 0.1
When the radius exceeds the radius, the shape of the chips becomes curved as shown in FIGS. 7 and 8, and the flow of chips shown by the arrows overlaps and interferes, generating heat and increasing the cutting resistance. In terms of cutting performance, when there is no R of the nick corner 3, the resistance is the smallest, so the cutting performance is good, but the corner is destroyed in a short time due to the cutting resistance of the workpiece, as shown in Figure 5. As a result, machinability and cutting resistance rapidly increase. If R is 0.05 or less, there is no big difference from the above. From this point of view, the optimum radius is 0.05 to 0.1. For the reasons mentioned above, the broach of the present invention prevents initial chipping by applying a required radius to the corner of the broach in order to increase the strength of the nick corner, thereby preventing wear of the broach and preventing chipping of the broach's blade. , equalizes the cutting resistance when pulling out the broach and prevents eccentricity of the workpiece.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIGS. 1 to 3 are side views showing each of the first to third embodiments of the present invention. In these figures, 3 indicates the nick corner of the broach. In the case of Fig. 1, the tip of the nick corner is rounded with R1, R1, and in Fig. 2, the tip of the nick corner is rounded with R1, R1. Fig. 3 shows the case where R2 and R2 radiuses were applied to the groove corners, and Figure 3 shows the case where R1 and R2 radiuses were applied to the tips of the nick corners, and R3 radiuses were applied to the bottom of the groove. It shows the case. It is best for the size of the rounded radius to be in the range of 0.05 to 0.1, and if it is less than that, there is almost no difference in function from one without rounding, and it is possible to cut only a few workpieces with a small radius. Chipping occurs and develops into wear at the nick of the broach. In addition, when the radius is 0.1 or more, the shape of the chips produced as a result of broaching becomes curved as shown in Figures 7 and 8, and the flow of chips becomes as shown by the arrows, which interferes and generates heat, resulting in cutting resistance. becomes larger and causes problems. As in the present invention, the broach 1 (Fig. 7,
By rounding the tip of the nick corner and/or the bottom of the nick corner (as shown in Figure 8) to the required size in advance, the strength of the nick corner can be increased, preventing the broach from chipping, and preventing the broach from chipping when the broach is pulled out. This makes it possible to equalize cutting resistance and prevent eccentricity of the workpiece. The brooch of the present invention is suitably applied to a round brooch, a spline brooch, and a surf ace brooch.

[0007]

[Effects of the Invention] As explained above, the present invention prevents chipping and tooth loss of the broach by adding a radius to the nick corner of the broach, equalizes the cutting resistance when the broach is pulled out, and prevents eccentricity of the workpiece. It has the effect of

[Brief explanation of the drawing]

FIG. 1 is an enlarged side view of a nick corner of a broach according to a first embodiment of the present invention.

FIG. 2 is an enlarged side view of a nick corner of a broach according to a second embodiment of the present invention.

FIG. 3 is an enlarged side view of a nick corner of a broach according to a third embodiment of the present invention.

FIG. 4 is a schematic side view of a nick shape in a conventional broach.

FIG. 5 is an explanatory diagram of the state of wear of a nick in a conventional broach.

FIG. 6 is a perspective view of a nick in a conventional broach.

FIG. 7 is an explanatory diagram showing the state of chips when the radius of the nick corner of the broach is large.

FIG. 8 is an explanatory diagram showing the state of chips when the radius of the nick corner of the broach is small.

[Explanation of symbols] 1 Broach 2 Broach rake face 3 Nick corner R1 R2 made at the tip of the nick corner R3 made at the corner of the nick groove R3 made at the bottom of the nick groove Conventional acute nick corner S Chips thickness of

Claims (1)

[Claims] 1. A broach for machine tools, characterized in that the tip of the nick corner and/or the bottom of the groove are rounded.