JPS60263612A - Broach tool - Google Patents

Abstract

PURPOSE:To make it possible to always maintain the difference between each height of a roughing and finishing teeth of a broach tool of which similar blades are arranged in plural number of axial directions at their bordersection constant even after having been polished. CONSTITUTION:A roughing tooth 3 at the last position among plural number of roughing teeth has the angle of relief of theta1 and also a finishing tooth 4 has the angle of relief of theta2 with their relation being theta1=theta2. The difference (a) between each height of the roughing and the finishing teeth at their bordersection shall be formed and (a)/2 be allowance for machining. The problem of deposition on the roughing tooth 3 and of roughness deterioration of a finished surface on the finishing tooth may be solved by applying nitriding treatment to a broach tool or by reworking its rake face 5. Thus, even after having been polished, the height difference at their bordersection can be maintained constant.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a broaching tool used for broaching.

(Prior Art) Conventionally, as a broaching tool used for machining holes having various shapes such as slotted holes, key grooves, square holes, etc., there is known one shown in FIG. 6, for example.

In Fig. 6, the brochet tool has a tensioning part 2 at the tip, followed by blades of similar shape arranged in the axial direction along the order of dimensions, and these blades include a rough blade 3 at the front end and a finishing blade at the rear end. The finishing blade is further divided into semi-finishing blade 4a and finishing blade 4.
It is divided into b.

By the way, as shown in Fig. 7, the roughing edge and finishing edge of such a broaching tool have a relief edge angle θ1 of about θ1-2°30' for the roughing edge 3 with a large depth of cut, whereas the finishing edge angle θ1 is about θ1-2°30'. The clearance angle θ2 of blade 4 is θ2-1°
It is set at a small angle of about 30'.

In other words, if the clearance angle of the rough blade is made small, welding is likely to occur due to the heat generated by frictional contact, and if the clearance angle of the finishing blade is made large, a biting phenomenon will occur and the finished surface will become rough. 2°30, relief angle of finishing blade 1°3
It is set to 0'.

(Problems to be Solved by the Invention) However, in such conventional broaching tools, as the broaching blade is polished, the step between the rough blade and the finished blade increases, and the boundary between the rough blade and the finished blade increases. Since the machining allowance per tooth also increases, the hole created by broaching will have an uneven shape.For example, if the hole obtained by broaching is supported by a collet as a proof of machining and is processed into a product,
There was a problem in that the contact surface between the collet and the hole machined by broaching was not constant, making it impossible to perform highly accurate machining.

To explain in more detail, as shown in FIG. 8, there is a step a1 between the rough blade 3 and the finishing blade 4 at the boundary before polishing, but if the rough blade 3 and the finishing blade 4 are polished by a dimension d as shown in FIG. Since the relief angles θ1 and 02 of the two are different, the step difference after polishing increases to a2, causing the above problem.

(Means for Solving the Problems) The present invention has been made in view of such conventional problems, and is designed to improve the roughness and finishing of a brochet tool in which blades of similar shapes are arranged in a plurality of axial directions. The clearance angle of the blade is made the same, so that even after polishing, the level difference at the boundary between the rough edge and the finished edge can always be kept constant.

(Example) FIG. 1 is an explanatory cross-sectional view showing an example of the present invention at the boundary between a rough blade and a finishing blade.

First, to explain the configuration, numeral 3 is the last rough edge among the plurality of rough edges, and 4 is the first finishing edge among the plurality of finishing edges. The rough blade 3 has a relief angle θ1, and the finishing blade 4
Also has a clearance angle θ2, and in the present invention, the clearance angles of the roughing blade 3 and the finishing blade 4 are set to be equal, θ1=θ2.

Here, the values of clearance angles θ1 and θ2 are based on the fact that conventionally, the clearance angle θ1 of the rough blade was θ1-2°30-, and the clearance angle θ2 of the finished blade was θ2-1°30-. ,θ
The clearance angle θ given by = θ1-θ2 is θ-1°3
It is set within the range of 0' to 2°30-, considering the problem of welding when the clearance angle of the rough blade is made small, and the problem of roughness of the machined surface when the clearance angle of the finishing blade is increased. θ
It is most desirable to set it at -2°.

Further, a step a is formed between the cutting edges of the rough blade 3 and the finishing blade 4 at the boundary portion shown in FIG. 1, and a/2 is the machining allowance during broaching.

On the other hand, since the clearance angle between the rough blade 3 and the finishing blade 4 is set to θ1 = θ2, the problem of welding occurs with the rough blade 3, and the problem of worsening the roughness of the finished surface with the finishing blade 4, but this welding and finishing The worsening of the conflict between the surfaces can be solved by subjecting the broaching tool to nitriding treatment, using activated sulfurized cutting oil during broaching, or changing the rake 5 of the broaching tool.

Fig. 2 is a cross-sectional view showing the polishing state when the clearance angle θ1-θ2 is between the rough blade 3 and the finishing blade 4, and the rough blade 3 and the finishing blade 4 are each polished by a dimension d. However, since the relief angle between the rough blade 3 and the finishing blade 4 is 01=θ2, the step a between the rough blade 3 and the finishing blade 4 at the boundary area does not change even after polishing, and even before and after polishing. It is possible to obtain a step a that always provides a constant machining allowance a/2.

Next, in the broaching tool of the present invention, the relief angle of the finishing blade of the rough blade is set to θ1 = θ2-2°, and the shaft hole of the companion norangement 5 shown in FIG. 3 is broached to form a broached hole 〇, When this broached hole 6 was attached to a collet and the spigot part 7 was cut with a tolerance of 0.05 as a proof of machining, the following evaluation results were obtained.

First, Fig. 4 is a bar graph showing the evaluation results when the hole 6 broached by a conventional broaching tool with different clearance angles of the rough cutting edge and the finishing edge is used as processing proof, and the number of samples is n=5.
As a result of measuring the cracking of the inlet part 7 using the broached hole 6 as the processed part for 0 pieces, a deviation of an average value of 20.7μ occurred, and the process capability index Cp = 0.707.

On the other hand, the clearance angle between the rough blade and the finishing blade is θ1-θ2-26
When the broached hole 6 by the broaching tool of the present invention is used as the processed part, the run-out of the inlet part 7 was measured for the number of samples n = 60 as shown in FIG. 5, and the average value × - The runout was reduced to 9°89μ, and a machining capacity index Cp of 3°80 was obtained.

As is clear from the results shown in Fig. 4.5, in the broaching tool of the present invention, when the collet and the broached hole 6 are used as the machining parts, the runout is suppressed to less than half that of the conventional one, and the broaching accuracy is improved. It was confirmed that there was a significant improvement.

(Effects of the Invention) As explained above, according to the present invention, in a brochet tool in which blades of similar shapes are arranged in multiple axial directions, the relief angle of the finishing blade of the rough blade is made the same, so that The level difference at the boundary between the rough cutting edge and the finishing edge can be kept constant at all times, ensuring high machining accuracy of the broached hole even if the broaching tool is reground and used. Even when machining other parts by attaching the broach to the machine, the high machining accuracy of the broached hole can minimize runout of the machined part, allowing for highly accurate machining using the broached hole. can be realized.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing an embodiment of the present invention at the boundary between a rough blade and a finishing blade, Fig. 2 is a cross-sectional view of the brochet tool shown in Fig. 1 after being reground, and Fig. 3 is a cross-sectional view of the present invention. A cross-sectional view of a companion flange with holes machined using a broaching tool.
Figure 4 is a graph showing the run-out evaluation of the companion flange shown in Figure 3 when the holes machined by the conventional broaching tool are based on the collet, and Figure 5 is the graph showing the runout evaluation when the holes machined by the broaching tool of the present invention are based on the collet. Fig. 6 is an explanatory diagram of a conventional broaching tool, Fig. 7 is a cross-sectional view showing the conventional roughing blade and finishing blade, and Fig. 8 is a graph showing the runout evaluation of the conventional broaching tool. FIG. 9 is a sectional view showing the relationship between the rough cutting edge and the finishing edge at the boundary area, and FIG. 9 is a sectional view of the boundary area when a conventional brochet tool is reground. 1 Knife broaching tool 2: Tension part 3: Rough blade 4: Finishing blade 5: Companion flange 6: Broach machining hole 7: Inro Partial patent applicant Fuji Iron Works Co., Ltd. Representative Patent attorney Susumu Takeuchi Figure 1 □ Tadasu blade −−−−A size η□ Fig. 6 Fig. 8

Claims (2)

[Claims] (1) A brochet tool in which blades of similar shapes are arranged in multiple axial directions, characterized in that the clearance blade angles of the rough blade and the finishing blade are made the same. (2) The broaching tool according to claim 1, characterized in that the escape edge angle is 2 degrees.