DD244305A1 - MILLING TOOL FOR MACHINING HAIRED TOOTHING - Google Patents

Abstract

The invention relates to a milling tool for machining gehaerteter gears, wherein insert blades made of carbide are used. This is to achieve an increase in productivity with uniform cutting load and an extension of the service life. This is achieved by the use of a pre and trimmer with a mutual staggering, which ensures a 50% division of the cutting depth per pair of blades and that the edges are arranged to each other so that a free chip flow is secured and that further the pairs of blades to each other in a misalignment are arranged on the milling tool. The proposed milling tool enables a 50% increase in productivity and can be used in the entire field of mechanical engineering for milling hardened gears. Fig. 1

Description

e _fN = e _f - en / 1.5 ςΔφ ² (Λ / - 4-- 1) = ε V ςΔφ ²

is executed.

4. Milling tool according to item 1 to 3, characterized in that the pre-and Nachschneider (1 and 2) on separate cutter carriers (5) are arranged.

5. Milling tool according to item 1. to 4., characterized in that the pre- and Nachschneider (1 and 2) consists of individual the tooth profile following juxtaposed cutting plates, which are mounted on a common cutter support (5).

For this 2 pages drawings

Field of application of the invention

The invention relates to a tungsten carbide-tipped milling tool for machining hardened gears, by means of which a substantial increase in chip power and labor productivity can be achieved while maintaining quality requirements. The invention is geared to maintain proven principles of milling and to complement so that the o. G. Effect is achieved.

Characteristic of the known technical solutions

For machining hardened gears are used in addition to the Zahnflankenschleifverfahren, Zahnform- and Wälzfräsverfahren that work with carbide tipped milling tools and allow finishing after hardening and thus eliminate the unwanted, mainly resulting from the hardening process deviations.

Such tools are offered by several companies, and their structural design is partially protected by copyright / 1,2,3 /.

A major disadvantage of this milling method is the per-cut ablatable layer thickness of the workpiece, the so-called delivery, which generally does not exceed values per edge by 0.2 mm.

The reason for this is the law that according to existing investigations / 4 / when milling the entry size compared to the length of the cutting arc of the milling cutter and the toothing, which is proportional to the feed, the cutting forces and thus the wear significantly increased and thus the resilience of the Tool cutting limited.

In the case of gears of large dimensions thus several cuts are required or the technological availability of the tool is substantially reduced.

Object of the invention

The object of the invention is to develop a carbide tipped milling tool for machining hardened gears, which allows a substantial increase in the feed and thus a reduction in cuts during milling. This is aimed at increasing productivity with the same workpiece quality by more than 50%.

Explanation of the essence of the invention

The invention has for its object to achieve such a cut division with larger delivery amounts by a special arrangement of cutting in carbide Verzahnungsfräswerkzeugen for the individual cutting, which simultaneously ensures a more uniform cutting load with a longer service life. According to the invention, the object is achieved in that a two-stage staggering of the cutting in realization of an imbalance, based on the pre- and Nachschneider a pair of blades to the following similar pair of blades, is provided. In each case 2 cutting edges are arranged in the shortest possible distance so that the in

Cutting direction subsequent cutting edge (trimmer) is offset perpendicular to the cutting direction and normal to the cutting edge by an amount ε, so that the same chip thicknesses are achieved on the pre and trimmer.

The trimmer thus penetrates by the amount ε deeper into the workpiece. The shortest possible distance between the cutting edges is properly chosen so that a free Spanfluß is guaranteed.

In the event that the gullet profile is embodied by the gullet cutters, the cutting load is determined by the chip thickness constant over the tooth height, which is dependent only on the mesh size on the tooth flank and the feed path per blade according to relationships (1), (2).

1 2e _f sina ₀

h S (D

hm ₂

<f> _s auscocps = 1 (2)

dwz

h _m = avg. chip thickness

ef = machining allowance per edge

dv «= cutter diameter

a ₀ = pressure angle of the toothing

On the basis of a same, allowable chip thickness on the pre-and post-cutter, the staggering ε between pre- and post-cutter is to be carried out with 50% in each case, whereby an increase of the feed per cut by 100% can be made.

In the case of the use of Wälzfräswerkzeugen results due to the rolling motion between the tool and the workpiece and the resulting Hüllschnittbildung an uneven cutting load on Hüllschnittbreite. The chip body (Span to be lifted) has approximately a triangular cross-section with a negative rake angle of the cut-curved sides. The maximum chip thickness determining the cutting load is calculated approximately for small angles Δφ according to conditions (3), (4) and (5) as follows:

(3)

mite = e = _f e _r sina _p. (4)

for gear hobs without pre- and post-cutter

e = ef - EFN = e _r sina ₀ - ε (5)

for gear hobs with pre- and post-cutter with h = chip thickness.

e = engagement size per flank and section

ς = radius of curvature of the tooth flank

Δφ = rolling angle cut

ef = machining allowance per edge

e _r = Radial feed of the hob

efv = intervention size of the pre-cutter

efN = size of intervention of the reamer

ε "= cutting edge graduation (distance between pre and trimmer perpendicular to the cutting and cutting direction)

When using the cutting edge graduation according to the invention, the pre-cutter has, in analogy to a conventional hobbing tool, a different cutting load over the enveloping cut width. The trimmer is loaded much more uniformly over the Hüllschnittbreite, since the chip thickness, which corresponds to the engagement _size e _fN of the reamer, remains constant over a portion of Hüllschnittbreite. By reduced by the amount of the intervention size of the reamer intervention size of the pre-cutter e ^ results in a relief of the pre-cutter.

Due to the different cross-sectional shape of the pre-cutter and post-cutter, the intervention quantities for pre- and post-cutters are to be calculated as follows, assuming uniform cutting load corresponding to the same chip thickness during pre- and post-cutting:

β, _Ν = 1,5ςΔφ ² (Λ / -? Τ-1) = ε (6)

V ςΔφ ²

ßfv = Sf - efN = ε (7)

ΓτιϊΐΔφ = - ^ - (8)

Z-I

g = number of gears of the hob

i = number of flutes of the hob

ζ = number of teeth of the workpiece

m = module

a = pressure angle

β = helix angle

'..' .... ς = radius of curvature of the tooth flank

Since the engagement size for the trimmer increases with increasing modulus and decreasing number of teeth, the edge graduation is preferably suitable for a hobbing cutter for processing large modulus pinion shafts.

embodiment

The inventively proposed cutter for machining hardened teeth is to be illustrated again by an example below. Show it:

Fig. 1: a hob in side view Fig.2: the front view of the hob Figure 3: the cross section through a cutter spiral.

The existing according to FIG. 1 of 3 spirals 4 hob 3 carries the existing of precut 1 and 2 trimmer carbide knife. The staggering of the carbide blades to each other takes place mutually on the helix 4 with an imbalance to each other.

This imbalance depends on the required installation play space and the intended number of blades for the milling cutter.

The distance between the pre- and trimmers 1 and 2 is chosen so that it ensures a free Spanfluß especially when Nachschneider 2 in the realization of the shortest possible distance. At the same time, a staggering ε to each other is provided to ensure a uniform blade load for the pre-and post-cutter 1 and 2, each of which ensures a 50% chip thickness, based on the Gesamttspanzustellung, for each blade.

According to FIG. 2, which shows the front view of a helix 4, the carbide inserts are composed of individual segments. In Figure 3 it can be seen that these segments are adapted to each tooth shape to be milled. This results in a high shape geometry and a more even chip flow as well as a gentle load on the edge of the cutting edge

guaranteed. *

Cutting process is carried out according to the known principles mentioned above with the effect of high cutting performance and good surface quality of the machined surfaces. In particular, hardened teeth can be processed properly with the proposed milling tool.

Literature:

*

1 DE OS 3039076 "Hobs with inserts"

2 DE OS 2700525 "Multipart hob"

3 DE PS 3241696 "High-performance hob"

4 Roos, V.

"Skiving Milling as a Finishing Process for Case-hardened Cylindrical Wheels" Dissertation TH Aachen, 1983

Claims (3)

1. Milling tool for machining hardened gears, characterized in that a two-stage staggering of the cutting in realizing a mismatch, based on the pre and Nachschneider a Schneidpäares to the following similar pair of blades, is provided, in each case 2 cutting in the shortest possible distance are arranged in that the cutting edge following in the cutting direction is offset by an amount ε, so that equal chip thicknesses on the roughing and finishing cutters (1 and 2), relative to the total chip thickness, are ensured. 2. Milling tool according to item 1. as Zahnformf räswerkzeug, characterized in that a graduated scale between pre- and Nachschneider (1 and 2) of a pair of cutting done only that the staggering ε of the reamer (2) 40-60% of the total delivery per flank is. 3. Milling tool according to item 1. as Wälzfräswerkzeug, characterized in that a graduated scale between pre- and Nachschneider (1 and 2) of a pair of blades, wherein the size of the staggering ε of the reamer (2) in relation to the total delivery per edge after the relationship