DE1627356C - Two-part worm-shaped hob - Google Patents

Description

dic spiral undercut. While, however, in the case of a cutter tooth that is usually undercut radially on the entire tooth profile, the head relief angle <5 _A must be selected so large that also on the flank cutting edges according to the relationship

sin d / - sin <> * · tan - * "

If there is still a sufficient clearance angle _{d f} , this consideration is not required with the milling cutter according to the invention. The clearance angles on the flanks and on the cutting edges, which are determined by the size of the axial or radial relief strokes, can be selected independently of one another, taking into account favorable machining conditions, i.e. the clearance angle on the flanks can be from 3 to 4 ° to 6 to 8 ° and the clearance angle at the tooth tip reduced accordingly compared to the usual values of 10 to 12 °.

When sharpening, the shape of the flank cutting edges remains within the same head and foot cylinder unchanged, since they always go through the intersection of the flank screw surfaces with the each Sharp grinds are newly created, but in the form of unchangeable rake faces are formed. the however, the thickness of the teeth measured on the reference cylinder (18 in Fig. 1) is reduced by the sharpening too sharp and also their head height above this, the latter, however, because of the smaller one Head relief angle is less pronounced than with one that is also radially reliefed on the flanks Milling cutter.

Especially when milling worm gears, the milling cutter is independent of its respective " Consumption status when milling the same wheel is always set to the same center distance. He Therefore, with increasing consumption, increasingly narrower tooth gaps with removable tooth root depth milling. In order to keep the gap width of the generated toothing constant, the respective consumption state of the milling cutter accordingly an intermediate ring 16 of such a thickness is used that with Referring to Fig. 3 the facing cutting edges 19 and 20 to the left and right of the Parting line in the axial direction the target distance, z. B. in finish milling

/ ₀ = / _a < ₂ = m _a π / 2

receive. Since the axis division does not change when sharpening, all the left cutting edges are then on the right and all right cutting edges on the left part of the cutter in the correct position, while the other cutting edges 21, 22 of the teeth in the axial direction by the size of the tooth thickness allowance of the new one Milling cutter = Js ₀
Is b ₀

the cutter teeth on the left as well as the left cutting edges of the cutter teeth on the right Half of the milling cutter completely pass through the area of engagement, then the milling cutter produces exactly the same S Flank shape and tooth thickness as in new condition.

In order to keep the tooth root depth within practically permissible limits during the service life of the milling cutter, If it is new, it will have a slightly larger diameter, i. H. with increased tooth head height, executed. Since its head clearance angle is smaller than with ■ milling cutters with radially undercut in the entire profile, results if you take into account the engagement of the worm with the "Wheel allows minimum tooth root depth, a service life that is sufficient for a finishing cutter. The milling cutter can also be used to advantage for separate roughing and finishing. To the Roughing it is used with an intermediate ring of the thickness

2O COS-X

55

_{J ()} stand back 0.1 m.

Lf _{0 is} the thickness of the intermediate ring 16 for the new condition of the milling cutter with the tooth thickness s _a and
_s - _s j

the tooth thickness in any consumption increment. then an intermediate ring from the thickness

K = K - -K

used. If a worm wheel is milled in a tangential pass with the milling cutter set in this way, the pass must be at least large enough that both the right cutting channel ρ is the addition to be left on the flanks of the wheel. Then the cutting edges 21, 22 of the teeth facing away from the parting line are in the roughing position on the two milling cutter parts, while the other cutting edges 19, 20 of the teeth are back. stand. During roughing with plunge feed, the main part of the machining work is therefore performed by the cutting edges 21, 22, while the cutting edges 19, 20 only make a little cut and are therefore hardly blunted. For finishing with tangential feed, the milling cutter with the intermediate ring is of the thickness

^b x = ^b o ⁼ 'U

used.

Only those hardly involved in roughing and therefore remained sharp come here Cutting edges 19, 20 for cutting so that a good surface is obtained.

As can be seen from the above description, the hob according to the invention is distinguished by the following properties:

1. Perfect profile accuracy of the toothing produced with it, regardless of its state of consumption, a property that is common to both worm and spur gear cutters the latter is particularly advantageous with regard to any profile corrections;

2. Freedom of movement in the choice of more favorable clearance angles for the flank cutting edges, which are also in adaptation the conditions of the hobbing process on the inlet and outlet side Flanks of different sizes can be chosen;

3. Easy setting in the machine for worm gear milling, regardless of the state of consumption the milling cutter can be set to the same axis intersection angle to the wheel;

4. the possibility of economically roughing and finishing with the same tool, whereby the cutting edges working during finishing are hardly stressed during roughing.

1 sheet of drawings

Claims (3)

1 .2 niger large deviations can be met, which claims: with increasing ·. The greater the consumption of the milling cutter on the flank shape of the milled wheel. 1. Worm-shaped hob cutters work for milling, the greater the cutter pitch angle and thereof Worm gears or spur gears initEvol- 5 with also the curvature of the flanks of its enveloping valve teeth with on the flanks is axial and worm. radially undercut on the tooth tips Task ¹ is therefore to create a worm Cutting teeth, thereby creating marked-shaped hob, which is of this, net that the cutter body is made up of two by one, especially when milling worm gears toothless intermediate ring (16) separated part io disruptive disadvantage is largely free and consequently Ien (10, 11) is made with cutting teeth, one of which during its entire useful life Distance after each sharpening of the milling cutter very good profile accuracy of the toothing generated with it guaranteed by using an intermediate ring from Solung. The task is cher thickness is set that the parting cutter according to the invention is achieved in that the joint facing cutting edges (19, 20) in FIG. 15 on the flanks of its cutting teeth axially and on using the target gap width / _{0 of} the milling cutter, radially undercut milling cutters at their tooth tips correct position. . two separated by a toothless intermediate ring 2. Hobs according to claim 1 preferably th parts with cutting teeth, the distance of which for milling spur gears with involute after each sharpening of the cutter through teeth, characterized by a flank ao use of an intermediate ring of such thickness einprofilwinkel (pressure angle) \ _lv , the is made smaller or that the parting line facing is at most as large as the flank profile angle ■ cutting edges in the innermost due to the target gap width are on the involute, ie on the distance determined by the milling cutter.
Form circle of the toothing lying profile point When designing the hob for milling in the normal section of the wheel with the smallest as of spur gears with involute toothing, the number of teeth that are milled with the milling cutter should can be exploited. the normal meshing pitch of the cutter the cutter is for this purpose with a flank profile that of the wheels to be milled is the same. running angle that is smaller or at most as large 3. Hob according to claim 1 and 2, characterized in that the flank profile angle is at the innermost on the 30 characterized that the "involute" with each sharp, i.e. on the form circle of the toothing grinding reducing tooth thickness of the cutter teeth lying profile point in the normal section of the wheel ■ when the cutter is new by about 0.1 module with the smallest number of teeth, that with the cutter is smaller is than half the tooth pitch. should be milled, whereby the pitch of the milling 35 gears is such that the normal engagement pitch of the milling cutter is equal to the normal meshing pitch of the with it is wheels to be milled. With a milling cutter designed in this way, the above requirement can almost be met; he offers The invention relates to a preferably 40 tet but, as the following description with reference to the Gear cutting of worm gears certain, with drawing will show, also other advantages. But also advantageous for toothing spur gears. The drawing shows an exemplary embodiment usable, from two by a toothless hob according to the invention.
Intermediate ring separate parts existing spiral F i g. 1 shows a longitudinal view with partial ken-shaped hob. It starts from the requirement 45 cut, · ■ from that with a hob that during its F i g. 2 is an end view of the milling cutter and entire service life from the new to the completely F i g. 3 and 4 schematic representations of the milling Consumed state always remains the same in the new or partially used state serration should produce the cutting edges after each. Sharp grinding on the flanks of the same envelope 50 The milling cutter is composed of the two parts 10 and 11 and worm, provided it is not a spur gear. The cutting teeth 12 of the milling cutter involve involute hob, even within which the same top and bottom cylinders have to run in their left and right flanks 13 and 14. Backed in the axial direction, so represent real. B. is a worm gear cutter, 55 screwing of the cutting edges 19 and 21 or 20 does not exactly match the operating worm and 22 arise as a generator around the cutter axis with which the milled wheel can later think together. The cutting edges are intended to be fenced, but certain rake faces 15 required to bring about the cut of the flank screw surfaces with the correct load-bearing and running properties can be formed. The rake faces can deviate, e.g. B. a slightly larger diameter flat surfaces (with straight-fluted milling cutters) or knife and have a different slope than this. Helical surfaces with a straight generating line (spiral-important in the sense of the aforementioned conditionally grooved milling cutter). Between the two halves, however, it is important that their milling cutter is arranged in an interchangeable, non-toothed, orderly shape during the service life of the intermediate ring 16.
Milling cutter remains unchanged. 65 The tooth tip cutting edges 17 are in usual It is easy to see that this requirement is way of keeping the clearance angle constant radially with in the usual way radially backed work according to a logarithmic or one of these in the required not exactly, but only with more or less area sufficiently approximating archimetric