DD240240A1 - PREPARATION LEVELS FOR HIGH-LOADED GEARS AND THEIR MANUFACTURING PROCESSES - Google Patents

Abstract

The invention relates to the production of toothed wheels whose tooth width is dissolved in order to increase the Tragfaehigkeit in individual width elements. It is for external gears as grade, Schraeg- and arrow toothing made of steel, hardened or not hardened, applicable. For a module, a module band z. B. produced by punching as a prefabrication stage, which has largely worked out the tooth gaps. By winding the tape around the gear main body arise sprockets with certain Zaehnezahl, whereby compliance with the division is enforced by marks on the basic body. From the toothed rollers can be obtained by separating a toothed disc of desired width, which has a sufficient measure to realize different profile shift factors. Fig. 2 shows a piece of modular tape as crimped as it is wrapped around a base body. Fig. 2

Description

For this 3 pages drawings

Field of application of the invention

The invention relates to prefabrication stages for heavy duty gears and their manufacturing processes. It is applicable to hardened and unhardened steel gears.

External gears can be created with straight, oblique and arrow teeth. For the economy of the process, it is important that about 50,000 teeth are manufactured with a module. These can be distributed over different gears. The gears should have numbers of teeth over 30.

Characteristic of the known technical solutions

Recently, it is known that the removal of the closed relationship of the material tooth along its width bring positive changes in the shear stress curve, which on the one hand allows a more favorable load distribution and thus a higher load capacity, on the other hand, extends the limits of the allowable tooth width.

It is also known to assemble a gear of stamped thin sheets (DE 3026685 A1). However, this method can only be used economically if a very specific tooth geometry (modulus, number of teeth, profile displacement) is used so frequently that the costs of a fineblanking tool are amortized. Cogs made of composite material with a high-quality material for the sprocket and cheap material for the body are also known. The lack of the prior art consists in the absence of a method and a semi-finished product, which decreases the nature of the composite rough cutting the high-quality gear cutting machines and teeth, the total width of which is composed of separate width elements.

Object of the invention

The object of the invention is to provide a step-by-step production method for steel gears, which has all the advantages of mass production in the first stage of prefabrication, or can be released from mass production, depending on the intended use, or for a higher level of prefabrication, to be used for a very specific purpose. It should be achieved using conventional materials by dissolving the tooth width in individual width elements a higher load capacity. The use of high quality gear material is to be limited to the area of the sprocket.

Explanation of the essence of the invention

- The technical problem to be solved by the invention consists in the indication of a manufacturing process in stages such that the first prefabrication stage has the character of mass production, the second prefabrication level can be attributed to mass production and in the third stage with cost-effective use the first and second stage can be made for an individual purpose in one-off production.

The products of the prefabrication stages should also have goods character.

The end product, the usable gear, should have a higher load capacity with low use of high quality material compared to conventionally produced gears made of the same material.

- The features of the invention consist both in the geometric shape and arrangement of the material and in the order of the method steps.

A main feature is that a steel strip is wound edgewise around a mandrel in a Schraublinie to be described as if a helical spring is to be produced with biasing force such that the length of the imaginary coil spring corresponds to the gear width and a turn corresponds to a width element ,

As is known, in the case of the helical spring, the turns can be rotated by a small amount.

According to the invention, a width element at the point of the tooth flank relative to the neighboring element to move thrust-free by tiny amounts to achieve a more favorable Lastverteilüngsfaktor in that the natural law form of the bending line of a homogeneous tooth is repealed.

Another feature of the steel strip mentioned is the nature of its processing. While the length of the belt is determined only by the ease of transport, thickness and width are dependent on the module of the gears to be produced. The strip thickness, from which a width element of the gearwheel later arises, is (0.1... 1) .m depending on the material and the means of production; the bandwidth is (3 ... 10) depending on the desired spread of the finished products, (m = module) On one side of the belt width, the later tooth gaps are worked out so that only a small amount of material needs to be removed for the subsequent fine machining. but on the other hand also so that a sufficient addition of material for different edge shapes due to different numbers of teeth and different edge sequence due to different profile displacement is present. On the opposite bandwidth gaps are also worked out, which have, in accordance with the invention, the following tasks together with the projections which have remained standing:

The projections should be supported later on the winding mandrel with the remaining band edge. The remaining approximately at right angles to the edge of the tape boundaries of the projections should rest on marks of the winding mandrel and enforce compliance with the division during winding.

The gaps between these projections are intended to facilitate bending around the winding mandrel by substantially reducing the moment of inertia of the tape.

This gap on one band side and the tooth gaps on the other band side are offset according to the invention by half a pitch. Thereby, the neutral fiber of a bend before the completion of the bend becomes a sine-like line, where a full swing corresponds to a pitch.

This particular form of neutral fiber is an essential feature of the invention, because it is the prerequisite that once fall the main deformation areas of the tape during winding not in the areas of the greatest operating stress of the later gear and that, secondly during the winding process to the mandrel an extension of the Bandes can be done. This stretching or elongation is required in order to be able to comply with the division of the pitch circle on average over several teeth for various freely selectable numbers of teeth. This is also possible when winding dart and helical gearing. This adherence to the division is enforced by material marks on the winding mandrel, which intervene in the gaps on the edge of the tape. When the tape is bent from its straight shape to the circular shape during winding, the circumference at the outer radius must be greater than the circumference at the inner radius. The circumference of the pitch circle must be strictly adhered to.

Since a shortening of the band, a compression of the material without wrinkling would require a high technological effort, the band length is selected according to the invention, which can be easily controlled by stretching the pitch and thereby reducing the amplitude of the sinusoidal neutral fiber during the winding process. The pitch of the tape before the winding process is about (0.9 · m · π).

The production of such a toothed belt of great length for a module represents the first stage of the process. Cutting-out in a follow-on tool with subsequent elimination of the warping by rolling or double-sided grinding in a continuous process is a special manufacturing process.

This tape can be offered as a product for further processing, like coil wrapped in rolls. It represents the first prefabrication stage for heavy duty gears and will be called in the following modular belt. The second prefabrication stage represents another key feature of the invention. Before its implementation, module also now still the number of teeth for the later gear must be set. The number of the reference profile, the profile shift factor and the gear width can still be left open.

The outer diameter of the mandrel results from the band geometry of the module band and the required number of teeth by prediction and technological experiment. The winding mandrel becomes the gear main body of the gears to be produced. Its length is determined by manufacturing considerations and includes the gear widths of a larger number of gears and the waste during separation.

On the circumference of the winding mandrel, reasonably evenly distributed under a winding difference resulting from the integer multiple of 360 ° / z (z = number of teeth), marks are for example in the form of feather keys mounted, which engage in the gaps of the modular belt and thus both the To enforce compliance with the division, as well as a number of teeth corresponding expansion of the module band.

This stretching during the winding process is achieved by a corresponding tensile stress, which together with a necessary guidance of the band by a pair of rollers tipping or an inclination or wrinkling

prevented. ·

The arrangement of the roller pair and the direction of the tensile force at the tape feed cause a dense packing of the turns of the modular belt, which can be compared with the block length of a prestressed helical tension spring.

If the parallel keys on the mandrel not parallel to the axis, but mounted as a steep helix, arises during winding the basic shape of a helical gear. Accordingly, the basic shape of Pfeilverzahnungen can be wrapped.

In order to reduce the stresses in the module belt due to the deformations during the winding process to residual stresses, then stress relief annealing must be done.

The sprocket, consisting of the gear main body with the feather keys and the wound module belt, is the second prefabrication stage. From her toothed pulleys can be cut to order. Notwithstanding a later attachment of the ends of the cut-through module band, for example by brazing, spot welding or template a disc, a winding is not to be feared as a result of the bias generated during winding an imaginary spring.

The merits of this cut off from the sprocket toothed disks as gear blanks consist in the extensive prefabrication of the tooth gaps, the use of high-quality material only for the sprocket, wasz. B. hardening without affecting the material on the body allowed, and in the resolution of the gear width in width elements.

In a third stage, fine machining takes place. Depending on the number of the same gears to be produced different work sequences can be selected.

For larger series of similar gears and unhardened teeth according to the chosen reference profile and the selected profile shift factor first the tip diameter is made on the sprocket, then fed the entire role of the gear cutting machine and only then separated to tooth width.

In the production of single wheels and in particular to be hardened tooth material is first cut to length, the band ends spot welded, hardened and then ground the tooth flanks.

embodiment

The invention will be explained in more detail below using the example of a gear with ζ = 37 and m = 4mm with reference to figures

 Show it:

Fig. 1: A section of a modular belt.

Fig. 2: The modular belt curved as it is wound around the gear main body.

Fig. 3: A division of the module band greatly enlarged with the location of different tooth flanks.

Fig.4: A sprocket completely.

Fig.5: A partial section through the sprocket.

Fig. 6: A partial section through the sprocket.

Fig. 7: A partial section through the sprocket.

Fig. 8: A detail of the sprocket with the feather key.

In Fig. 1, a section of a modular belt is shown, as it represents as a product from a first prefabrication stage.

The module is the scale factor for all sizes. A line 1 is to give the later circle, a sinusoidal line corresponds approximately to the neutral fiber 2. Your geometric mean over the circumference is the line 3. teeth with machining allowance are denoted by 4. Projections 5 are supported with a modular belt outside 6 on the winding mandrel. Gaps 7 should facilitate bending.

In Fig. 2, the module band is drawn in a curved shape. A subgroup pitch 8 must give the amount ρ = m · π . The difference between the normal division and end division due to the slope of the helix of the module band is less than one thousandths. However, another phenomenon must be considered.

Assuming a pure bending of the neutral fiber 2, this must in the unwrapped state of Fig. 1, a band division. 9

7p

where k = 3 ... 4. The choice k = 4 applies to virtually any positive and negative profile shifts.

When winding small numbers of teeth, the module belt is only bent, with large numbers of teeth it must be stretched more and more. For helical teeth, two amounts of draft for a helix angle are possible. The bevel angle may also be selected so that a solution for the amount of stretch becomes zero.

Fig. 3 shows an enlarged division of the modular belt, from which tooth flanks 10 with positive profile displacement χ = 0.5 or tooth flanks 11 without profile displacement or tooth flanks 12 with negative profile displacement χ = -0.3 can be made. The measures given in Figure 3 in fractions of the module were found theoretically. They can still be optimized after technological trials.

Fig. 4 shows the gear embodiment mitz = 37, m = 4 mm. On a gear main body 13, which served as a winding mandrel, sitting three parallel keys 14 at a distance of 12 or 13 teeth. The partial sections are for illustrative purposes and are shown in FIGS. 5, 6, 7. The key 14 is pulled out as a detail D in Fig. 8 separately.

Claims (1)

Invention claim: Prefabrication stages for heavy-duty gears and their manufacturing processes, characterized in that the end product special gears arise whose teeth along the tooth width are not closed and therefore have a better load distribution factor and characterized in that this property is produced in a process of manufacturing stages, wherein in a first stage in mass production a module belt is produced with prefabricated tooth gaps on one side of the belt and function- and production-related gaps on the other side of the belt so that a sinusoidal neutral fiber is formed, which allows a belt extension and thereby the module belt a prefabrication stage for all possible Stirnradarten and sizes of this module can be used and thereafter produced in a second prefabrication stage by a winding process of this module tape around a gear main body at the end spannungsfreigeglühte sprockets, wherein compliance with the division is enforced by physical marks on the body, which engage in the prefabricated gaps of the modular belt and are characterized in that in a third stage manufacturing the finishing of the gear takes place, the machining of the tip diameter, the finishing of the tooth flanks, the separation can be made of the sprocket and optionally a heat treatment in an appropriate order.