CA2086043C - Method of and apparatus for cold forming toothed wheels from sheet metal - Google Patents
Method of and apparatus for cold forming toothed wheels from sheet metal Download PDFInfo
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- CA2086043C CA2086043C CA 2086043 CA2086043A CA2086043C CA 2086043 C CA2086043 C CA 2086043C CA 2086043 CA2086043 CA 2086043 CA 2086043 A CA2086043 A CA 2086043A CA 2086043 C CA2086043 C CA 2086043C
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- Prior art keywords
- tool
- blank
- preform
- flange
- teeth
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D53/00—Making other particular articles
- B21D53/26—Making other particular articles wheels or the like
- B21D53/28—Making other particular articles wheels or the like gear wheels
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21H—MAKING PARTICULAR METAL OBJECTS BY ROLLING, e.g. SCREWS, WHEELS, RINGS, BARRELS, BALLS
- B21H5/00—Making gear wheels, racks, spline shafts or worms
- B21H5/02—Making gear wheels, racks, spline shafts or worms with cylindrical outline, e.g. by means of die rolls
Abstract
A one-piece gear with an externally toothed rim extending at right angles to the hub of the gear arid preferably having a smooth internal surface is obtained by converting a circular disc-shaped blank of ductile metallic material into a preform with a concavo-convex or otherwise configurated flange extending to one side of the central portion of the thus deformed blank. The central portion of the deformed blank is clamped between the sections of a first rotary tool while an externally toothed second rotary tool advances radially toward the first tool to convert the flange into an externally toothed rim within a space which is defined in part by a peripheral recess of the first tool and in part by a registering peripheral recess of the second tool.
Description
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METHOD OF AND APPAT2ATUS FOR COLD fOf~'2T1VG '.I'OO~I'I~IED Wt-IEELS , FROM SHE~'I' METAL
The invention relates to improvements in methods of and in apparatus for cold forming toothed wheels from sheet metal. t4ore particularly, the invention relates to improvements in methods of and in apparatus for converting ductile blanks of metallic sheet material into spur gears, ring gears or analogous gears of the type wherein the externally toothed rim is of one piece with the hub.
Externally toothed gears of the character to which the present. invention pertains can be utilized in various types of transmissions, e.g., in indexing drives, in starters of engines for motor vehicles, in belt transmissions and for many other purposes. For example, it is known to construct a flywheel for use in the starter for the engine of a motor vehicle in such a way that the central portion or hub is produced as a discrete or separate first part and the toothed rim is produced as a discrete or separate second part. The hub is made of cold formed metallic sheet stock, and the rim is made from a ring which is provided with teeth as a result of machining in a material removing tool. The thus finished ring, i.e., a rim with external teeth formed therein as a result of material removal, is then welded to the hub. A
drawback of such procedure is that the gear is expensive and, furthermore, the welding operation is likely to cause highly unpredictable changes in the material of the hub and/or in the material of the rim. Moreover, the weight and bulk of the ultimate product are excessive for many purposes.
European Pat. No. 0 333 917 A2 proposes to reduce the overall weight of a spur gear, a ring gear or an analogous gear; iaithout unduly affecting the stability of its rim and/or hub, by utilizing a preform which is provided with a relatively thick marginal portion. The relatively thick marginal portion is obtained by increasing the thickness of the marginal portion of a circular metallic blank of constant . thickness so that the cross--sectional area of the thickened 1 marginal portion exceeds the cross-sectional area of a corresponding length of an annular zone having the thickness of the blank.
The thickness of the marginal portion of the blank is increased by resorting to a standard sheet metal treating.
operation, such as upsetting or the like. The treatment involves pronouced changes in the texture of the material of the blank. Since a blank of the just outlined character is normally made of carbon steel, the aforediscussed upsetting or an analogpus treatment necessarily entails an increase of hardness which is undesirable in connection with the carrying out of the next-following steps, i.e., conversion of the preform into a gear with external teeth. Such conversion normally involves hammering the thickened marginal portion of the preform in a well known manner in order to provide the external surface of the marginal portion with an annulus of teeth. The method which is produced in European patent No.
0 333 917 A2 exhibits the drawback that the flanks of the thus obtained teeth are often too weak so that the teeth are likely to break in response to the application of moderate stresses: Moreover, the just discussed method involves the making of external teeth which extend radially outwardly as well as radially inwardly, i.e., also beyond the internal surface of the rim to thus impart to the internal surface an undulate shape which entails the generation of pronounced noise when the gear is in use.
European Pat. No. 0 140 576 A1 proposes the making of a flywheel from a pressed article, namely from a so-called first draw. The patent proposes to roll the teeth into the peripheral surface of an axially extending portion of the first draw. The drawing of the patent shows a finished product which appears to have a smooth internal surface so that the product is less likely to generate pronounced noise in actual use. However, this proposal again exhibits another drawback, namely that a blank must be converted into a first 1 draw in a first operation and the thus obtained first draw must be transferred into a second machine in order to convert it into a gear. Furthermore, the thickness of the marginal portion which is converted into the toothed rim is the same as that of the hub; this can result in the making of a weak toothed rim whose teeth are likely to break (if the thickness of the marginal portion of the preform is insufficient) or in the making of a heavy and bulky gear if the thickness of the marginal portion of the preform (and hence the thickness of the hub) is selected with a view to ensure the making of a toothed rim which is sufficiently sturdy to avoid the breaking of its teeth.
Commonly owned German Pat. No. 38 19 957 C1 discloses a method of making a pulley from a circular metallic blank of constant thickness. The blank is clamped between two portions of a rotary tool so that its marginal portion extends beyond the peripheral surface of the tool.
The projecting marginal portion is thereupon flexed by a second tool to be converted into a flange extending to, one side of the central portion of the thus deformed blank and having a concavo-convex crass-sectional outline. Tie flange is thereafter acted upon by a third tool which flattens the flange by forcing it into a peripheral recess of the first tool and thus increases its thickness. The patent discloses that the external surface of the flattened and thickened flange can be provided with circumferentially extending grooves if the thus obtained pulley is to be used in connection with vee belts, or the external surface of the flange can be provided with transversely extending teeth for engagement with the teeth of a toothed belt.
Commonly owned German Pat. No. 39 32 823 C1 discloses a method of making a gear wherein the rim extends to one side of the hub and is provided with internal as well _ as with external teeth. The marginal portion of a circular metallic blank is flexed to one side of the central portion KlJ 1~ (~ %,,~ '17 l~: c.1 1 of the blank with simultaneous thickening of the marginal portion and the forming of internal teeth. The thus treated blank is thereupon acted upon by a different tool which provides its previously treated marginal portion with external teeth. The overall axial length of the toothed rim of the finished product is not predictable because some material of the blank can flow axially during the making of internal teeth and again during the making of external teeth.
German patent application Serial No. 40 06 582 A1 of Grob (published September 13, 1990) discloses a method of making a gear by cold forming a metallic preform having a marginal portion of U-shaped cross-sectional outline and extending to one side of the hub. The marginal portion is provided with external teeth by resorting to a rolling operation. The internal surface of the externally toothed rim of the finished product has an undulate shape, and the material of the rim can flow in the axial direction of the hub in the course of the rolling operation. ThP marginal portion must be propped from within while a rotary rolling tool provides the external surface of the marginal portion with a set of axially parallel teeth. , An object of the invention is to provide a method which renders it possible to convert a blank or a preform into an externally toothed gear without any, or with negligible, changes in the texture of the material of the blank or preform.
Another object of. the invention is to provide a method of making an externally toothed gear from a blank or from a preform in such a way that the tYxickness of the toothed rim of the ultimate product can be increased without any; or without excessive, changes in the characteristic of the metallic material of the blank.
A further object of the invention is to provide a method which renders it possible to increase the thickness of the marginal portion of a blank ar preform simultaneously with the making of external teeth therein.
An additional object of the invention is to provide a novel and improved preform which can be utilized.for the practice of the above outlined method.
Still another object of the invention is to provide a method which renders it possible to rapidly convert a simple circular metallic blank into a gear with an externally toothed rim having a smooth cylindrical internal surface.
A further object of the invention is to provide a ~ novel and impraved method of making one-piece spur gears, ring gears or analogous gears in a simple and time-saving operation.
Another object of the invention is to provide a method which renders it possible to convert a blank or a reform into an externally toothed gear with a strong rim even if the thickness of that portion of the blank or preform which is converted into the rim is the same as the thickness of a relatively thin blank or preform of constant thickness.
An additional object of the invention is to provide ,a method which can be practiced to turn out inexpensive but "fir ~.'~ ~ ~ ~ '~~'~
1 strong and reliable externally toothed gears for use, for example, in the starters for the engines of motor vehicles.
Still another object of the invention is to provide a novel and improved apparatus for the practice of the above outlined method.
A further object of the invention is to provide the apparatus with novel and improved means for synchronizing the movements of various blank- or preform-supporting and treating tools.
Another abject of the invention is to provide the apparatus with novel and improved means for transmitting torque to various rotary parts.
An additional object of the invention is to provide an apparatus which can treat blanks and/or preforms of various sizes, thicknesses and/or materials.
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J ,r One feature of the present invention resides in the provision of a method of making a rotary member having a hub, a rim surrounding the hub and external teeth in the rim. The improved method comprises the steps of mounting a substantially circular metallic blank of ductile material on ~a first tool having a circumferential recess for a marginal portion of the blank, deforming the marginal portion of the blank into or at least close to the recess to convert the marginal portion into a flange surrounding a central portion which constitutes the hub of the thus deformed blank, and cold forming the flange including subjecting the flange to the deforming action of a rotary tooth forming second tool having an annulus of teeth in a circumferential recess adjacent the recess of the first tool to thus transform the flange of the deformed blank into a rim with external teeth while the flange is confined in the recesses of the first and second tools.
The deforming step can include subjecting the marginal portion of the blank to the cold forming action of a third tool having a circumferential recess for a portion or part of the marginal portion of the blank, moving at least one of the first and third tools toward the other of the first and third tools, and rotating at least one of the first and third tools.
The cold forming step can include moving at least one of the first and second tools toward the other of the first and second tools and rotating at least one of these tools.
The deforming step can comprise moving the marginal portion of the blank in the direction of the axis of the rotary member and to one side of the central portion of the blank, i.e., the deforming step can involve a shifting of the entire marginal portion to one side of the central portion of the blank, namely of that portion which constitutes the hub _ g ~~~ ~~ ~ ~'~ ~ ~~ ;~
1 of the deformed blank and of the ultimate product, a.g., a starter gear for use on a flywheel which is driven by the output element (e. g., a crankshaft) of the engine in a motor .vehicle. Otherwise stated, the deforming step can involve conversion of the marginal portion of the blank into a flange, and such flange can have a concavo-convex cross-sectional outline, preferably with a convex external surface and a concave internal surface.
The deformed blank can constitute a preform having the aforementioned central portion or hub and a converted marginal portion in the form of a flange having a substantially cylindrical first portion which is spaced apart from the hub and a substantially annular second portion having a substantially U-shaped cross-sectional outline and disposed between and of one piece with the hub and the first portion.
The cold forming step can further include providing the rim with a smooth substantially cylindrical internal surface. This cold forming step can involve a movement of the second tool relative to the first tool, and the cold forming step can include. increasing the thickness of the rim, i.e., the rim can be thicker than the marginal portion of the underformod blank.
Another feature of the invention resides in the provision of a method of making a rotary member (e. g, a spur gear, a ring gear or an analogous externally toothed gear) having a hub, a rim surrounding the hub and external teeth in the rim. This method comprises the s eps of mounting on a first tool having a circumferential recess a substantially circular metallic preform made of a ductile material and hawing a substantially disc-shaped central portion and a marginal flange extending to one side of the central portion and overly ng the circumferential recess of the first tool, deforming the flange into the recess to convert suoh flange . into the rim which surrounds the central portzon. the latter _ g _ 1 constituting the hub of the deformed preform, and simultaneously cold forming the flange including subjecting the flange to the deforming action of a rotary tooth forming second tool (e. g., a rolling tool) having an annulus of teeth in a circumferential recess which is adjacent the recess of the first tool to thus provide the flange with external teeth within the recesses of the first and second tools.
The mounting step can include mounting on the first tool a preform wherein at least a portion of the flange extends at least.substantially at right angles to the central portion, and such method can further comprise the step of forming the preform prior to the mounting step. Such forming step can include deforming a marginal portion of a substantially circular metallic blank of ductile material into the marginal flange of the preform.
The mounting step of the second method can include mounting on the first tool a preform wherein the flange includes a cylindrical portion in the recess of the first tool and a second portion having a substantially U-shaped cross-sectional outline, extending from the recess of the first tool, and connecting the first portion with.t,he central portion of the preform. The cold forming step of such method can comprise moving the second portion of the flange toward the recess of the first tool. The cold forming step can comprise confining the entire flange of the preform in the recesses of the first and second tools.
As already mentioned above, the second method can further comprise the step of converting a substantially circular blank of ductile metallic material into the preform.
A further feature of the present invention resides in the provision of an apparatus for converting a metallic blank into an externally toothed rotary member. The apparatus comprises a blank supporting first rotary tool, a carriage which is movable substantially radially of the first . tool, an externally toothed secand tool which is rotatably 1 mounted on the carriage, a chain transmission connecting the tools for rotation about discrete axes, and means for moving the carriage relative to the first tool. In accordance with a presently preferred embodiment of the improved apparatus, the transmission comprises a first shaft which mounts the first tool, a first sprocket wheel on the first shaft, a second shaft provided an the carriage and mounting the second tool, a second sprocket wheel on the second shaft, at least one tensioning device, and an endless chain which is trained over the sprocket wheels and over the at least one tensioning device. The at least one tensioning device can comprise a second carriage which is movable substantially radially of the first tool, at least one additional sprocket wheel rotatably mounted on the second carriage, and means for moving the second carriage relative to the first tool. The means for moving the second carriage can comprise. a fluid-operated motor (e. g., a hydraulic cylinder-and-piston unit).
The first tool is or can be mounted for rotation about a fixed axis, and the means for moving the first carriage relative to the first tool can also comprise a fluid-operated motor, e.g., a hydraulic cylinder-and-piston unit.
Still another feature of the present invention resides in the provision of a method of forming a toothed wheel including a series of cold-formed peripheral teeth having sides spaced apart a predetermined distance utilizing (1) a rotary holding unit having structure providing generally radially outwardly facing control surface means, and (2) a rotary tooth-forming tool unit having a rotational axis and a tooth-forming periphery extending annularly about the rotational axis, the rotary units including a total of two annular flanges extending outwardly thereof having two smooth tooth-side forming surface means facing toward one another spaced apart the aforementioned predetermined 35' distance. This method comprises the steps of cold-forming a 1 circular piece of sheet metal of predetermined thickness into a preform having an outer annular section of generally uniform cross--sectional configuration and an integral sheet metal central wall generally of the predetermined thickness extending generally radially inwardly from the outer annular section toward a preform axis, the outer annular section having (1) a width greater than the predetermined thickness but no greater than the predetermined distance, and (2) an outer periphery which will allow a meshing action with the tooth-forming periphery of the tooth-forming tool unit, rotating the rotary holding unit with the preform secured thereto about the preform axis and with the control surface means underlying at least a portion of the annular section and (2) the tooth-forming tool unit about the rotational axis thereof in a predetermined rotational relation wherein the axes are parallel and their rotational speeds are synchronized, and while the rotary holding unit with the preform secured thereto and the tooth-forming tool unit are in the predetermined rotational relation, effecting a relative movement between the two units and their axes in a direction toward one another to engage the tooth-forming periphery of the tooth-forming tool unit in cooperating metal-deforming relation with the exterior periphery of the annular section and deforming the same inwardly of the exterior periphery thereof until the sheet metal of the annular section is cold-formed into the series of teeth, the peripheries of which are cold-formed by rolling contact with the tooth- orming periphery of the tooth-forming tool unit and portions of the sides of which are smooth and cold-formed by contact with the smooth tooth-side forming surface means so that an amount of sheet metal which would otherwise uncontrollably flow axially outwardly of the smooth tooth-side forming surface means is concentrated within the teeth and/or the radially inward back-up therefor.
35. The novel features which are considered as - 12 _ 1 characteristic of the invention are set forth in particular in the appended claims. The improved apparatus itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain presently preferred specific embodiments with reference to the accompanying drawings.
1 BRIEF DESCRI~TIOPJ OF THE DR?~WINGS
FIG. 1 is a fragmentary axial sectional view of a first tool which mounts a circular metallic blank, and a fragmentary partly elevational arid partly central sectional view of a tool which serves to deform the marginal portion of the blank;
FIG. 2 is a similar view of the tools of FIG. 1 but with the marginal portion of the blank in deformed condition in which it constitutes a flange having a concavo-convex cross-sectional outline;
FIG. 3 shows the first tool of FIGS. 1 and 2, the deformed blank of FIG. 2 and an externally toothed tool which is to convert the deformed marginal portion or flange of the blank into an externally toothed rim;
FIG. 4 shows the structure of FIG. 3 with the externally toothed tool in the process of cold forming the deformed marginal portion or flange of the blank;
FIG. 5 is an axial sectional view of an externally toothed gear obtained in accordance with the method which can be carried out with the tools of FIGS. 1 to 4;
FIG. 6 is a fragmentary axzal sectional view of a tool corresponding to the first tool of FIG. 1 but mounting a preform having a deformed flange-like marginal portion which overlies a circumferential recess of the tool, and a partly elevational and partly axial sectional view of a tool corresponding to the upper tool shown in FIGS. 3-4 and serving to convert the flange-like marginal portion of the preform into an externally toothed rim of the type corresponding to that forming part of the gear of F3G. 5;
FIG: 7 is aview similar to that of FIG. 6 but showing a different preform and a tooth forming or rolling tool constituting a modification of the upper tool which is shown in FIGS. f, 4 and 6; and FIG: 8 is a fragmentary schematic partially plan , and'partly horizontal sectional view of an apparatus which L
1 can be utilized for the practice of the improved method and wherein the tooth-farming or rolling tool can be moved radially of the tool which mounts a blank or a preform.
FIG. 1 shows a portion of a circular blank 1 of ductile metallic material having a central portion clamped between two coaxial sections 2 and 3 of a rotary tool having a circumferentially complete peripheral recess 7 between two radially outwardly extending smooth control surfaces 2A, 3A.
These surfaces are respectively provided on a radially outwardly extending portion or collar 2B of the section 2, and on a radially outermost portion 3B of the section 3. The axis of rotation of the tool including the sections 2, 3 is denoted by a line X-X or is parallel to and is located below the level of the line X-X (as viewed in FIG. 1).
The marginal portion lb of the blank 1 extends radially outwardly well beyond the portions 2B and 3B so that it can be deformed by a tool 4 into a flange 6 of the type shown in FIG. 2. The flange 6 extend between the portions 2B, 3B and abuts the control surfaces 2A, 3A. The tool 4 is rotatable about an axis which is parallel to the axis X-X and includes two disc-shaped end portions 4a, 4b and an intermediate or central portion 4c having a concave peripheral surface 4d extending all the way betweep the end portions 4a, 4b. The surface 4d converts the radially outwardly extending marginal portion lb of the blank 1 into the concavo-convex flange 6 of the deformed blank or preform lA which is shown in FIG. 2. Such deformation of the marginal portion lb takes place in response to a reduction of the distance between the axes of the tool including the sections 2, 3 and the tool 4. For example, the tool 4 can be fed toward the axis X-X in the direction of arrow A; at such time, the radially outermost part o~ the marginal portion lb slides along the concave peripheral surface 4d of the intermediate portion 4c of the tool 4.
The deformed blank or preform lA is ready to be Converted into'an externally toothed gear or wheel of the type shown in EIG. 5, as at 150 This is achieved by moving _.
1 the tool including the sections 2, 3 into proper position relative to a tooth forming tool 5 which is shown in FIGS. 3 and 4, or by repJ.acing the tool 4 with the tool 5 while the radial and axial positions of the tool including the sections 2, 3 remain unchanged. The tool S has two disc-shaped end portions 5a, 5b and an intermediate portion or central portion 5c provided with an annulus of external teeth 9 within a recess 8 between the smooth confronting surfaces 5A, 5B of the end portion 5a, 5b, respectively. The distance between the surfaces 5A, 5B is the same as that between the surfaces 2A, 2B (as measured in the direction of the axis X-X). The tool including the sections 2, 3 and/or the tool 5 is movable radially of the axis X-X in order to flatten the flange 6, to increase its thickness, and to provide the thus obtained rim 11 (FIG. S) with external teeth 10 complementary to the teeth 9 on the tool 5. The arrow B in FIG. 3 denotes that the tool 5 is movable radially of and toward the axis X-X. The surfaces 2B, 3B and 5A, 5B cooperate to seal the peripheral recesses 7 and 8 when the end walls 5a, 5b respectively abut the portions 2B, 3B of the sections 2, 3 to thus ensure that the material of the preform lA cannot flow in an uncontrolled manner, i.e., that the axial length o~ the rim ll and its teeth matches the distance of the surfaces 2A,, 3A or SA,-5B from each other. The dimensions of the blank 1, the thickness of this blank, the distance of the surfaces 2A, 3A or SA, 5B from each other, the depths of the recesses 7, 8 and the dimensions of the teeth 9 are selected in such a way that the recesses 7, 8 and the spaces between the teeth 9 are filled with the material of the flange 6 when the tool 5 reaches the position of FIG. 4, i.e., when the preform lA is converted into the rotary externally toothed gear 15 of FIG.
4 or 5. The smooth side surfaces of the rim 11 and its teeth l0 are shown at l0a and lOb.
The end walls 4a, gb can constitute two separately 35. produced parts which are affixed to the central or 1 intermediate portion 4c of the tool 4 in a manner not forming part of the present invention. Analogously, the end walls 5a, 5b can constitute separately produced parts which are affixed to the central or intermediate portion 5c of the tool 5 in any suitable manner not forming part of. the invention.
The specific configuration of the hub 12 of the gear 15 can be obtained in response to clamping of the blank 1 between the sections 2, 3. Alternatively, a blank having a central portion corresponding to that of the hub 12 can be clamped between the sections 2, 3 so that these sections perform no deforming or shaping action but merely limit the axial length of the flange 6 (see FIG. 2). The thickness of the blank 1 can be constant, the same as the thickness a of the hub 12. The thickness of the rim 11 (as measured in the radial direction of the gear 15) may but need not be less than the thickness a; this depends on the selected dimensions of the recesses 7, 8 and of the spaces between the teeth 9 as well as on the thickness of the flange 6. It is often preferred to select the thickness of the rim ll in such a way that it at least matches the thickness _a of the hub 12. The internal surface lla of the rim ll is preferably smooth and is complementary to the smooth surface 7a in the radially innermost portion of the recess 7.
The gear 15 which is shown in FIG. 5 can constitute .
a spur gear in a starter which is used for the engine of a motor vehicle. For example, the gear 15 can be welded or otherwise secured to a flywheel which is mounted on and receives torque from the crankshaft of an internal combustion engine.
FIG. 6 shows a tool including the sections 2, 3 which are identical or analogous to the similarly referenced sections of the tool shown in the lower parts of FIGS. 1 to :4, and a somewhat modified tool 105 which is used in lieu of the tool 5 of FIGS. 3~-4. The preform lOlA differs from the 35. preform lA in that its flange 106 merely overlies but does '~a~~~~i'~j~'~
1 not extend into the recess 7 of the section 2. The preform lOlA can be obtained from a blank 1 by resorting to a tool corresponding to the tool 4 in that the tool 4 is not moved from the position of FIG. 1 and all the way to the position of FIG. 2. The tool 105 of FIG. 6 performs initially the function of corwerting the flange 106 into a flange corresponding to the flange 6 of FIG. 2 or 3, and thereupon the function of the tool 5, i.e., converting the deformed flange 106 into an externally toothed rim corresponding to the part 11 (with teeth 10) shown in FIG. 5. The end portions 105a, 105b of the tool 105 are provided with confronting frustoconical smooth internal surfaces 105A, 105B, and the central or intermediate portion 105c of the tool 105 has an annulus of teeth 109 in a recess 108 extending between the frustoconical surfaces 105A, 105B.
The tool 105 of FIG. 6 can be replaced with the tool 5 of FIGS. 3-4, or vice versa, without departing from the spirit of the invention.
FIG. 7 shows a tool including the sections 2 and 3, a different preform 201A (which can be obtained from a circular metallic blank 1), and a tool 20 which constitutes a modification of the tool 105'shown at FIG. 6. The preform 2OlA includes a flange 16 having a cylindrical first portion 18 which is received in the recess 7 and~is normal to the radially extending central portion 201a, i.e., to the hub of the finished product. The flange l6 of the preform 20.1A
further includes a second portion l7 which is of one piece with the central portion 201a and with the cylindrical portion 18 and has a substantially U-shaped cross-sectional outline. The portion 17 of the flange 16 extends radially outwardly from and beyond the recess 7. It will be noted that, in all illustrated embodiments of the preform or gear, the flange or the rim is located in its entirety at one side _ of the central portion or hub.
The tool 20 has a relatively narrow end wall 20b, a fT
~ l'/, ~ C
1 wider end wall 20a and a central portion 20c with an annulus of external teeth 9a in a recess 8a between the confronting smooth frustoconical surfaces 20A, 20B of the respective end portions 20a, 20b. The teeth 9a serve to cold form teeth into the portion 17 as well as to force the portion 17 toward the surface in the radially innermost portion of the recess 7 (when the tool 20 is moved in the direction of arrow B) to provide the thus obtained rim with a smooth cylindrical internal surface and with a set of external teeth in that portion of the rim which constitutes the converted (cold formed) portion 17 of the flange 16 of the preform 201A. The cylindrical portion 18 remains, or can remain, at least substantially unchanged and can be provided (e.g., at the time of making a blank or at the time of converting such blank into the preform 201A) with one or more openings which can constitute so-called pulse openings to permit the .
generation of signals in connection with the use of the gear in or with a computer-controlled internal combustion engine.
A gear which has openings in the cylindrical portion 18 can .
be used in the starter for a combustion engine.
The method which can be carried out in the apparatus employing the tools of FIGS. 1 to 4 exhibits the advantage that a blank 1 which has been clamped between the sections 2, 3 remains between these sections all the way until completion of the gear 15. On the other hand, the apparatus employing the tools of FIG. 6 or 7 exhibits the advantage that, though it is necessary to shape the preform lOlA or 201A in a separate machine or in a separate part of a machine which is designed to make gears in accordance with the method of the present invention, the gear can be provided with a rim having an externally toothed portion (namely the converted flange 106 or the converted portion 17 of the flange 16) as well as (in FIG. 7) a cylindrical portion 18 which can be provided with the aforediscussed openings.
The end portions 20a, 20b of the tool 20 cooperate 1 with the radially outermost portions 2B, 3B of the sections 2, 3 to prevent any uncontrolled axial flow of the material of the preform 201A during movement of the tool 20 in the direction of arrow B. Again, the dimensions of the recesses 7, 8a and of spaces between the teeth 9a are selected with a view to ensure that a preform 201A matching a standard preform or norm will be converted into a gear with a rim having external teeth formed by the teeth 9a and a cylindrical portion constituted by the portion 18 of the flange 16 shown in FIG. 7. When the conversion of the flange 16 of the preform 201A into a rim is completed, the recess 7 is preferably completely filled with the metallic maternal to thus ensure that the rim of the resulting gear will have an internal surface conforming to the surface in the innermost portion of the recess 7.
An important advantage of the improved method is that the making of a flange 6. 106 or 16 merely involves flexing of the marginal portion of a blank so that the texture of the material of the marginal portion of the blank or preform remains at least substantially unchanged. Any changes in the texture of the material of the blank or preform, or any pronounced changes of texture, take place only when the flange 6 or 106 or 16 is acted upon by the tool 5 or 105 or 20, i.e., at the time the blank or preform is provided with a finished rim having an annulus of external teeth and preferably a smooth cylindrical internal surface.
Experiments indicate that the improved method renders it possible to obtain a gear 15 or a similar gear which has a relatively thin hub 12 arid wherein the thickness of the rim lI (as measured in the radial direction of the gear) suffices to ensure the required strength, and the dimensions of the teeth are also such as to ensure the required stability and long useful life in actual use in a motor vehicle or elsewhere. The depth of spaces between the teeth 10 can be selected practically at will by appropriate zl 1 selection of the tool 5, 105 or 20 as well as of all other parameters which influence the dimensions of the teeth at the exterior of the finished rim 11. The latter can extend exactly at right angles to the plane of the hub 12.
' FIG. 8 shows a portion of an apparatus which can be utilized for the practice of the improved method. The apparatus includes a frame or base 33 supporting a rotary shaft 22 connected to a sprocket wheel 23 and also carrying ' the tool (for example, a tool including the sections 2, 3) which mounts the blank 1, the preform lOIA or the preform 201A. A carriage 21 which is reciprocable in the base 33 along tracks 34 radially of the shaft 22 rotatably supports a second shaft 24 which is parallel to the shaft 22. The shaft 24 is connected with a sprocket wheel 25 and also supports the tool 4, 5, 105 or 20. The transmission including the sprocket wheels 23, 25 further comprises an endless chain 26 which is trained over guide wheels 35 adjacent the sprocket wheel 23 as well as over a chain tensioning unit including a second caxriage 29 reciprocable in the base 33 radially of the shaft 22 and supporting two rotary sprocket wheels 27, 28. The carriage 21 is movable toward the shaft 2,2 by a first motor 36 (e.g., a fluid-operated motor such as a hydraulic cylinder and piston unit), and the carriage 29 is reciprocable by a second motor 30, e.g., a fluid-operated motor including a hydraulic cylinder and piston unit. It is also possible to provide the apparatus of FIG. 8 with other types of means for moving the carriages 21 and 29;
for example, the means for moving the carriage 21 can comprise aprime mover and a mechanical power train between such grime. mover and the carriage 2l. The motor 36 serves to feed the carriage 21 (and the tool on the shaft 25) toward the blank or preform mounted in the tool which is carried by the shaft 22: The carriage 29 is movable by the motor 30 in order to maintain the chain 26 under requisite tension so 35. that the chain ensures synchronous rotary movements of the , ~~8~~~~~
1 shafts 22 and 24, i.e., that blank or preform on the shaft 22 is rotated in synchronism with the tool on the shaft 24. The reference characters 31 and 32 denote in FIG. 8 bolts or other adjusting devices which can move the shafts 37, 38 for the sprocket wheels 27, 28 relative to the carriage 29. The chain 26 is driven by a motor (not shown) which rotates the shaft 22 or 24, i.e., a single motor suffices to drive the blank or preform on the shaft 22 in synchronism with the cold forming (flange-forming and/or tooth-forming) tool on the shaft 25. Such synchronism is achieved in spite of pronounced stresses which develop when the apparatus of FIG.
8 is in use to feed a tool on the shaft 25 toward and against a blank or against a preform on the shaft 22.
The synchronizing means of the apparatus which is shown in FIG. 8 has been found to be more reliable and simpler than heretofore known synchronizing means which rely on electronic circuita. The main reason for the superiority of the illustrated apparatus is believed to be that it can stand pronounced stresses which develop during cold forming the flange of a blank or preform to convert it into an externally toothed rim.
1 Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic and specific aspects of my contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and range, of equivalence of the appended claims.
METHOD OF AND APPAT2ATUS FOR COLD fOf~'2T1VG '.I'OO~I'I~IED Wt-IEELS , FROM SHE~'I' METAL
The invention relates to improvements in methods of and in apparatus for cold forming toothed wheels from sheet metal. t4ore particularly, the invention relates to improvements in methods of and in apparatus for converting ductile blanks of metallic sheet material into spur gears, ring gears or analogous gears of the type wherein the externally toothed rim is of one piece with the hub.
Externally toothed gears of the character to which the present. invention pertains can be utilized in various types of transmissions, e.g., in indexing drives, in starters of engines for motor vehicles, in belt transmissions and for many other purposes. For example, it is known to construct a flywheel for use in the starter for the engine of a motor vehicle in such a way that the central portion or hub is produced as a discrete or separate first part and the toothed rim is produced as a discrete or separate second part. The hub is made of cold formed metallic sheet stock, and the rim is made from a ring which is provided with teeth as a result of machining in a material removing tool. The thus finished ring, i.e., a rim with external teeth formed therein as a result of material removal, is then welded to the hub. A
drawback of such procedure is that the gear is expensive and, furthermore, the welding operation is likely to cause highly unpredictable changes in the material of the hub and/or in the material of the rim. Moreover, the weight and bulk of the ultimate product are excessive for many purposes.
European Pat. No. 0 333 917 A2 proposes to reduce the overall weight of a spur gear, a ring gear or an analogous gear; iaithout unduly affecting the stability of its rim and/or hub, by utilizing a preform which is provided with a relatively thick marginal portion. The relatively thick marginal portion is obtained by increasing the thickness of the marginal portion of a circular metallic blank of constant . thickness so that the cross--sectional area of the thickened 1 marginal portion exceeds the cross-sectional area of a corresponding length of an annular zone having the thickness of the blank.
The thickness of the marginal portion of the blank is increased by resorting to a standard sheet metal treating.
operation, such as upsetting or the like. The treatment involves pronouced changes in the texture of the material of the blank. Since a blank of the just outlined character is normally made of carbon steel, the aforediscussed upsetting or an analogpus treatment necessarily entails an increase of hardness which is undesirable in connection with the carrying out of the next-following steps, i.e., conversion of the preform into a gear with external teeth. Such conversion normally involves hammering the thickened marginal portion of the preform in a well known manner in order to provide the external surface of the marginal portion with an annulus of teeth. The method which is produced in European patent No.
0 333 917 A2 exhibits the drawback that the flanks of the thus obtained teeth are often too weak so that the teeth are likely to break in response to the application of moderate stresses: Moreover, the just discussed method involves the making of external teeth which extend radially outwardly as well as radially inwardly, i.e., also beyond the internal surface of the rim to thus impart to the internal surface an undulate shape which entails the generation of pronounced noise when the gear is in use.
European Pat. No. 0 140 576 A1 proposes the making of a flywheel from a pressed article, namely from a so-called first draw. The patent proposes to roll the teeth into the peripheral surface of an axially extending portion of the first draw. The drawing of the patent shows a finished product which appears to have a smooth internal surface so that the product is less likely to generate pronounced noise in actual use. However, this proposal again exhibits another drawback, namely that a blank must be converted into a first 1 draw in a first operation and the thus obtained first draw must be transferred into a second machine in order to convert it into a gear. Furthermore, the thickness of the marginal portion which is converted into the toothed rim is the same as that of the hub; this can result in the making of a weak toothed rim whose teeth are likely to break (if the thickness of the marginal portion of the preform is insufficient) or in the making of a heavy and bulky gear if the thickness of the marginal portion of the preform (and hence the thickness of the hub) is selected with a view to ensure the making of a toothed rim which is sufficiently sturdy to avoid the breaking of its teeth.
Commonly owned German Pat. No. 38 19 957 C1 discloses a method of making a pulley from a circular metallic blank of constant thickness. The blank is clamped between two portions of a rotary tool so that its marginal portion extends beyond the peripheral surface of the tool.
The projecting marginal portion is thereupon flexed by a second tool to be converted into a flange extending to, one side of the central portion of the thus deformed blank and having a concavo-convex crass-sectional outline. Tie flange is thereafter acted upon by a third tool which flattens the flange by forcing it into a peripheral recess of the first tool and thus increases its thickness. The patent discloses that the external surface of the flattened and thickened flange can be provided with circumferentially extending grooves if the thus obtained pulley is to be used in connection with vee belts, or the external surface of the flange can be provided with transversely extending teeth for engagement with the teeth of a toothed belt.
Commonly owned German Pat. No. 39 32 823 C1 discloses a method of making a gear wherein the rim extends to one side of the hub and is provided with internal as well _ as with external teeth. The marginal portion of a circular metallic blank is flexed to one side of the central portion KlJ 1~ (~ %,,~ '17 l~: c.1 1 of the blank with simultaneous thickening of the marginal portion and the forming of internal teeth. The thus treated blank is thereupon acted upon by a different tool which provides its previously treated marginal portion with external teeth. The overall axial length of the toothed rim of the finished product is not predictable because some material of the blank can flow axially during the making of internal teeth and again during the making of external teeth.
German patent application Serial No. 40 06 582 A1 of Grob (published September 13, 1990) discloses a method of making a gear by cold forming a metallic preform having a marginal portion of U-shaped cross-sectional outline and extending to one side of the hub. The marginal portion is provided with external teeth by resorting to a rolling operation. The internal surface of the externally toothed rim of the finished product has an undulate shape, and the material of the rim can flow in the axial direction of the hub in the course of the rolling operation. ThP marginal portion must be propped from within while a rotary rolling tool provides the external surface of the marginal portion with a set of axially parallel teeth. , An object of the invention is to provide a method which renders it possible to convert a blank or a preform into an externally toothed gear without any, or with negligible, changes in the texture of the material of the blank or preform.
Another object of. the invention is to provide a method of making an externally toothed gear from a blank or from a preform in such a way that the tYxickness of the toothed rim of the ultimate product can be increased without any; or without excessive, changes in the characteristic of the metallic material of the blank.
A further object of the invention is to provide a method which renders it possible to increase the thickness of the marginal portion of a blank ar preform simultaneously with the making of external teeth therein.
An additional object of the invention is to provide a novel and improved preform which can be utilized.for the practice of the above outlined method.
Still another object of the invention is to provide a method which renders it possible to rapidly convert a simple circular metallic blank into a gear with an externally toothed rim having a smooth cylindrical internal surface.
A further object of the invention is to provide a ~ novel and impraved method of making one-piece spur gears, ring gears or analogous gears in a simple and time-saving operation.
Another object of the invention is to provide a method which renders it possible to convert a blank or a reform into an externally toothed gear with a strong rim even if the thickness of that portion of the blank or preform which is converted into the rim is the same as the thickness of a relatively thin blank or preform of constant thickness.
An additional object of the invention is to provide ,a method which can be practiced to turn out inexpensive but "fir ~.'~ ~ ~ ~ '~~'~
1 strong and reliable externally toothed gears for use, for example, in the starters for the engines of motor vehicles.
Still another object of the invention is to provide a novel and improved apparatus for the practice of the above outlined method.
A further object of the invention is to provide the apparatus with novel and improved means for synchronizing the movements of various blank- or preform-supporting and treating tools.
Another abject of the invention is to provide the apparatus with novel and improved means for transmitting torque to various rotary parts.
An additional object of the invention is to provide an apparatus which can treat blanks and/or preforms of various sizes, thicknesses and/or materials.
sG ad ~ ~'~J ~ L~.
J ,r One feature of the present invention resides in the provision of a method of making a rotary member having a hub, a rim surrounding the hub and external teeth in the rim. The improved method comprises the steps of mounting a substantially circular metallic blank of ductile material on ~a first tool having a circumferential recess for a marginal portion of the blank, deforming the marginal portion of the blank into or at least close to the recess to convert the marginal portion into a flange surrounding a central portion which constitutes the hub of the thus deformed blank, and cold forming the flange including subjecting the flange to the deforming action of a rotary tooth forming second tool having an annulus of teeth in a circumferential recess adjacent the recess of the first tool to thus transform the flange of the deformed blank into a rim with external teeth while the flange is confined in the recesses of the first and second tools.
The deforming step can include subjecting the marginal portion of the blank to the cold forming action of a third tool having a circumferential recess for a portion or part of the marginal portion of the blank, moving at least one of the first and third tools toward the other of the first and third tools, and rotating at least one of the first and third tools.
The cold forming step can include moving at least one of the first and second tools toward the other of the first and second tools and rotating at least one of these tools.
The deforming step can comprise moving the marginal portion of the blank in the direction of the axis of the rotary member and to one side of the central portion of the blank, i.e., the deforming step can involve a shifting of the entire marginal portion to one side of the central portion of the blank, namely of that portion which constitutes the hub _ g ~~~ ~~ ~ ~'~ ~ ~~ ;~
1 of the deformed blank and of the ultimate product, a.g., a starter gear for use on a flywheel which is driven by the output element (e. g., a crankshaft) of the engine in a motor .vehicle. Otherwise stated, the deforming step can involve conversion of the marginal portion of the blank into a flange, and such flange can have a concavo-convex cross-sectional outline, preferably with a convex external surface and a concave internal surface.
The deformed blank can constitute a preform having the aforementioned central portion or hub and a converted marginal portion in the form of a flange having a substantially cylindrical first portion which is spaced apart from the hub and a substantially annular second portion having a substantially U-shaped cross-sectional outline and disposed between and of one piece with the hub and the first portion.
The cold forming step can further include providing the rim with a smooth substantially cylindrical internal surface. This cold forming step can involve a movement of the second tool relative to the first tool, and the cold forming step can include. increasing the thickness of the rim, i.e., the rim can be thicker than the marginal portion of the underformod blank.
Another feature of the invention resides in the provision of a method of making a rotary member (e. g, a spur gear, a ring gear or an analogous externally toothed gear) having a hub, a rim surrounding the hub and external teeth in the rim. This method comprises the s eps of mounting on a first tool having a circumferential recess a substantially circular metallic preform made of a ductile material and hawing a substantially disc-shaped central portion and a marginal flange extending to one side of the central portion and overly ng the circumferential recess of the first tool, deforming the flange into the recess to convert suoh flange . into the rim which surrounds the central portzon. the latter _ g _ 1 constituting the hub of the deformed preform, and simultaneously cold forming the flange including subjecting the flange to the deforming action of a rotary tooth forming second tool (e. g., a rolling tool) having an annulus of teeth in a circumferential recess which is adjacent the recess of the first tool to thus provide the flange with external teeth within the recesses of the first and second tools.
The mounting step can include mounting on the first tool a preform wherein at least a portion of the flange extends at least.substantially at right angles to the central portion, and such method can further comprise the step of forming the preform prior to the mounting step. Such forming step can include deforming a marginal portion of a substantially circular metallic blank of ductile material into the marginal flange of the preform.
The mounting step of the second method can include mounting on the first tool a preform wherein the flange includes a cylindrical portion in the recess of the first tool and a second portion having a substantially U-shaped cross-sectional outline, extending from the recess of the first tool, and connecting the first portion with.t,he central portion of the preform. The cold forming step of such method can comprise moving the second portion of the flange toward the recess of the first tool. The cold forming step can comprise confining the entire flange of the preform in the recesses of the first and second tools.
As already mentioned above, the second method can further comprise the step of converting a substantially circular blank of ductile metallic material into the preform.
A further feature of the present invention resides in the provision of an apparatus for converting a metallic blank into an externally toothed rotary member. The apparatus comprises a blank supporting first rotary tool, a carriage which is movable substantially radially of the first . tool, an externally toothed secand tool which is rotatably 1 mounted on the carriage, a chain transmission connecting the tools for rotation about discrete axes, and means for moving the carriage relative to the first tool. In accordance with a presently preferred embodiment of the improved apparatus, the transmission comprises a first shaft which mounts the first tool, a first sprocket wheel on the first shaft, a second shaft provided an the carriage and mounting the second tool, a second sprocket wheel on the second shaft, at least one tensioning device, and an endless chain which is trained over the sprocket wheels and over the at least one tensioning device. The at least one tensioning device can comprise a second carriage which is movable substantially radially of the first tool, at least one additional sprocket wheel rotatably mounted on the second carriage, and means for moving the second carriage relative to the first tool. The means for moving the second carriage can comprise. a fluid-operated motor (e. g., a hydraulic cylinder-and-piston unit).
The first tool is or can be mounted for rotation about a fixed axis, and the means for moving the first carriage relative to the first tool can also comprise a fluid-operated motor, e.g., a hydraulic cylinder-and-piston unit.
Still another feature of the present invention resides in the provision of a method of forming a toothed wheel including a series of cold-formed peripheral teeth having sides spaced apart a predetermined distance utilizing (1) a rotary holding unit having structure providing generally radially outwardly facing control surface means, and (2) a rotary tooth-forming tool unit having a rotational axis and a tooth-forming periphery extending annularly about the rotational axis, the rotary units including a total of two annular flanges extending outwardly thereof having two smooth tooth-side forming surface means facing toward one another spaced apart the aforementioned predetermined 35' distance. This method comprises the steps of cold-forming a 1 circular piece of sheet metal of predetermined thickness into a preform having an outer annular section of generally uniform cross--sectional configuration and an integral sheet metal central wall generally of the predetermined thickness extending generally radially inwardly from the outer annular section toward a preform axis, the outer annular section having (1) a width greater than the predetermined thickness but no greater than the predetermined distance, and (2) an outer periphery which will allow a meshing action with the tooth-forming periphery of the tooth-forming tool unit, rotating the rotary holding unit with the preform secured thereto about the preform axis and with the control surface means underlying at least a portion of the annular section and (2) the tooth-forming tool unit about the rotational axis thereof in a predetermined rotational relation wherein the axes are parallel and their rotational speeds are synchronized, and while the rotary holding unit with the preform secured thereto and the tooth-forming tool unit are in the predetermined rotational relation, effecting a relative movement between the two units and their axes in a direction toward one another to engage the tooth-forming periphery of the tooth-forming tool unit in cooperating metal-deforming relation with the exterior periphery of the annular section and deforming the same inwardly of the exterior periphery thereof until the sheet metal of the annular section is cold-formed into the series of teeth, the peripheries of which are cold-formed by rolling contact with the tooth- orming periphery of the tooth-forming tool unit and portions of the sides of which are smooth and cold-formed by contact with the smooth tooth-side forming surface means so that an amount of sheet metal which would otherwise uncontrollably flow axially outwardly of the smooth tooth-side forming surface means is concentrated within the teeth and/or the radially inward back-up therefor.
35. The novel features which are considered as - 12 _ 1 characteristic of the invention are set forth in particular in the appended claims. The improved apparatus itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain presently preferred specific embodiments with reference to the accompanying drawings.
1 BRIEF DESCRI~TIOPJ OF THE DR?~WINGS
FIG. 1 is a fragmentary axial sectional view of a first tool which mounts a circular metallic blank, and a fragmentary partly elevational arid partly central sectional view of a tool which serves to deform the marginal portion of the blank;
FIG. 2 is a similar view of the tools of FIG. 1 but with the marginal portion of the blank in deformed condition in which it constitutes a flange having a concavo-convex cross-sectional outline;
FIG. 3 shows the first tool of FIGS. 1 and 2, the deformed blank of FIG. 2 and an externally toothed tool which is to convert the deformed marginal portion or flange of the blank into an externally toothed rim;
FIG. 4 shows the structure of FIG. 3 with the externally toothed tool in the process of cold forming the deformed marginal portion or flange of the blank;
FIG. 5 is an axial sectional view of an externally toothed gear obtained in accordance with the method which can be carried out with the tools of FIGS. 1 to 4;
FIG. 6 is a fragmentary axzal sectional view of a tool corresponding to the first tool of FIG. 1 but mounting a preform having a deformed flange-like marginal portion which overlies a circumferential recess of the tool, and a partly elevational and partly axial sectional view of a tool corresponding to the upper tool shown in FIGS. 3-4 and serving to convert the flange-like marginal portion of the preform into an externally toothed rim of the type corresponding to that forming part of the gear of F3G. 5;
FIG: 7 is aview similar to that of FIG. 6 but showing a different preform and a tooth forming or rolling tool constituting a modification of the upper tool which is shown in FIGS. f, 4 and 6; and FIG: 8 is a fragmentary schematic partially plan , and'partly horizontal sectional view of an apparatus which L
1 can be utilized for the practice of the improved method and wherein the tooth-farming or rolling tool can be moved radially of the tool which mounts a blank or a preform.
FIG. 1 shows a portion of a circular blank 1 of ductile metallic material having a central portion clamped between two coaxial sections 2 and 3 of a rotary tool having a circumferentially complete peripheral recess 7 between two radially outwardly extending smooth control surfaces 2A, 3A.
These surfaces are respectively provided on a radially outwardly extending portion or collar 2B of the section 2, and on a radially outermost portion 3B of the section 3. The axis of rotation of the tool including the sections 2, 3 is denoted by a line X-X or is parallel to and is located below the level of the line X-X (as viewed in FIG. 1).
The marginal portion lb of the blank 1 extends radially outwardly well beyond the portions 2B and 3B so that it can be deformed by a tool 4 into a flange 6 of the type shown in FIG. 2. The flange 6 extend between the portions 2B, 3B and abuts the control surfaces 2A, 3A. The tool 4 is rotatable about an axis which is parallel to the axis X-X and includes two disc-shaped end portions 4a, 4b and an intermediate or central portion 4c having a concave peripheral surface 4d extending all the way betweep the end portions 4a, 4b. The surface 4d converts the radially outwardly extending marginal portion lb of the blank 1 into the concavo-convex flange 6 of the deformed blank or preform lA which is shown in FIG. 2. Such deformation of the marginal portion lb takes place in response to a reduction of the distance between the axes of the tool including the sections 2, 3 and the tool 4. For example, the tool 4 can be fed toward the axis X-X in the direction of arrow A; at such time, the radially outermost part o~ the marginal portion lb slides along the concave peripheral surface 4d of the intermediate portion 4c of the tool 4.
The deformed blank or preform lA is ready to be Converted into'an externally toothed gear or wheel of the type shown in EIG. 5, as at 150 This is achieved by moving _.
1 the tool including the sections 2, 3 into proper position relative to a tooth forming tool 5 which is shown in FIGS. 3 and 4, or by repJ.acing the tool 4 with the tool 5 while the radial and axial positions of the tool including the sections 2, 3 remain unchanged. The tool S has two disc-shaped end portions 5a, 5b and an intermediate portion or central portion 5c provided with an annulus of external teeth 9 within a recess 8 between the smooth confronting surfaces 5A, 5B of the end portion 5a, 5b, respectively. The distance between the surfaces 5A, 5B is the same as that between the surfaces 2A, 2B (as measured in the direction of the axis X-X). The tool including the sections 2, 3 and/or the tool 5 is movable radially of the axis X-X in order to flatten the flange 6, to increase its thickness, and to provide the thus obtained rim 11 (FIG. S) with external teeth 10 complementary to the teeth 9 on the tool 5. The arrow B in FIG. 3 denotes that the tool 5 is movable radially of and toward the axis X-X. The surfaces 2B, 3B and 5A, 5B cooperate to seal the peripheral recesses 7 and 8 when the end walls 5a, 5b respectively abut the portions 2B, 3B of the sections 2, 3 to thus ensure that the material of the preform lA cannot flow in an uncontrolled manner, i.e., that the axial length o~ the rim ll and its teeth matches the distance of the surfaces 2A,, 3A or SA,-5B from each other. The dimensions of the blank 1, the thickness of this blank, the distance of the surfaces 2A, 3A or SA, 5B from each other, the depths of the recesses 7, 8 and the dimensions of the teeth 9 are selected in such a way that the recesses 7, 8 and the spaces between the teeth 9 are filled with the material of the flange 6 when the tool 5 reaches the position of FIG. 4, i.e., when the preform lA is converted into the rotary externally toothed gear 15 of FIG.
4 or 5. The smooth side surfaces of the rim 11 and its teeth l0 are shown at l0a and lOb.
The end walls 4a, gb can constitute two separately 35. produced parts which are affixed to the central or 1 intermediate portion 4c of the tool 4 in a manner not forming part of the present invention. Analogously, the end walls 5a, 5b can constitute separately produced parts which are affixed to the central or intermediate portion 5c of the tool 5 in any suitable manner not forming part of. the invention.
The specific configuration of the hub 12 of the gear 15 can be obtained in response to clamping of the blank 1 between the sections 2, 3. Alternatively, a blank having a central portion corresponding to that of the hub 12 can be clamped between the sections 2, 3 so that these sections perform no deforming or shaping action but merely limit the axial length of the flange 6 (see FIG. 2). The thickness of the blank 1 can be constant, the same as the thickness a of the hub 12. The thickness of the rim 11 (as measured in the radial direction of the gear 15) may but need not be less than the thickness a; this depends on the selected dimensions of the recesses 7, 8 and of the spaces between the teeth 9 as well as on the thickness of the flange 6. It is often preferred to select the thickness of the rim ll in such a way that it at least matches the thickness _a of the hub 12. The internal surface lla of the rim ll is preferably smooth and is complementary to the smooth surface 7a in the radially innermost portion of the recess 7.
The gear 15 which is shown in FIG. 5 can constitute .
a spur gear in a starter which is used for the engine of a motor vehicle. For example, the gear 15 can be welded or otherwise secured to a flywheel which is mounted on and receives torque from the crankshaft of an internal combustion engine.
FIG. 6 shows a tool including the sections 2, 3 which are identical or analogous to the similarly referenced sections of the tool shown in the lower parts of FIGS. 1 to :4, and a somewhat modified tool 105 which is used in lieu of the tool 5 of FIGS. 3~-4. The preform lOlA differs from the 35. preform lA in that its flange 106 merely overlies but does '~a~~~~i'~j~'~
1 not extend into the recess 7 of the section 2. The preform lOlA can be obtained from a blank 1 by resorting to a tool corresponding to the tool 4 in that the tool 4 is not moved from the position of FIG. 1 and all the way to the position of FIG. 2. The tool 105 of FIG. 6 performs initially the function of corwerting the flange 106 into a flange corresponding to the flange 6 of FIG. 2 or 3, and thereupon the function of the tool 5, i.e., converting the deformed flange 106 into an externally toothed rim corresponding to the part 11 (with teeth 10) shown in FIG. 5. The end portions 105a, 105b of the tool 105 are provided with confronting frustoconical smooth internal surfaces 105A, 105B, and the central or intermediate portion 105c of the tool 105 has an annulus of teeth 109 in a recess 108 extending between the frustoconical surfaces 105A, 105B.
The tool 105 of FIG. 6 can be replaced with the tool 5 of FIGS. 3-4, or vice versa, without departing from the spirit of the invention.
FIG. 7 shows a tool including the sections 2 and 3, a different preform 201A (which can be obtained from a circular metallic blank 1), and a tool 20 which constitutes a modification of the tool 105'shown at FIG. 6. The preform 2OlA includes a flange 16 having a cylindrical first portion 18 which is received in the recess 7 and~is normal to the radially extending central portion 201a, i.e., to the hub of the finished product. The flange l6 of the preform 20.1A
further includes a second portion l7 which is of one piece with the central portion 201a and with the cylindrical portion 18 and has a substantially U-shaped cross-sectional outline. The portion 17 of the flange 16 extends radially outwardly from and beyond the recess 7. It will be noted that, in all illustrated embodiments of the preform or gear, the flange or the rim is located in its entirety at one side _ of the central portion or hub.
The tool 20 has a relatively narrow end wall 20b, a fT
~ l'/, ~ C
1 wider end wall 20a and a central portion 20c with an annulus of external teeth 9a in a recess 8a between the confronting smooth frustoconical surfaces 20A, 20B of the respective end portions 20a, 20b. The teeth 9a serve to cold form teeth into the portion 17 as well as to force the portion 17 toward the surface in the radially innermost portion of the recess 7 (when the tool 20 is moved in the direction of arrow B) to provide the thus obtained rim with a smooth cylindrical internal surface and with a set of external teeth in that portion of the rim which constitutes the converted (cold formed) portion 17 of the flange 16 of the preform 201A. The cylindrical portion 18 remains, or can remain, at least substantially unchanged and can be provided (e.g., at the time of making a blank or at the time of converting such blank into the preform 201A) with one or more openings which can constitute so-called pulse openings to permit the .
generation of signals in connection with the use of the gear in or with a computer-controlled internal combustion engine.
A gear which has openings in the cylindrical portion 18 can .
be used in the starter for a combustion engine.
The method which can be carried out in the apparatus employing the tools of FIGS. 1 to 4 exhibits the advantage that a blank 1 which has been clamped between the sections 2, 3 remains between these sections all the way until completion of the gear 15. On the other hand, the apparatus employing the tools of FIG. 6 or 7 exhibits the advantage that, though it is necessary to shape the preform lOlA or 201A in a separate machine or in a separate part of a machine which is designed to make gears in accordance with the method of the present invention, the gear can be provided with a rim having an externally toothed portion (namely the converted flange 106 or the converted portion 17 of the flange 16) as well as (in FIG. 7) a cylindrical portion 18 which can be provided with the aforediscussed openings.
The end portions 20a, 20b of the tool 20 cooperate 1 with the radially outermost portions 2B, 3B of the sections 2, 3 to prevent any uncontrolled axial flow of the material of the preform 201A during movement of the tool 20 in the direction of arrow B. Again, the dimensions of the recesses 7, 8a and of spaces between the teeth 9a are selected with a view to ensure that a preform 201A matching a standard preform or norm will be converted into a gear with a rim having external teeth formed by the teeth 9a and a cylindrical portion constituted by the portion 18 of the flange 16 shown in FIG. 7. When the conversion of the flange 16 of the preform 201A into a rim is completed, the recess 7 is preferably completely filled with the metallic maternal to thus ensure that the rim of the resulting gear will have an internal surface conforming to the surface in the innermost portion of the recess 7.
An important advantage of the improved method is that the making of a flange 6. 106 or 16 merely involves flexing of the marginal portion of a blank so that the texture of the material of the marginal portion of the blank or preform remains at least substantially unchanged. Any changes in the texture of the material of the blank or preform, or any pronounced changes of texture, take place only when the flange 6 or 106 or 16 is acted upon by the tool 5 or 105 or 20, i.e., at the time the blank or preform is provided with a finished rim having an annulus of external teeth and preferably a smooth cylindrical internal surface.
Experiments indicate that the improved method renders it possible to obtain a gear 15 or a similar gear which has a relatively thin hub 12 arid wherein the thickness of the rim lI (as measured in the radial direction of the gear) suffices to ensure the required strength, and the dimensions of the teeth are also such as to ensure the required stability and long useful life in actual use in a motor vehicle or elsewhere. The depth of spaces between the teeth 10 can be selected practically at will by appropriate zl 1 selection of the tool 5, 105 or 20 as well as of all other parameters which influence the dimensions of the teeth at the exterior of the finished rim 11. The latter can extend exactly at right angles to the plane of the hub 12.
' FIG. 8 shows a portion of an apparatus which can be utilized for the practice of the improved method. The apparatus includes a frame or base 33 supporting a rotary shaft 22 connected to a sprocket wheel 23 and also carrying ' the tool (for example, a tool including the sections 2, 3) which mounts the blank 1, the preform lOIA or the preform 201A. A carriage 21 which is reciprocable in the base 33 along tracks 34 radially of the shaft 22 rotatably supports a second shaft 24 which is parallel to the shaft 22. The shaft 24 is connected with a sprocket wheel 25 and also supports the tool 4, 5, 105 or 20. The transmission including the sprocket wheels 23, 25 further comprises an endless chain 26 which is trained over guide wheels 35 adjacent the sprocket wheel 23 as well as over a chain tensioning unit including a second caxriage 29 reciprocable in the base 33 radially of the shaft 22 and supporting two rotary sprocket wheels 27, 28. The carriage 21 is movable toward the shaft 2,2 by a first motor 36 (e.g., a fluid-operated motor such as a hydraulic cylinder and piston unit), and the carriage 29 is reciprocable by a second motor 30, e.g., a fluid-operated motor including a hydraulic cylinder and piston unit. It is also possible to provide the apparatus of FIG. 8 with other types of means for moving the carriages 21 and 29;
for example, the means for moving the carriage 21 can comprise aprime mover and a mechanical power train between such grime. mover and the carriage 2l. The motor 36 serves to feed the carriage 21 (and the tool on the shaft 25) toward the blank or preform mounted in the tool which is carried by the shaft 22: The carriage 29 is movable by the motor 30 in order to maintain the chain 26 under requisite tension so 35. that the chain ensures synchronous rotary movements of the , ~~8~~~~~
1 shafts 22 and 24, i.e., that blank or preform on the shaft 22 is rotated in synchronism with the tool on the shaft 24. The reference characters 31 and 32 denote in FIG. 8 bolts or other adjusting devices which can move the shafts 37, 38 for the sprocket wheels 27, 28 relative to the carriage 29. The chain 26 is driven by a motor (not shown) which rotates the shaft 22 or 24, i.e., a single motor suffices to drive the blank or preform on the shaft 22 in synchronism with the cold forming (flange-forming and/or tooth-forming) tool on the shaft 25. Such synchronism is achieved in spite of pronounced stresses which develop when the apparatus of FIG.
8 is in use to feed a tool on the shaft 25 toward and against a blank or against a preform on the shaft 22.
The synchronizing means of the apparatus which is shown in FIG. 8 has been found to be more reliable and simpler than heretofore known synchronizing means which rely on electronic circuita. The main reason for the superiority of the illustrated apparatus is believed to be that it can stand pronounced stresses which develop during cold forming the flange of a blank or preform to convert it into an externally toothed rim.
1 Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic and specific aspects of my contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and range, of equivalence of the appended claims.
Claims (5)
1. A method of producing an externally toothed precision gear member from a circular metal blank (1) with a hub face (12) and a surrounding toothed rim formed of a base rim (11) and teeth (10) projecting outwardly thereon, which toothed rim extends substantially perpendicularly to the hub face (12), the circular metal blank (1) being curled in its circumferential area and the curl (6, 17) then being pressed flat in a receiving space (7) of a tool (2) and provided with teeth (10), characterized in that the teeth are formed without cutting by pressing flat the curl (6, 17) with simultaneous tooth (10) formation in a receiving space (7) of a tool (2) and in a receiving space (8) of a tooth roller (5).
2. A method according to claim 1, characterized in that a first draw (16) is produced from the circular metal blank, said first draw (16) comprising a curl (17) and a flange (18) adjacent thereto and extending substantially perpendicularly to the hub face (12).
3. A method according to claim 1 or 2, characterized in that the curl (6, 17) is effected by means of a forming roller constructed as a toothed roller (5, 20).
4. A device for producing an externally toothed gear member, profiling being effected, after infeed of at least one toothed roller, by means of the latter with simultaneous flattening of a curl by compression, a tool (2, 2a) being arranged stationarily on a receiving spindle, the toothed roller (5, 20) being arranged on a carriage (21) which is movable towards the tool (2), the receiving spindle which carries the tool comprising a chain wheel (23) and the shaft (24), which drives the toothed roller (5, 20) through the intermediate connection of a gear synchronously as the tool, carrying a chain wheel (25), said chain wheels being connected via a chain (26), two deflecting and tensioning rollers (27, 28) being inserted in this chain (26) and accommodated on a carriage (29) and being adjustable with respect to the carriage (21) carrying the shaft (24) via a hydraulic piston/cylinder arrangement (30) and acting as a chain adjuster.
5. A device according to claim 4, characterized by adjusting screws (31, 32) enabling adjustment of the tensioning rollers (27, 28).
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP4204248.8 | 1992-02-13 | ||
| DE4204248 | 1992-02-13 | ||
| DE4205711A DE4205711C3 (en) | 1992-02-13 | 1992-02-25 | Device for producing an externally toothed gear part |
| DEP4205711.6 | 1992-02-25 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2086043A1 CA2086043A1 (en) | 1993-08-14 |
| CA2086043C true CA2086043C (en) | 2004-12-28 |
Family
ID=25911806
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2086043 Expired - Fee Related CA2086043C (en) | 1992-02-13 | 1992-12-22 | Method of and apparatus for cold forming toothed wheels from sheet metal |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0555631B2 (en) |
| CA (1) | CA2086043C (en) |
| DE (1) | DE4244720A1 (en) |
| ES (1) | ES2086139T3 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0966330A (en) * | 1995-08-31 | 1997-03-11 | Fuji Kiko Co Ltd | Method for thickening outer part of disk and method for forming disk member with drive part on outer periphery |
| WO1998006521A1 (en) * | 1996-08-14 | 1998-02-19 | Wf-Maschinenbau Und Blechformtechnik Gmbh & Co. Kommanditgesellschaft | Process and device for manufacturing a gear part with outer teeth |
| DE19850740A1 (en) * | 1998-09-09 | 2000-03-23 | Wf Maschinenbau Blechformtech | Transmission parts, especially gears, production from round metal blanks uses pressure rollers to press blanks to reduce thickness and increase external diameter |
| DE102005043498A1 (en) * | 2005-09-12 | 2007-03-15 | Rollwalztechnik Abele + Höltich GmbH | Mechanism advancing two tools against workpiece being processed, e.g. thread rolling machine, includes tool with rigid connection to drive |
| CN106001230A (en) * | 2016-05-31 | 2016-10-12 | 安徽赛爵机械制造有限公司 | Forming technology of belt wheel for compound shock absorber |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3436801A (en) * | 1966-06-23 | 1969-04-08 | Pig Design Corp | Method of making geared pulley to eliminate burrs in pulley groove and to facilitate entry of belt into pulley |
| DE2439690A1 (en) * | 1974-08-19 | 1976-03-04 | Emil Siegwart | METHOD FOR MANUFACTURING GEARS, GEAR SEGMENTS OR THE SAME FROM METAL SHEET AND DEVICE FOR CARRYING OUT THE PROCESS |
| CA1094356A (en) * | 1977-02-04 | 1981-01-27 | Drive Manufacturing Inc. | Method of pulley manufacture and product |
| ES2046368T3 (en) * | 1989-05-17 | 1994-02-01 | Leifeld Gmbh & Co. | PROCEDURE FOR THE MANUFACTURE OF A PULLEY. |
| DE3932823C1 (en) * | 1989-09-30 | 1990-12-06 | Wf-Maschinenbau Und Blechformtechnik Gmbh & Co Kg, 4415 Sendenhorst, De | Toothed transmission component mfr. - involves tool with external teeth forming inside teeth on workpiece |
| DE4205711C3 (en) * | 1992-02-13 | 2000-02-24 | Wf Maschinenbau Blechformtech | Device for producing an externally toothed gear part |
-
1992
- 1992-02-25 DE DE4244720A patent/DE4244720A1/en not_active Ceased
- 1992-12-22 CA CA 2086043 patent/CA2086043C/en not_active Expired - Fee Related
-
1993
- 1993-01-07 EP EP19930100136 patent/EP0555631B2/en not_active Expired - Lifetime
- 1993-01-07 ES ES93100136T patent/ES2086139T3/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| DE4244720A1 (en) | 1994-03-03 |
| EP0555631A1 (en) | 1993-08-18 |
| ES2086139T3 (en) | 1996-06-16 |
| CA2086043A1 (en) | 1993-08-14 |
| EP0555631B2 (en) | 1998-12-23 |
| EP0555631B1 (en) | 1996-04-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |
Effective date: 20121224 |