Title of Invention

METHOD FOR PREPARING A WORKPIECE, PARTICULARLY A BRAKE CALIPER, FOR FURTHER MACHINING AND A CLAMPING APPARATUS FOR CARRYING OUT SAID METHOD

Abstract Method for Preparing a Workpiece, Particularly a Brake Caliper, for Further Machining and a Clamping Apparatus for Carrying out said Method A funnel-shaped first seat surface (20) as well as two plane second seat surfaces (22) are formed at a workpiece (10). The workpiece is placed with these seat surfaces (20, 22) on to a first support surface (40) and two second sup¬port surfaces (22), respectively, of a clamping apparatus (30) . The first seat surface (20) and the first support surface (40) form a revolute joint, the rotation axis (D) of which lying within a reference plane (C). Between the second seat surface (22) of the workpiece (10) and the second support surfaces (42) of the clamping apparatus (30) only support forces (H) can be transferred parallel to the axis of rotation (D). The clamping apparatus (30) includes a clamping jaw (50) with clamping surfaces (58) converging relative to the reference plane (C), and which can be applied to correspondingly arranged converging application surfaces (28) of the workpiece. Upon tightening of the clamping jaw (50), the workpiece (10) rotates about the axis of rotation (D) to a central position in which the moments of the clamping forces (F) exerted by the converg¬ing clamping surfaces (58) are in an equilibrium.
Full Text The invention relates to a method according to the preamble of Claim l and to a clamping apparatus according to the preamble o£ Claim 6.
Workpieces with at least one cylindrical section can be centered and clamped for machining and measuring operations in a simple manner by placing their cylindrical section on to a pair of converging support surfaces of a clamping apparatus and securely clamping it by means of a clamping jaw with a corresponding pair of converging clamping sur¬faces (brochure of Messrs. MWT, Maschlnen - und Werkzeug -technik GmbH, Nauenstadt/Heilbronn, fixture kit to the modular clamping system, as well as brochure of Messrs. Horst Witte Geratebau, Bleckede, Witte-Alufix). This known approach snd the clamping apparatuses used for its imple¬mentation to which the preambles of Claims 1 and 5 refer ere, however, not applicable to workpieces where a cylin¬drical surface suitable for centering is either not avail¬able, too short or is inaccessible for supporting and clamping prisms. This applies particularly to floating calipers and other housing-type components of disk brakes

which are usually manufactured as cast or die forged blanks which subsequently have to be machined. These floating calipers for disk brakes together with a brake cylinder are, for example, cast in moulds as integral components. However, reinforcing and cooling ribs are arranged at the brake cylinder in such a manner that it cannot be placed into a simple clamping apparatus equipped with clamping prisms. However, even when sufficiently large surface sec¬tions of such a brake cylinder are accessible, this does not necessarily imply that it is suited for such a defined clamging operation. A great number of workpieces, occa¬sionally more than one million, are capable of being cast or forged with an adequate quality in moulds and dies; generally it must be accepted, however, that due to wear of certain wall sections of the moulds and dies, surface areas of varying size of the castings or forgings gradually change their shape and dimensions. Provided that certain surface areas are not or only slightly affected by such changes, such areas are often unsuitable for a sufficiently precise workpiece clamping by means of known methods and known clamping apparatuses.
It is also known (DE 42 02 989 Al) to clamp workpieces in such a manner that two conical centering openings are form¬ed at a distance to each other, for example, in a vertical surface of each workpiece and have clamping elements en¬gaging one each of the centering openings with a spherical clamping surface each and then pressing the workpiece

against plane support surfaces. With such am arrangement the workpiece can only be clamped specifically and in a given position if the distance between the conical center¬ing openings formed in the workpiece is exactly equal to the distance between the spherical clamping surfaces of the clamping elements. Often, this condition can not be met from the outset or it will be lost due to thermal expan¬sion.
Inaccurate distances between paired centering and clanging elements can be compensated in a manner which is also known {DE 37 29 601 C1) where clamping elements which are arrang¬ed at a certain distance from each other and have one conical pin each are applied not immediately to the work-piece to be clamped, but rather to a workpiece carrier which includes two centering bars which are arranged at a distance to each other which corresponds to the mutual distance of the clamping elements. Each of the two cen¬tering bars is secured to the workpiece carrier via both ends and comprises a centering sleeve in its central area. One of the two centering bars is rigid so that the center¬ing sleeve which is arranged on it together with the associated clamping element provide a fixed point for the arrangement of the workpiece carrier. The other centering bar, however, is flexible transverse to its longitudinal direction so that the centering sleeve in its central area can change its distance from the centering sleeve of the rigid centering bar to adapt itself to the mutual distance

of the clamping elements. In the longitudinal direction, however, the flexible centering bar is rigid so that the workpiece carrier is prevented from rotating about the centering sleeve of the rigid centering bar. This results in a unique assignment between the clamping elements and the workpiece carrier. A workpiece which is clamped on the workpiece carrier can therefore together with the workpiece carrier pass several machining stations, each of which include a pair of clamping elements for position-controlled clamping of the workpiece carrier. However, the problem of clamping workpiece blanks in a predetermined position on the workpiece carrier remains unsolved.
The invention is therefore based on the object of facili¬tating a defined and essentially constant accurate clamping of complex workpiece blanks, in particular of cast or forg¬ed brake calipers.
The object is solved by the characteristics of Claim 1 with respect to the pertinent method and by the characteristics of Claim 6 with respect to the pertinent apparatus. Advan¬tageous embodiments will result from the dependent claims.
Embodiments of the invention will be explained in the following with reference to schematic drawings which show further details. In the drawings:

Fig. 1 shows the plan view of a clamping apparatus
according to the invention with a clamped work-piece;
Fig. 2 shows the section through the vertical longi¬tudinal centre plane II-II in Fig. 1;
Fig. 3 shows the section through the vertical trans¬verse plane III-III in Fig. 1;
Fig. 4 shows an enlarged portion of Fig. 3;
Fig. 5 shows the still further enlarged portion V in Fig. 4;
Fig. 6 shows a section corresponding to Fig. 3 of a modified clamping apparatus according to the invention; and
Fig. 7 shows the plan view of a clamping apparatus according to the invention which is modified compared to Fig. l.
Figs. 1 through 5 show as an exanple for a workpiece 10 a floating caliper of a disk brake, which as usual includes among other elements a cylinder 12 with a pair of lateral bosses 14 as well as a fork part 16 with a pair of fingers 18. This workpiece 10 is cast for example from aluminium and has to be machined at several places; in particular, the cylinder 12 is bored along its axis A, and the two bosses 14 are face-milled on both sides (in Fig. 1 on the left and on the right) and provided with one hole each, the axis A' of which extending parallel to the axis A. For the purpose of the following description the plane which is

parallel to the common plane of the two axes A' and which includes the axis A will be designated as base plane B, and the orthogonal centre plane which includes, the axis A will be designated as reference plane C.
Compared to conventional floating calipers for disk brakes, the illustrated workpiece 10 is special in that a conical recessed first seat surface 20 is cast into the side of the cylinder 12 the geometric axis of which, referred to as rotation axis D in the following, is arranged perpendicular to the base plane B and which is contained in the reference plane C. At a distance E from the hollow cone-shaped first seat surface 20 and at a distance E' from one another, two plane second seat surfaces 22 are formed in the fork part 16. The seat surfaces 20 and 22 are arranged in inter¬mediate spaces between ribs 24 which extend parallel to the axis A of the cylinder 12 and which have the function of reinforcing the caliper and primarily of keeping the cylinder 12 cool under operating conditions.
Opposite to the seat surfaces 20 and 22 (Figs. 2 through 5, top) first and second application surfaces 26 and 28, re¬spectively, are formed at the workpiece 10. The first application surfaces 26 are arranged near the axis of rota¬tion D, for example formed by upper boundary surfaces of the lateral bosses 14 (Fig. 2), and are located at a small distance from the base plane B in a common plane E which extends parallel to it. The second application surfaces 28,

however, are formed at the fork part 16 at a distance from the axis of rotation D which approximately corresponds to the distance E, that is, in the embodiment according to Figs. 1 through 5 at the outside of one each of the two fingers 18. The two second application surfaces 28 are each to be loaded with a clamping force F the direction of which intersects the reference plane C at an angle of approx. 45° and thus also extends at an angle of approx. 45° relative to the base plane B.
For clamping a workpiece 10 for machining operations of the described type and/or for measuring the workpiece, a clamp¬ing apparatus 30 is provided. Said apparatus includes a plate-shaped base 32 with sliding blocks 34 guided in grooves in its bottom side, via which it is adjustable on a machine table 36 which belongs, for example, to a boring and milling machine so that it can be subsequently secured to the machine table by means of clamping bodies 38. The base 32 defines the arrangement of three support surfaces, i.e. of a spherical or dome-shaped first support surface 40 and of two plane or also dome-shaped second support sur¬faces 42. Each of the support surfaces 40 and 42 is formed at one of three inserts 44 which are seated in one hole each in the base 32 and which are fastened by means of a screw 46 each in a replaceable manner. The base 32 can be provided with more than three such holes so that it is possible to arrange the three inserts 44 at different

distances from each other for workpieces 10 of different sizes.
In each case, the three inserts 44 constitute the three corners of a preferably isosceles triangle, the spherical or dome-shaped first support surface 40 having the re¬latively large distance E from the connecting line between the two second support surfaces 42, and the two second support surfaces 42 being arranged at a distance E' from one another which can be somewhat smaller than the distance E. The three support surfaces 40 and 42 can be included in a common plane or can be tangent to it, respectively, which, in the illustrated normal position of the clamping apparatus, is horizontal and which extends parallel to the base plane B; in the shown example, however, the spherical first support surface 40 is arranged at a somewhat higher level than the two second support surfaces 42 which are arranged in a common horizontal plane. The height of the first and second support surfaces 40 and 42 can be adapted to the workpieces 10 to be clanged by means of plane and parallel ground washers 48.
For the application of the clamping forces F a clanging jaw 50 is provided which is pivotably supported at the base 32 by means of a bearing journal 52 which extends orthogonal to the reference plane C, and which has a downwardly pro¬jecting extension 54 which is connected with a pivoting actuator 56, e.g. a hydraulic piston/cylinder unit. At the

clamping jaw 50 two converging clamping surfaces 58 are formed which face each other in the fork-shaped design of the clamping jaw 50 shown in Figs. 1 through 5. In the illustrated operating position with a workpiece 10 being clamped, the two clamping surfaces 58 lie in a plane E' each which is orthogonal to the direction of the associated clamping force F, and said planes F' converge in such a manner that they intersect in the reference plane C. The second application surfaces 28 are adapted to the inclined arrangement of the associated respective clamping surface 58 and may be slightly convex, as can best be seen from Fig. 5; in this case one each of the two converging planes F' is tangent.
In order to securely clamp the workpiece 10 also in the area of the hollow cone-shaped first seat surface 20, two additional clamping arms 60 are arranged opposite the clamping jaw 50 (Figs. 1 through 3) which are connected via one tie bolt 62 each with one actuator 64 each, e.g. of a hydraulic piston/cylinder unit. The two clanging arms 60 are provided for subjecting one each of the first appli¬cation surfaces 26 of the workpiece 10 to an additional clamping force G in a vertically downward direction. Each of the two clamping arms 60 can be pivoted about its tie bolt 62 from the illustrated operating position laterally outwards in such a manner that the workpiece 10 can be removed readily after machining and be replaced by a blank.

Fig. 6 shows a modified clamping apparatus which differs from the one shown in Figs. 1 through 5 in that the clamp¬ing jaw 50 is not fork-shaped but undivided and engages the space between the two fingers 18 at the fork part 16 of the workpiece 10. The converging second application surfaces 28 of the workpiece 10 consequently face each other while the converging clamping surfaces 58 of the clamping jaw 50 face away from one another as shown in Fig. 6.
According to Pig. 7 it is sufficient to provide the clang¬ing apparatus 30 with only one clanping arm 60 in addition to the clamping jaw 50, provided that it is arranged in such a manner that the effective line of the additional clamping force G applied by it to the workpiece 10 lies at least approximately within the reference plane C.
For all illustrated embodiments of the clamping apparatus 30 it holds true that in the outwardly pivoted position of the clanging jaw 50 and the clamping arms 60 a workpiece 10 is placed with its hollow cone-shaped first seat surface 20 on to the spherical first support surface 40 whereby it is centered with respect to the axis of rotation D. At the same time the second seat surfaces 22 of the workpiece 10 are placed on to the second support surfaces 42 without necessarily having to maintain a predetermined position. The clamping jaw 50 and the clamping arms 60 are then pivoted inwardly, and the clamping jaw 50 is loaded by the associated pivoting actuator 56 in such a manner that it

exerts a force F each on to the two application surfaces 28 via its clamping surfaces 58, the forces F converging in the embodiments according to Figs. 1 through 5 but diverg¬ing according to Fig. 6. In both cases said forces F have a component each which is orthogonal to the reference plane C, i.e. horizontal in the illustrated arrangement, and which, with respect to the axis of rotation D, has the lever arm E.
If, by chance, the workpiece 10 is not placed into the clamping apparatus 30 in such a manner that its central plane is exactly in alignment with the reference plane C, the horizontal components of the forces F are initially not balanced. This results in a momentum by which the workpiece 10 is slightly rotated about the axis of rotation D until an equilibrium of moments is obtained in that the workpiece is centered with respect to the reference plane C. There¬upon the two clamping arms 60 (Pigs. 1 through 3) or the single clamping arm 60 according to Fig. 7, respectively, are pulled downwards by their actuator 64 so that the work-piece 10 is securely clamped also in the area of the axis of rotation D.


We Claims
1. A method for preparing a workpiece blank, in particu¬lar a cast brake caliper, for further machining, where
- a base plane (B) and an orthogonal reference plane (C) are defined at a workpiece (10) and seat surfaces (20, 22) as well as application surfaces (26, 28) are formed, and
- the workpiece (10) is clamped in a clamping apparatus (30) by placing its seat surfaces (20, 22) on to one support surface (40, 42) each of the clamping apparatus and by pressing a clamping jaw (50) with clamping surfaces (58) converging, with respect to the reference plane (C) against a pair of correspondingly converging application surfaces (28) of the workpiece (10),
characterized in that
- a first seat surface (20) of the workpiece (10) is formed
by a first seat element which is coupled with a support
element which forms a first support surface (40) of the
clamping apparatus (30) to form a revolute joint with an
axis of rotation (D) which is orthogonal to the base plane
(B) and which lies within the reference plane (C),
- the remaining seat surfaces (22) of the workpiece (10)
and the associated support surfaces (42) of the clamping
apparatus (30) transfer only support forces (H) parallel to
the axis of rotation (D), and
- the converging clamping surfaces (58) of the clamping jaw
(50) as well as the associated application surfaces (28) of

the workpiece (10) are arranged at a distance (E) from the axis of rotation (D) in such a manner that, upon tightening of the clamping jaw (50), the workpiece rotates about the axis of rotation (D) to a central position in which the moments of the clamping forces (F) exerted by the converg¬ing clamping surfaces (58) are in an equilibrium.
2. A method according to Claim l,
characterized in that in addition to the clamping forces (F) exerted by the converging clamping surfaces (58) an additional clamping force (G) parallel to the axis of rotation (D) is applied to the workpiece (10) at at least one point adjacent to the axis of rotation (D) for securing said workpiece in the centre position.
3. A method according to Claim 2,
characterized in that the additional clamping force (G) is applied with a delay with respect to the clamping forces (F) exerted by the converging clamping surfaces (58).
4. A method according to one of Claims 1 to 3,
characterized in that the workpiece (10) is manufactured
with a cone-shaped recess which defines the axis of rota¬
tion (D) as the first seat surface (20).

5. A method according to Claim 4,
characterized in that the remaining seat surfaces (22) of the workpiece (10) are formed as plane surfaces orthogonal to the axis of rotation (D).
6. A clamping apparatus for carrying out the method
according to Claim 1, comprising
- a base (32) at which the support surfaces (40, 42) for accommodating a workpiece (10) are arranged, and
- a clamping jaw (50) with converging clamping surfaces (58) for pressing down the workpiece (10) resting on the support surfaces (40, 42),
characterized in that
- a first support surface (40) is formed by a rotation-symmetrical support element which defines an axis of rotation (D) and which can be coupled together with a seat element at the workpiece (10) to form a revolute joint about which the workpiece (10) is rotatable on the base (32),
- the remaining support surfaces (42) are adapted to trans¬fer only support forces (H) parallel to the axis of rota¬tion (D), and
- the converging clamping surfaces (58) of the clamping jaw (50) are arranged at a distance (E) from the axis of rota-
' tion (D).

7. A clamping apparatus according to Claim 6,
characterized in that the first support surface (40) is
spherical.
8. A clamping apparatus according to Claim 6 or 7,
characterized in that the support surfaces (40, 42) are
formed at one each of a total of three inserts (44) which
are fastened replaceably at the base (32).
9. A clamping apparatus according to Claim 8,
characterized in that at least one of the inserts (44) is
adjustable relative to the base (32) in a direction paral¬
lel to the axis of rotation (D).
10. A clamping apparatus according to one of Claims 6 to
9,
characterized in that in addition to the clamping jaw (50) with the converging clamping surfaces (58) at least one clamping arm (60) is provided, by means of which an addi¬tional clamping force (G) can be applied to the workpiece (10) parallel to the axis of rotation (D) at at least one point adjacent to same.


Documents:

1567-mas-96 abstract-duplicate.pdf

1567-mas-96 abstract.pdf

1567-mas-96 claims-duplicate.pdf

1567-mas-96 claims.pdf

1567-mas-96 correspondence-others.pdf

1567-mas-96 correspondence-po.pdf

1567-mas-96 description (complete)-duplicate.pdf

1567-mas-96 description (complete).pdf

1567-mas-96 drawings-duplicate.pdf

1567-mas-96 drawings.pdf

1567-mas-96 form-1.pdf

1567-mas-96 form-13.pdf

1567-mas-96 form-26.pdf

1567-mas-96 form-4.pdf

1567-mas-96 form-62.pdf

1567-mas-96 others.pdf

1567-mas-96 petition.pdf


Patent Number 198259
Indian Patent Application Number 1567/MAS/1996
PG Journal Number 20/2006
Publication Date 19-May-2006
Grant Date 13-Jan-2006
Date of Filing 09-Sep-1996
Name of Patentee LUCAS INDUSTRIES PUBLIC LIMITED COMPANY
Applicant Address STRAGFORA ROAD SOLIHULL B90 4LA ENGLAND
Inventors:
# Inventor's Name Inventor's Address
1 GERD PREKER AM GRAUEN KREUZ 8 56075 KOBLENZ
2 CHRISTIAN DILLA STEINACKERSTRABE 19 56191 WEITERSBURG
3 THOMAS WILLMES BRUCKENSTRABE 2 56179 NIEDERWERTH
4 ACHIM THIEROFF ISENBURGERSTRABE 1 56237 CAAN
PCT International Classification Number B23Q16/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA