US3377711A

US3377711A - Precision machine

Info

Publication number: US3377711A
Application number: US306533A
Authority: US
Inventors: Wempe Bernhard
Original assignee: Firma Wenczler and Heidenhain
Current assignee: Firma Wenczler and Heidenhain
Priority date: 1962-09-05
Filing date: 1963-09-04
Publication date: 1968-04-16
Anticipated expiration: 1985-04-16
Also published as: DE1194669B; GB1056108A

Description

April 16, 1968 Filed Sept. 4, 1965 B. WEMPE PRECISION MACHINE 2 Sheets-Sheet 1 FIG. I.

I INVENTOR BERNHARD WEMPE BY ATTORNEY.

April 16, 1968 B. WEMPE 3,377,711

PRECISION MACHINE Filed Sept. 4. 1965 2 Sheets-Sheet 2 FIG. 2.

INVENTOR BERNHARD WEMPE ATTORNEY.

United States Patent 3,377,711 PRECISION MACHINE Bernhard Wempe, Egerer, Chieming, Upper Bavaria, Germany, assignor to Wenczler and Heidenhain, near Fraunstein, Germany, a corporation of Germany Filed Sept. 4, 1963, Ser. No. 306,533 Claims priority, application Germany, Sept. 5, 1962, W 32,901 13 Claims. (Cl. 33-174) The present invention relates to a precision machine, for example a measuring machine or a dividing machine, with a structure which is displaceable on a guide track.

This displaceable structure may be, for example, a table on which a workpiece is fastened, which by displacement of the table is brought into different positions for working or measuring. In order to lead exactly into the desired positions, it is a presumption that the guide track for the displaceable structure is disposed in a line as straight as possible and, furthermore, that the guide track is not subjected to any variations.

The guide tracks are, however, heavily loaded by the usually considerable weights of such displaceable structures, so that the guide tracks are subjected to wear after a certain time period.

In order to remove this drawback, it has been pro, posed, to provide a further track in addition to the guide track and to subject to this further track, a so-called supporting track, the weight of the displaceable structure. The guide faces of the guide track are thereby relieved and are subjected in this manner only to a negligible wear.

It has been found, however, that even this expedient alone did not bring about the desired result, since the weight of the displaceable structure on the supporting track exerts, during its displacement different deformation forces to the guide track, these deformation forces being transmitted from the supporting track. This known arrangement does not permit, therefore, extreme accuracies.

It has been proposed for this reason to eliminate completely the special supporting track and to transmit the weight of the displaceable structure to a liquid by means of displacement members.

It is, therefore, one object of the present invention to provide a precision machine, wherein the cited drawbacks are avoided.

It is another object of the present invention to provide a precision machine, without the use of liquid baths, wherein no perceptible deformation of the guide track can occur.

It is still another object of the present invention to provide a precision machine with a structure which is displaceable on a guide track, which structure is supported on a supporting track in order to relieve the guide track and in which machine a connecting member is provided between the guide track and the supporting track, which connecting member does not transmit any bending forces.

It is yet another object of the present invention to provide a precision machine, in which the connecting member between the guide track and the supporting track is a so-called reproducible set-up or a single, relatively rigid pin.

It is known to connect two or more bodies in such manner, that one body cannot transmit any bending force to the other. In the known arrangements, however, the weight of a displaceable structure has always been assumed by that body on which also the guide track of the same structure is disposed. Due to this fact, a deformation of the guide means had to occur in these known devices during the displacement of the displaceable structure.

It is another object of the present invention to provide a precision machine in which an additional security against a reaction of the deformation. of the supporting track on the guide track is brought about such that the forces supporting the guide track are exclusively directed through a connecting member disposed between the guide track and the supporting track while the forces supporting the supporting track are directed to the foundation by avoiding the connecting member.

It is still another object of the present invention to provide a precision machine in which the least possible deformation of the guide track is brought about such that the supporting forces acting between the supporting track and the displaceable structure assume the entire weight of the displaceable structure. In this case, however, it is suitable to pull the displaceable structure against the guide track by means of resiliently operating counterpressure elements which engage a face disposed directly opposite the face of the guide track so that the forces on the guide track comprise a closed force system in the shortest path, without exerting any bending moments.

It is yet another object of the present invention to provide a precision machine, wherein, in order to assume the entire weight of the displaceable structure, the supporting forces effective between the supporting track and the displace-able structure can be effected by a pneumatic or hydraulic system having a constantly controlled pressure. Yet, the entire weight of the displaceable structure can also be assumed in a simpler manner and with sufficient accuracy such, that the supporting forces effective between the supporting track and the displaceable struc ture exerted by means of strongly pretensioned spring elements having a fiat characteristic curve.

It is a further object of the present invention to provide a precision machine, wherein a stiffness of the total arrangement favorable for the purpose of the present invention, is obtained such, that the brackets supporting the guide track are disposed inside the brackets corresponding to the supporting track and the side portions of the outer of the two brackets are connected by brace rods to form a frame, the brace rods extending through openings of the inner bracket, without engaging the latter.

It is still another object "of the present invention to provide a precision machine wherein in case the measuring or working tools which are to cooperate with the work pieces secured to said displaceable structure are stationary, the measuring or working tools are secured to the bracket of the guide track.

It is yet another object of the present invention to provide a precision machine, wherein in case the measuring or working tools are also movable, an exact guidance, without disturbance by the mutual movements, is brought about by an arrangement according to which these tools are supported by a second supporting track similar to said displaceable structure, which second supporting track is connected with the bracket of the first supporting track and are guided by a second guide track which is connected with the bracket of the first guide track.

It is still a further object of the present invention to provide a precision machine, wherein the influence exerted by varying tractive forces by possibly required flexible supply conduits to a displaceable structure is suitably eliminated such, that the supply conduits ex tending between a stationary place and the displaceable structure are attached to a cable car, which is driven by a position control device equipped with an auxiliary motor into such a position that the supply conduits between the cable car and the displaceable structure always retain the same orientation in space, so that the supply conduits can exert forces upon the displaceable structure, which forces are always of the same or constant size and direction.

With these and other objects in view, which will become apparent in the following detailed description, the present invention will be clearly understood in connection with the accompaying drawings, in which.

FIGURE 1 is an elevation in cross-section of a measuring machine;

FIG. 2 is a section along the lines 22 of FIG. 1;

FIG. 3 is a section along the lines 33 of FIG. 1; and

FIG. 4 is a fragmentary elevation, partly in section, of another embodiment of the present invention.

Referring now to the drawings, and in particular to FIGS. 1 to 3, the workpiece 1, for example a scale, is secured to a displaceable support table 2, which is dis placeable perpendicularly to the piane of the drawing by any known means (not shown), for example by a threaded spindle. The weight of the table 2 is carried by a supporting track 7 by two

intermediate levers

3 and 4 having

rollers

5 and 6 mounted thereon and pivotally secured to the table 2. The

levers

3 and 4 are urged against the supporting track 7 by very highly tensioned springs 8 and 9. The springs 8 and 9 have a very fiat characteristic curve, so that the torque exerted by the springs is nearly independent upon the angular position of the

levers

3 and 4.

As can be readily determined from FIGS. 1 and 2, the

levers

3 and 4 consist of two parts, so that their length can be adjusted and retained in the chosen length by means of screws 19. In this manner, the supporting force acting upon the supporting track 7 can be varied, since, provided that the torque remains constant, the supporting force becomes smaller with the increase of the length of the

levers

3 and 4. Thus it is possible, to adapt exactly the supporting force to the prevailing weight of the table 2.

The supporting track 7 rests on tubular brace rods or cross-beams 11, which extend through openings 12 of a bracket structure 13 without engaging the latter, the bracket structure 13 to be explained below. Furthermore, the cross-beams 11 connect the side portions of a bracket 14. The bracket 14 rests on a foundation 16 by means of three-point support means 15.

While the weight load of the table 2 is completely assumed by the supporting track 7 and is transmitted to the foundation '16 by the intermediate elements 11, 14 and 15, the exact level position of the table 2 is determined by means of

guide tracks

17 and 18 of two

rails

19 and 20. The table 2 is pulled against these

guide tracks

17 and 18 by the action of springs 21 which urge rollers 23 against the faces 24 and 25 of the

rails

19 and 26, which faces 24 and 25 are disposed directly opposite the

guide tracks

17 and 18, and which rollers 23 are rotatabiy mounted on levers 22 pivotally secured to the table 2. By this arrangement, no bending moments are exerted upon the

guide tracks

17 and 18.

The

rails

19 and 20 are secured to the bracket 13 which rests on the bracket 14 in a statically determined threepoint support 26, a so-called reproduceable set-up. This three-point support 26 has the characteristic not to transmit bending moments of one structure to the other structure. Thus, if during a displacement of the table 2 the load carrying bracket 14 is deformed, the bracket 13 of the

guide tracks

17 and 18 remains nevertheless nondeformed.

The same effect can be brought about by other types of connections. Thus, by example, FIG. 4 demonstrates that a single pin 27 for the connection of the two brackets 13a and 14a likewise does not transmit any bending moments. The bracket 13 and the support 26 and/or support 27 constitute a connecting means which does not transmit bending moments from the bracket 14 to the bracket 13.

A bridge 28 is supported and guided in a manner similar to that of the table 2. The bridge 28 carries, for example, photoelectric measuring microscopes 29 for the measuring of the scale 1. Instead of the measuring microscopes 29, it is possible to provide a tracer device for the Cir tracing of lines. The rails 30 and 31 serve again the purpose of providing an exact guidance, while the weight of the bridge 28 is assumed by supporting

tracks

32 and 33 of the bracket 14. The necessary supporting forces are here effected by

hydraulic cylinders

34 and 35, the pressure of which

cylinders

34 and 35 is controlled by a pressure control device 36 Which provides a constantly con trolled pressure such that the weight of the bridge 28 is just carried. Thus, no bending moments are exerted here again upon the guide rails 30 and 31.

Supply conduits 37, originating from a stationary place and leading to the bridge 23, are fed over a cable car 39 running on a track 38 and driven by an auxiliary motor (not shown). The auxiliary motor is in turn controlled by a sensing contact (likewise not shown), which according to the inclination of the part of the supply conduits 37 leading from the cable car 39 to the bridge 28, switches on the forward or back-up drive of the auxiliary motor. During any displacements of the bridge 28 the conduits 3'7 retain nevertheless their direction, so that the tractive force exerted upon the bridge 28 by the conduits 37 remains constant concerning its size and direction.

It should be added that the table 2 is the carrier for the working piece 1 and the bridge 28 is the carrier for the tool 29. The

members

2 and 28 are movable relative to each other only for a relative repositioning, if required. The relative movement is brought about by conventional means, as a threaded spindle or any other suitable means.

The supporting track means is herein defined to include the bracket 14 as well as the track 7 and cross bar 11.

While I have disclosed two embodiments of the resent invention, it is to be understood that these embodiments are given by example only and not in a limiting sense, the scope of the present invention being determined by the objects and the claims.

I claim:

1. A precision machine such as a measuring or division machine including a displaceable structure, comprising a foundation,

a structure adapted to support a work piece,

at least one longitudinal guide track displaceably receiving said structure,

a supporting track means including a longitudinal supporting track supporting said structure and operatively supported on said foundation in order to relieve said guide track from its load, and

connecting means disposed between said guide track and said supporting track means and supporting said guide track independently of said supporting track for preventing the transmission of bending movements from said supporting track means to said guide track, and said connecting means being operatively supported by said foundation.

2. The machine, as set forth in claim 1, wherein said connecting means includes a reproducible set-up, comprising a three-point support means resting upon said supporting track means.

3. The machine, as set forth in claim 1, wherein said connecting means includes a single relatively rigid pin secured to said supporting track means.

4. The machine, as set forth in claim 1, wherein said connecting means is disposed so as to be acted upon exclusively by forces supporting said guide track, and

said supporting track means is disposed so that the forces supporting said supporting track are directed exclusively to said foundation avoiding said connecting means.

5. The machine, as set forth in claim 1, which includes yieldingly operating counter-pressure means for urging said structure towards said guide track,

said guide track defining a first guide face for engagement with said structure and a second guide face disposed on said guide track opposite to said first guide face,

said yieldingly operating counter-pressure means engaging directly said second guide face so that the forces acting upon said guide track comprises a closed force system acting along the shortest path without exerting any bending moments, and

means operatively disposed between said supporting track and said structure assuming the entire weight of the latter.

6. The machine, as set forth in claim 5, wherein said means assuming the total weight of said displaceable structure comprises a fluid system means having constantly controlled fluid pressure.

7. The machine, as set forth in claim 5, wherein said means assuming the total weight of said displaceable structure comprises strongly pretensioned spring elements having a flat characteristic curve.

8. The machine, as set forth in claim 1, wherein said supporting track means includes a first bracket at least one stationary tool, and

said stationary tool being adapted to cooperate with a workpiece secured to said structure.

12. The machine, as set forth in claim 10, which ineludes fluid system means comprises a plurality of flexible fluid supply conduits leading from an immovable location to one of said displaceable structures,

operatively connected to said supporting track, a cable car running parallel to said guide tracks and said connecting means includes a second bracket supto said supporting tracks,

porting said guide track, and said supply conduits being secured to said cable car, and said second bracket being disposed operatively upon means for controlling the direction of movement of said first bracket. said cable car, in order to maintain the orientation The machine, as Set forth in Claim Whefeifl of said supply conduits, whereby forces of constant said connecting means further includes a support means for supporting said second bracket upon said first bracket.

10. The machine, as set forth in claim 8, wherein said brackets have side portions,

said second bracket is disposed inside of said first References (Jited UNITED STATES PATENTS bracket 1,315,922 9/1919 Franklin 108-443 a brace rod connects said side portions of said first 9/1965 Rawstron 2,695,015 11/1954 Cooper 269-55 X bracket mm a frame 3 012 521 12/1961 Lich 104l18 X I said second bracket has openings 1n its side portions, 3.) 3,166,361 1/1965 Panzer et a1 n 308 said connecting brace rod extends through said openings of said second bracket Without engaging the latter,

SAMUEL S. MATTHEWS, Primary Examiner.

ROBERT C. RIORDON, Examiner. R. J. BUENZLE, Assistant Examiner.

and said supporting track is secured to said brace rods. 11. The machine, as set forth in claim 10, which ineludes UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,377,711 April 16, 1968 Bernhard Wempe It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

In the heading to the printed specification,

lines

4 and 5 "near Fraunstein, Germany, a corporation of Germany" should read Traunreut/Obb. near Traunstein, Germany Signed and sealed this 7th day of July 1970.

(SEAL) Attest:

Edward M. Fletcher, Jr. E.

Attesting Officer Commissioner of Patents

Claims

1. A PRECISION MACHINE SUCH AS A MEASURING OR DIVISION MACHINE INCLUDING A DISPLACEABLE STRUCTURE, COMPRISING A FOUNDATION, A STRUCTURE ADAPTED TO SUPPORT A WORK PIECE, AT LEAST ONE LONGITUDINAL GUIDE TRACK DISPLACEABLY RECEIVING SAID STRUCTURE, A SUPPORTING TRACK MEANS INCLUDING A LONGITUDINAL SUPPORTING TRACK SUPPORTING SAID STRUCTUREAND OPERATIVELY SUPPORTED ON SAID FOUNDATION IN ORDER TO RELIEVE SAID GUIDE TRACK FROM ITS LOAD, AND CONNECTING MEANS DISPOSED BETWEEN SAID GUIDE TRACK AND SAID SUPPORTING TRACK MEANS AND SUPPORTING SAID GUIDE TRACK INDEPENDENTLY OF SAID SUPPORTING TRACK FOR PREVENTING THE TRANSMISSION OF BENDING MOVEFOR PREVENTING THE TRANSMISSION OF BENDING MOVETRACK, AND SAID CONNECTING MEANS BEING OPERATIVELY SUPPORTED BY SAID FOUNDATION.