US3040620A

US3040620A - Grid ruling machine

Info

Publication number: US3040620A
Application number: US739123A
Authority: US
Inventors: John T Ferris
Original assignee: Dresser Industries Inc
Current assignee: Dresser Industries Inc
Priority date: 1958-06-02
Filing date: 1958-06-02
Publication date: 1962-06-26
Anticipated expiration: 1979-06-26

Description

IIIMI,

L/O/7/7 7'. Fer/vs ATTOR/VEVJ United States Patent tries, Incorporated, Dallas, Tex., Ware a corporation of Dela- Filed June 2, was, Set. No. 739,123 15 claims. or. 88-44) This invention relates to grid ruling machine and, more particularly, to apparatus for effecting an accurate transverse ruling of a grid blank of extensive length.

In the past grids have been ruled by machines using conventional mechanical drives and stop and start controls in conjunction with a reciprocating mechanical scribing carriage. However, it is apparent that the numerous increments of short movement of the carriage interrupted by a complete stop during the operating stroke of the scribing carriage permits a repeated back lash or play between the machine elements within the limits of manufacturing tolerances. Since perfect accuracy in the design and construction of conventional machine elements is unattainable, even small errors in scribing are multiplied with repetition so that grids scribed by such machines are necessarily limited in length.

More recently interferometers have been employed to control the longitudinal increment of. movement of the scribing carriages but since interference fringes lose their brilliance and contrast to an unusable level beyond certain minimum limits of movement, grids of more than a few centimeters in length cannot be produced under conventional interferometric control.

It is, therefore, an object of my invention to provide a machine capable of producing ruled grids of alength unlimited by the necessity of minimizing multiplication of machine errors, or by the limits of practical interferometric operation.

It is a further object of my invention to provide a means for ruling grids during continuous motion of the ruling device along the length of the grid blank.

It is a further object of my invention to provide an inter ferometer having an operating range limited only by the length of the machine ways along which it is guided.

It is ,a further object of my invention to provide a novel method of ruling a grid blank which does not require start and stop increments of movement of the sup porting carriage.

' 2 light is fired at intervals during continuous movement of the marking carriage in response to signals generated by the interferometer.

Tern, assignorto Dresser Indus-v It is a further object of my invention to provide a grid ruling machine that is automatic and, at the same time,

reliable and accurate in operation. 7

In carrying out my invention, I provide a pair of carriages adapted to move along well machined ways. Drive means and stop means which may be integrated are provided for independentmovement of each carrier. Elements of an interferometer are arranged on the carriages so that relatively movable elements thereof are separately movable. Control means are provided to move the carriages along the ways alternately, step by step, in increments within the practical rangeof the interferometer, with one carriage supporting a unique marking device that is operable during movement of that carriage. Thus, there is a setting stroke of one carriage, an active stroke of the marking carriage, a setting stroke and so on until the full length of the ways has been traversed if desired. For marking the grid blank, I provide a coating of light sensitive emulsion on the blank and employ as the marking device a source of light capable of exposing a fine Other objects and advantages of my invention will become apparent from the description following when read in connection with the drawing wherein:

FIG. 1 is an isometric view of my apparatus; and

FIG. ;2 is a schematic plan view of the ruling machine.

Referring now to the drawing, my grid ruling machine comprises two carriages 1 and :2 separately driven along well machined ways by any conventional drive means such as pinions 3 and 4, engaging racks '5 and 6 along the machined ways. Each gear 3, 4 is driven by an

electric motor

7 and 8, preferably of the servo type so that the velocity, starting and stopping of the

carriages

1 and 2 along the ways, can be maintained under close control. As is well known, thedesired velocity control is achieved with a servo motor by modifying the current delivered thereto in response to variations in speed actually delivered thereby. But in any event, for the carriages is not material and the motors and gears described are shown by way of illustration only. Other speed control mechanisms such as speed reducers can be utilized to supplement the means shown. Moreover, other mechanisms such as constant tension springs or even gravity may be substituted as drive means. The important consideration in the apparatus to be hereinafter described collimating lens 13 which directs a column of light into a dividing prism 14, comprising two 30'-60--90 degree prisms 15 and locemented together. Significantly, at least one of the

prisms

15, 16 is aluminized at their union face 17 so that equal amounts oflight will be reflected and transmitted by the plane of union, the reflected light being designated by the arrows R and the transmitted light by the arrows T. From the dividing prism 14 the reflected and transmitted light R and T pass into tetrahedral or

corner prisms

18 and 19, respectively, which characteristically reflect light back along a path parallel to its path of entry, even though the prism is displaced in any direction transverse to such path of entry.

After being reflected from their respective

tetrahedral prisms

18, 19, the reflected and transmitted light R and T return to the dividing prism. 14 where each is again divided by the plane of union 17. Here we are concerned with the transmitted components of the originally reflected light R and the reflected components of the originally transmitted light T bothv issuing from prism 14 along the lines RT toward a lens 20 which controls the diameter of the column of light impinging upon a shield or mask 21 having an annular aperture 22 thereon carriage 2 to move therewith. As is well known. in

interferometers, relative movement between the reflecting

prisms

18 and 19 will vary progressively the phase relathe specific drive means employed movements of the carlength out of phase.

tionship of the light reflected therefrom and reunited in its exit from dividing prism 14. That is, a prism movement of one-half wave length will increase the distance traveled by the light over both the paths of incidence and reflection of one full wave length. Consequently,

after a relative movement of one-half wave length, the originally reflected and transmitted light waves R and T will exit toward shield 21 in phase again. By the same token, a relative movement of one-fourth wave length Will cause the reflected and transmitted light R and T to exit from prism 14 in interference, i.e. one-half wave Consequently, continuous move ment through the maximum light of phase coincidence and the darkness of interference produces a successively light and dark fringe pattern which from the collimated light emitted from lens 13 is in the form of concentric rings moving outwardly from or inwardly toward the center, depending upon the direction of relative movement between reflecting

prisms

18 and 19.

As each ring of light in the fringe pattern produced assumes a diameter wherein it coincides with the annular aperture 22 of shield 21, a pulse of light impinges upon the photo-electric cell 23 to be converted into a pulse of electricity fed by conductors 23a to an electronic counter and control circuit 24 for counting such pulses. Thus, relative movement between the reflecting

prisms

18 and 19, and hence

carriages

1 and 2, can be indicated by electrical pulses in increments of one-fourth wave length of the monochromatic light particular significance is the capability of my apparatus to extend this indication or measurement of minute increments over a total travel of the

carriages

1 and 2 7 limited only by the length of the ways and 6.

The electronic counter and control circuit 24 functions to control the speed of the

carriages

1 and 2 and the operation of electrical switches in accordance with the receipt of given numbers of electrical pulses. Through such switches, a source of alternating current 25 may be varied and selectively connected through

conductors

26 and 27 to

motors

7 and 8, respectively, driving

carriages

1 and 2. For example, when the

carriages

1 and 2 are in the position shown, a signal produced by the counter and control circuit 24' will close an appropriate switch to direct current from the source 25 to the motor 8 for driving the leading carriage 2. During this movement intermittent fringes impinge upon photo-electric cell 23 to produce electrical pulses to be counted by control circuit 24. When a predetermined number of pulses have been counted, the circuit of motor 8 is opened to stop further movement of the carriage 2. The number of pulses measuring this movement is determined by the effective range of the interferometer relative movement of this and, in fact, all interferometers must be within a range wherein the fringe pattern produced thereby is sufliciently sharp and brilliant to effect reliable functioning of the photo-electric cell 23. Therefore, assuming that the reflecting

prisms

18 and 19 as illustrated in FIG. 2 are within the usable range, the carriage 2 may be moved until prism 18 has moved from the left of prism 19 (in FIG. 2) to the same distance to the right thereof.

After the circuit of motor 8 has been opened, a delayed signal closes the circuit of motor 7 to move carriage 1 to the right in FIG. 2 and, hence, prism 19 first toward and then beyond prism 18 to the original position, shown in FIG. 2. Again, electrical pulses are fed to the counter and control circuit 24 until in response to appropriate signal the circuit of motor 7 is opened. Subsequently, motor 8 is energized and the cycle repeated. Therefore, it is apparent that the

carriages

1 and 2 can be moved along over indefinite lengths in step by step stages measured in terms of one-fourth wave length of'monochromatic light source 11. Such apparatus is particularly adapted to produce elongate grids by a novel means.

10. That is, the

emitted from source 11. Of

Adjacent to the path traveled by the

carriages

1 and 2 is secured an elongate grid blank 30'' of metal, glass, plastic or the like. The grid blank 30 may be held stationary by any conventional fasteners, clamps or other holding means and disposed as shown with its longitudinal axis parallel to the ways5 and 6 and its transverse axis perpendicular to the plane of the

carriages

1 and 2. On the adjacent surface of the grid blank 30 is a coating 31 of a light sensitive emulsion requiring the maintenance of controlled conditions of area illumination to avoid inadvertent exposure.

Mounted on carriage 1 to travel therewith is an elongate electronic flash tube 34 having its longitudinal axis disposed perpendicular to the plane of the carriage 1 and, hence, parallel to the surface of the grid blank 30. The flash tube 34 has the surface thereof aluminized to prevent the transmission of light except through a narrow straight line slit 35 etched or scribed along the length thereof by accurate machine tool methods. Therefore, each time the tube is flashed, a narrow, vertical beam of light is transmitted to and through a lens 35a which focuses the beam to a narrow line of light impinging upon the light sensitive coating 31 to expose a fine line L transversely across the surface of grid blank 30.

The flash tube 34 is energized upon closing of an appropriate switch in the control circuit 24 by the source of stored electrical power of a conventional power supply and trigger circuit 36 and conductors 37. The control circuit is adapted to trigger the power supply each time a predetermined number of pulses are delivered byphoto electric cell 23 only during the movement of carriage 1.

It is believed that the operation of my apparatus can now be readily understood. In response to appropriate signal the motor 8 is energized to move carriage 2 in advance of carriage 1 to set the grid ruling apparatus for operation. Throughout the movement of carriage 2, the power supply 36 is inactive. Then, carriage 1 is driven by motor 7 through a distance measuredby a predetermined number of pulses delivered by photo-electric cell 23. Throughout this movement power supply 36 is operative and repeatedly on appropriate signal from control circuit 24 in response to a fixed number of pulses delivered thereto releases an electrical signal to energize the flash tube 34 and expose a narrow line on the face of grid blank 30. After exposure the light sensitive emulsion is processed by conventional photographic techniques. In the case of extremely long grids the develop ing process can be performed with the grid still in position by manual application of developing chemicals,

Again, while I have referred specifically to a motor and gear and rack drive for the carriage, it is obvious that many difl erent types of drive means may be employed. It is significant only that start and stop means for the carriage be under the control of mechanism operated in response to signals generated by the interferometer 10.

' While I have shown a preferred embodiment of my invention, it is apparent that many modifications and changes may be made therein without departing from r the spirit and scope of my invention which is defined by the claims appended hereto.

Having described my invention, I claim: 1. Apparatus for ruling a grid blank comprising, a grid marking device, a first and second carriages independently movable along a fixed path parallel to said grid blank, said grid marking device being mounted upon said second carriage for movement relative to said grid blank, an interferometer including a pair of light reflectors, one of said reflectors being mounted on said first carriage, the other of said reflectors being mounted on said second carriage, movement of said one reflector relative to said other reflector producing interference fringes of relative light and dark,

a transducer for converting such fringes of relative light and dark into electrical pulses upon relative movement between said first and 'said second carriages, means for effecting movement of said first carriage along its said path over a predetermined distance and then terminating such movement,

activating means operative after completion of said first carriage movement for moving said second carriage,

and means connected to said transducer for energizing periodically said grid marking device upon receipt of a predetermined number of electrical pulses during movement of said second carriage.

2. A grid ruling apparatus as defined in claim 1 including means for stopping movement of said second carriage, said stopping means being energized in response to a given number of electrical pulses.

3. Apparatus for ruling a grid blank comprising, first and second carriages movable along a fixed path parallel to said grid blank, an interferometer including a pair of lightreflectors, movement of one of said reflectors relative to the other of said reflectors of said interferometer producing interference fringes, said one reflector being "mounted on said first carriage and said other reflector being mounted on said second carriage, a transducer for converting light pulses into electrical pulses, a shield having an aperture therein concentric to said interference fringes to permit intermittent light pulses to impinge upon said transducer during relative movement of said first and second carriages, setting means for effecting movement of said first carriage, first carriage stopping means connected to said transducer and energized responsive to transmission of a given number of electrical pulses for preventing further movement of said first carriage, activating means operative after energization of said first carriage stopping means for effecting movement of said second carriage, a grid marking device, one of said grid marking devices and said grid blank being mounted on said second carriage, and means connected to said transducer for energizing periodically said grid marking device upon every receipt of predetermined number of electrical pulses during movement of said second carriage.

4. A grid ruling apparatus as defined, in claim '3 including means connected to said transducer for stopping movement of said second carriage, said stopping means being energized in response to a given number of electrical pulses.

5. Apparatus for ruling a stationary grid blank having alight sensitive coating thereon comprising first andsecond carriages movable along a fixed path parallel to said grid blank, an interferometer including a pair of light reflectors, one of said reflectors being mounted on said first carriage and the other of said reflectors being mounted on said second carriage, movement of said one reflector relative to other reflector producing interference fringes, a transducer on said second carriage for converting light pulses into electrical pulses, a shield having an aperture therein concentric to'said interference fringes to permit intermittent light pulses to impinge upon said transducer during relative movement of said first and second carriages, setting means for effecting movement of said first carriage, first carriage stopping means connected to said transducer and energized upon transmission of a given number of electrical pulses for preventing further movement of said first carriage, activating means operative after energization of said first carriage stopping means for effecting movement of said second carriage, a light source operative when energized to project a line of light on said light sensitive coating transverse to said fixed path, and means connected to said transducer for energizing said lightsource periodically in response to transmission by said transducer of predetermined ones of electrical pulses produced during movement of said second carriage.

having a light sensitivecoating thereon comprising,

6. A grid ruling apparatus as defined in claim 5 including means for stopping movement of said second carriage, said stopping means being energized in response to a given number of electrical pulses.

7. Apparatus for ruling an elongate stationary grid blank comprising, first and second carriages movable along a fixed path parallel to said fixed path, driving means for each of said first and second carriages, an interferometer including a. pair of light reflectors, oneof said reflectors being mounted on said first carriage and the other of said reflectors being mounted on said second carriage, movement of said one reflector relative to said other reflector producing interference fringes, a transducer on said second carriagev for converting light pulses into electrical pulses, a shield having an aperture therein concentric to said interference fringes to permit intermittent light pulses to impinge upon said transducer during relative movement of said first and second carriages, energizing means for said first carriage driving means, signal means connected to said transducer and operative upon receiving a first given number of electrical pulses for def-energizing said first carriage driving means and then energizing said second carriage driving means, said signal means being further operative upon receiving a second given number of electrical pulses to de-energize said second carriage driving means and then to energize said first carriage driving means, a grid marking device on said second carriage, and power means actuated upon receiving predetermined ones ofsaid second given number of electrical pulses to energize said grid marking device.

8. Apparatus for ruling an elongate stationary grid first and second carriages movable along a fixed path parallel to said fixed path, driving means for each of'said first and second carriages, an interferometer including a pair of light reflectors, one of said reflectors being mounted on said first carriage and the other of said reflectors being mounted on said second carriage, movement of said one reflector relative to said other reflector producing interference fringes, a transducer on said second carriage for converting light pulses into electrical pulses, a shield having an aperture therein concentric to said interference fringes to permit intermittent light pulses to impinge upon said transducer during relative movement of said first and second carriages, means energizing said first carriage driving means, signal means connected to said transducer and operative upon receiving a first given the other of said reflectors being numberof electrical pulses for de-energizing said first carriage driving means and then energizing said second carriage driving means, said signal means being further operative upon receiving a second given number of electrical pulses to de-energize said second carriage driving means and then to energize said first carriage driving means, a light source operative when energized to direct a line of light on said grid blank and power means actuated upon receiving predetermined ones of said second given number of electrical light source. i

9. Apparatus for ruling an elongate stationary grid blank comprising, first and second carriages movable along a fixed path parallel to said fixed path, driving means for each of said first and second carriages, a power source connectable to each of said driving means, an interferometer including a pair of light reflectors, one of said reflectors being mounted on said first carriage and mounted on said second carriage, movement of said one reflector relative to said other reflector producing interference fringes, a transducer on said second carriage for converting light pulses into electrical pulses, a shield having an aperture therein concentric to said interference fringes to permit intermittent lightpulses to impinge upon said transducer during relative movement of said first and second carriages, means connecting said'source to said first carpulses for energizing said riage driving means, switch means connected to said "transducer and operative upon receiving a first given number of pulses therefrom to disconnect said power source from said first carriage driving means and then to connect said power source to said second carriage driving means and operative upon receiving a second given number of pulses from said transducer to disconnect said power source from said second carriage driving means and then to connect said power source to said first carriage driving means, a grid marking device on said second carriage, and power means actuated upon receiving predetermined ones of said second given number of electrical pulses to energize said grid marking device.

10. vApparatus for ruling an elongate stationary grid blank comprising, first and second carriages movable along a fixed path parallel to said fixed path, driving means for each of said first and second carriages, a power source connectable to each of said driving means, an interferometer including a pair of light reflectors, movement of one of said reflectors relative to the other of said reflectors producing interference fringes, said one reflector being mounted on said first carriage and said other reflector being mounted on said second carriage, a transducer on said second carriage for converting light pulses into electrical pulses, a shield having an aperture therein concentric to said interference fringes to permit intermittent light pulses to impinge upon said transducer during relative movement of said first and second carriages, means connecting said source to said first carriage driving means, switch means connected to said transducer and operative upon receiving a first given number of pulses therefrom to disconnect said power source from said first carriage driving means and then to connect said power source tosaid second carriage driving means and operative upon receiving a second given number of pulses from said transducer to disconnect said power source from said second carriage driving means and then to connect said power source to said first carriage driving means, a light source on said second carriage operative when energized to direct a line of light on said grid blank and power means actuated upon receiving predetermined Ones of said second given number of electrical pulses for energizing said light source.

11. Apparatus for a member comprising first and second carriages movable independently along a fixed path, said member being carried on one of saidcarriages, an interferometer including a pair of light reflectors, movement of one of said reflectors relative to the other of said reflectors producing interference fringes, said one reflector being mounted on said first carriage and said other reflector being mounted on said second carriage, a transducer for converting light pulses into electrical pulses, a shield having an aperture therein concentric to said interference fringes to permit intermittent light pulses to impinge upon said transducer during relative movement of said first and second carriages, setting means for effecting movement of said first carriage, first carriage stopping means connected to said transducer and energized upon transmission of a first given number of electrical pulses for preventing further move ment of said first carriage,- activating means operative after energization of said first carriage stopping means for effecting movement of said second carriage.

12. The apparatus defined in claim 11 including means connected to said transducer for stopping movement of said second carriage, stopping means being energized in response to a second given number of electrical pulses.

13. Apparatus for producing controlled movement of a member comprising first and second carriages movable independently along a fixed path, said member being carried on one of said carriages, driving means for each of said first and second carriages, an interferometer including a pair of light reflectors, movement of one of said reflectors relative to the other of said reflectors producing interference fringes, said one reflector being mounted on producing controlled movement of v said first carriage and said other reflector being mounted on said second carriage, a transducer on said second carriage for converting light pulses into electrical pulses, a shield having an aperture therein concentric to said interference fringes to permit intermittent light Pulsesto impinge upon said transducer during relative movement of said first and second carriages, means energizing said first carriage driving means, signal means connected to said transducer and operative upon receiving a first given number of electrical pulses for de-energizing said first carriage driving means and then energizing said second carriage driving means, said signal means being further operative upon receiving a second given number of elec trical pulses to de-encrgize said second carriage driving means and then to energize said first carriage driving means.

14-. Apparatus for producing controlled movement of a member comprising first and second carriages movable independently along a fixed path, said member being,

carried on one of said carriages, driving means for each of said first and second carri ges, a power source connectable to each of said driving means, an interferometer including a pair of light reflectors, movement of one of said reflectors relative to the other of said reflectors producing interference fringes, said one reflector being mounted on said first carriage and said other reflector being mounted on said second carriage, a transducer on said second carriage for converting light pulses into electrical pulses, a shield having an aperture therein concentric to said interference fringes to permit intermittent light pulses to impinge upon said transducer during relative movement of said first and second carriages, means connecting said source to said first carriage driving means, switch means connected to said transducer and operative upon receiving a first given number of pulses therefrom to, disconnect said power source from said first carriage driving means and then to connect said power source to said second carriage driving means and operative upon receiving a second given number of pulses from said transducer to disconnect said power source from said second carriage driving means and then to connect said power source to said first carriage driving means.

15. Apparatus for producing controlled movement of a member comprising first and secondcarriages movable independently along a fixed path,

said member being carried on one of said carriages,

driving means for each of said first and second carriages,

an interferometer including a pair of light reflectors,

movement of one of said reflectors relative to the other of said reflectors producing interference fringes of relative light and dark,

said one reflector being mounted on said first carriage and said other reflector being mounted on said second carriage,

a transducer for converting such fringes of relative light and dark into electrical pulses upon relative movement between said first and second carriages,

means energizing said first carriage driving means,

signal means connected'to said transducer and operative upon receiving a first given number of electrical pulses for de-energizing said first carriage driving means and then energizing said second carriage driving means,

said signal means being further operative upon receiv ing a second given number of electrical pulses to deenergize said second carriage driving means and then to energize said first carriage driving means.

References Cited in the file of this patent UNITED STATES PATENTS 9 UNITED STATES PATENTS Kondo Jan. 21, 1930 Ives July 14, 1931 E'ckerlin July 12, 1938 Drouin May 2, 1950 Stamm Q. Oct. 24, 1950 Strong Nov. 20, 1951 Merton Feb. 22 1955 10 FOREIGN PATENTS 745,919 Great Britain Mar. 7, 1956 OTHER REFERENCES Jenkins and White, Fundamentals of Optics, second edition, 1950 McGraw-Hill Book Co., 1110., New York, N.Y., pages 247-249. (Copy in Div. 7.)