US2643491A - Grinding machine - Google Patents

Description

June 30, 1953 c, BURROUGHS 2,643,491

GRINDING MACHINE FiledDec. 5, 1950 s Sheets-Sheet 1 POLISH ROUGH FINE GRINDING GRINDING POLISH Fi POLISH FINE GRINDING INVENTOR. KE N NETH C- BURROUGHS 75% II/W June 30, 1953 K. c. BURROUGHS GRINDING MACHINE 3 Sheets-Sheet 2 Filed Dec. 5, 1950 S w U m ma U B C H l E N N E K 0.

June 30, 1953 K, c. BURROUGHS 2,643,491

' GRINDING MACHINE Filed D80. 5, 1950 3 Sheets-Sheet 3 INVENTOR. KENNETH c. BU RROUGHS Patented June 30, 1 953 UNITED STATES ATENT ()FFICE GRINDING MACHINE Application December 5, 1950, Serial No. 199,335

This invention relates to the grinding, finishing and polishing of lenses or the like and particularly to a rough grinding operation.

In the grinding and finishing of lenses for eye-glasses, one of the problems is the provision of a method and equipment which will grind the lenses accurately and with a minimum of supervision. Machines used for this purpose must be ones that can be adjusted accurately to finish lenses of diiierent curvatures according to the particular setting of the machinery.

One of the objects of the invention is to p vide a new and improved lens grinding machine and process.

Another object is to provide a lens grindin machine which can be adjusted to produce lenses of different curvatures.

still further object of the invention is to provide an improved work spindle operating arrangeinent.

Other objects, features and advantages of the invention will become apparent from the following description and drawings which are merely exemplary.

In the drawings:

Figure 1 is a schematic flow diagram of one manner in which the process can be performed.

Figure 2 is a front view of one type of machine which can be used, portions being omitted and the two inner heads being indicated schematically.

Figure 3 is a side view of Figure 2.

Figure l is a fragmentary top view of one of the stations of Figures 2 and 3.

Figure 5 is an enlarged fragmentary view of one of the work spindle devices of Figures 2 and 3.

Figure 6 is a fragmentary side View of the lower end of the yieldable connection of Figure 5, this view being an enlargement of Figure 5.

Figure '7 is a side view, partially in section, of the connection shown in Figure 6.

Figure 8 is an enlarged top View of a blank holder, a lens blank thereon being broken away.

Figure 9 is a side sectional View of Figure 8.

Figure 10 is an enlarged fragmentary side view or" one of the tool heads.

Figure 11 is a fragmentary enlarged top view of one of the tool head supports illustrating the adjusting means.

Figure 12 is a sectional view taken approximately along the line l2l 2 of Figure 11.

In the generation of lens surfaces, a lens blank can be held on a blank holder or block which is placed on a Work spindle. The Work spinill 12 Claims. (01. 51-131) dle can be arranged to be moved axially and to be rotated. The tool may be of the ring typ and can be mounted on a tool spindle havin its axis angularly displaced relative to the axis of rotation of the lens blank. l he axes must be substantially in the same plane to produce correct lenses. Such is particularly necessary for the finishing tool. The angle between the axis of the tool and the axis of the blank and the diameter of the tool will determine the curvature of the lens ground as is known in the art of lens generation.

The first operation of the invention may be performed by a machine having a plurality of tool heads and work stations. Four stations are illustrated. herein for the rough grinding operation. I'he blank of glass is made slightly thicker than that desired and is suitably mounted on a work blank holder.

In the rough grinding operation, a diamond type ring tool can be employed, the tool bein fixed axially and the work brought to a predetermined point or stop in relation to said tool. The blank holders are precision fitted to the tapered work spindles so that the correct relationship of parts will be maintained.

After the blank has been rough ground, it may be transferred to a fine grinding apparatus such as described in copending application Serial Number 199,336, filed December 5, 1950. In the fine grinding operation, a special metal tool a1- rangement preferably is employed using an abrasive in conjunction therewith, the work being moved upwardly to a fixed stop and the tool being movable axially. Following the fine grinding operation wherein the surface is brought to its desired radius of curvature, the blanks are moved to a polishing machine. A polishing arrangement can be used advantageously similar to that disclosed in copending application Serial Number 199,337, filed December 5, 1950.

As'will be described hereafter, the lens blanks are mounted on a work holder, the work holder having tapered apertures therein which are ground so as to accurately fit the tapered Work spindles at the various stations of the various grinding and polishing machines. The taper is chosen so as to correctly fix the position of the holder and blank on a spindle and yet be removable With ease. A blank holder with the blank thereon can be transferred to the next operation after the previous operation has been completed. The finishing of the convex side of the lens is described herein, the concave side 3 being finished by using suitably faced blank holders and tools.

This application is concerned particularly with the machine applicable to the rough and to the fine grinding operation as Well as for other purposes as will be apparent in the following description.

In the rough grinding operation described herein, the tool spindle is not moved axially and the rotating blank holder spindle is moved upwardly to a fixed stop in relation to a tool spindle. Previously, the angle between axes of the spindles has been properly adjusted so that the axes are in the same plane. Thus, a predetermined curvature will be ground on the surface of' the lens blank according to the relationship of the parts.

In one form of the machine, frame 20 may have four tool spindle heads illustrated-generally at 2| mounted thereon. It is to be understood that any desired number can be used. The tool spindle heads may comprise a frame 22 upon which there is' mou'nted the'to'ol' spindle assembly 23; and a motor 24 at'the opposite side. The 'tool'head frame 22' is slidable longitudinally'of the machine on the tool head'ways 25, said ways-having a projection'ffi, one'face'2'ij thereof being inclined inwardly so as to receiveand hold'front spacer or holding means 218. Set screws 29 (Figures 11, 12) urge the spacer 28 into engagement with face 2}. Wedges '33 and 3! can be adjusted longitudinall relative to" each other so as'to'move the tool'head frame 22 transversely relative to the longitudinal axis of the machine. 'Wedge 3! may have a 'pin'32 carried by' frame 22 engageable in a transverse slot 32" in 'wedgefil. This will permit transverse movement of the frame 22 relative to the wedge 31. Wedge 30 can 'be'moved longitudinally of the slideway so as'to adjust the transverseposition of' the frame 22. After the rear wedges 30 and Blfare'adjusted, set screws 29 are tightened so as to properly hold'andfposition the head in place. This will serve to move the axis=33 of the tool spindle relative to the work spindle axis 38 so that theycanbe correctly aligned. v v U Frame 22' has a bore'iat (Figure therethlqugh receivingashaft said shaft being'suitably 'fastenedI to the 7 frame of spindle holder '2 3 by alpin or other means 3 W The shaft or a projection is threaded to receivenutstfi. Motor. bracket 31 is slidable on the end 31' of'shaftj35 and can have' a key 37A'for holdingjit against rotation relative'th'ereto. Set screw 313 permits the bra cket to be locked in adjusted position, the

bracketfand motor being movable inwardly and outwardly relative to the tool spindle to obtain the correct tension inbelt d5 (Figure 3) connecting the motor 24 with the tool spindle 23. By loosening nuts .38, the tool spindle 23 and motor z lmay be rotated so as to obtain the desired angular relationship relative to the axis 36'of the work spindle 39. In this manner, the tool spindle 23 may tie adjusted so that its axis is in the same plane, as the plane'passing through the'axis 38 of the work spindle 39. V The angular'relationship between the axis 33 (Figure 1) of the tool spindle 23 and the axis 38 of the work spindle can be'adjusted by loosening nuts 36 and turnin g'the assembly.

The lens blanks can be mounted on blocks or work holders illustrated in Figures 8 and 9 by means of pitch or other similar material as is known in the art. The blank holder comprises abasemember 40, of steel or similar metal, said block having a tapered aperture 4! therein. The

' ment.

aperture preferably is made so that the walls diverge at an angle of about 20 or other suitable angle. The aperture 4| of the various blocks must be made so that the upper surface of the body 40 will be at the height for each of the work holder bodies. The work spindles also must be made accurately so that a lens blank 42 in place on any of the blank holders will always be in the same-relative position relative to the other parts of the machine for a particular adjust- Successive and difierent blank holders can be used with blanks mounted thereon in successive operations. If the blocks are of slightly dif ferent heights, a lens of slightly different thicknessmayfresult but this will not be serious.

v Fastened to the base 40 is a blocking member 43, said member being formed of brass or other similar m-aterialof good heat transfer characteristics, and held in place by screws 43A. Again, the relationship of the upper surface of member 43 must be correct. The blocking member 43 ma-yhave a spiral groove therein for receiving thepit'ch, the ridges 43B 'of block 43 being in contact with the lensglass and thus providinga path for transferring'heat from the glass to the block. The blocking members can be changed as needed in accordance with the lens curvature involved. 7

It is evident'that when a concave side of the lens'is to be formed, that a suitable blocking member can 'be provided to receive the other surface of the lens blank.

'After blocking, the work'holders with lenses thereon are placed on their respective spindles on the machine mechanism which is operated to start the variousparts as will bedescribed.

In the rough grinding operation, each tool spindle and tool 45 is rotated by amotor 24 through its belt-45. In the rough grinding operation, it is preferable to use a conventional diamond type ring abrasive tool, suitable coolant liquid being furnished. Merely'by wayofexample, the tool may befrot'ated at LOOO'R'. P. M. and the lens blank at 450 R. P. M. "For rough'grinding, the work blank holder is brought or raised to afixed stop, the tool being axially fixed. Pr'evious'theretmthe angleof theaxis'of the tool spindle relative to thej'wo'rk spindle axis has been determined and the position of the tool head on the slideway and on its frame adjusted'so' that the axes are in the same plane, and sothat the axis of the tool spindle intersects the work spindle axis at the center of curvature of the ground lens.

It is necessaryto be able to adjust the amount each of the Work spindles is raised with accuracy. When a plurality'of'spindles are involved, each must be adjustable independently of the raising means. One manner of accomplishing this is to provide a common operating motor and to employ a yieldable means in each spindle raising connection.

In a preferredembodiment, work-triadic 3.) can'be raised and lowered by operated. motor 51. Cylinder t? operates a lever 33 connected to shafttfl, shaft 45 being mounted in bearings 59 on the frame of the machine. Opposite each of the Work spindles, a lever arm 5! fastened to shaft 49. Each lever 5! is connected to a forked means 55, said forked means having an aperture 55"(Figure 7) therein through which rod 5l can reciprocate. Rod STmay have adjusting nuts 58 thereon holding spring'abutment 59. Spring Si! is located between spring abutmentftll and the top surface 5! of forked connecting means55. Adjustable nuts 62 are located within the apertures 63 of forked means Spring Bil normally urges the rod upwardly, its upward movement being limited by engagement of nut 62 with an interior surface of aperture f forked means 55.

Rod is fastened at it to work spindle slide work spindle slide ll being vertically slidea -e the dovetail slot 12 located on frame member it or the machine. Work spindle slide "55 carries tapered work spindle it having a pulley the lower end thereof. Pulley i5 is connected to pulley E5 by means of belt 11, pulley it": being suitably driven by shaft '18. The tapered end it of the work spindle suitably receives work holders, as previously described. An adjustable stop screw 8i] is contactable with a stop surface 35 on frame 73. Each of the stops on the various work spindles can be suitably adjusted so as to raise the work spindle the desired amount as the machine is set.

Upon oscillation of lever til (Figure 5) in a cioc .vise direction by air motor ll, rod 57 and slide "it will move upwardly until stop 8!) contact-s its ace 8!. Further movement of arm by shalt then will compress spring 69 without further movement of slide ll. Thus, there is a yieldable means in the driving connection for a work spindle slide ii.

Splash pan its is carried by the work spindle l, splash pan 32 having front shield membey pivoted thereon at M. Pivot B l may have an arm. 8E5 extending rearwardly therefrom, said arm being connected to bracket 8'? through adjustable link means having turnbuckle 8d. Bracket ti has an elongated slot 88 therein receiving the end of connecting link 89.

As a work spindle ll moves upwardly, connect link will move to the upper portion of slot at which time further movement of the worv slide at will cause downward pivoted moven -.t of arm thus rotating the shield 83 clockwise so as to cover the parts as grinding proceeds.

Upon lowering of the slide 'l'l, shield 83 will not start to open until connecting link 89 has moved to the lower end of the slot. A suitable drain may be provided in the splash pan 82 (not shown) for returning coolant or abrasive supplied as grinding takes place, the drain returning the fluid to a central supply.

In the rough grinding operation, the spring pressure exerted on the work spindle through spring as it is moved upwardly by the air ll, will govern the pressure exerted by k blank relative to its tool surface. Such e con inues until the particular stop is for the spindle involved limiting further novement of the work spindle. At this ,he work the work spindle has been completed and the desired curvature formed on supply for the air motor 41. The solenoid valve can be connected with any type of timer arrangement so that sufficient time will be allowed for the work spindle to reach its stop and complete the grinding operation. The air solenoid then will be operated by the timer to permit the work spindle to drop downwardly. The timer also can operate a suitable relay mechstoppini the work spindle motor so that the work blank can be removed.

What is claimed is:

1. In a grinding machine having a frame, the combination including a pair of spindles for rotatably carrying the tool and work to be engaged thereby, supporting means on said frame for one of said spindles holding the axis thereof in a relatively fixed position, slideway means on said frame, spindle holding means for the other spindle carried on said slideway means, said holding means being adjustably movable longitudinally relative to said slideway means, and wedge means located between said slideway and said holding means for moving said holding means transversely relative to said slideway.

2. In a grinding machine having a frame, the combination including a pair of spindles for rotatably carrying the tool and work to be engaged thereby, supporting means on said frame for one of said spindles holding the axis thereof in a relatively fixed position, slideway means on said frame, spindle holding means for the other spindle carried on said slideway and adjustably movable longitudinally and transversely relative thereto, wedge means located between said slideway and said holding means for moving said holdin means transversely relative to said slide way, and means rotatably holding said other spindle in said spindle holding means so that it can be turned relative thereto.

3. In a grinding machine, the combination including a main frame, a head slidably mounted on said frame, wedge means movable to adjust the transverse position of said head on said frame, a tool spindle means having a pulley, a rotatable shaft passing through said head, means non-rotatably mounting said tool spindle means on said shaft at one side of said head, a motor bracket axially slidably mounted on said shaft spaced from said tool spind1e means, a motor mounted on said bracket, said motor having a pulley, and a belt connecting said pulleys, whereby the motor and spindle can be moved axially relative to each other to regulate the belttension, and the shaft turned to change the angular relationship of the spindle and motor relative to said frame.

4. In a grinding machine, the combination including a plurality of pairs of spindles for carrying tools and work, means for reciprocating one of each of said spindles relative to the other in each of said pairs, said reciprocating means including motor means and connections with a yieldable means therein for the reciprocable spindle of each of said pairs, and stop means for arresting the movement of each of said reciprocable spindles in a desired predetermined position relative to the other spindle of the pair before said motor means has completed its movement.

5. In a grinding machine, the combination including a plurality of reciprocable work spindles, a motor means, stop means for each of said work spindles limiting movement thereof, connections between each of said work spindles and said motor means, and yieldable means in said connections, so that said motor means can move after said work spindles have been stopped by their respective stop means.

6. In a grinding machine, the combination including a plurality of reciprocable work spindles, a motor means, adjustable stop means for each of said work spindles limiting movement thereof, connections between each of said work spindles and said motor means, and yieldable means in said connections arranged to stop each work spindle at a predetermined point, so that said motor mean can move after said work spindles have been stopped by their respective stop means.

'7. In a grinding machine having a machine frame, th mbina o nclud a plurality o reciprocable work spindles, a motor means, adjustable stop means for each of said work spindles limiting movement thereof, connections between .each of said work spindles and said motor means, yieldable means in said connections arranged to stop each work spindle at a'predetermined point, so that said motor means can move after said work spindles have been stopped by their respective stop means, tool spindles for each work spindle, a slidable head on .said machine frame, means for adjusting said head .transversely of said frame to bring said spindles in the same plane, and means for angularly adjusting said tool spindles on its slidable head. i

8. In a grinding machine, the combination including a machine vframe, a plurality of work spindles, work spindle slides mounted on said frame and carrying said work spindles, stop means limiting movement of said slides, a motor means, connecting links between each slide .and said motor means, and a spring connectionin each connecting link yielding when a stop means operates-to limit movement of its slide.

9. In a grinding machine having aframe, a tool and a reciprocable workspindle, the combination including a splash pan connected to the work spindle, a shield mounted on said splash pan movable to closed and openpositions,link means connected between said shield and .frame closing said shield as said work spindle is-reciprocated toward an active position-relative to said tool.

10. In a grinding machine, the combination including a machine frame, a plurality of work spindles, ,work spindle slides mounted on said frame and carrying said work spindles, stop means limiting movement of said slides, a motor means, connectinglinks between each slide and said motor means, a spring connection in each connecting link yielding when a stop means operates to limit movement of its slide, a splash pan and .closable shield on each work spindle, and means closing said shields as said work spindles are moved.

11. A machine of the character described in claim 10 having a loose connection between said link and said frame, so that said work spindle moves a predetermined distance before the shield is moved.

12. In a lens grinding machine, the combination including work and tool spindles, means reciprocating said work spindle relative to said tool spindle so that the tool and work will engage, motor means for reciprocating said work spindle, stop means limiting movement of said Work spindle, and spring means connecting said motor means and said work spindles yieldable when said stop is reached and exerting substantially constant force on said work relative to said tool.

KENNETH C. BURROUGHS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,260,022 Paige Mar. 19, 1918 1,617,167 Schramm Feb. 8, 1927 1,996,842 Stevens Apr. '9, 1935 2,174,146 Turrettini Sept. 26, 1939 2,286,361 Goddu Q June 16, 1942 2,325,740 Canning Aug. 3, 1943 2,352,616 Canning July 4, 1944 2,377,991 Carlson June 12, 1945 2,419,543 Ellis et a1 Apr. 29, 1947 2,441,472 DAvaucourt -May 11,1948 2,516,493 Waite et a1 July 25, 1950 2,527,791 Brink Oct. 31, 1950 OTHER REFERENCES Industrial Diamond Review, October 1947, vol. 7, pages 304-307.

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