US3309188A

US3309188A - Method and apparatus for manufacturing pipettes

Info

Publication number: US3309188A
Application number: US306024A
Authority: US
Inventors: Charles A Porter; Wilbur A Schreiner
Original assignee: Owens Illinois Inc
Current assignee: OI Glass Inc
Priority date: 1963-09-03
Filing date: 1963-09-03
Publication date: 1967-03-14
Anticipated expiration: 1984-03-14

Description

14, 1967 c. A PORTER ETAL 3,309,188

METHOD AND APPARATUS FOR MANUFACTURING PIPETTES Filed Sept. 5, 1 963 3 Sheets-Sheet l INVENTORS CHARLES APORTER WILBUR A.SCHRE(NER A'IT RNEVS 1967 c. A. PORTER ETAL 3,309,18

METHOD AND APPARATUS FOR MANUFACTURING PIPETTES Filed Sept. 5, 1963 3 SheetsSheet 2 F i G u 2 INVENTOR5 CHARLES A. PORTER BY LON-BUR A SCHP-EINER ATTO RN EVS Max-ch14, 196? c. A. PORTER ETAL METHOD AND APPARATUS FOR MANUFACTURING PIPETTES 3 Sheets-Sheet 5 Filed Sept. 3, 1963 INVENTORS CHARLES A. PORTER wLBuR A. SCHREINER A'ITORNEVS United States Patent Filed Sept. 3, 1963, Ser. No. 306,024 6 Claims. (Cl. 65-109) This invention relates to a method and apparatus for forming constant volume bulbs of pipettes and similar items of glassware from tubular blanks.

More particularly, this invention relates to a method and apparatus for forming pipettes from tubing blanks by heating a portion of the blank and expanding the heated and softened portion thereof against precisely located, complementary rotating dies which are moved into close proximity to the heated portion of the tubing.

It has been the practice in the past to form the bulb portion of a pipette from two separate pieces of glass having enlarged ends which are then joined together. Such a procedure is set forth in US. Patent No. 2,735,230 of V. Morrill, Jr., dated Feb. 21, 1956. One problem encountered in the making of pipettes is the calibration of the pipette and frequently it is necessary that each pipette be calibrated individually. This is due to the fact that in present processes for forming pipettes there is no assurance that each pipette will have the same precise internal volume configuration throughout the length of the pipette. It can readily be appreciated that the calibration of pipettes on an individual basis is a time consuming and thus a costly step in the production of precision calibrated pipettes.

With the foregoing in view, it is an object of this invention to provide a method of forming pipettes with bulb portions from a length of tubing in which the internal volume of the pipette is made with precision and accuracy.

It is an additional object of this invention to provide a method of making successive pipettes in which all of the pipettes have the same precise volume.

It is a further object of this invention to provide apparatus for forming pipettes in which thevolume of the pipettes is made with precision.

It is a still further object of this invention to provide apparatus for expanding a portion of a heated tubing against precisely positioned roller dies so that the volume of successively produced pipettes is the same.

Other and further objects will be apparent from the following description taken in conjunction with the annexed sheets of drawings, wherein:

FIG. 1 is a perspective view of the apparatus of the invention;

FIG. 2 is a perspective View of a portion of the apparatus illustrated in FIG. 1, on an enlarged scale, showing the initial step of heating a tubular blank;

FIG. 3 is a perspective view, similar to FIG. 2, illustrating the position of the roller dies when in forming position during the expansion of the bulb portion of the pipette into the area between the dies;

FIG. 4 is a partial, sectional view taken at line 44 of FIG. 2; and

FIG. 5 is a plan view of the roller dies and tubing 3,309,188 Patented Mar. 14, 1967 blank illustrating the relationship therebetween during the forming of the bulb portion of a pipette.

With particular reference to the drawings, the appara tus of the invention takes the form of a lathe having a base or bed 10 which serves to support a pair of parallel,

horizontal bed rails

11 and 12 in fixed position spaced above the base of the lathe. The left hand end of the lathe, as shown in FIG. 1, carries a fixed head stock 13 and the

bed rails

11 and 12 support a tail stock 14 for adjustable movement toward and away from the head stook. Both the head stock and tail stock carry horizontally extending

co-axial shafts

15 and 16 in opposing relationship with the shafts carrying chucks 17 and 18 respectively at their extending ends. The shaft 15 has a spur gear 19 fixed thereto which is in mesh with a drive gear 20. The drive gear 20 is mounted on a splined shaft 21 which extends into a complementary spline opening in the drive shaft 22 of a motor 23. The motor 23 is mounted on the moveable tail stock 14 and its drive shaft 22 also carries a drive gear 24 which is in mesh with a spur gear 25 carried by the shaft 16 for driving the chuck 18. The splined connection between the two shafts 2'1 and 22 is necessary from the standpoint that the tail stock is moveable relative to the head stock for holding glass tubing or blanks of varying lengths in proper position in the chucks 17 and 18.

It should be pointed out that the chuck 18 and its shaft 16 is provided with an axial opening 26 therethrough to provide access for air under pressure being fed thereto through a flexible line 27. The line 27 is connected to the shaft 16 by a rotary connector 28 so that the shaft 16 may rotate while the flexible line 27 remains stationary. The chucks 17 and 18 are of the type having three spring biased jaws 29 3 1. Each of the jaws is biased in a counterclockwise direction, as viewed in FIGS. 1-3. With the placing of the tubing T in position between the jaws, it can readily be seen that the sides of the jaws 29-3-1 contact the side of the tubing at three equal, circumferentially spaced points on the tubing and effectively grip the tubing and center it with respect to the chuck body-18. In this manner both ends of the tubing T are supported by the chucks 17 and 18 and held in precise horizontal position. The details of the chucks are not important to the invention except to the extent that they provide an arrangement for supporting a length of tubing and for rotating the tubing about its longitudinal axis, with both chucks being rotated at the same speed. The chuck 1 8, as previously described, has an opening 26 therethrough and within the inner end of this opening 26, is fixed an annular sleeve 32.

The sleeve 32 carries within its bore a bushing 33 which extends through the bore to a point less than the full length of the sleeve 3'2. The sleeve, at its forward end, has an enlarged annular recess 34 and the end of the bushing 33 extends to a point within this recess 34. The extending end of the bushing 33 is provided with elongated slots 35 which extend through the wall thereof and provides communication between the bore of the bushing 33 and the annular recess 34 of the sleeve 32. The end of the bushing 33 serves as the locating surface against which the tubing T is seated and, in effect, defines the position of the moveable chuck 1-8 with respect to the tubing T.

It can readily be seen that the introduction of air under pressure within the opening 26 in the chuck 18 will convey air under pressure through the bushing 33 and into the open end of the tubing T, with the volume of air being diminished to a certain extent by the escape of air through the slots 35 of the bushing. The slots 35 also serve as air bleed openings to prevent development of excessive pressure within the tubing T.

It should be understood that the air under pressure which is blown into the open end of the tubing T is supplied in a predetermined cycle, as will be explained later with respect to the operation of the apparatus.

It should also be understood that the chuck 17 has jaws similar to those shown with respect to the chuck 18. However, the chuck 17 is not supplied with air under pressure and the tubing T used to form the pipettes actually has a tapered, restricted end and it is this tapered end which is gripped by the jaws of the chuck 17. This end of the blank is left open with the restriction therein being suflicient to provide a back pressure in the blank to expand same.

Intermediate the length of the

rails

11 and 12 there is provided sleeve-

like members

36 and 37 which are adapted to slide on the

rails

11 and 12. The sleeve-

like members

36 and 37 support a relatively flat platform 38. The platform 38 spans the distance between the two

rails

11 and 12 and serves as the mounting base for a pair of roller dies 39 and 40.

As best shown in FIGS. 1 and 3, the platform 38 is formed with two vertically extending portions 41 and 42 which extend vertically to the same extent with upper ends thereof being below the span of the tubing T. The portions 41 and 42 serve as end supports for a pair of horizontally extending

shafts

43 and 44. Both

shafts

43 and 44 extend through the portion 41 and carry a pair of

sprockets

45 and 46 fixed thereto. In addition to the

sprockets

45 and 46, the shaft 44 has a third sprocket 47 fixed thereto which serves as the drive sprocket.

The shaft 44, intermediate the vertical portions 41 and 42, carries a pair of spaced

sleeve bearings

48 and 49. Both the

sleeve bearings

48 and 49 have vertically extending

arms

50 and 51 connected thereto respectively and to the upper ends of these arms are fixed

sleeve bearings

52 and 53. A horizontal shaft 54 is supported in the sleeve bearing 52 at one end thereof and extends through the sleeve bearing 53. Intermediate the two

sleeve bearings

52 and 53 the shaft 54 carries the roller die 40. The extending end of the shaft 54 carries, or has fixed thereto, a sprocket 55. In a similar manner the shaft 43 carries a pair of

sleeve bearings

56 and 57 from which a pair of

arms

58 and 59 extend. These

arms

58 and 59 carry sleeve bearings 60 and 61 at their upper ends, which bearings serve as a support for a horizontal shaft 62 parallel to shaft 54. The shaft 62 supports the other roller die 39. It should be understood that the two roller dies 39 and 40 are positioned on their

respective shafts

54 and 62 so that they are directly opposite each other. One end of the shaft 62, as is the case with the shaft 54, extends through the sleeve bearing 61 and carries a sprocket 63 on its extending end.

As best shown in FIGS. 1 and 3, a motor 64 connected to, or supported from, the platform 38 rotates a sprocket 65 connected to its shafts. A chain 66 serves as the driving connection between the motor driven sprocket 65 and the drive sprocket 47. The sprockets 46, of which there is one on each of the

shafts

43 and 44, are connected by a chain 67, thus insuring that both

shafts

43 and 44 rotate in the same direction and with the same speed. The sprockets 45, of which there is one on each of the

shafts

43 and 44, drive sprockets 55 and 63 through chains 68 and 69. The resultant rotation of the sprockets 55 and 63 in the same direction will insure that the two roller dies 39 and 40 are rotated in the same direction and at the same velocity.

It should be understood that the roller dies 39 and 40 are mounted, with respect to the

shafts

43 and 44,

so that they may swing toward and away from each other about the axes of

shafts

43 and 44, with the extent of their movement toward each other being limited to a definite predetermined position. This closest position of the dies in relation to each other is such that the flat portions of the dies 39 and 40 are close to, but not actually touching the tubing T. This precise positioning of the dies, when in their forming position as illustrated in FIGS. 3 and 5, is controlled by adjusting screws 70, of which there are four. Each screw is adjustably mounted with respect to each of the

arms

50, 51, 58 and 59. The ends of the screws 70 are adapted to abut the vertically extending portions 41 and 42 of the platform 38.

As clearly shown in FIGS. 2 and 3, the screws 70 are received in internally threaded blocks 71 carried by the arms and a lock nut 72 is provided to insure that the adjusted position of the screws 70 will not change once the adjustment is properly made. The

arms

50 and 58 are biased toward each other by a spring 73 and, in a like manner, the

arms

51 and 59 are biased toward each other.

During the operation of the apparatus for forming pipettes, it is necessary that the dies 39 and 40 be positioned some distance apart and that the dies be moved into forni= ing position with respect to the tubing T only after the tubing has been preconditioned by heating. Control of the movement of the roller dies toward and away from each other is accomplished by the interposition of a pair of cams 74 and 75 between the arms 51 and 5-9 and

arms

50 and 58 respectively. The two earns 74 and 75 are connected together by a shaft 76 with both cams oriented with respect to the shaft so that they actuate the arms in a like manner. Rotation of the shaft to effect rotation of the cams in carried out by a crank arm 77 which has one end fixed to the shaft 76 and is pivotally connected at its other end to a horizontal piston rod 78 which we tends from a fluid motor 79. The motor 79 is mounted on a bracket portion 80 which may conveniently be an integral part of the platform 38.

The above-referred-to conditioning of the tubing prior to forming involves heating of that portion of the tubing T which is to be expanded into the bulb portion of a pi pette. Heating of the tubing is accomplished by the use of a flame burner 81. The burner 81 has a thin, elongated opening through which the gas and air mixture is fed and burned, with the length of the burner opening being parallel to the tubing so that its coverage will be sufficient to heat the tubing in the area where the expansion is to be accomplished. Gas for the burner is supplied through a flexible tube 82 and the burner itself is supported by a horizontal post 83 which in turn is connected to the vertical portion 42 of the platform 38.

Having described the detailed mechanism which comprises the invention, the following description will set forth the sequence of operation of the apparatus and the process of the invention.

With the tail stock 14 of the lathe in its retracted position, a length of tubing T is placed with its already tapered end into the chuck 17. The tail stock 14 is then moved toward the head stock 13 and the tubing is inserted within the chuck 18 until it is seated in abutting relation to the bushing 33. With the tubing thus positioned, the motor 23 is started and the two chucks will rotate the tubing at a predetermined peripheral speed. The burner 81 is then turned on. At this time the dies 39 and 40 are in retracted position as illustrated in FIG. 2. After the tubing has been heated so that the exposed portion thereof has reached a plastic state, the fluid motor 79 is actuated to move the dies 39 and 40 into forming position. As the dies move into forming position the burner 81 is shut oif. It should be understood that the motor 64 is continuously running and the dies 39 and 40 are continuously rotating at a predetermined velocity so that upon their approach to the tubing T they will be rotating in the direction indicated by the arrows on FIGS. 2 and 3 and the,

tubing will be rotating in the direction of the arrow 84. With the dies in closed position, as shown in FIGS. 3 and 5, the air is turned on to the interior of the chuck 18 which permits a controlled air stream to blow against the open end of the tubular blank or tubing T. Pressure will build up within the tubing T and the softened portion of the tubing will be expanded outwardly against the concave surface of the roller dies 39 and 40. From an operating standpoint it should be pointed out that the dies 39 and 40 do not actually touch the tubing or blank along their straight areas and that the velocity of the dies is such, in relation to the rotation-a1 velocity of the surface of the tubing blank, that the tubing is rotated at the same velocity as the concave portions of the dies 39 and 40. After the blowing of air within the tubing is continued for a predetermined length of time and the tubing is expanded, the blowing air is cut off and the motor 79 is reversed to move the dies 39 and 40 away from each other.

Inasmuch as the dies are always moved into the same position relative to the tubing T, and the tubing is expanded within the area defined by the contours of the dies, the bulb or expanded portion of successively produced pipettes will always be the same. In this manner, successively produced pipettes will all be of the same precise dimensions. Thus, the volumetric calibration of the pipettes may be automatically accomplished without requiring individual calibration, as is the present practice.

Other and further modifications may be resorted to within the spirit and scope of the appended claims.

We claim:

1. A method of forming a pipette from a length of glass tubing comprising, the steps of supporting the tube at the ends only and rotating said length of tubing about its longitudinal axis, applying heat to a predetermined length of said tubing to render a circumferential portion thereof plastic, moving a pair of opposed concave members into close proximity to the heated portion of said tubing, expanding the heated portion against the members by introducing air at a controlled pressure into the tubing, discontinuing the introduction of air into the pipette after expansion is complete, moving the concave members apart and removing the formed pipette.

2. Apparatus for forming a pipette from a length of glass tubing comprising, means for mounting the glass tube only at the ends thereof, means for rotating said length of tubing about its longitudina laxis in a horizontal plane, a pair of concave roller dies, means mounting said roller dies for rotation about their axes and with their axes parallel to and on opposite sides of the axis of the tubing, means supporting said die mounting means for movement toward and away from each other, means connected to said dies for rotating same at the same peripheral velocity and in the same direction, means connected between said die supporting means for biasing same toward each other, means positioned between said die supporting means for controlling the movement of said dies toward and away from each other and into close proximity to said tubing, a motor connected to said means for controlling the movement of the dies, means associated with said die mounting means for limiting movement of said dies toward each other, a heater positioned beneath the tubing for heating the tubing in the area between the roller dies and means in engagement with one end of said tubing for introducing fluid into the interior of said tubing under a controlled pressure to expand said heated area into engaging and forming relation with said dies.

3. Apparatus for forming pipettes from lengths of glass tubing comprising, means for supporting said tube at the ends only and rotating a length of tubing about its longitudinal axis, a support positioned beneath and intermediate the length of said rotating tubing, a pair of concave roller dies, means for mounting said roller dies with their axes horizontal and parallel to the axis of the tubing with a die positioned on either side of said tubing,

means for pivotally supporting said mounting means on said support, means connected tosaid dies for rotating same at the same peripheral velocity and in the same direction, means biasing said die supporting means to ward each other, cam means positioned between said die support members for controlling the movement of said dies toward and away from each other and into close proximity to said tubing, means associated with said die supporting means for limiting movement of said dies toward each other, a motor mounted on said support and connected to said cam for rotating said cam means, a heater positioned beneath the tubing for heating the tubing in the area between the roller dies and means for blowing air into the interior of said tubing under controlled pressure to expand said heated area into engaging and forming relation with said dies.

4. Apparatus for forming glass tubing into pipettes comprising, a lathe with rotating chucks for supporting the glass tube only at the ends thereof and rotating a length of tubing, means for driving said chucks at the same speed, a pair of roller dies, a pair of horizontal shafts for supporting said dies on opposite sides of the length of tubing with their axes parallel to the tubing, pivoted lever means connected to said shafts for supporting said shafts for swinging movement toward and away from the tubing, means connected to said shafts for rotating said dies at the same peripheral velocity and in the same direction, means connected to said pivoted levers for swinging said dies into and out of close, equal proximity with the tubing, stop means on said lever means for limiting movement of said dies toward each other, means for introducing air under pressure to the interior of the length of tubing carried in said lathe and means mounted on said lathe for heating that portion of the length of the tubing that is located between the dies, said area under pressure expanding the heated portion of the tube into engaging and forming relation with said dies.

5. Apparatus for forming pipettes from a length of glass tubing comprising, means for supporting entirely at its ends and rotating a length of tubing about its longitudinal axis, a support plate positioned beneath and intermediate the length of said rotating tubing, a pair of concave roller dies, a pair of horizontal shafts for mounting said roller dies with their axes parallel to the axis of the tubing, a pair of pivotally supported arms connecting each shaft to said support plate, means connected to said shafts for rotating same at the same peripheral velocity and in the same direction, means connected between the arms for supporting said shafts for biasing said pivoted arms toward each other, cam means positioned between said arms for controlling the position of said dies and shafts with respect to each other, means on said pivoted arms for limiting movement of said dies toward each other, a motor mounted on said support plate and connected to said cam means for rotating same, a heater positioned beneath the tubing for heat softening the tubing in the area between the roller dies and means for blowing air into the interior of said tubing under controlled pressure to expand said heat softened area into engaging and forming relation with said dies.

6. Apparatus for forming pipettes from a length of glass tubing comprising, means for supporting at the ends only and rotating a length of tubing about its longitudianl axis, a support member positioned beneath said tubing and intermediate its length, said support member having a pair of spaced apart, upstanding ears, a first pair of arms, means pivotally supporting said first pair of arms on said support member at spaced apart intervals, a second pair of arms, means pivotally supporting said second pair of arms on said support in parallel with said first pair of arms, a shaft extending between each pair of arms at their outer ends, a pair of concave roller dies, means for mounting said roller dies on said shafts, means connected to said shafts for rotating same at the same peripheral velocity and in the same direction, means biasing said shafts toward each other, a cam positioned between said pair of arms for controlling the position of said shafts and dies in relation to each other, said cams permitting said dies to move into close proximity to said tubing, a motor mounted on said support member, means connecting said motor to said cam for rotating said cam,radjustable means carried by said arms and adapted to engage said upstanding ears upon movement of said arms to limit movement of said arms toward each other, a heater positioned beneath the tubing for softening the tubing in the area between the roller dies and means for blowing air into the interior of said tubing under control pressure, whereby the tubing is expanded into contact with the accurately positioned, rotating, concave dies.

References Cited by the Examiner UNITED STATES PATENTS 1,914,205 6/1933 Hooper et al. 65109 X 2,393,979 2/1946 Everett 65-277 3,171,730 3/1965 Zauner 65l09 10 DONALL H. SYLVESTER, Primary Examiner.

S. LEON BASHORE, A. D. KELLOGG,

Assistant Examiners.

Claims

1. A METHOD OF FORMING A PIPETTE FROM A LENGTH OF GLASS TUBING COMPRISING, THE STEPS OF SUPPORTING THE TUBE AT THE ENDS ONLY AND ROTATING SAID LENGTH OF TUBING ABOUT ITS LONGITUDINAL AXIS, APPLYING HEAT TO A PREDETERMINED LENGTH OF SAID TUBING TO RENDER A CIRCUMFERENTIAL PORTION THEREOF PLASTIC, MOVING A PAIR OF OPPOSED CONVACE MEMBERS INTO CLOSE PROXIMITY TO THE HEATED PORTION OF SAID TUBING, EXPANDING THE HEATED PORTION AGAINST THE MEMBERS BY INTRODUCING AIR AT A CONTROLLED PRESSURE INTO THE TUBING, DISCONTINUING THE INTRODUCTION OF AIR INTO THE PIPETTE AFTER EXPANSION IS COMPLETE, MOVING THE CONCAVE MEMBERS APART AND REMOVING THE FORMED PIPETTE.

2. APPARATUS FOR FORMING A PIPETTE FROM A LENGTH OF GLASS TUBING COMPRISING, MEANS FOR MOUNTING THE GLASS TUBE ONLY AT THE ENDS THEREOF, MEANS FOR ROTATING SAID LENGTH OF TUBING ABOUT ITS LONGITUDINA LAXIS IN A HORIZONTAL PLANE, A PAIR OF CONCAVE ROLLER DIES, MEANS MOUNTING SAID ROLLER DIES FOR ROTATION ABOUT THEIR AXES AND WITH THEIR AXES PARALLEL TO AND ON OPPOSITE SIDES OF THE AXIS OF THE TUBING, MEANS SUPPORTING SAID DIE MOUNTING MEANS FOR MOVEMENT TOWARD AND AWAY FROM EACH OTHER, MEANS CONNECTED TO SAID DIES FOR ROTATING SAME AT THE SAME PERIPHERAL VELOCITY AND IN THE SAME DIRECTION, MEANS CONNECTED BETWEEN SAID DIE SUPPORTING MEANS FOR BIASING SAME TOWARD EACH OTHER, MEANS POSITIONED BETWEEN SAID DIE SUPPORTING MEANS FOR CONTROLLING THE MOVEMENT OF SAID DIES TOWARD AND AWAY FROM EACH OTHER AND INT O CLOSE PROXIMITY TO SAID TUBING, A MOTOR CONNECTED TO SAID MEANS FOR CONTROLLING THE MOVEMENT OF HE DIES MEANS ASSOCIATED WITH SAID DIE MOUNTING MEANS FOR LIMITNG MOVEMENT OF SAID DIES TOWARD EACH OTHER, A HEATER POSITIONED BENEATH THE TUBING FOR HEATING THE TUBING IN THE AREA BETWEEN THE ROLLER DIES AND MEANS IN ENGAGEMENT WITH ONE END OF SAID TUBING FOR INTRODUCING FLUID INTO THE INTERIOR OF SAID TUBING UNDER A CONTROLLED PRESSURE TO EXPAND SAID HEATED AREA INTO ENGAGING AND FORMING RELATION WITH SAID DIES.