US2304664A - Lens molding press - Google Patents

Description

LENS MOLDING PRESS Filed April 2e, 1941 INVENTOQ CHAQLES SMITH ATTORNEYS Patenie 89 i2` [PATENT OFFICE sMoLnmG rnnssv Charles V. Smith, Dayton, Ohio, assigner to The Univis Lens Company, Dayton, Ohio, a corpo- `ration of Ohio Original application October 29, 1940, Serial No. 363.322. Divided and this application April 28,

1941, Serial No. 390,659

Claims.

This invention to die apparatus used informing various materials'.

It is an object of the invention to provide a simplied die holding apparatus, and one which may be constructed relatively inexpensively.

Another object oi the invention is to provide a die holding device having means for the circulation oi duid therethrough, the fluid passage being nnned for greater .thermal transfer oi heat.

Another object oi' the invention is to provide a die holding apparatus wherein the die element is arranged in good thermal transfer with nuid circulating therethrough, and is removably posi- Another object oi the invention is to provide a forming die and holding apparatus wherein fluid is circulated through the die, or holding apparatus. and wherein means are provided for insuring that the uid passage is completely filled with uid when circulating therethrough.

Another object of the invention is to provide means for adjusting the position of the perpendicular axis o! the die with respect the platen of a forming press.

A still further object of the invention is to provide means for coaxially aligning a pair of die elements, which means is removable, upon the die elements being positioned properly within a forming press.

A still further object of the invention is to provide a slmplied forming press for forming small masses oi material.

Another object of the invention is to provide a simplified forming press for forming small masses of material, which is substantially irictionless, to provide a smoothly operating pressing stroke of the platen.

Another object of the invention is to provide a simpliiied forming press wherein a diaphragm Figure 1 is a vertical cross-sectional view of a forming press having die holding devices and die'elements positioned therein constructed in accordance with the teachings of the invention;

Figure 2 is a horizontal cross-sectional view taken along line 2--2 of Figure 1;

Figure 3 is a cross-sectional view of a portion of the die holding device and die elements. showing the means for aligning the die elements and holding devices. Y

In this invention a simpliiied forming press is provided wherein the die holding elements are of a simpliiied construction, and wherein the forming die elements are removably positioned.

The die elements, and the die holding members are provided with means for coaxially aligning the die members for insertion into the simplified press. Upon positioning the die holding mem bers with their die inserts therein within the forming press, in their aligned condition, suitable means is provided for properly supporting the die holding members upon the platen and the head o! the press so that the aligned relation oi the die holding members, and thus the die elements, is maintained.

' The simplied die holding members i0 and lila consist of an internally threaded cylinder ii. This cylinder II can be a common internally threaded pipe member, the accuracy of the threads i2 being ci no particular value. The cylinder II is cut irom'a length of the internally motor provides the jpower element for operating the press, the motor being operated either by pneumatic or hydraulic pressure.

Another object of the invention is to provide a simplified forming pressior forming small masses oi material at relatively low pressures.

Further objects and advantages will be apparent from the description and the drawing.

Inthe drawing:

threaded pipe to the desired length to provide the body for the die holding member I0.' Since the die holding members I0 and Illa are oi identical construction only one of said members will be described, it being understood that like parts are represented by like numerals. A mounting plate I3 is positioned adjacent one end of the cylinder II, the cylinder being secured to the plate I3 by suitable means such as brazing or welding, as indicated at I4. The mounting plate I3 thus seals one end of the cylinder II.

The opposite end of the cylinder I I is closed by means oi' a disk I6 which is provided with j external threads I8. The threads I8 `are adapted to match the threads I2 of the cylinder i I so that the disk l5 can be threaded into the open. end of the cylinder iI. The disk i5 is positioned a substantial distance inwardly from the end I3 of and the end of the cylinder.

ably vfastening the disk therein through such means as brazing or welding. A plurality of circular slots I9 are positioned in the inner face of the disk I5. These slots are for the purpose ci providing additional surface area to the inner face oi the disk I5. The mounting plate I3 and the disk I5 thereby provide a sealed chamber'lll within the cylinder II. The chamber 20 is provided with a fluid inlet 2I and with a. fluid outlet 22. The fluid outlet 22 is provided with means for restricting the outlet 22, such as the valve 23. While a. valve 23 is used for purposes of refstriction in the outlet 22, the valve 23 may be dis pensed with if the discharge liner't-is of smaller diameter than the inlet line 2 I This restriction to the ilow or fluid through the chamber 20 is provided to insure that the chamber 20 is completely lled with fluid circulating therethrough. Since the inlet 2I can pass more iiuid than the outlet 22, when the valve 23 is restricted, it may be seen thatA the chamber 20 will be completely lled with fluid in thermal transfer with the walls thereof. It is, of course, to be understood that the use of the valve 23 is optional, but its use is advantageous to insure complete lling of the chamber 2U and to prevent short-circuiting of fluid from the inlet directly to the outlet opening.

When using cooling and heating iiuid for cooling and heating the dieI carrying members ID and Illa it is, of course, desirable that the fluid outlet shall be arranged in a' manner that the chambers 20 can bedrained of fluid. Hence. the duid outlet is usually positioned at` the lowest point of the chamber 20. In the case of the upper die carrying member I0, a short-circuiting of fluid between the inlet and the outlet is not as serious as in the case of the lower die carrying member I0a. If the fluid circulating through the chamber 20 short-circuits between the inlet 2| and the outlet 22 of the die carrying member Illa it may readily be seen that the disk I5 of the die carrying member I0a will not have good thermal transfer with the maximum quantity of inlet iluid circulating into the chamber 20. Hence, the restrictions in the outlet 22 are of value to insure that the end closure disks I5 will be in heat exchange relation with the maxs imum volume of iiuid passing through the chamber 20.

As heretofore mentioned, the cylinder II consists of an internally threaded pipe member, hence the threads I2 will extend throughout the length of the chamber 2U. These threads provide means for increasing the surface area of the chamber 2@ exposed to the duid circulating therethrough, and in eil'ect provide ilns for the internal surface of the chamber 2D. The circular grooves I9 provided in the end closure disks I5 increase the surface area of the disk exposed to the iiuid within the chamber 20, and hence the portions betweenv the grooves I9 serve as heat transfer fins for the disk IE.

The die element Sil is removably positioned within the recesses provided between the outer exposed face of the disk it and the end I8 oi the cylinder il. The die element 3@ consists of a disk 3i which is provided with external threads 32 which are adapted to engage the threads l2 within the cylinder Il to retain the die all in position Within tl'lerecess. The threading of the disk 3l into the recess provides a means whereby the heat transfer area between the cylinder II and the disk 3I is increased, the threads serving this purpose. Also, the disk 3l is in thermal transfer relation with the end closure disk I5. The disk 3i of the die 30 carries a forming die insert 38. This insert 36 is suitably secured within the carrying disk 3l. and may consist of any one of a number oi materials suitable for forming masses of material under pressure. The exposed laces of the inserts 35 are provided with the desired contour which will produce an article of the desired shape when the die members 35 are brought into the proper adjacent relation. lit is of course to be understood that the die inserts are not essential but that the contoured face could be provided upon the disk 3l.

In order to strengthen the end closure disks I5 for the cylinder II a centrally disposed post 36,15 positioned between the disk I5 and the mounting plate I3. The post $6 is suitably attached to the disk I5 and the mounting plate I3. The die carrying members I0 and Ia are. suitably positioned within a forming press, which inthe invention ,consists of. a stationary head 40a which forms a part of the press frame III and a movable platen 4I. 'I'he movable platen 4I is mounted upon the end of a plunger I2 which is connected to a diaphragm type motor I3. The motor Q3 is mounted upon the bed portion of the frame 40 of the press. The bed and head 40a are both parts of the press frame l!! and are stationary with respect each other.

, The plunger 42 is guided in its reciprocal movement by means of a plurality of rollers M mounted therearound. The rollers 44 are bearinged upon the press frame 40 in any suitable manner, as by the axles 45. The diaphragm motor 43 provides an extremely simplified form of press motor, and improves the performance of the forming operation in that the platen 4I can be moved in an absolutely uniform stroke. Since the diaphragm motor 4I is a friction-free piece of apparatus, and since the rollers 44 are also friction-free apparatus with respect to the movement of the plunger 42, it can be seen that slight additional pressure application to the motor 43 will produce a corresponding movement of the platen Il.

When molding or forming certain articles, such as optical articles, and more particularly lenses, it is essential that the movement of the die member shall be at an/absolutely uniform rate. The use of a diaphragm motor permits the movement of the die at a uniform rate and eliminates allvlbration or jerky movement of the platen 4I. The diaphragm type motor 43 is particularly advantageous for use in forming optical articles since this type motor is a friction-free piece of apparatus. When using a conventional forming press there is a slight amount of vibration produced in the plunger caused by the pressure against the plunger over coming the friction of the sealing device for the plunger. Such vibration is not produced when using a. diaphragm type motor. Further, these motors can be used with either pneumatic or hydraulic presses and since the pressures involved when forming optical articles from resinous material are not high, it is quite possible to use ordinary city water pressure as the press operating means, or air pressure of like degree.

The die carrying members l@ and ma'. are-se- `cured to the platen 4I and the head 40a of the press frame #i0 by means of mounting bolts 50 which extend through the mounting plate I3 into engagement with the platen 4I and the head 40a of the press frame. Y

To provide for proper alignment i'or'the vdie carrying members i and lila, and thus for the die elements' 85, a circular groove B0 is provided in the die supporting disks 31. These grooves 60 are concentric with the central axis of the die inserts S5, and thus concentric with the axis of the contoured surface of the die insert BB. A hollow cylinder 6i is adapted to be positioned within the grooves 6d in order to provide proper alignment of the die inserts 35. The hollow cylinder 6| will thus cause the grooves 60 to be brought into proper coaxial alignment, and since the grooves B are concentric with the axis of 'the contoured face of the disk 35 it maybe seen that the inserts 35 will be brought into coaxial alignment,

It is oi' course 'to be understood that the die elements I have been previously positioned within the respective die carrying members i and lila, so

. that when the die elements 30 have been properly aligned. the die carrying members IB and 'ma will also be in proper coaxial alignment. The die carrying members I@ aniiifiia are then positioned between the platen di and the head 40a of the press frame of the forming press in this assembled and 'aligned relation. To maintain this aligned relation a plurality of adjusting screws 6E are in threaded engagement with the mounting plate i3.

' These screws t5 engage the surfaces of the platen si and the head iia adjacent the mounting plate i3. By properly adjusting the screws 65 so that the ends thereof engage the platen di and the head 40a it may be seen that the mounting support for the die carrying members I@ and ita can be 'adjusted in a manner that slight angular irregularities between the die carrying members and the platen and head of the press can be compensated for, to permit the maintenance ofvthe proper coaxial alignment of the die elements 30. After the adjustable supporting screws BB have been properly adjusted the binding bolts t0 may then be drawn tightly against the mounting plates i3 to secure the die carrying elements I6 and ma at their proper aligned relation. The platen and head of the press can then be opened to permit removal of the ring 8l from between thedie carrying disks 3|. I

By the use ofthe ring 6i and the adjusting bolts 65, it may be seen that I provide` means for coaxially aligning the die elements 30 and the die members i0 and "la, and also provide means whereby the angularity of the axis oi' the die carrying members perpendicular tothe platen and head of the press can be altered slightly to correct misalignment. It is also possible to use the adjusting bolts 65 as means for obtaining angular relation between the perpendicular axis of the die carrying members i0 and Ilia,` should such angular misalignment be desired.

The structure of the die carrying members, thxe-,Lsiia forming die carried by said column and spaced adjustments therefore, and the structure ofthe press. as described in this invention, are particularly adaptable for use in connection with the forming of optical articles from resinous materials. When forming a mass of resinous material it is not required that tremendous pressures be used, hence the construction of the die carrying members and the dies, can be greatly simplied to the extent wherein lighter structure can be used than has heretofore been common when molding or forming masses of material. Further, I have been able to simplify the die structures, and die carrying members to such an extent that the production cost of the dies and press are considerably reduced, whereby the advantages oi' single mold cavities for the production of optical articles can be used advantageously. When producing arthe same temperature as other portions.

optical work requires exacting production, it may ticles of reslnous material it isvrequired that al1 articles be heated or cooled uniformly. Such uniform cooling or heating is not possible in a multiple mold since fluid passing through the mold will lose some of its heat transfer value, whereby certain portions of the mold are not at exactly Since be seen that such inaccuracies as would result from slightly different expansion of diilerent parts of the mold would be detrimental. Further, since the production of optical articles requires that the mold surfaces be in constant engagement with the articles during forming and also while the articles are being set, it may be seen that any nonuniiormity of spacing of the mold elements would.

cause some of the mold surfaces to permit the formed mass of material to draw away from the mold surfaces. Hence, the follow up of the mold surface. required by shrinkage of the material.

would not be uniform; and would result in con-l uniformity of the articles produced in the multiple mold. Hence, by simplifying the mold'structure. the advantages of single mold structures. such as uniformityV of heating and cooling, uniformity of follow up, and uniformity or surface align-A ment, are brought within the economical range for production use.

This application is a division of my application Ser. No. 363,322, led October 29, 1940.

Having thus fully described my invention, what' I claim as new and desire to secure by Letters Patent is:

1. 'A forming presstfor producing lenses from plastic material comprising a stationary head, a forming die carried thereby, a diaphragm type Ymotor stationarily mounted with respect to said head, a plunger member carried by said motor, a forming die carried by said '.plunger, and substantially friction-free means engaging said plunger for guiding the reclprocable motion thereof as caused by said motor to maintain said die carried by said plunger in axial alignment with said first mentioned die.

2. A forming press for producing lenses from plastic material comprising a stationary head, a forming die carried thereby, a diaphragm type motor stationarily mounted with respect to said head, `a plunger member carried by said motor, a forming die carried by said plunger, and means for adjusting the axis of the dies with respect to their supporting means.

3. A forming press for producing lser, from plastic material comprising a stationary head, a forming die carried by said head, a diaphragm motor stationarily mounted with respect to said head, a supporting column carried by said motor.

from said motor, and substantially friction-free means engaging said column between said motor and said die carried by said column for guiding vertical reciprocable motion of said column to maintain said die carried thereby in axial alignment with said first mentioned die throughout the tain said die carried thereby in axial alignment with said rst mentioned die throughout the stroke of said motor, means extending between said dies and their respective supporting means for supporting said dies thereupon and adjusting the angular relationship of said dies with respect to their respective supporting means, and means extending between said dies and their respective supporting means -for securing said dies upon said adjusting means.

5. A forming press for producing lenses from plastic material which includes a stationary head adapted to support a forming die, a diaphragm motor stationarily mounted with respect to said head and having at least one 4expansible side thereof adapted to assumev the contour of a spherical segment, a supporting column adapted to carry a forming die and supported upon'said motor on the side thereof adapted to assume the contour of a spherical segment and positioned coaxially with the axis of said segment. and substantially friction-free means engaging said column for guiding the vertical reciprocation `thereof as caused by said motor to maintain coaxial alignment between thev dies adapted to be carried by said column and said head.

CHARLES V. SMITH.

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