JPH04135153A - Injection molding plastic lap - Google Patents

Abstract

PURPOSE: To reduce weight of a lap, to reduce the manufacturing cost, and to facilitate manufacture by forming a main body as an integral injection- moldings of a polymer reinforced by fiber and/or an inorganic substance. CONSTITUTION: A lens polishing lap 10 is composed of a main body 12 which has the front side part and the rear side part and is integrally injection-molded by a polymer reinforced by fiber and/or an inorganic substance. A front face of this lap 10 curves, and is suitable for receiving a polishing pad. The rear face of the lap 10 is also constituted by having the skeletal rib structure part 19 having projecting plural mutually connected ribs 20, 22, 24, 26. The polymer suitable for forming this lap 10 contains various crystalline polymers and copolymers having adequate chemical resistance, strength, rigidity and thermal resistance. Thus, the plastic lap 10 can be accurately/quickly/inexpensively manufactured by integral injection molding, and weight can also be reduced.

Description

[Detailed description of the invention]

[0001]

[Industrial application field]

The present invention is suitable for polishing, fining and polishing glass and plastic eye lenses.
The present invention relates to wrapping articles used for ishing, and in particular to wraps made of plastic. [0002]

[Conventional technology]

Wrapping of glass eye lenses is originally done by rotating and/or vibrating the wraps against a roughly polished glass lens placed between cast iron wraps to polish, fine and polish the blank. It was conducted. Eventually, polishing machines were developed to perform the polishing process, but fining and polishing continued to be done with cast iron laps. Among the disadvantages of cast iron wraps were that the wraps wore quickly and often required recutting and readjustment. Also, cast iron laps were quite heavy, causing rapid bearing wear and placing limitations on the maximum vibration speeds that could be achieved and the energy efficiency of the lap drive mechanism. [0003] Finally, the actual use of rough abrasives was gradually discontinued in favor of attaching replaceable polishing pads to the lap surface. Because the wrap itself is subject to less wear, the wrap can be formed from materials that are less tough and lighter in weight than cast iron, such as aluminum and plastic. German Patent Application Publication No. 3640678 and 3
No. 712,148 describes a plastic wrap for use with replaceable pads. The wrap described herein is a solid structure with conventional side notches and a central rectangular opening in its bottom surface for proper alignment with the surface of the receiver to which the wrap is to be attached. [0004] The weight reduction provided by the plastic wrap reduces the rate of bearing wear and improves the efficiency of the wrap drive mechanism. However, if the wrap weight can be further reduced,
There is room for improvement. [0005] Furthermore, the technology currently available for manufacturing plastic wraps is limited by the need to achieve and maintain precise curvature of the padding front surface of the wrap. In this regard, the primary function performed by such a wrap is to give the polishing pad a suitable shape, the pad being flexible and assuming the shape of the front surface of the wrap. This surface must therefore exhibit the true optical curvature imparted to the lens. It is therefore necessary that the technique for making the plastic wrap ensures that the proper curvature of the front surface is maintained. [0006] One method of manufacturing solid plastic wrap is to extrude a solid cylindrical plastic and then cut the cylinder into disks. then machining a curved surface on one side of the disk to define a pad support surface;
The other side of the disk is cut to form the side notches and a central rectangular opening. Due to its solid construction, the wrap exhibits sufficient strength to maintain the shape of the polishing pad applied to it. However, wraps made using such technology are extremely expensive. Wrapping is a faster and less expensive technology,
For example, it cannot be made by high-speed injection molding. The reason for this is that such large solid plastics cool too slowly in the mold, shrink excessively as they cool, and shrink in different directions and at different rates, which causes the resulting wrap to warp and lengthen the forming cycle. This is because it is too much. [0007]

[Problem to be solved by the invention]

Therefore, not only does it provide a lightweight wrap, but it also provides a faster layering process.
The object is to provide a wrap that is inexpensive and can be made using more precise techniques. [0008] Such semifinished plastics can also be precisely cut on a standard lap cutting machine, as has heretofore been done with solid plastics and aluminum wraps to match the precise curvature desired on the lens surface. It is desirable that the front surface curvature can be easily machined. [0009]

[Means to solve the problem]

FIELD OF THE INVENTION This invention relates to wrapping articles used for polishing, fining and polishing glass and plastic ophthalmic lenses, and more particularly to plastic wraps. [0010] The wrap has an integrally injection molded polymeric body with a curved front surface adapted to receive a polishing pad for polishing, fining and polishing glass or plastic ophthalmic lenses. A skeletal rib structure projects from the rear side of the wrap, the structure comprising a plurality of interconnected ribs, the polymer comprising fibers and/or mineral reinforcement. [0011] In a preferred embodiment, the rear side of the wrap includes an annular peripheral rim extending along at least a portion of the outer periphery of the rear side and radially inwardly of the rim and relative to the rim in a direction toward the front. and a recessed surface with the skeletal rib structure projecting rearwardly from the recessed surface. [0012] Preferred polymers suitable for forming the wrap are various homopolymers and copolymers of polyester, polyacetal, polyamide, polysulfide, and polyimide. [0013] Next, the present invention will be explained with reference to the drawings. Objects and advantages of the invention will become apparent from the following detailed description of the preferred embodiments. However, the same numbers in the drawings indicate the same items. [0014] As shown in FIGS. 1 and 2, the wrap 10 of the present invention has a curved front surface 14 adapted to receive a polishing pad for polishing, fining or polishing glass or plastic eye lenses. An integral injection molded body 1 having
It has 2. The curvature of the front surface therefore corresponds to the shape of the lens surface being created. The molded front curvature of the semi-finished plastic wrap is close to the desired lens surface curvature while the final exact curvature is cut on a standard wrap cutter as is done for aluminum and plastic wraps. [0015] The rear side of the body 12 has an annular peripheral rim 15 that extends along at least a portion of the outer circumference of the body 12. The rim 15 includes an annular ridge 16 with a rearwardly facing annular surface 17. A recessed surface 18 is arranged within the confines of the rim 15, which extends into the rim in a direction towards the front surface 14. It is preferred that the recessed surface 18 is generally curved to complement the front surface 14. [0016] A skeletal rib structure 19 projects rearwardly from the recessed surface 18. The rib structure 19 has a pair of parallel main ribs 20 which are recessed radially inwardly at the rim 15 to form side notches 21 (see FIG. 3). A plurality of short parallel second ribs 22 interconnect the main ribs 20 . The two second ribs 22 are spaced apart to define a central rectangular opening 23 . The plurality of intermediate ribs 24 are
It is arranged parallel to the main rib 20 and interconnects the second rib 22. A pair of end ribs 26 extend parallel to second rib 22 and interconnect each major rib 20 with ridge 16 . The ends of the main rib 20 are interconnected by a curved wall 28 defining a high extension of the beam 16. [0017] The cross-sectional thickness t of the rib (see FIGS. 5 and 6) and the cross-sectional thickness t' between surfaces 14 and 18 (see FIG. 6) are 1.27
Preferably, it does not exceed 0.5 inches. The thickness of these is 0.25~0.89cm (0.1~0.3
most preferably in the range of 5 inches). As a result of this, it cools quickly enough to be made by high speed injection molding. [0018] As a result of such construction, the wrap can be economically formed by high speed injection molding processes. i.e. the maximum cross-sectional thickness of the ribs and front part is 1.27 cm (0.5 inch)
As such, the injection molded wrap cools quickly enough to be compatible with high speed injection molding. Furthermore, the rib structure provides the anterior surface with sufficient strength and rigidity to ensure that it retains its shape while in contact with the lens from which it is made. Therefore, the lens is molded with an appropriate curvature. [0019] In addition to being moldable, the polymer used to make the wrap must have suitable stiffness, strength, heat resistance, and stability against chemical attack, such as resistance to organic solvents, for repeated use as a wrapping tool. Must have drug properties. Suitable materials include crystalline engineering plastics. Crystallinity provides the necessary chemical resistance, and together with the specific molecular structure of the polymer, crystallinity provides engineering properties such as strength and stiffness. [0020] Chemical resistance is important because typical formulation laboratories use chemicals such as acetone or other ketones and esters that readily dissolve most amorphous polymers. [0021] However, the present invention is not limited to the use of crystalline polymers, but encompasses any type of polymeric material that is suitable for injection molding and has the necessary engineering properties and chemical resistance. [0022] Specific strength and stiffness and/or other properties of the polymer;
For example, the expected life of the wrap, the size of the wrap, and the curvature of the wrap are dictated by the particular intended use. One skilled in the art can readily select a particular polymer with the required properties based on known properties of polymers, such as strength and modulus values. [0023] Examples of polymers useful in the present invention include homopolymers and copolymers of polyesters and polyacetals, polyamides, polysulfides, and polyimides. Although polyamide inlays of nylon have good properties, some absorb significant amounts of water and change dimensions during actual use. Other polyamides absorb less water but are more expensive. Polysulfides and polyimides both have good properties, but are significantly more expensive. [0024] Specific examples of suitable polymers include polybutylene terephthalate, polyethylene terephthalate, polyoxymethylene, various nylons, polyphenylene sulfides, and polyimides. [0025] Preferably, the polymer is filled. Unfilled polymers are strong and chemically resistant, but often cannot be easily processed by injection molding. The reason for this is that upon cooling, various excessive shrinkages occur in the flow direction and in the transverse direction. Moreover, unfilled polymers cannot be made to maintain easy tolerances because they warp on cooling. Incorporation of inorganic fillers, which may be glass or carbon fibers, allows for more or less uniform shrinkage. Warpage is generally eliminated and the molded part maintains the required tolerances. [0026] Typical short glass fibers useful as fillers are about 0.015
cm to approximately 0.036 cm (approximately 0.006 to approximately 0.014
Suitable long fiber glass consists of fine grains with a length of about 0.25 cm to about 0.76 cm (about 0.1 inch).
to about 0.3 inch), with a length of about 0.200 inch being typical. [0027] Typical inorganic fillers are finely divided and incorporated with calcium carbonate or mica. The filler content can range from about 10 to about 50% by weight of the polymer composition;
The polymer itself constitutes about 90 to about 50% by weight. The preferred amount of filler is from about 20 to about 45 weight percent, with the balance being polymer. The mineral filler to glass ratio can range from 100% mineral to 25% mineral and 75% glass. Similar ratios apply to the use of carbon fiber fillers. [0028]

【Example】

The invention will be illustrated by the following examples and comparative examples. For comparison, thickness (3,66 cm) machined from a molded block of an unfilled polymer blend of polystyrene and polyphenylene oxide under the trade name Noryl N-190 from General Electric Company.
, 44 inches) resulted in a useful but heavy wrap. This wrap contains acetone and other common laboratory chemicals such as Pad Cement Solvent, Cobain Optical Part Number 9839-70.
It had no chemical resistance because it was attacked by a solution of a ketone and an aromatic solvent called . [0029] Comparative Example Injection molded from unfilled polybutylene terephthalate under the trade name Barox 325 from General Electric Company Thickness (3.10 cm) 0. ,22
inch) solid wrap had a longer molding cycle (3 minutes or longer). Excessive shrinkage and warping was observed. This wrap could not be used. [0030] Comparison Hollow core rough rough injection molded from unfilled polyoxymethylene under trade name Delrin 500 from Hirochi E.I. DuPont Co., Ltd. Large section thickness 0.838 cm (0.33
0 inch); Height 3.51cm 0. ,38 inches))
0. had a short molding cycle. (less than 10 minutes) showed unacceptable non-uniform shrinkage and poor dimensional reproducibility. This wrap could not be used because it warped. [0031] For implementation ↓ Thin (2,46 cm) (0,9 finch) injection molded polybutylene terephthalate filled with 20% mineral and 20% glass under the trade name Barox 735 from General Electric Company. ) had a long molding cycle. This wrap exhibited more controllable and uniform shrinkage and could be used over a range of curvatures. [0032] Example Lid A thin (25%) injection molded lid from 25% mineral-filled polybutylene terephthalate under the trade name Barox 745 from General Electric Company.
, 46 cm) (0.9 finch) solid wrap had a longer molding cycle. This wrap exhibited layer-controllable and uniform shrinkage and could be used for a range of curves. [0033] Hollow core trap (maximum cross-sectional thickness 0.838
cm (0,330 inches); height 3°51cm0. ，
0.38 inch) had a short molding cycle. minutes). This wrap had minimal and uniform shrinkage and good dimensional reproducibility. Once the wrap was available, the optical surface could be machined over a full range of curves. [0034] Example ↓ Hollow core trap injection molded from 25% mineral-filled polybutylene terephthalate under the trade name Barox 745 from General Electric Company (maximum cross-sectional thickness 0.838 cm (0.330 inches); high 3.51 cm 0., 38 inches) has a short molding cycle. (less than 1 minute) exhibits minimal and uniform shrinkage and good dimensional reproducibility. This wrap was usable and the optical surface could be machined over a full range of curvature. [0035] A hollow core trap injection molded from a 33% glass-filled polyamide under the trade name Zytel nylon 70G-33L from EI DuPont.
Maximum cross-sectional thickness 0.838 cm (0,330 inches);
Height 3.51cm 0. , 38 inches)) had a short molding cycle. minutes). This wrap had minimal and uniform shrinkage and good dimensional reproducibility. This wrap could be used over a full range of curves.

[Brief explanation of drawings]

[Figure 1] FIG. 2 is a perspective view of the wrap of the present invention seen from the rear side.

[Figure 2] FIG. 3 is a bottom view of the wrap of the present invention.

[Figure 3] Figure 3 is a side view of the wrap viewed in the direction of arrow A in Figure 2;

[Figure 4] Figure 3 is a side view of the wrap viewed in the direction of arrow B in Figure 2;

[Figure 5] Cut along line 5-5 in Figure 2 and look in the direction of the arrow.

[Figure 6] Cut along line 6-6 in Figure 2 and view in the direction of the arrow

[Explanation of symbols]

wrap One-piece injection molded body curved front rim annular ridge annular surface concave surface Skeletal rib structure main rib side notch 2nd rib rectangular opening middle rib end rib curved wall It is a sectional view of a whelk. It is a sectional view of a whelk.

【Document name】

drawing

[Figure 4]

[Figure 5] [Figure 61

Claims (1)

[Scope of Claims] [Claim 1] A wrap for holding a polishing pad when making an eye lens surface, including a front side and a rear side, a curved front formed on the front side and the rear side. a body having a skeletal rib structure having a plurality of interconnected ribs projecting from the body, the body being integrally injection molded of a fibrous and/or inorganic reinforced polymer; A wrap to do. 2. The rear side comprises an annular peripheral rim extending along at least a portion of the outer periphery of the rear side and a rib disposed radially inwardly of the rim in a direction toward the front side. 2. The wrap of claim 1, wherein the wrap has a recessed surface, the skeletal rib structure projecting rearwardly from the recessed surface. 3. The wrap of claim 2, wherein said rim includes an annular ridge having a rearwardly facing annular surface. 4. said skeletal rib structure comprising two parallel first ribs extending radially inwardly relative to said rim portion to define two side notches; Wrap according to claim 2 or 3, characterized in that it comprises additional ribs extending between the first ribs. [Claim 5
10. The wrap of claim 4, wherein said additional ribs include second parallel ribs defining a generally central rectangular opening. 6. The wrap of claim 5, wherein said additional ribs include at least two third ribs extending between said first rib and said rim. 7. A wrap according to claim 1, wherein each rib has a cross-sectional thickness not greater than 0.50 inches. 8. The wrap of claim 7, wherein each of said ribs has a cross-sectional thickness not greater than 0.35 inches. Claim 9: Each rib is 0.25 to 0.89 cm (0.1
9. The wrap of claim 8, wherein the wrap has a cross-sectional thickness ranging from 0 to 0.35 inches. 10. A wrap according to claim 2, wherein the maximum thickness between the front surface and the recessed surface is 1.27 cm (0.50 inch). . Claim 11: The maximum thickness is 0.89 cm (0.35 cm).
11. The wrap according to claim 10, wherein the wrap is 1.5 inches. 12. A wrap according to claim 1, wherein the fiber- and/or mineral-reinforced polymer consists of fibers and/or mineral filler and a polymer. Claim 13: 20 to 45% by weight of polymer and filler.
13. A wrap according to claim 12, characterized in that it is a mixture of 80 to 55% by weight of polymer. 14. A wrap according to claim 12 or 13, characterized in that the filler is a combination of 100-25% by weight of inorganic material and 0-75% by weight of glass. 15. The wrap according to claim 12, 13 or 14, wherein the polymer is a crystalline polymer. 16. The wrap according to claim 15, wherein the polymer is polyester, polyacetal, polyamide, polyimide or polyphenylene sulfide. 17. The wrap according to claim 16, wherein the polyester is polybutylene terephthalate or polyethylene terephthalate. 18. The wrap according to claim 16, wherein the polyacetal is a polyoxymethylene homopolymer or copolymer. 19. The filler is about 0.015 to about 0.036c.
19. A wrap according to any one of claims 12 to 18, characterized in that it comprises staple glass fibers sized to have a length of about 0.006 to about 0.014 inches. Claim 20: The filler is about 0.25 to about 0.76 cm (
20. A wrap according to any one of claims 12 to 19, characterized in that it comprises long fibers sized to have a length (from about 0.1 to about 0.3 inches). 21. A wrap according to claim 12, wherein the filler comprises calcium carbonate and/or mica.