Source: http://www.google.com/patents/US4807775?dq=7222078
Timestamp: 2014-07-24 12:10:10
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Patent US4807775 - Injection molding of thin-walled plastic products - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign in<nobr>Advanced Patent Search</nobr>PatentsAn injection-molded, thin-walled, plastic product is formed by a mold cavity having a thin-cavity region; a pair of flow channels, which are thicker than the thin-cavity region for directing injected plastic into the thin-cavity region; and a meld chamber, which is thicker than the thin cavity region,...http://www.google.com/patents/US4807775?utm_source=gb-gplus-sharePatent US4807775 - Injection molding of thin-walled plastic productsAdvanced Patent SearchPublication numberUS4807775 APublication typeGrantApplication numberUS 07/027,511Publication dateFeb 28, 1989Filing dateMar 18, 1987Priority dateJan 26, 1987Fee statusLapsedAlso published asEP0355091A1, EP0355091A4, WO1988005404A1Publication number027511, 07027511, US 4807775 A, US 4807775A, US-A-4807775, US4807775 A, US4807775AInventorsJens O. SorensenOriginal AssigneeAcebo CompanyExport CitationBiBTeX, EndNote, RefManPatent Citations (6), Referenced by (8), Classifications (14), Legal Events (7) External Links: USPTO, USPTO Assignment, EspacenetInjection molding of thin-walled plastic productsUS 4807775 AAbstract An injection-molded, thin-walled, plastic product is formed by a mold cavity having a thin-cavity region; a pair of flow channels, which are thicker than the thin-cavity region for directing injected plastic into the thin-cavity region; and a meld chamber, which is thicker than the thin cavity region, is displaced from the flow channels, and is at least partially located extensively between the flow channels for melding plastic flowing together from different directions. The product includes a thin-walled area formed by the thin-cavity region; first and second ribs formed by the pair of flow channels, with the first and second ribs being thicker than the thin-walled area; and a third rib formed by the meld chamber, wherein the third rib is displaced from the first and second ribs and is at least partially located extensively between the first and second ribs, with the third rib being thicker than the thin-walled area. Products that are injection molded to include a rib formed by a meld chamber that is so located have enhanced flexure strength in the portion of the product between the ribs formed by the flow channels.
I claim: 1. An injection-molded, thin-walled, plastic product formed by a mold cavity having a thin-cavity region; first and second flow channels, which are thicker than the thin-cavity region for directing injected plastic into the thin-cavity region; and a meld chamber, which is thicker than the thin-cavity region, and is displaced from the flow channels and at least partially located extensively between the flow channels where molten plastic directed into the thin-cavity region by the first flow channel joins molten plastic directed into the thin-cavity region by the second flow channel for melding plastic flowing together from different directions after flowing through the thin cavity region, the product comprisinga thin-walled area formed by the thin-cavity region; first and second ribs formed by the pair of flow channels, said first and second ribs being thicker than the thin-walled area; and a third rib formed by the meld chamber, wherein the third rib is displaced from the first and second ribs by the thin-walled area and is at least partially located extensively between the first and second ribs, said third rib being thicker than the thin-walled area. 2. An injection-molded, thin-walled, plastic product formed by a mold cavity having a thin-cavity region; a gate, a flow channel, which is thicker than the thin-cavity region for directing injected plastic into the thin-cavity region; and a meld chamber, which is thicker than the thin-cavity region, and is displaced from the flow channel and the gate and at least partially located extensively between the flow channel and the gate where molten plastic directed into the thin-cavity region by the first flow channel joins molten plastic directed into the thin-cavity region by the second flow channel for melding plastic flowing together from different directions after flowing through the thin cavity region, the product comprisinga thin-walled area formed by the thin-cavity region; a gate mark formed at the gate; a first rib formed by the flow channel, said first rib being thicker than the thin-walled area; and a second rib formed by the meld chamber, wherein the second rib is displaced from the first rib and the gate mark by the thin-walled area and is at least partially located extensively between the gate mark and the first rib, said second rib being thicker than the thin-walled area 3. An injection-molded, thin-walled, plastic product formed by a mold cavity having a thin-cavity region; a nonlinear flow channel, which is thicker than the thin-cavity region for directing injected plastic into the thin-cavity region; and a meld chamber, which is thicker than the thin-cavity region, and is displaced from the flow channel and at least partially located extensively between different portions of the flow channel where molten plastic directed into the thin-cavity region by one portion of the flow channel joins molten plastic directed into the thin-cavity region by another portion of the flow channel for melding plastic flowing together from different directions after flowing through the thin cavity region, the product comprisinga thin-walled area formed by the thin-cavity region; a nonlinear first rib formed by the flow channel, said first rib being thicker than the thin-walled area; and a second rib formed by the meld chamber, wherein the second rib is displaced from the nonlinear first rib by the thin-walled area and is at least partially located extensively between different portions of the first rib, said second rib being thicker than the thin-walled area. 4. An injection-molded, thin-walled, plastic product, comprisinga gate mark; a thin-walled area; first and second ribs, which are thicker than the thin-walled area; and a third rib consisting of plastic which flowed together from different directions, which third rib is is at least partially located extensively between the first and second ribs, is thicker than the thin-walled area, and is displaced from the gate mark and the first and second ribs by the thin-walled area; wherein one end of each said rib is closer to the gate mark than another end of said rib; and wherein the end of the third rib that is closest to the gate mark is separated from the gate mark by a greater distance than the ends of the first and second ribs that are closest to the gate mark. 5. A product according to claim 4, wherein the end of the third rib that is farthest from the gate mark is separated from the gate mark by a greater distance than ends of the first and second ribs that are farthest from the gate mark.
6. An injection-molded, thin-walled, plastic product comprisinga gate mark; a thin-walled area; first and second ribs, which are thicker than the thin-walled area; and a third rib consisting of plastic which flowed together from different directions, which second rib is at least partially located extensively between the first and second ribs, is thicker than the thin-walled area, and is displaced from the gate mark and the first and second ribs by the thin-walled area; wherein one end of each said rib is closer to the gate mark than another end of said rib; and wherein the end of the third rib that is farthest from the gate mark is separated from the gate mark by a greater distance than the ends of the first and second ribs that are farthest from the gate mark. 7. An injection-molded, thin-walled, plastic product, comprisinga gate mark; a thin-walled area; a nonlinear first, which is thicker than the thin-walled area; and a second rib consisting of plastic which flowed together from different directions, which second rib is at least partially located extensively between different portions of the first rib, is thicker than the thin-walled area, and is displaced from the gate mark and the first rib by the thin-walled area; wherein one end of each said rib is closer to the gate mark than another end of said rib; and wherein the end of the second rib that is closest to the gate mark is separated from the gate mark by a greater distance than the end of the first rib that is closest to the gate mark. Description
This is a continuation-in-part of Application Ser. No. 007,463 filed Jan. 26, 1987, now U.S. Pat. No. 4,369,519.
A prior art mold for molding thin-walled plastic products having a thin-walled area includes a first mold part and a second mold part defining a mold cavity therebetween, encompassed by a parting line, for forming the plastic product, and further defining a gate for admitting injected molten plastic into the cavity. The mold parts define a thin cavity region for defining the thin-walled area of the plastic product; and first and second flow channels, defining opposite boundaries of the thin cavity region, and for directing the injected molten plastic from the gate into the thin cavity region, whereby the molten plastic directed from the first flow channel joins with the molten plastic directed from the second flwo channel. A "flow channel" is defined as a portion of the mold cavity which directs the flow of molten plastic. Thin-walled plastic products made with such molds are structurally weak, especially in the regions where the molten plastic directed from the first flow channel joins with the molten plastic directed from the second flow channel.
SUMMARY OF THE INVENTION The present invention provides an improved thin-walled plastic product made with a mold of the type described above.
The product of the present invention is made with mold parts that further define a meld chamber, which is portion of the mold cavity that is thicker than the thin cavity region to enhance the melding of plastic flowing from different directions into and joining together in the meld chamber, wherein the thickest portion of the meld chamber is displaced from the gate. The meld chamber is located where molten plastic directed into the thin cavity region by the first flow channel joins molten plastic directed into the thin cavity region by the second flow channel, whereby the strength of the molded thin-walled plastic product is significantly enhanced, particularly in the region of the product defined by the meld chamber.
In one aspect, the product of the present invention is an injection-molded, hollow, thin-walled, plastic product formed by a mold cavity having a thin-cavity region; a pair of flow channels, which are thicker than the thin-cavity region for directing injected plastic into the thin-cavity region; and a meld chamber, which is thicker than the thin cavity region, is displaced from the flow channels, and is at least partially located extensively between the flow channels for melding plastic flowing together from different directions. The injection-molded product of the present invention includes a thin-walled area formed by the thin-cavity region; first and second ribs formed by the pair of flow channels, the first and second ribs being thicker than the thin-walled area; and a third rib formed by the meld chamber, wherein the third rib is displaced from the first and second ribs and is at least partially located extensively between the first and second ribs, with the third rib being thicker than the thin-walled area.
It has been discovered that within the area of the wall between a pair of the ribs, the flexure strength is greater in a direction normal to a line that is generally aligned with the direction of the pair of ribs than in a direction parallel to said line. The greatest flexure strength within such area is in the direction defined by the flow of the molten plastic toward the meld chamber within the meld cavity.
Even though the flexure strength of the ribs in a direction normal to the alignment of the ribs is not as great as the flexure strength in such direction within the area between the ribs when the product is bent along a line generally aligned with the ribs, the ribs are not subjected to as much stress when the product is so bent since the area between the ribs is thinner and bends to absorb most of the stresses applied by such bending.
BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic view of a mold used to make a preferred embodiment of the product of the present invention.
FIG. 3 illustrates a preferred embodiment of a thin-walled plastic product according to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, a mold for use in making a product according to the present invention includes a hollow mold part 10 and a core mold part 11. The core mold part has a retractable inner portion 12 and an outer portion 13. When clamped together to form the mold, the hollow mold part 10 and the core mold part 11 define a mold cavity 14 therebetween for forming a hollow plastic product. The two mold parts 10, 11 are encompassed by a parting line 16 and further define a gate 17 for admitting molten injected plastic into the mold cavity 14. The mold cavity 14 is centered about an axis 18, and the gate 17 is axially disposed in the mold cavity 14. The retractable inner core portion 12 is axially-movable and when protracted, is in contact with the hollow mold part 10 adjacent the gate 17.
A mold defining such primary and secondary flow channels and the use of such a mold are the subject of U.S. patent application Ser. No. 007,462, entitled "Stabilized-Core Injection Molding of Hollow Thin-Walled Plastic Products" filed by the present inventor, Jens Ole Sorensen, on Jan. 26, 1987.
The product 39 is a cup including a thin-walled area 41 having a plurality of protruding spaced-apart ribs 43a and 43b. The ribs 43a are formed by the secondry flow channels 27 and the rib 43b are formed by the meld chambers 30 of the mold cavity 14. The product 39 further includes a gate mark (not shown) formed at the gate 17 of the mold (FIG. 1).
The ribs 43b formed by the meld chambers 30 are at least partially located extensively between the ribs 43a formed by the flow channels 27. Each of the ribs 43a and 43b is thicker than the thin-walled area 41, and has one end that is closer to the gate mark than another end of such rib. The end of each rib 43b that is closest to the gate mark is separated from the gate mark by a greater distance than the ends of the ribs 43a that are closest to the gate mark. Also, the end of each rib 43b that is farthest from the gate mark is separated from the gate mark by a greater distance than the ends of the ribs 43a that are farthest from the gate mark.
Within the area of the wall between a pair of the ribs 43a and 43b, the flexure strength is greater in a direction normal to a line that is generally aligned with the direction of the pair of ribs 43a and 43b than in a direction parallel to said line.
The cross-sectional areas of the respective flow channels and meld channels have approximately the same cross-sectional area, and are elliptical as shown in FIGS. 5 and 6. A circular cross-sectional area is preferrd, as shown in FIGS. 7 and 8, for enhancing the meld. However, if the dimension of the ellipse normal to the breadth of the thin cavity region 28 is reduced in relation to its perpendicular dimension, the stacking height of conical-shaped products made with the mold, such as shown in FIG. 3, is minimized.
FIG. 9 also depicts a product formed with such a mold. This product includes a gate mark 52, a rib 54 formed by a flow channel and a rib 56 formed by a meld chamber. In this product, the rib 56 formed by the meld chamber is at least partially located extensively between different portions 58, 60 of the rib 54 formed by the flow channel; and the end of the rib 56 that is closest to the gate mark 52 is separated from the gate mark 52 by a greater distance than the end of the rib 54 that is closest to the gate mark 54.
FIG. 10 also depicts a product formed with such a mold. This product includes a gate mark 62, a rib 66 formed by a flow channel and a rib 68 formed by a meld chamber. In this product the rib 68 formed by the meld chamber is at least partially located extensively between the gate mark 62 and the rib 66 formed by the flow channel.
Patent CitationsCited PatentFiling datePublication dateApplicantTitleUS2859557 *Jul 9, 1956Nov 11, 1958Best Plastics CorpPlastic flower potUS3070275 *May 2, 1960Dec 25, 1962Poster Packaging IncReusable containerUS3194468 *Jun 11, 1962Jul 13, 1965Somerville Ind LtdPlastic drinking cupsUS3237834 *Jul 29, 1963Mar 1, 1966Sweetheart PlasticsLaminated container and method of making the sameUS3606262 *Apr 1, 1969Sep 20, 1971Impromex AgCup,mug or other drinking vessel,more especially made of plasticUS3944124 *Jul 24, 1972Mar 16, 1976Schmalbach-Lubeca-Werke AgPlastic containers* Cited by examinerReferenced byCiting PatentFiling datePublication dateApplicantTitleUS5008064 *Jun 5, 1989Apr 16, 1991PrimtecInjection-molding dimension-control and clamp-reductionUS5132071 *Jun 12, 1991Jul 21, 1992Sorensen Jens OleUltra thin wall injection molding by utilizing film section insert and flow channels combinationUS5149482 *May 30, 1990Sep 22, 1992PrimtecControlling wall thickness, solidification of initially injected plastic to stabilizer core of moldUS5262112 *Jul 10, 1992Nov 16, 1993PrimtecDimension-control and clamp reduction during injection molding of laminated productsUS5267685 *Feb 25, 1993Dec 7, 1993PrimtecStackability of hollow products with conically contoured sidewalls having longitudinal foldsUS6059432 *Feb 26, 1998May 9, 2000Koito Manufacturing Co., Ltd.Injection molded vehicle lamp and method of makingUS6599460Jul 3, 2000Jul 29, 2003Sorensen Research And Develpoment TrustPrevention of void-based-irregularity formation in thin-wall, injection-molded plastic productEP2607047A1 *Nov 23, 2012Jun 26, 2013Valeo VisionDevice for moulding an element comprising a lip* Cited by examinerClassifications U.S. Classification220/675, 229/400International ClassificationB29C45/00, B65D1/26, B29C45/16, B29C45/36, B29C45/26Cooperative ClassificationB29C45/36, B65D1/26, B29C2045/363, B29C45/0046European ClassificationB65D1/26, B29C45/00H, B29C45/36Legal EventsDateCodeEventDescriptionMay 11, 1993FPExpired due to failure to pay maintenance feeEffective date: 19930228Feb 28, 1993LAPSLapse for failure to pay maintenance feesSep 29, 1992REMIMaintenance fee reminder mailedDec 17, 1991CCCertificate of correctionJan 22, 1988ASAssignmentOwner name: ACEBO COMPANY, 7910 IVANHOE AVENUE, SUITE 203, LAFree format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:SORENSEN, JENS O.;REEL/FRAME:004817/0575Effective date: 19880118Aug 17, 1987ASAssignmentOwner name: PRIMTEC, P.O. BOX 2403, RANCHO SANTA FE, CALIFORNIFree format text: LICENSE;ASSIGNOR:ACEBO COMPANY;REEL/FRAME:004763/0257Effective date: 19870812Owner name: PRIMTEC,CALIFORNIAMay 19, 1987ASAssignmentOwner name: ACEBO COMPANY, 7910 IVANHOE AVENUE, SUITE 203, LAFree format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:SORENSEN, JENS O.;REEL/FRAME:004778/0997Effective date: 19870512RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services©2012 Google