1. Technical Field
The invention relates to laminate tools for molding articles.
2. Background Art
Various tools are conventionally utilized for forming articles using various forming processes, such as injection molding, blow molding, reaction injection molding, die casting, stamping and the like. These tools often utilize a first mold half and a second mold half, each having opposing forming surfaces for collectively forming an article therebetween. The mold halves are often formed separately, and one half translates relative to the other for closing, forming the article, opening, removing the article and repeating these steps.
Often, mold halves are each formed from a solid block of material that is capable of withstanding the stresses, pressures, impacts and other fatigue associated with the forming processes. The mold halves can be formed from laminate sheets.
A first embodiment provides a tool for forming an article in a forming operation. The tool has a plurality of individually formed laminate sheets that are aligned, stacked and assembled to collectively form a tool body, each having a coefficient of thermal expansion. A series of the laminate sheets has a plurality of apertures coaxially formed therethrough. A plurality of pins collectively have a coefficient of thermal expansion and sized to be received within the plurality of apertures the plurality of pins extending through at least a plurality of the laminate sheets and collectively extend through the series of the laminate sheets. The coefficient of thermal expansion of the pins is higher than the coefficient of thermal expansion of the laminate sheets such that the laminate sheets and pins expand to secure each of the pins within each of the apertures to maintain the laminate sheets in stacked alignment after being heated to form the tool.
Another embodiment provides a method for assembling a tool for forming an article in a forming operation. The method comprises forming a first laminate sheet with a profile to define a first portion of a tool body. A first aperture is formed in the first laminate sheet. A second laminate sheet is formed with a profile to define a second portion of the tool body. A second aperture is formed in the second laminate sheet aligned with the first aperture in the first laminate sheet. The first and second laminate sheets are stacked in alignment to collectively provide at least a portion of the tool body. A first pin is inserted into the first laminate sheet first aperture and the second laminate sheet second aperture. The first and second laminate sheets and the first pin are heated such that the first pin expands at a first coefficient of thermal expansion and the first and second laminate sheets expand at a second coefficient of thermal expansion. The first coefficient of thermal expansion being greater than the second coefficient of thermal expansion such that the first pin maintains the first and second laminate sheets in stacked alignment while being heated to form the tool.
In still another embodiment, a tool for forming an article in a forming operation is disclosed. The tool is formed by a method comprising forming a first laminate sheet with a profile to define a first portion of a tool body. A first aperture is formed in the first laminate sheet. A second laminate sheet is formed with a profile to define a second portion of the tool body. A second aperture is formed in the second laminate sheet aligned with the first aperture in the first laminate sheet. The first and second laminate sheets are stacked in alignment to collectively provide at least a portion of the tool body. A first pin is inserted into the first laminate sheet first aperture and the second laminate sheet second aperture. The first and second laminate sheets and the first pin are heated such that the first pin expands at a first coefficient of thermal expansion and the first and second laminate sheets expand at a second coefficient of thermal expansion. The first coefficient of thermal expansion being greater than the second coefficient of thermal expansion such that the first pin maintains the first and second laminate sheets in stacked alignment while being heated to form the tool.
In yet another embodiment, a tool for forming an article in a forming operation is provided. The tool has N number of individually formed laminate sheets that are aligned, stacked and assembled to collectively form a tool body for forming an article in a forming operation and collectively having a laminate sheet expansion rate. A series of the N number of laminate sheets has a plurality of apertures coaxially formed therethrough. The tool has a plurality of pins collectively having a pin expansion rate and sized to be received within the plurality of apertures. The plurality of pins extend through at least a plurality of N number of the laminate sheets and collectively extend through the series of the laminate sheets. The pin expansion rate is higher than the laminate sheet expansion rate such that the N number of laminate sheets and the plurality of pins secures each of the pins within each of the apertures to maintain the N number of laminate sheets in stacked alignment while being heated to form the tool.
As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for the claims and/or as a representative basis for teaching one skilled in the art to variously employ the present invention.
With reference now to
The tool 10 includes a tool body 12, which has a forming surface 14 for forming the article. The tool body 12 is formed from a multiple layer process, for example, a laminate process, such as that disclosed in U.S. Pat. No. 6,587,742 B2, which issued on Jul. 1, 2003 to Manuel et al.; U.S. Pat. No. 5,031,483, which issued on Jul. 16, 1991 to Weaver; and U.S. Pat. No. 7,021,523 B2, which issued on Apr. 4, 2006 to Manuel; the disclosures of which are incorporated in their entirety by reference herein.
As illustrated, the tool body 12 is provided by a series of laminate sheets or plates 16. As discussed in the incorporated references, each of the laminate sheets 16 may be formed individually from a stock material by a cutting operation that cuts each laminate sheet 16 to a predetermined size such that the series of laminate sheets 16 provide a portion of the tool body 12, or provide the entire tool body 12 as illustrated in the embodiment of
As disclosed in the incorporated references, the laminate sheets 16 may be assembled in multiple ways to achieve the desired characteristics of the tool body 12 for providing the forming operation. For example, the laminate sheets 16 may be bonded together by a bonding agent 18 displaced between adjacent sheets. The bonding agent 18 may be an adhesive or a brazing material. For example, if the laminate sheets 16 are each formed of a structural metal, such as stainless steel or aluminum, a brazing material 18, such as a copper sheet or an aluminum sheet, may be displaced between sequential laminate sheets 16, and the tool body 12 may be heated to assemble the adjacent sheets 16 into the collective tool body 12. Alternatively, the brazing material 18 may be displaced adjacent to the tool body 12, and then the tool body 12 and brazing material 18 may be heated until the brazing material 18 wicks between adjacent sheets 16 via capillary action. The tool body 12 is then cooled such that the brazing material 18 bonds the adjacent sheets 16. Alternatively, the brazing material 18 may be cast into the tool body 12 and the brazing material 18 may be conveyed to the gaps between sheets 16.
As laminate tools, such as the laminate tool 10, are assembled by utilization of a bonding agent, brazing operation, or casting operation, fasteners are often employed for maintaining the laminate sheets 16 in stacked alignment to avoid misalignment of the laminate sheets 16. For example, apertures 22, 24, 30 and 32 may be formed lengthwise through the laminate sheets 16 and fasteners may be disposed through the apertures. The apertures 22, 24, 30 and 32 are formed in non-critical areas of the laminate tool 10 to keep structural integrity of the laminate tool 10. Alternatively, stamped projections may be formed through the individual laminate sheets for securing the adjacent laminate sheets 16 together, such as that disclosed in U.S. Published Patent Application 2005/0196232 A1, which published on Sep. 8, 2005 to Manuel, which is incorporated in its entirety by reference herein. Alternatively, the adjacent laminate sheets 16 may be bonded together by a welding operation or by welded fasteners, such as that disclosed in U.S. Published Patent Application 2007/0039153 A1, which published on Feb. 22, 2007 to Manuel, which is incorporated in its entirety by reference herein.
Lengthwise fasteners and sequential interlocking stamped projections are limited in applicability because the cumulative friction of these friction fasteners and the cumulative force along the length is limited and may lead to breaking, warping, misalignment or the like under extreme loading conditions, such as extreme temperatures during brazing or casting or extreme mechanical loads applied during these processes. The stacking of welded fasteners also provides cumulative friction and forces that may lead to breaking, warpage, misalignment or the like.
The loads experienced by the individual laminate sheets 16 of the tool body 12 can be distributed amongst the individual laminate sheets 16 by an array of fasteners interconnecting the laminate sheets 16.
Referring now to
The dowel pins 26, 28 may be formed from a material having a higher expansion rate than an expansion rate of the first laminate sheet 20 and other subsequent laminate sheets. For example, the dowel pins 26, 28 may be made out of nickel or steel. When the dowel pins 26, 28 have a higher expansion rate than the first laminate sheet 20 and other subsequent laminate sheets, heating the dowel pins 26, 28 and the first laminate sheet 20 causes the dowel pins 26, 28 to expand at a faster rate than the first laminate sheet 20 to secure the first laminate sheet 20 and other subsequent laminate sheets together during brazing to maintain alignment.
Any array of apertures is formed through one of the laminate sheets such as the first laminate sheet 20. As illustrated in
In one embodiment, to distribute the loading of the fastened connections, the apertures 22, 24, 30 and 32 are sized for press-fit engagement with a dowel pin. Thus, the apertures 22, 24, 30 and 32 are slightly undersized relative to the dowel pin such that an interference fit is provided, thereby securing the pin to the first laminate sheet 20 once the pin is inserted or pressed into one of the apertures 22, 24, 30 and 32. In another embodiment, the apertures 22, 24, 30 and 32 are sized to receive a pin in a slip fit engagement so that the apertures 22, 24, 30 and 32 are slightly oversized relative to the pin.
Referring now to
The second laminate sheet 34 further includes a second aperture 38 formed therethrough for receiving a third pin 40. The second sheet second aperture 38 may be aligned coaxially with the second aperture 22 of the first sheet 20 for simplicity and design, assembly and uniform distribution of loading.
In continuation of the pattern, a third laminate sheet 42 is provided with a first aperture 44 coaxial with the second sheet second aperture 38 for receiving the third pin 40, thereby fastening the third sheet 42 to the second sheet 34. The third sheet 42 also includes a fourth aperture 46 for receipt of a fourth pin 48. A fourth laminate sheet 50 is provided with a first aperture 52 for receipt of the fourth pin 48 thereby securing the fourth sheet 50 to the third sheet 42.
The fourth sheet 50 also includes a second aperture 54 for receipt of a fifth pin 56. In further continuation of the pattern, a fifth sheet 58 is provided with a first aperture 60, which receives the fifth pin 56 for securing the fifth sheet 58 to the fourth sheet 50. The fifth sheet 58 also includes a second aperture 62, which receives a sixth pin 64 for securing the fifth sheet 58 to an adjacent sheet in the series of sheets 16.
The staggered arrangement of the fasteners to the laminate sheets 16 maintains the stacked alignment of the sheet 16 during the heating and bonding operation, such as brazing or casting within a furnace for reducing the cumulative friction in forces applied to the fasteners and to laminate sheets 16 for adequately distributing the load for reducing failure of the fasteners, or misalignement of the laminate sheets 16. Once bonded, the tool body 12 is at a near net shape, which may be machined or otherwise finished if a higher tolerance is desired.
Referring now to
The tool 10 may have a brazing material 18 that can be introduced in a brazing operation, to facilitate continued alignment of the laminate sheets 16 of the tool. As illustrated, the first and second dowel pins 26 and 40 have a gap 27 therebetween and the second and third dowel pins 40 and 56 have a gap 41. The gaps 27 and 41 avoid interference by the expanding dowel pins 40 and 56 since the dowel pins 40 and 56 expand at a faster rate than the laminate sheets 16 when heated to form at least a portion of a tool. The gaps 27 and 41 may exist between corresponding dowel pins 16 and 40, and 40 and 56 even after the heating and brazing operation. After the brazing operation, between each of the laminate sheets 16, a braze thickness per plate may be 0.0008 of an inch.
Referring now to
The tool 10 may have a brazing material 18 that can be introduced in a brazing operation, to facilitate continued alignment of the laminate sheets 16 of the tool and fill in any gaps which exist between the pins 26, 40 and 56. The gaps filled by the brazing material 18 exist to avoid interference by the expanding dowel pins 40 and 56 since the dowel pins 40 and 56 expand at a faster rate than the laminate sheets 16 when heated. After the brazing operation, between each of the laminate sheets 16, a braze thickness per plate may be 0.0006 of an inch.
Laminate tools, such as the tool 10 illustrated in
Adjacent sheets are then stacked in alignment at step 78 and fastened together at step 80 by insertion of a dowel pin in a hole of one sheet, such as the first aperture 22 in the first sheet 20 and through other subsequent sheets and insertion of another dowel pin into the aperture 32 provided at an opposite corner. Additional sheets may then be added and dowel pins may then be inserted through apertures aligned with apertures 24, 30 of the first sheet. These steps are repeated, as illustrated in
Of course, the invention contemplates utilizing other laminate tool features, such as heat transfer lines for heating or cooling the forming surface 14 and the article formed by the forming surface 14 in combination with the fastener arrangement disclosed herein.
While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention.