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Publication numberUS2991216 A
Publication typeGrant
Publication dateJul 4, 1961
Filing dateMar 26, 1957
Priority dateMar 26, 1957
Publication numberUS 2991216 A, US 2991216A, US-A-2991216, US2991216 A, US2991216A
InventorsMing C Hsu, Ralph M Stallard
Original AssigneeGen Motors Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method for making and embossing decorative articles
US 2991216 A
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Description  (OCR text may contain errors)

July 4, 1961 MING Hsu ETAL 2,991,216

METHOD EoR MAKING AND EMBossING DECORATIVE ARTICLES Filed March 26, 1957 2 Sheets-Sheet 1 @Hafer/aon:

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METHOD FOR MAKING AND EMBOSSING DECORATIVE ARTICLES Filed March 26, 1957 2 Sheets-Sheet 2 4% j? l/Z1 y L/ f j? INVENTORS.

wie ai@ e Byap/wzfQ/ymz Unted States PatentO This invention relates to a method and apparatus for making and embossing decorative articles and more particularly to a continuous method for making and embossing inlaid decorative articles by means of dielectric heating.

Dielectric heating is a selective heating process whereby heat can be `developed within an electrical insulating or f dielectric material. Since the dielectric material is one which also does not normally conduct any appreciable amount of electrical current, dielectric heating does not result from the resistance of the material to current flow but rather from the frictional heating caused by the forced back and forth rotating movement of the molecules of the material. The force that produces the heating will be uniform throughout the material if the material has a uniform molecular arrangement and if the electrical field strength is uniform.

When the d-ielectric material is placed in an electrical L field such as exists between two plates or electrodes having a voltage impressed across them whereby one of the planes is operative and the other is negative, the molecules of the dielectric material appear to stretch out and elongate themselves so that one end of the molecule has a positive charge which points toward the electrode with the negative charge and the other end of the molecule has a negative charge which points toward the electrode with the positive charge.

If the charge between the plates is reversed so that i the positive plate now becomes negative and vice versa, the molecules will rotate to realign themselves. Thus, if an alternating current of radio frequency is impressed across the electrodes, the electrodes will continually change their charge and the molecules of the dielectric material will be forced to rotate back and forth as the electrodes change their charge. As the molecules of the dielectric material rotate back and forth, heat will be developed within the dielectric material, although the electrodes will not become heated except by conduction from the heated dielectric material if they are in contact therewith.

This invention utilizes the property of dielectric materials to become heated when subjected to an alternating current of radio frequency to provide a method for making and embossing inlaid decorative articles by means of dielectric heating, and, in its preferred embodiment, provides a continuous method for cutting a finite portion from a sheet of thermoplastic material and embossing the finite portion on a trim assembly by means of dielectric heating.

In the preferred embodiment of the invention, a holder for the sheet of thermoplastic material includes a pair of releasable members having openings therethrough which are aligned when the members are assembled. The sheet of thermoplastic material is secured in place between the members so as to be held taut across the openings therethrough.

One of the members of the holder is provided with a facing of resilient material.

The heating off the sheet of thermoplastic material and also the trim assembly is provided by a dielectric heating press. Such presses are commonly known and used and, therefore, the details of the press are unimportant to Van understanding of the invention. However, it will be under- 2,991,2l6, ,.aienfed Jalye. ,1.961,

P ice stood that the press generally includes a lower or stationary press electrode and anvupper or movable press electrode having a die secured thereto of the desired size or shape of the finite portion to be cut from the sheet of thermoplastic material and subsequently embossed on the trim assembly. y v The trim assembly is supported on the lower electrode of the press. Although the subject method may be used with various types of trim assemblies, as-will be hereinafter set forth, it is preferred that all of the trim assemblies include an outer sheet of thermoplastic material which may be provided with one or more'b'acking or other layers as desired. 'Ihe holder for the sheet of thermoplastic material is supported upon they outer sheet ofthermoplastic material of the trim assembly, with the facing of resilient material of the holder in` engagement therewith. When the holder has been positioned on the outer sheet of thermoplastic material of the trim assembly, the upper press electrode is moved downwardly until the die engages the portion of the sheet' of thermoplastic material held taut across the opening of the holder. Thereafter, as the diev continues to be lowered, it will depress ,a finite portion of the sheet of thermoplastic material 'out of the plane thereof under tension and move this finite portion into engagement with the outer sheet of thermoplastic material of the trim assembly. During this forcing of the finite portion out of the plane of the sheet of thermoplastic material, thek resilient facing of the holder will be partially compressed. An Valternating current of radio frequency is then impressed across the upper and lower electrodes of the press. Since the electric field will concentrate around the edge of the die, the concentration of the field between the die and the lower electrode will be greatest immediately adjacent the periphery of the die. Thus, a relatively narrow continuous area of the thermoplastic material immediately adjacent the die will become heated to the highest temperature to cause this narrow area to be softened. The tens-ion in the sheet of thermoplastic material will thereupon cause the finite portion of the material to become cleanly separated along the relatively narrow area of highest temperature. vThe separation of the finite portion will also allow the resilient facing of the holder to shift the frame upwardly and remove the remainder of the sheet of thermoplastic material away from the finite portion and die face. Thus, the finite portion is cut from `the remainder of the thermoplastic sheet solely by means of dielectric heating. v 'The finite portion remains in engagement with the outer sheet of the trim assembly after the cutting operation and the electric ield passing between the die and the lower press electrode will subsequently emboss the finite portion on the trim assembly. Since the remainder of the sheet of thermoplastic material which was cut has been moved out of engagement with the finite portion and the trim assembly by means of the resilient Ifacing of the holder, there is no chance that the remainder of the sheet of thermoplastic material will in any way interfere with this embossing operation. Thereafter, the press may be opened and the holder removed. The finished trim as,- sembly may then be removed and will `comprise a trim assembly having an outer sheet of thermoplastic material provided with an insert which is embossed'thereon. Thus, this invention provides a continuous method for cutting a finite portion from a sheet of thermoplastic material and embossing the finite portion on a trim assemblyV by means of dielectric heating.

The primary object of this invention is to provide an improved method for making and embossing inlaid decorative articles. Another object of this invention is to provide a method for cutting finite vportions from thermoplastic material and securing the portions on trim assemblies by means of dielectric heating tovmake Iinlaid decrativearticles. more Yspecific object of this invent i's vt 'pim/ide 'c'tiis method for 'cutting a finite portion from a sheet of thermoplastic material and embossing this portion on a sheetpofvthermoplastic material of 'a t'rim assembly by means of 'dielectric-heating to make an `.inlaid 'and embossed decorative article.

These arid fother objects "of this invention will be readily apparentfrom the following specification and drawings, in which: 1 h FIGURE l is a schematic view ofa dielectric press having the sheet of thermoplastic material positioned therein prior 'to the cutting operation; Y e

'FIGURE 2 it a view similar to FIGURE l and showing the press and sheet of thermoplastic material during the jcuvtt'ipg operation; 4

FIGURE 3 is a view of the holder for the sheet of thermoplastic material; I e e FIGURE 4 is a sectional view taken on the plane indicated bylinerj4-4 of FIGURE 3;

vFIGURE. 5 is fa view of thedie;

FIGURE 6 is a sectional view taken on the plane indicated hy line `6--6 o f FIGURE 5; and

,Y FIGURE 7 is an 'enlarged view of a portion of FIG- URE 6. V h p a Before 'proceeding lwith a further description, it will beunderstood that the subject method may either be used to cut nite portions from sheets of thermoplastic material without 'any further 'operation on the finite portion pr may be used to cut the finite portion and then emboss the finite portion on a trim assembly in a continuous oper/ation.

Although this invention is herein disclosed and claimed in conjuhction with a continuous operation for making inlaidfah'd 'embossed decorative articles, reference may be had toV applicants co-'pending application, Serial No. 648.673, 4filed March 26, 1957, and assigned 'to the assignee 'of the present invention, for a further disclosure of the `cutting operation which 'is claimed therein.

Referring now to FIGURE l of the drawings,'a dielectric heating press of common type includes a lower or stationary-press electrode `10 and an upper or movable press electrode 12 which is movable toward and away from the lower press electrode by suitable operating means. An alternating current lgenerator 14 is connected 'inseries with the upper and lower press electrodes in order to impress an alternating current of radio frequency therebetween. `One or more buffer sheets l16 of silicone rubber or butyl rubber are laid on the lower press electrode in order to prevent arcing between the upper and `lowerfelectrodes when the press is closed and also to provide a resilient support for a trim assembly 17 to insure equal pressure of the die on all areas of the trim assembly engagedthereby. As previously mentioned, the sublject invention will be described in conjunction with a continuous operation wliereby a finite portion is cut from a sheet 4o'f thermoplasticmateril and then embossed on a rrtrim assembly.

Although one particular trim assembly 17 will now be 'described it will be understood that other trim assemblies iriay'b'e liis'ed with equal Ysuccess as hereinafter set jforth.

The Vtrim as's'embly17 includes a backing 18 which is suppbr'ted bythe sheets 16 on the press `electrode 10. The'b'acking may Abe-cardboard `or Kraft board or may be ofother rigidysemi-rigidfor exible material as desird. Immediately adjacent the backing, a layer of riser 'material 20pisiprovided. This riser material may be hair 'or wool padding which has been impregnated with a *thermoplastic material in fiber or powdered form. A sheet-22 of trim material is then laid upon the layer of riser material. The trim material may be any thermo- 'plastic material such as vinyl chloride, vinylidene cholride either supported or unsupported, other plastics or synthetics formed into iexible` sheets, or leather, etc.

As'previously mentioned, other trim'assembliesemay be used with equal success, but it is preferred that the trim assembly include an outer sheet of thermoplastic material. Excellent results have been obtained with a trim assembly of the type disclosed in application Serial No. 538,914, tiled October 6, 1955, Dusina et al., and assigned to the assignee of the present invention. The trim assembly disclosed in this application includes an outer sheet thermoplastic material and a backing of sponge rubber. During the embossing operation, portions of the thermoplastic sheet and the sponge rubber are depressed and are fused together by means of dielectric heating. Excellent results have also been obtained from a trim assembly which comprises only a sheet 22 of 16 gauge thermoplastic material provided with a fabric backing, without any backing or other intermediate layers between the sheet 22 and the buffer sheets 16. Thus, although a particular trim assembly 17 has been disclosed and described herein, it is obvious that other trim assemblies maybe used as long as the trim assembly includes the outer sheet of thermoplastic material, which may be supported or unsupported as desired.

Referring particularly to FIGURES 3 and 4 of the drawings, the frame or holder 28 for the sheet of thermoplastic material to be cut will now be described. The holder generally comprises upper and lower members 30 and 32, respectively, which are provided with central openings 34 and 36 in alignment with each other when the holders are in assembled relationship as shown. A number of openings 38, which may be equally spaced or otherwise are provided around the opening 36 in the lower member 32. A needle 40 is forced within each of the openings 3,8 and extends upwardly from the lower member 32. The needles are preferably formed with uniform conical points, as shown, to prevent tearing of the sheet of thermoplastic material, when assembled therewith as will be described. When the members 30 and 32 are assembled, 'the conical points of the needles are received within openings 42 in the upper member 30, with the number of openings 42 being equal to the number of openings 38, although the openings 40 are larger. Thus, it Vmay be seen that the upper and lower members may be assembled by positioning the needles 40 of the lower member V32 within the openings 42 of the upper member and then moving the members together to align the openings 34 and 36.

In order to accurately assemble the members, three studs 44 are xedly secured within openings 46 in the lower member 32 and are received within openings 48 in the upper member which are of substantially the size Aof the studs. It will be noted that the studs are unequally positioned so that it is impossible to assembly the 'upper and lower members in the wrong manner. In order to provide a means for separating the members, portions 50 of opposing side edges of the upper and lower members are cut out to provide linger grips.

When the upper and lower members are disassembled, a sheet 52 of thermoplastic material is forced over the conical points of the needles 40 in the lower member so that the sheet of thermoplastic material is tautly held across the opening 36 of the lower member. Thereafter, the upper member 30 is assembled with the lower mem- Iber so ythat ,the sheet of thermoplastic material is tautly held across the aligned openings 34 and 36 of the members. Since the sheet of thermoplastic material is under tension during the cutting operation, it is preferred that the needles`40 have uniform conical points to prevent `tearing of the sheet when under tension.

It is preferred that the sheet of thermoplastic material be unsupported,ri.e., have no fabric or other backing. `Excellent results have been obtained with sheets of vinyl chloride and vinylidene chloride of sixteen gauge, although other gauges of the material or of other materials may be used. However, it is preferred that all be in sheet form. The sheet may be of any known thermoplastic material, such as -vinyl` chloride, vinylidene chloride, etc., and may be tooled or otherwise provided with a decorativeI surface. The sheets may also be of any color desired.

It will be noted that the llower member 32 of frame 28 is provided with a continuous facing 54 of resilient material secured to its free surface. This resilient material may either be foam rubber, polyurethane foam, or sponge Silicone rubber, with the latter two materials being preferred over the former material. The purpose of the facing 54 will be hereinafter discussed. After the sheet of thermoplastic material 52 has been assembled within the frame or holder, the holder is then positioned on the sheet 22 of trim material, with the facing 54 of resilient material on the lower member of the holder in engagement therewith. Thus, the sheet 52 of thermoplastic material is positioned in a horizontal plane generally parallel to the lplane of the lower press electrode and sheet 22.

A die 56 is secured in a suitable manner to the upper or movable press electrode 12. Referring now to Figures 5 and 6, one or more openings 58 may be provided in the die to receive bolts which may be threaded into the electrode to .rigidly secure the die in place. The die generally comprises a block of thermally conductive metal, such as steel, bronze, brass or copper, or other material. The outer periphery of the die generally comprises a continuous vertical wall 60 which defines the size or shape of the finite portion to be cut from the sheet 52 of thermoplastic material.

A continuous rib 62 provided at the juncture of wall 60 with the flat or horizontal base wall 64 of the die controls the cutting of the finite portion from the sheet 52 of material and also acts to provide an embossing line around the periphery of the finite portion when the finite portion is embossed on the trim assembly 17. It is preferable that the rib 62 be integral with the material ofthe die although it may be formed separate and secured thereto in a suitable manner if so desired. It is also preferable that the outer wall 65 of the rib 62 be coplanar with or a continuation of the vertical wall 60 of the die and that the inner wall 66 thereof be generally parallel to the outer wall. The radius of the outer edge 67 of rib 62 controls the electrical field around the outer edge of the die to cause selective heating of the sheet 52 of thermoplastic material in a relatively narrow area immediately adjacent the outer edge of the die as will be described. Although the radius is not critical, it is preferable that it be from .005 to .010 inch.

If additional embossing lines are desired within the periphery of the finite portion, one or more embossing ribs 70, equally spaced or otherwise, may be provided within the continuous -rib 62 as shown in Figure 5. As indicatedrin Figure 1 of the drawings, the ribs 70 extend outwardly from the base wall 64 of the die a greater distance than does the rib 62. Although the disparity in extent is somewhat exaggerated in Figure l, it is preferred that the embossing ribs extend outwardly further from wall 64 of the die from .010 to .060 inch morey than does the rib 62. In addition, it is also preferred that the edges 72 of ribs 70 be formed on a .03125 inch radius, as compared to a radius of .005 to .010 inch for the edge 67 of rib 62. The reason for this arrangement of the extent and radius of the ribs 70 and 62 will be hereinafter described.

When the trim assembly and the holder 28 with its sheet 52 of thermoplastic material have been positioned within the press, as shown in Figure 1, the upper or movable press electrode 12 is moved downwardly until the die 56 engages the sheet S2 of thermoplastic material within the openings 34 and 36 of the holder and depresses a finite portion 74 thereof out of the horizontal plane of the material and into engagement with the sheet 22 of thermoplastic material, as shown particularly in Figure 2. 'Ihis finite portion 74 lies in a horizontal plane and is generally of the shape of the outer periphery of the die 56 as Adefined by the wall 60 thereof and the outer wall 65 of yrib 62. The portion 74 is joinedto the remainder portion 75 of the sheet 52.in a horizontal.,plane by a continuous intermediate portion 76 which is angular to the horizontal plane of the finite portion 74 and to the horizontal plane of the remainder portion 75 of the thermoplastic sheet 52. It will also be noted that when the die 56 engages the sheet 52 to depress the finite portiony 74, the force ofthe die causes the resilient facing 54 on the lower member. 32 of the holder to become partially compressed.

The distance through which the holder 28 moves dow wardly upon compression of the resilient facing 54 is less than the distance between the planes of the remainder portion 75 and the finite portion 74 so that the finite portion 74, the intermediate portion 76, and the remainder portion 75, from its attachment to the needles 40 to its juncture with the intermediate portion 76, are placed in tension. In the arrangement shown, the lower member 32 of the holder is .25 inch thick and the resilient facing S4 of the lower member -is also .25 inch thick when free. When the die 56 engages the sheet 52 of thermoplastic material with a pressure, preferably from to 500 lbs. `per square inch, the facing 54 will be compressed approximately 50%.

The -above dimensions together with the distance between the wall 60 of die 56 and the walls of the openings 34 and 36 of holder 28 further control the angle 0, theta, which the intermediate portion 76 makes with the horizontal plane of portion 74. This angle preferably should fall between 30 and 55 degrees as will be hereinafter described. If the distance between the wall 60 of the die and the walls of openings 34 and 36 is .375 inch and the other dimensions remain as outlined above, the angle theta will be approximately 45 degrees.

When the die 56 has been moved into engagement with the sheet 52 of thermoplastic material, as shown in Figure 2 of the drawings, an alternating current of radio' frequency is impressed across the upper and lower electrodes 12 and 10, respectively. The voltage may be between 1,200 and 4,000 volts, and the frequency between l and 100 megacycles. It is intended that the A.C. generator 1'4, which is in series with the electrodes, be capable of generating a field within this voltage range and frequency range.

Since an electric field tends to concentrate at sharp corners or edges, the field will tend to concentrate around the periphery of the die 56, particularly at the edge 67 of the rib 62 thereof, in order to pass from this edge to the lower electrode 10. It will be remembered that the radius of the edge 67 of rib 62 is smaller than the radius of the edges 72 of the embossing ribs 70. This difference in radius is desirable in order to reduce the intensity of the electric field between the edges 72 of the ribs 70 and the lower electrode 10 so as to prevent any cutting of the finite portion within its boundary.

As the electric field passes between the edge 67 of rib 62 and the lower electrode 10, the greatest concentration of the field will be immediately adjacent the edge 67 so that a relatively narrow area of the intermediate portion 76 immediately adjacent the edge 67 will be heated to the highest temperature. This relatively narrow area will be spaced approximately 10 to l5 thousandths of an inch from the edge 67 of the rib 62 and the temperature range in the area will be from F. to 300 F. It is intended that the softening temperature of the sheet 52 of the thermoplastic material be within this range so that the relatively narrow area of the intermediate portion 76 will -be softened more than any otherA area but will not be burned or charred. As the relatively narrow area in the intermediate portion'76 becomes softened, the tension between the finite portion 74 of the sheet and the intermediate portion 76 Will cause the finite portion 74 to be separated `from the remainder of the sheet. This separation is clean along a continuous line without any ragged edges being left on either the finite portion or on the inter.-

`7 mediate portion 76. When the finite portion 74 becomes separated, the resilient Ifacing `54 on the lower member 32 of holder 28 causes the holder `to move slightly upwardly to 'remove the -intermediate portion Y7 6 away from the finite portion and the sheet 22 of thermoplastic `material of the trim assembly `17.

Thereafter, as the die 56 continues to hold the finite portion against the -sheet 22 of the trim assembly, the electric field passing between the die yand. the lower electrode 10 will cause a softening of the finite portion and sheet 422 along embossing lines defined by the rib 62 and the ribs 70 to fuse the finite portion to the sheet 22 of thermoplastic material along these lines. However, intermediate the lines, there `is no fusing between the finite portion and the sheet 22 of thermoplastic material.

It will be remembered that the layer 20 of padding between the sheet 22 of thermoplastic material and the backing 18 of the trim assembly is provided with thermoplastic 'material in either powdered or fiber form. The electric field passingbetween the die and the lower electrode 10 Vwill also `heat this thermoplastic material within the layer 20 so that the thermoplastic material softens and flows to fuse the sheet 22 to the backing 18 through the layer of padding 20. Again, this fusing will be along lines defined by the ribs 62 and 70'with no fusing taking place intermediate these lines.

As perviously mentioned, other types of trim assemblies 17 may be used. If a trim assembly of the type which includes an outer sheet 22 of thermoplastic trim material and the backing of vulcanized sponge rubber is used, then the finite portion will be embossed on `the sheet 22 'along embossing -lines defined by the ribs 62 and 70 with these embossing lines being depressed within lthe sponge rubber backing and with the backing being fused -along the embossing lines as is `fully set forth in application 'Serial No. 538,914, hereinbefore mentioned. If the trim assembly includes only the outer sheet 22 of the thermoplastic material, then the finite portion and the sheet 22 will be embossed along the embossing lines defined by the ribs 62 and 70.

As previously stated, the pressure of the die 56 on the finite portion is from 100 to 500 lbs. per square inch. This pressure continues through the cutting operation and the subsequent embossing operation of the finite portion on the trim assembly. The electric field remains for a period of from 1 to 20 seconds, with a normal heating cycle being about l seconds. However, the electric field between the die and the lower electrode is turned off before the upper electrode 12 and the die 56 are moved out of engagement with the finite portion after the embossing operation. It is preferred that the die 56 remain in engagement with the finite portion for a period of from 2 to 10 seconds after the heating cycle `in order to quench the finite portion and sheet 22 along the embossing lines. When the electrode 12 and the Vdie 56 have moved out of engagement with the `finite portion 74 after the embossing operation, the frame 28 is removed and the entire assembly is then removed rfrom the press. The finished assembly will then include the backing 18, the intermediate layer 20, and the sheet 22 of thermoplastic material which will be provided with an insert defined by the finite portion 74, with each of these materials being secured together along embossing lines to define a pattern which is defined Vby the rib pattern of the die 56. If desired, the finite portion 74 and the outer layer `22 of thermoplastic material may be of different colors to provide a more pleasing appearance to lche finished assembly.

It will be remembered that the ribs 70 extend further from the base wall 64 of the die than does the rib 62. By so locating the ribs with respect to each other, the ribs 70 will provide the major engagement between the die and the finite portion during the cutting operation while the rib 62 will only slightly engage the finite fpo'rt'ion. As previously mentioned,the die 56 is noti-heated in -any manner except by conduction. `By having the ribs 70 extend further than rib 62, the ribs will quench the thermoplasticmaterial at their areas of engagement therewith to a much greater degree than rib 62 at its areaof engagement with tne material, so that this quenching together with 'the difference in radius between the edges 72 of the ribs 70 and the edge 67 of the rib 62 will prevent any cutting of the finite portion within its peripheral edge during the cutting operation of the finite portion `from the sheet 52.

It will be noted, however, that the ribs 70 do not necessarily have to extend further outwardly from the base wall 64 of the die than does rib 62 in all instances. The discrepancy in extent of the ribs is controlled primarily by the thickness of the sheet 22 of trim material. If the thickness is large, in the range of %4 inch to J/16 inch, then it is preferable that ribs 70 be of a greater extent than rib 62. However, as the thickness decreases the discrepancy in extent becomes less critical and the ribs 62 and 70 may either be of the same extent or ribs 70 may be of greater extent. Thus, the discrepancy in extent varies with particular trim materials.

It will also be noted that the differences in radii of the edges of ribs 62 and 70 may not be necessary in instances. Again, this will depend on the particular trim assembly land in certain instances the radii of the edges of the ribs 70 may be the same as the radius of the edge 67 of rib 62.

It will also be remembered that the angle theta between the intermediate portion 76 and the horizontal plane of the finite portion 74 -should fall between 30 and 55 degrees, and will be 45 degrees in the particular arrangement shown in the drawings. If this angle were zero degrees, then the efciency of the electric field would be maximum since there would be no engagement between the rib 62 and the sheet 52 of .thermoplastic material 52, the only engagement being between `the ribs 70 and the sheet of thermoplastic material. Thus, without iany engagement between the rib 62 and the sheet 52 of vthermoplastic material, the rib 62 could not in lanymanner quench the thermoplastic material to draw heat away from the material at the relatively narrow :area of highest temperature immediately :adjacent the rib. Likewise, if the angle theta were degrees, the efiiciency of the electric -field would be minimum since the area of greatest heating would then be in engagement with the die so as to be quenched While it is heated. Thus, the preferred range between 30 and 55 degrees is a compromise between maximum and minimum efficiency. Within this range, the sheet 52 of thermoplastic material will be in engagement with the outer edge 67 of rib 62, although the relatively narrow area of greatest heating of the sheet will be out of engagement With the rib. However, since the distance between the edge 67 and the area of greatest heating is relatively small, there will be some quenching of this narrow area by -rib 62 and the die 56. However, this quenching `does not reduce the efficiency of the electric field to `a point where it will prevent the field from cutting the finite portion from the sheet 52 of thermoplastic material.

When the method for cutting the finite portion from a sheet of thermoplastic material is used in conjunction with la subsequent embossing operation to provide a continuous operation, it is preferable that the finite portion 74 be held in engagement with the sheet 22 of the trim assembly during the cutting operation so that the finite por tion, when cut, is accurately positioned in place with respect to the trim assembly. This engagement of the finite portion and sheet 22 also decreases the time required for the cutting oper-ation since the sheet 22 is being heated in the area of rib 62 at the same time as the portion '76 of the sheet 52 is heated in the same area. Thus, heat willbe transferred by conduction from the sheet 22 to the sheet 52 to the area of yhighest temperature to decrease the time required for cutting. It will also necessarily follow that the time required for the embossing operation will be decreasedlsince the `periphery of the finite :portion 74 jshape of the die although larger.

i and the sheet 22 in the area of rib `62 will already be softened.

, if the-method is usedonly for cutting fini-te portions from sheets of thermoplastic material, it is not necessary ,that the finite portion 74 be held in engagement with any .cutting the, mte portion 74 from the sheet 52 of thermoplastic material may be used withequal success ifthere is no subsequent embossing operation. Of course, if the Ymethod of this invention is used only for cutting finite por- -tions from sheets of thermoplastic material, there is no need for providing any of the ribs 70 or otherwise, since only the rib 62 is needed.

, It will also be noted that the method of this invention can be used with equal success to merelycut a piece of thermoplastic material intol two pieces, whether in sheet yform or otherwise.y A'Ihus, .if a sheet of thermoplastic material is to be cut into two pieces opposite portions of the sheet to either side ofthe cut line may be `fixed within la suitable holder with the edge portions of the sheet transverse to the cut line being free. Thereafter, adie having ay-rib can engage the sheetyat the cut line, with the rib .extending beyond the free edge portions of the sheet. fSincefthe cut line and engagement of the rib with .the sheet will bcv transverse to the tension in the sheet, the sheet .will be cut as hereinbefore set forth. Thus, this invention .broadly encompasses the cutting of thermoplastic trim ymaterials by means of dielectric heating. f

I'Ihus, this invention provides an improved method-for cutting finite portions from sheets `of thermoplastic materialand embossing the finite portions on assemblies by means of dielectric heating. 'Ihe finite portions may be of any size or shape land will have a sharp and welldelned peripheral edge which is not ragged in any manner. Although various types of trim assemblies may be used, it is preferable that each such trim assembly include an outer sheet 22 of thermoplastic material which may be supported or unsupported las desired.

The subject method is entirely different trom mechanical cutting and subsequent embossing processes since it does not depend on a sharp blade or other member engaging and entering the thermoplastic material to thereby provide the requiredseparation prior to the subsequent embossing operation. lIn such' other processes, the sheet 52 of thermoplastic material is placed directly on the sheet 22 in surface to. surface contacting relationship therewith.

When the die has embossed a'portion of sheet 52 corresponding to the finite portion 74 on the sheet 22, the recutting operation.

Although the die 56 has been shown of a particular l.shape with regard .to the shape vof the rib 62, other dies 'of other shapes may be used with equal success whether lthe dies are symmetrical or asymmetrical. However, it

is preferable vin all instances that the shape of the openings 34 and `36 in the holder 28 he of the same shape as the By so arranging the openings 34 and,36 with respect to the die equal tension vis provided around theperiphery of the finite portion 74 so lthat the finite portion will separate as a unit in one ,simultaneous -step rather than in a series of discontinuous steps. In addition, itis not necessary that any ribs or otherwise be provided within the continuous rib 62 or otherwise of the'die since the rib 62 act in and of itself .to not only cut a iinite portion from a sheet of thermo- .plastic `material but also to emboss this finite portion on the trim :assembly 17 and to secure Vvarious layers of trim ,assembly to each other land to the nite portion alongan :embossing line. If the trim assembly includes only the sheet 22 of thermoplastic material, then the iiniteiportion and the sheet 22 will be secured only to each other.

We claim: .1. A method for Amaking a decorative article having a base sheet provided with an insert comprising, position- .ing a sheet of heat softenable material over the ba'se sheet, holding a portion of the heat softenable sheet of the size of the insert in engagement with the base sheet, :applying tension between the portion of the sheet in engagement with the base sheet and the remainder of the sheet, applying ,high -frequency energy -to the sheet of heat softenable material at the periphery of the portion in engagement with the base sheet to thereby soften the sheet in this Varea and allow the tension in the sheet of heat softenable material to separate therefrom the portion in engagementk with the base sheet, and thereafter securing the portion separated from the heat softenable sheet to the base sheet.

2.Y A method for making Ia decorative-article having -a base sheet provided with an insert comprising, positioning asheet of heat softenable material over the base sheet, rholding a portion of the heat softenable sheet of the sizeof .the insert in engagement with the base sheet, applying tension between the portion of the sheet iu engagement with the base sheet and the remainder of the sheet, .applying high frequency energy to the sheet of heat softenable material in the area of the periphery of the portion in engagement 'with the base sheet to thereby soften the sheetV in this area and allow the tension in Vthe sheet of heat softenable material to separate from the sheet the portion thereof in engagement with the base sheet, and thereafter applying pressure -to the heat softened area of the separated portion to secure the separated portion on the base sheet.

3. A method for making a decorative larticle having a Ibase sheet provided with an insert comprising, positioninga sheet of the heat softenable material over the base sheet, holding a portion of the heat softenable sheet of the size of the insert in engagement with the base sheet, applying tension between the portion of the sheet in engagement with the base sheet :and the remainder of the sheet, applying high Ifrequency energy to the sheet of heat softenable material in the area of the periphery of the portion in engagement with the base sheet to thereby soften the sheet in this area and allow the tension in the sheet of heat softenable material to separate therefrom the portion in engagement with the base sheet, and

lthereafter continuing to hold the heat softened area of the portion separated from the heat softenable sheet in engagement with the base sheet to secure the separated portion thereto.

4. A method for making a decorative article having a base sheet provided with an insert comprising, positioning a sheet of thermoplastic material in spaced relationship to a base sheet, `applying pressure to a portion of the lthermoplastic sheet of the size of the insert to displace this portion into engagement with the base sheet -under tension, applying high frequency energy to the sheet of thermoplastic material in the area of the periphery of the displaced portion to thereby soften .the sheet of thermoplastic material in this area and allow the tension in the sheet to separate the displaced portion therefrom, and applying pressure to the heat softened area of the vdisplaced portion to secure the displaced portion tothe ,base sheet.

5. A method for making a decorative article having a base sheet provided with an insert comprising, positioning a sheet of thermoplastic material in spaced relationship to a base sheet, applying pressure to a portion of the thermoplastic sheet of the size of the insert to displace this portion into engagement with the base sheet under tension, applying high frequency energy to the sheet of thermoplastic material in the area of the periphery 0f. the ,dsplacedrortion to thereby soften, the .sheet 11 of thermoplastic material Ain this area and .allow the tension in the sheet to separate the displaced portion therefrom, and securing the displaced portion to the base sheet.

6. A method for making a decorative article having a base sheet provided with an insert comprising, positioning a sheet of thermoplastic material over a base sheet, holding a finite portion of the sheet of thermoplastic material under pressure in engagement with the base sheet, maintaining the remainder of the sheet of thermoplastic material under tension, applying high frequency energy to the sheet of thermoplastic material in a relatively narrow area at the boundary of the finite portion thereof to soften the sheet in this area and allow separation of the finite portion from the remainder tof the sheet by means of the tension therebetween, and securing the heat softened area of the finite portion to the base sheet.

7. A method for making a decorative article having .a base sheet provided with an insert comprising, positioning a sheet of thermoplastic material over a base sheet, holding a finite portion of the sheet of thermoplastic material under pressure in engagement with the base sheet, .maintaining the remainder of the sheet of thermoplastic material under tension, applying high frequency energy to the sheet of thermoplastic material in a relatively narrow -area at the boundary of the finite portion thereof to soften the sheet in this -area and allow separation of the finite portion from the remainder of the sheet by means of the tension therebetween, and continuing the .application of pressure on the heat softened area of the `finite portion to secure the finite portion to the base sheet.

8. A method for making a decorative article having a Abase 'sheet provided with an insert comprising, positioning a pair of sheets of thermoplastic material in spaced relationship to each other, applying pressure to a m'te `portion of one of the sheets to displace this portion into engagement with the other sheet under tension, applying high frequency energy to each ofthe sheets in a relatively `narrow area immediately adjacent the periphery of the finite portion of the one sheet to thereby soften each of the sheets in this area and allow separation of the finite portion of the one sheet from the remainder of the one sheet by means of the tension therebetween, and continuing the application of pressure after separation to fuse the heat softened areas of the finite portion and the other sheet 'of thermoplastic material.

9. Amethod for making a decorative article having a base sheet provided with an insert comprising, positioning a sheet of thermoplastic material in spaced relationship to a base sheet, positioning the sheets between a pair of electrodes, displacing a finite portion of the sheet of thermoplastic material into engagement with the base `sheet under tension, applying high frequency energy to the yelectrodes to generate a field therebetween, concentrating the "field in a relatively narrow continuous area immediately adjacent the periphery of the finite portion to thereby soften lthe sheet of thermoplastic material in this area andallow separation of the finite portion from the remainder of the sheet by means of the tension therein, and continuing the application of pressure in the heat softened area of the finite portion to secure the vfinite portion on the base sheet.

yl0. A method for making a decorative article having 'a base 'sheet provided with an insert comprising, positioning a pair of sheets of thermoplastic material in spaced relationship to eachother between a pair of electrodes, applying pressure to a finite portion of one of the sheets to displace this portion into'engagement with the other sheet under tension, applying high frequency energy to the electrodes to generate a field therebetween, concentrating the field in a relatively narrow continuous area immediately adjacent the periphery of the finite portion of the `one sheet to thereby softeneach of the sheetsin this'areaiand allow separation-ofthenite por- 12 tion from? the remainder of the one sheet lby means of the tension therein, and continuing the application of pressure Ito secure the finite portion `to the other sheet of thermoplastic material.

1l. A method for making a `decorative article having a base sheet provided with an insert comprising, resiliently supporting a vsheet of thermoplastic material on the base `sheet in spaced relationship thereto, lapplying pressure to a finite portion of the ysheet of thermoplastic material to displace this portion into engagement with the base sheet under tension and partially compress the resilient supporting means of the sheet of thermoplastic material, applying high frequencyenergy to the sheet of thermoplastic -material in 1a relatively narrow continuous area immediately adjacent the finiteportion thereof to thereby soften the sheet in this area and `allow separation of the finite portion from the remainder of thesheet by means of the tension and the resilient support, and applying -pressure to the heat softened area ofthe finite portion to'secure the finite -portion to the base sheet.

12. A method Afor making a decorative article having a base sheet provided with an insert comprising, positioning `a sheet of thermoplastic material in spaced relationship `to the base sheet, applying pressure to the sheet of thermoplastic material along a relatively narrow continuous area thereof vdefining a finite portion to thereby displace this finite portion into Aengagement with the base sheet under tension, applying `high frequency-energy to the sheet of 'thermoplastic material adjacent the relatively narrow area thereof fto thereby'soften the sheet in this area and allow vseparation of the finite portion from'the remainder of the sheet by means ofthe tensiontherein, and continuingthe application of 'pressure to secure the heat softened area of thefinite portion to the base sheet.

l13. Dielectric lapparatus for `bonding a layer of flexible heat-fusible `material to a `base layer of material and for forming an embossed pattern therein comprising an electrode having a surface `adapted to `receive the base layer-of material yand `an opposed electrode shaped as a Idie with raised embossing surfaces and a continuous rib about -its periphery, said electrodes being connected in series to a rsource of 4high frequency electrical energy, means for holding tautly a sheet of fiexible heat-fusible material between, and in spacedrelationship to said die and the base layer vof Vmaterial on said iirst mentioned electrode, and means for moving said electrodes toward each other so that said die `presses a portion of said sheet into'contactwith said layer of lbase material to bondsaid portion to said base layer `and form an embossed` pattern therein and so that said Yportion separates from theremaining portions of saidsheet at the periphery of said embossing die.

14. V.Dielectric apparatus `for bonding a layer of flexible 'heat-fusible material to abase layer of material and for forming an embossed pattern therein comprising a bottom electrode lhaving a surface adapted `to receive the baselayer of material and an upper electrode shaped as a die with raised embossing surfaces `and a continuous rib about its periphery, saidelectrodes being connected in series to -a source of high frequency electrical energy, a frame for holdingtautly a sheet of fiexible heat-fusible material between, and .in spaced relationship to said die and the layer of base materialon said bottom electrode, and means for ,moving said electrodes toward each other so-that said die presses a portion of said sheet into contact with said base layer to bond said portion to said baselayer and-form an embossed pattern therein and so that said portion separates from the remaining portions of said sheet Aat the periphery of said embossing die.

15. Dielectric apparatus as defined in claim 14 and wherein said frame comprises upper and lower matched frame members adapted -to 'clamp the Ysheet of exible heat-fusible material therebetween, one of said members having a series ofneedlesadapted to extent through said sheet-of materialand the other ofsaidmembers having a series of openings for mating engagement with said needles.

References Cited in the le of this patent UNITED STATES PATENTS Lyiiynen Oct. 30, 1951 10 14 Paquette et a1. 0ct. 21, 1952 Gannon et a1. Mar. 17, 1953 Fordyce et al. Nov. 16, 1954 Wilcox Feb. 28, 1956 Lippman May 29, 1956 Feuer et al June 25, 1957 Noyes et a1. June 25, 1957 Hoagland Sept. 10, 1957 Hoagland Feb. 4, 1958 Warnken July 22, 1958

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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
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Classifications
U.S. Classification156/163, 156/380.8, 156/309.6, 156/308.4, 156/273.7, 156/274.4, 156/500, 156/270
International ClassificationB26F3/06, B29C65/04, B29C65/78, B29C59/02, B44B5/00, B44B5/02
Cooperative ClassificationB44B5/028, B26F3/06, B29C65/04, B44B5/0019, B29C66/80, B29L2031/3005, B29C2793/00, B29C59/02, B29C70/58, B29C65/78, B29C66/47
European ClassificationB29C66/47, B29C70/58, B26F3/06, B29C66/80, B29C65/04, B29C65/78, B44B5/00A4, B44B5/02W