FEEDING MAT
United States Patent 3637454
An infant's feeding mat is provided with a substantially flat bottom and an upstanding ridge lying within a marginal zone adjacent the peripheral edges. The mat is formed of a base ply of foamed resilient flexible plastic and a top ply of nonfoamed flexible plastic. A thick border strip of foamed flexible resilient plastic is interposed between the plies and within the marginal zone, and the two plies are subsequently heat sealed to one another along their peripheries. An additional heat sealed seam between the plies surrounds the inner border of the strip and encloses the strip. The strip is held under compression between the plies and imparts the ridge to the mat.
US Patent References:
Place mat
Borland - August 1956 - 2757478
Food server
Innis - February 1964 - 3122265
Coaster
Low - June 1935 - 2004166
Serving and utility tray
Eberhardt - May 1952 - 2597460
Tray with cork surface portions and method of making
French - January 1957 - 2777626
Place mat
Borland - August 1956 - 2757478
Food server
Innis - February 1964 - 3122265
Coaster
Low - June 1935 - 2004166
Serving and utility tray
Eberhardt - May 1952 - 2597460
Tray with cork surface portions and method of making
French - January 1957 - 2777626
Application Number:
04/857522
Publication Date:
01/25/1972
Filing Date:
09/12/1969
View Patent Images:
Export Citation:
Primary Class:
Other Classes:
248/346.010, 206/557, D06/614, 428/141, 156/308.400
International Classes:
A47D5/00; A47D15/00; A47G11/00; B29C65/04; B29C67/00; B29C59/02; B32B1/04; B65D1/34
Field of Search:
161/44,149,160,161,118 248/346.1 206/72 156/309 D44/13.1,14
Primary Examiner:
Ansher, Harold
Assistant Examiner:
Gil, Joseph C.
Claims:
Having thus described the present invention, there is claimed as new and desired to be secured by Letters Patent
1. A feeding mat comprising: a soft base ply of resilient flexible foamed synthetic thermoplastic sheet material the undersurface of which has a liquid impervious skin and a rough antiskid surface, a coextensive top ply of a liquid impervious sheet of flexible synthetic unfoamed thermoplastic material, said plies having their common peripheral edges in registry, a marginal zone of said plies lying alongside the common peripheral edges, an elongate strip of foamed soft resilient flexible material, said strip being interposed between said plies and within said marginal zone, a first seam joining said plies along their common peripheral edges, a second seam joining the said plies, said second seam being spaced inwardly from the first seam, said marginal zone being interposed between said seams, said second seam peripherally enclosing an area of said top ply, the portion of said top ply within said area lying substantially within a plane, the portion of said top ply within said marginal zone being elevated from the plane of said area, the foamed base ply serving to resiliently support the top ply to prevent a child from injuring himself, the elongate strip serving to raise the portion of the top ply within the marginal zone, the portion of the top ply within said marginal zone preventing the outflow of spilled foods from the area of the top ply over the peripheral edges of the mat.
2. A mat as set forth in claim 1, wherein the strip is compressed by the two plies to round the elevated portion of the top ply.
3. A mat as set forth in claim 1, wherein a design is formed on the area of the top ply, said design including heat welded depressed portions between the top ply and the base ply.
4. A mat as set forth in claim 1, wherein the plies are mutually heat-sealed at the first and second seams.
1. A feeding mat comprising: a soft base ply of resilient flexible foamed synthetic thermoplastic sheet material the undersurface of which has a liquid impervious skin and a rough antiskid surface, a coextensive top ply of a liquid impervious sheet of flexible synthetic unfoamed thermoplastic material, said plies having their common peripheral edges in registry, a marginal zone of said plies lying alongside the common peripheral edges, an elongate strip of foamed soft resilient flexible material, said strip being interposed between said plies and within said marginal zone, a first seam joining said plies along their common peripheral edges, a second seam joining the said plies, said second seam being spaced inwardly from the first seam, said marginal zone being interposed between said seams, said second seam peripherally enclosing an area of said top ply, the portion of said top ply within said area lying substantially within a plane, the portion of said top ply within said marginal zone being elevated from the plane of said area, the foamed base ply serving to resiliently support the top ply to prevent a child from injuring himself, the elongate strip serving to raise the portion of the top ply within the marginal zone, the portion of the top ply within said marginal zone preventing the outflow of spilled foods from the area of the top ply over the peripheral edges of the mat.
2. A mat as set forth in claim 1, wherein the strip is compressed by the two plies to round the elevated portion of the top ply.
3. A mat as set forth in claim 1, wherein a design is formed on the area of the top ply, said design including heat welded depressed portions between the top ply and the base ply.
4. A mat as set forth in claim 1, wherein the plies are mutually heat-sealed at the first and second seams.
Description:
BACKGROUND OF THE INVENTION
1. Field of the Invention
A feeding mat having upstanding peripheral edges for preventing overflow of liquids that are spilled during feeding.
2. Description of the Prior Art
Articles have been heretofore used to provide protection for a dining table top when a young child is eating. These usually were in the form of a place mat or sheet although oftentimes rigid metal or plastic trays with flat bottoms and upstanding flanges were used. Additionally used heretofore were high chairs having a small feeding top and flanges at the edges thereof.
These prior devices were deficient in various aspects. For example, there has been a long felt need for an infant's feeding tray which was simpler and more attractive than the prior devices. Furthermore, some of the prior devices were difficult to clean and this has always been a problem because young children seldom eat without spilling liquids or dropping food.
A further disadvantage of these prior devices was that because children were prone to bang their hand or some other part of their body upon the table, some of the previous feeding trays were liable to harm the child with their hard surfaces and upstanding flanges.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a feeding mat which is so constructed that it is not subject to any of the foregoing disadvantages.
More specifically, it is an object of the invention to provide a feeding mat of the character described which is simple and rugged in construction, yet can be fabricated by mass production methods at an appreciably lower cost than prior devices designed to serve the same general function.
A still further object of the present invention is to provide a feeding mat of the character described which is soft and flexible, providing maximum safety to a young child, while remaining resilient and durable.
Yet another object of the present invention is to provide a feeding mat of the character described which is not only easy to wash but also facilitates wiping and removal of spilled or dropped foods.
A still further object of the present invention is to provide a feeding mat of the character described wherein the upper surface of the mat is liquid impermeable with the portions adjacent the peripheral edges of said upper surface resiliently projecting upwardly to provide a ridge for preventing the outflow of spilled foods.
Other objects of the invention in part will be obvious and in part will be pointed out hereinafter.
The invention accordingly consists in the features of construction, combinations of elements and arrangements of parts which will be exemplified in the feeding mat hereinafter described and of which the scope of application will be indicated in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings in which is shown one of the various possible embodiments of the invention,
FIG. 1 is a top view of a feeding mat constructed in accordance with and embodying the instant invention;
FIG. 2 is an enlarged fragmentary sectional view through the feeding mat, the same being taken substantially along the line 2--2 of FIG. 1 and showing the top and bottom plies of thermoplastic sheet material of which the mat is constructed, as well as the upstanding peripheral ridge formed by a thick border strip of foamed material and sandwiched between the plies;
FIG. 3 is a fragmentary view of a corner of the bottom of the feeding mat;
FIG. 4 is an isometric fragmentary exploded view of the components of the feeding mat during the assembly; and
FIG. 5 is an enlarged fragmentary sectional view illustrating a step during the construction of the feeding mat and specifically showing a heat-sealing steel rule die and platen prior to engagement with the feeding mat components.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The feeding mat of the present invention is a laminated structure formed of a base ply of foamed soft resilient thermoplastic sheet material and a coextensive top ply of a liquid impermeable soft flexible thermoplastic sheet material. The base and top plies are sealed to one another along the common registered peripheries of the two plies by a first seam. A thick border strip of foamed flexible soft resilient plastic or the like is interposed between the plies along a marginal zone. A further heat-sealed seam between the base and top plies extends substantially parallel to peripheries of the two plies and is spaced inwardly of the first seam. Thus, the border strip is sandwiched between the two plies. The border strip is tightly compressed between the two plies so that the ensuing peripheral ridge has a rounded upper surface. Because of the use of the materials just mentioned, the entire mat is soft and flexible, yet resilient and durable. The mat seams are formed by a heat-sealing process which includes the use of a steel rule die activated by a high-frequency electric welding apparatus.
Referring now in detail to the drawings, the reference number 10 denotes a feeding mat constructed in accordance with and embodying the present invention. The mat is formed of a laminated structure including a base ply 12 of a soft resilient flexible synthetic thermoplastic, e.g., of foamed polyvinyl chloride. The base ply sheet material preferably has an unstressed thickness in the order of 5/8 inch to provide the desired resiliency and soft texture for the mat. The undersurface of the base ply includes a liquid impermeable layer or skin 14. This skin serves to prevent any of the spilled liquids which are on the table top adjacent or beneath the mat from entering into and being absorbed by the base ply. Washing and cleaning of the entire feeding mat is also facilitated because the skin 14 prevents absorption of the washing liquids by the foamed base ply. The use of a foamed material for this ply makes the undersurface rough so that it has an antiskid characteristic and thus tends to remain where positioned, resisting lateral displacement forces applied by an infant making brushing movements as infants are prone to do.
In addition, the foamed material of the base ply is the major contributing factor to the softness and resiliency of the mat which minimizes the possibility of self-inflicted damage by an infant who bangs a hand, limb or head on the table top in a tantrum or effort to gain attention.
A top ply 16 is also provided, said top ply being of the same length and width as the base ply so that the common edges of both plies may be located in registry to form a composite mat in accordance with the invention. The top ply is a soft flexible synthetic thermoplastic compatible with the material of the base ply, e.g., polyvinyl chloride. It is not foamed and has a smooth, e.g., polished, top surface so that it is easy to wipe off and is visually attractive. The base and top plies are heat sealed to one another along their common peripheral edges by a peripheral seam 18.
The feeding mat 10 includes a ridge 22 in a marginal zone adjacent the inner side of the seam 18. The ridge 22 serves to prevent the flow of spilled liquids from the feeding mat onto the table by maintaining such liquids in the area surrounded by the marginal zone. For this purpose, there is provided a thick narrow strip 20 of foamed soft flexible resilient material, e.g., foamed polyurethane, foam rubber or foamed polyvinyl chloride. This need not be compatible with the material of the base and top plies. The strip 20 is interposed between the top and bottom plies and within the marginal zone. Inasmuch as the strip is foamed, soft and resilient, the ensuring ridge 22 is incapable of harming an infant willfully striking himself against the mat, as would the hard unyielding peripheral flanges of a metal or hard plastic feeding tray.
The thick strip 20 is in a shape which conforms with the mat shape, e.g., rectangular to conform with a rectangular mat. It should be mentioned that the plan shape of the mat is not a feature of the invention.
To define the inner side of the ridge 22 and hold the strip 20 under compression between the top 16 and base 12 plies, there is a seam 24 joining the top and base plies at the inner side of the marginal zone which is also heat sealed.
An area 25 of the mat surrounded by the ridge 22 is generally flat and upon this area the infant's feeding bowl is placed. It is because foods will be splattered about and spilled on the top ply 16 that it is formed of a liquid impervious nonfoamed plastic sheet. If it is desired to have this interior smooth, the top and bottom plies are only joined by the heat welds at the seams 18 and 24.
Optionally, the area 25 of the feeding mat may be decorated with the use of a heat-welding die which will provide decorative seams 26 in a desired pattern. The seams 26 are surfaces wherein there is a heat-sealed welded seam between the two plies 14, 16 resulting in welded depressions on both plies.
The manner in which the feeding mat is assembled and constructed is an additional feature of the invention. In accordance with this feature, the feeding mat components, i.e., the top ply 16, the thick border strip 20 and the base ply 14, are assembled and aligned for heat welding in an assembly frame 30. The sheets forming the top and base plies are cut to dimensions larger than the finished mat so that a border extends beyond the area which ultimately will be enclosed by the peripheral seam 18. Within this border area there is provided a plurality of locating holes 32 and 33 in the top 16 and base 14 plies, respectively. The holes 32, 33 in both plies are in registry when the plies themselves are in alignment. The frame 30 includes a plurality of projecting placement pins 34. Each of the pins 34 are spaced and positioned to be registered with the holes 32, 33 when the aligned plies 14, 16 are placed over the frame. With the pins projecting through the holes, the plies of the mat are maintained in alignment during the heat-sealing process.
The thick strip 20 is placed between the plies 14, 16 of the composite mat prior to the placing of the top ply 16 over the base ply 12 on the frame. The strip 20 includes a similar border zone within which there is provided a plurality of locating holes 36. The border zones of the strip extend beyond the seam 18 of the mat. The holes 36 are spaced to be aligned with the holes 32, 33.
To assemble the mat, first the base ply 14 is placed on the frame 30 which is rectangular, to conform with a rectangular mat. Of course, the frame may be of any other appropriate shape, e.g., oval or circular if the mat is so shaped. After the base ply is positioned and the pins are disposed in their locating holes 33 the thick strip 20 is emplaced with the pins 34 projecting through locating holes 36 of the strip 20. Subsequently, the top ply is placed over the base ply and strip with pins 34 extending through the locating holes 33. It should be noted that the plies and the thick strip 20 are maintained in their respective aligned positions on the frame by the placement pins 34 which extend through the locating holes 32, 33 and additionally through the locating holes 36 of the thick narrow border strip 20.
After the plies and the strip 20 have been assembled on the frame 30, the frame is positioned on a platen 38 of a high-frequency dielectric heat-welding machine. The frame 30 is of a larger dimension than the platen 38 so that when the frame is inserted over the platen, the frame will peripherally surround the platen. With the frame in this position (see FIG. 5) the plies 12 and 16, and the foam strip 20 will have their border zones extending beyond the platen 38.
The platen 38 of the dielectric heat-sealing machine is electrically conductive to act as a platen electrode for a high-frequency dielectric welding machine that is energized by a high-frequency oscillator 40. One terminal of the oscillator is connected to said platen electrode 38 as schematically illustrated in FIG. 5.
The peripheral seam 18 and the parallel inwardly disposed seam 24 are formed by the dielectric welding machine through the cooperation between the platen 38 and a rule die 42 movable toward and away from the platen. The rule die 42 includes a block of electrically nonconductive material, e.g., plywood. Steel rule die strips 44 and 46 extend through kerfs in the plywood block of the movable die and a metal chase 45 peripherally compresses the block to bind the blocks and die strips together. The lower edges of the strips 44, 46 project beneath the block and define closed shapes that appropriately extend against the plies forming the mat when the movable die 40 is lowered to press the plies against the platen 38. These strips form the seams 18, 24. The upper edges of the steel strips 44 and 46 are electrically interconnected as by an electrically conductive electrode film or layer 48 which extends over the upper surface of the movable die 42. The other terminal of the oscillator is connected to this layer. It should be noted that the steel strip 44 forms the peripheral seam 18 and includes a sharp depending knife edge 50 which serves to cut the peripheral edges of the plies 16 and 12 as well as the thick strip 20 at the border zone. The excess material which has been cut by the edge 50 is the border zone and includes the openings 32, 33 and 36. The strip 46 forms the inner seam 24.
In operation, the frame 30 with the mat plies and thick strip mounted thereon is inserted over the platen 38, the movable die 42 is then lowered over the platen and pressed against the plies of the mat. This action compresses the strip 20. Thereupon the high-frequency oscillator is energized. The high-frequency oscillations between the steel strips and the platen electrode base 38 results in a dielectric heating which autogenously fuses the plies together around the edges of the strip and captures the thick strip 20 between the plies. Subsequently, the movable die 42 is raised and the frame removed from the platen. Thereupon, the border zones are stripped from the peripheral seam 18, It should be noted that because the strip 20 was compressed between the movable die 42 and the platen during welding, the strip will be under residual compression after the movable die has been raised. The strip urges the top ply 16 upward, forming the ridge 22. Because the plies are joined by the seams 18, 24 along the side edges of the ridge 22, the peripheral ridge is rounded.
Thus it will be seen that there is provided an infant's mat and method for making the same which achieves the various objects of the invention and which is well adapted to meet the conditions of practical use.
As various possible embodiments might be made of the present invention, and as various changes might be made in the embodiment and method above set forth, it is to be understood that all matter herein described or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.
1. Field of the Invention
A feeding mat having upstanding peripheral edges for preventing overflow of liquids that are spilled during feeding.
2. Description of the Prior Art
Articles have been heretofore used to provide protection for a dining table top when a young child is eating. These usually were in the form of a place mat or sheet although oftentimes rigid metal or plastic trays with flat bottoms and upstanding flanges were used. Additionally used heretofore were high chairs having a small feeding top and flanges at the edges thereof.
These prior devices were deficient in various aspects. For example, there has been a long felt need for an infant's feeding tray which was simpler and more attractive than the prior devices. Furthermore, some of the prior devices were difficult to clean and this has always been a problem because young children seldom eat without spilling liquids or dropping food.
A further disadvantage of these prior devices was that because children were prone to bang their hand or some other part of their body upon the table, some of the previous feeding trays were liable to harm the child with their hard surfaces and upstanding flanges.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a feeding mat which is so constructed that it is not subject to any of the foregoing disadvantages.
More specifically, it is an object of the invention to provide a feeding mat of the character described which is simple and rugged in construction, yet can be fabricated by mass production methods at an appreciably lower cost than prior devices designed to serve the same general function.
A still further object of the present invention is to provide a feeding mat of the character described which is soft and flexible, providing maximum safety to a young child, while remaining resilient and durable.
Yet another object of the present invention is to provide a feeding mat of the character described which is not only easy to wash but also facilitates wiping and removal of spilled or dropped foods.
A still further object of the present invention is to provide a feeding mat of the character described wherein the upper surface of the mat is liquid impermeable with the portions adjacent the peripheral edges of said upper surface resiliently projecting upwardly to provide a ridge for preventing the outflow of spilled foods.
Other objects of the invention in part will be obvious and in part will be pointed out hereinafter.
The invention accordingly consists in the features of construction, combinations of elements and arrangements of parts which will be exemplified in the feeding mat hereinafter described and of which the scope of application will be indicated in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings in which is shown one of the various possible embodiments of the invention,
FIG. 1 is a top view of a feeding mat constructed in accordance with and embodying the instant invention;
FIG. 2 is an enlarged fragmentary sectional view through the feeding mat, the same being taken substantially along the line 2--2 of FIG. 1 and showing the top and bottom plies of thermoplastic sheet material of which the mat is constructed, as well as the upstanding peripheral ridge formed by a thick border strip of foamed material and sandwiched between the plies;
FIG. 3 is a fragmentary view of a corner of the bottom of the feeding mat;
FIG. 4 is an isometric fragmentary exploded view of the components of the feeding mat during the assembly; and
FIG. 5 is an enlarged fragmentary sectional view illustrating a step during the construction of the feeding mat and specifically showing a heat-sealing steel rule die and platen prior to engagement with the feeding mat components.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The feeding mat of the present invention is a laminated structure formed of a base ply of foamed soft resilient thermoplastic sheet material and a coextensive top ply of a liquid impermeable soft flexible thermoplastic sheet material. The base and top plies are sealed to one another along the common registered peripheries of the two plies by a first seam. A thick border strip of foamed flexible soft resilient plastic or the like is interposed between the plies along a marginal zone. A further heat-sealed seam between the base and top plies extends substantially parallel to peripheries of the two plies and is spaced inwardly of the first seam. Thus, the border strip is sandwiched between the two plies. The border strip is tightly compressed between the two plies so that the ensuing peripheral ridge has a rounded upper surface. Because of the use of the materials just mentioned, the entire mat is soft and flexible, yet resilient and durable. The mat seams are formed by a heat-sealing process which includes the use of a steel rule die activated by a high-frequency electric welding apparatus.
Referring now in detail to the drawings, the reference number 10 denotes a feeding mat constructed in accordance with and embodying the present invention. The mat is formed of a laminated structure including a base ply 12 of a soft resilient flexible synthetic thermoplastic, e.g., of foamed polyvinyl chloride. The base ply sheet material preferably has an unstressed thickness in the order of 5/8 inch to provide the desired resiliency and soft texture for the mat. The undersurface of the base ply includes a liquid impermeable layer or skin 14. This skin serves to prevent any of the spilled liquids which are on the table top adjacent or beneath the mat from entering into and being absorbed by the base ply. Washing and cleaning of the entire feeding mat is also facilitated because the skin 14 prevents absorption of the washing liquids by the foamed base ply. The use of a foamed material for this ply makes the undersurface rough so that it has an antiskid characteristic and thus tends to remain where positioned, resisting lateral displacement forces applied by an infant making brushing movements as infants are prone to do.
In addition, the foamed material of the base ply is the major contributing factor to the softness and resiliency of the mat which minimizes the possibility of self-inflicted damage by an infant who bangs a hand, limb or head on the table top in a tantrum or effort to gain attention.
A top ply 16 is also provided, said top ply being of the same length and width as the base ply so that the common edges of both plies may be located in registry to form a composite mat in accordance with the invention. The top ply is a soft flexible synthetic thermoplastic compatible with the material of the base ply, e.g., polyvinyl chloride. It is not foamed and has a smooth, e.g., polished, top surface so that it is easy to wipe off and is visually attractive. The base and top plies are heat sealed to one another along their common peripheral edges by a peripheral seam 18.
The feeding mat 10 includes a ridge 22 in a marginal zone adjacent the inner side of the seam 18. The ridge 22 serves to prevent the flow of spilled liquids from the feeding mat onto the table by maintaining such liquids in the area surrounded by the marginal zone. For this purpose, there is provided a thick narrow strip 20 of foamed soft flexible resilient material, e.g., foamed polyurethane, foam rubber or foamed polyvinyl chloride. This need not be compatible with the material of the base and top plies. The strip 20 is interposed between the top and bottom plies and within the marginal zone. Inasmuch as the strip is foamed, soft and resilient, the ensuring ridge 22 is incapable of harming an infant willfully striking himself against the mat, as would the hard unyielding peripheral flanges of a metal or hard plastic feeding tray.
The thick strip 20 is in a shape which conforms with the mat shape, e.g., rectangular to conform with a rectangular mat. It should be mentioned that the plan shape of the mat is not a feature of the invention.
To define the inner side of the ridge 22 and hold the strip 20 under compression between the top 16 and base 12 plies, there is a seam 24 joining the top and base plies at the inner side of the marginal zone which is also heat sealed.
An area 25 of the mat surrounded by the ridge 22 is generally flat and upon this area the infant's feeding bowl is placed. It is because foods will be splattered about and spilled on the top ply 16 that it is formed of a liquid impervious nonfoamed plastic sheet. If it is desired to have this interior smooth, the top and bottom plies are only joined by the heat welds at the seams 18 and 24.
Optionally, the area 25 of the feeding mat may be decorated with the use of a heat-welding die which will provide decorative seams 26 in a desired pattern. The seams 26 are surfaces wherein there is a heat-sealed welded seam between the two plies 14, 16 resulting in welded depressions on both plies.
The manner in which the feeding mat is assembled and constructed is an additional feature of the invention. In accordance with this feature, the feeding mat components, i.e., the top ply 16, the thick border strip 20 and the base ply 14, are assembled and aligned for heat welding in an assembly frame 30. The sheets forming the top and base plies are cut to dimensions larger than the finished mat so that a border extends beyond the area which ultimately will be enclosed by the peripheral seam 18. Within this border area there is provided a plurality of locating holes 32 and 33 in the top 16 and base 14 plies, respectively. The holes 32, 33 in both plies are in registry when the plies themselves are in alignment. The frame 30 includes a plurality of projecting placement pins 34. Each of the pins 34 are spaced and positioned to be registered with the holes 32, 33 when the aligned plies 14, 16 are placed over the frame. With the pins projecting through the holes, the plies of the mat are maintained in alignment during the heat-sealing process.
The thick strip 20 is placed between the plies 14, 16 of the composite mat prior to the placing of the top ply 16 over the base ply 12 on the frame. The strip 20 includes a similar border zone within which there is provided a plurality of locating holes 36. The border zones of the strip extend beyond the seam 18 of the mat. The holes 36 are spaced to be aligned with the holes 32, 33.
To assemble the mat, first the base ply 14 is placed on the frame 30 which is rectangular, to conform with a rectangular mat. Of course, the frame may be of any other appropriate shape, e.g., oval or circular if the mat is so shaped. After the base ply is positioned and the pins are disposed in their locating holes 33 the thick strip 20 is emplaced with the pins 34 projecting through locating holes 36 of the strip 20. Subsequently, the top ply is placed over the base ply and strip with pins 34 extending through the locating holes 33. It should be noted that the plies and the thick strip 20 are maintained in their respective aligned positions on the frame by the placement pins 34 which extend through the locating holes 32, 33 and additionally through the locating holes 36 of the thick narrow border strip 20.
After the plies and the strip 20 have been assembled on the frame 30, the frame is positioned on a platen 38 of a high-frequency dielectric heat-welding machine. The frame 30 is of a larger dimension than the platen 38 so that when the frame is inserted over the platen, the frame will peripherally surround the platen. With the frame in this position (see FIG. 5) the plies 12 and 16, and the foam strip 20 will have their border zones extending beyond the platen 38.
The platen 38 of the dielectric heat-sealing machine is electrically conductive to act as a platen electrode for a high-frequency dielectric welding machine that is energized by a high-frequency oscillator 40. One terminal of the oscillator is connected to said platen electrode 38 as schematically illustrated in FIG. 5.
The peripheral seam 18 and the parallel inwardly disposed seam 24 are formed by the dielectric welding machine through the cooperation between the platen 38 and a rule die 42 movable toward and away from the platen. The rule die 42 includes a block of electrically nonconductive material, e.g., plywood. Steel rule die strips 44 and 46 extend through kerfs in the plywood block of the movable die and a metal chase 45 peripherally compresses the block to bind the blocks and die strips together. The lower edges of the strips 44, 46 project beneath the block and define closed shapes that appropriately extend against the plies forming the mat when the movable die 40 is lowered to press the plies against the platen 38. These strips form the seams 18, 24. The upper edges of the steel strips 44 and 46 are electrically interconnected as by an electrically conductive electrode film or layer 48 which extends over the upper surface of the movable die 42. The other terminal of the oscillator is connected to this layer. It should be noted that the steel strip 44 forms the peripheral seam 18 and includes a sharp depending knife edge 50 which serves to cut the peripheral edges of the plies 16 and 12 as well as the thick strip 20 at the border zone. The excess material which has been cut by the edge 50 is the border zone and includes the openings 32, 33 and 36. The strip 46 forms the inner seam 24.
In operation, the frame 30 with the mat plies and thick strip mounted thereon is inserted over the platen 38, the movable die 42 is then lowered over the platen and pressed against the plies of the mat. This action compresses the strip 20. Thereupon the high-frequency oscillator is energized. The high-frequency oscillations between the steel strips and the platen electrode base 38 results in a dielectric heating which autogenously fuses the plies together around the edges of the strip and captures the thick strip 20 between the plies. Subsequently, the movable die 42 is raised and the frame removed from the platen. Thereupon, the border zones are stripped from the peripheral seam 18, It should be noted that because the strip 20 was compressed between the movable die 42 and the platen during welding, the strip will be under residual compression after the movable die has been raised. The strip urges the top ply 16 upward, forming the ridge 22. Because the plies are joined by the seams 18, 24 along the side edges of the ridge 22, the peripheral ridge is rounded.
Thus it will be seen that there is provided an infant's mat and method for making the same which achieves the various objects of the invention and which is well adapted to meet the conditions of practical use.
As various possible embodiments might be made of the present invention, and as various changes might be made in the embodiment and method above set forth, it is to be understood that all matter herein described or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.