P R OC E S S

Tec hnological area of invention:

¾ This invention is related to the equipment and process for manufacturing inner liners for household refrigerators.

In this invention, inner liners for household refrigerators are manufactured by applying a chosen melted polymer material over a mold surface by thermal spraying technique. The spraying is performed in a layer-by-layer fashion in order to obtain desired part thickness using multiple 3 thermal spray nozzles which are moved over the mold surface at desired trajectories similar to cutting tools in CNC machines. Thermal spraying parameters such as melted material temperature and velocity at the spray nozzle, and nozzle distance from the mold surface are adjusted so that sprayed plastic material will not permanently adhere to the mold surface and seperate from it after cooling and becoming solid.

5¾ C urrent state of the technology:

C urrently, household refrigerator inner liners are manufactured by a two-step process. In the first step, granular polymer material is melted and formed into sheets of desired length, width, and thickness by extrusion process. In the second step, the previously manufactured sheets are heated upto a set temperature where sheets become soft and forma ble, and then made into i l household refrigerator inner liners by thermoforming process. Being a two-step process, current state of art regarding household refrigerator inner liner manufacturing requires large initial capital investment and occupies large factory space.

During the first extrusion step, thickness variations occur in the sheets due to the nature of the sheet material properties and extrusion process. During the second thermoforming step, the t& thickness variations in the sheets become worse due to uneven heating of the sheets and large deformations and strains that occur during thermoforming. Therefore, thickness variation in the final part is usually large and results in significant percentages of scrapped parts. Out-of- tolerange thicknesses, even ruptures, occur in the corner regions of the pa rt where material strains and deformations are maximum during thermoforming. Manufacturers are forced to ttl increase thickness of the sheets in order to decrease out-of-tolerance part numbers at the expense of increasing part cost.

During the first extrusion step, residual stresses are formed within the sheets largely due to uneven cooling of the various regions of the sheets. These residual stresses are somewhat relieved by heating prior to the second thermoforming step only to be formed again by large strains ¾ and deformations during thermoforming, followed by uneven cooling of the final part. As a result, inner liners with built-in residual stresses may develop cracks on their surfaces when these residual stresses combine with thermal stresses during lifetime of the refrigerator. These cracks on the inner liners cannot be repaired and manufacturers are forced to replace customers refrigerators.

3 During thermoforming step, surface quality of the corner regions of the final part where large strains and deformations occur is negatively affected. In these regions, surface loses its luster and becomes dull and whitening occurs. In order to minimize these negative effects, manufacturers are limited to to choose from a few different materials.

S ince the current state of the technology is a two-step process, the material that becomes inner 5¾ liner is heated twice from ambient temperatures to relatively high process temperatures once during the extrusion, and the second time, before the thermoforming steps. Considering the large amount materials processed, current state of the technology is energy intensive.

To sum it up, household refrigerator inner liners are currently manufactured by a two- step( extrusion + thermoforming) process that is energy intensive, occupies a large factory i l space, allows limited material selection, and produces inner liners with undesired thickness variations, built-in residual stresses, and less than desired surface qualities.

Purpose of the invention:

This invention is about an alternative equipment and process to the current state of the art for manufacturing household refrigerator inner liners. The alternative equipment and process t& overcomes all the deficiencies of the current state of the art mentioned above. Additionally, the invention has futher advantages over the current state of the art.

With this invention, household refrigerator inner liners are manufactured in a single step where plastic raw material in powder form is sprayed over mold surface until desired part thicknes is obtained by multiple thermal spray nozzles working in pa rallel. Therefore, this invention ttl significantly decreases initial capital investment and required factory space for inner liner manufacturing compared to the current state of the art which is a two step process(extrusion + thermoforming).

With this invention, plastic material is not stretched and does not undergo large deformations and strains during the manufacturing process. Therefore, part thickness is completely under control ¾ unlike the current state of the art where large deviations from the desired part thickness are common. Pa rt thickness being completely under control, thinner and lighter inner liners could be manufactured with significant material cost savings. F urthermore, scraps due to out-of-tolerance part thicknesses are eliminated.

With this invention, plastic material is not stretched and does not undergo large deformations and 3 strains. Therefore, residual stresses that are formed in inner liners during manufacturing are greatly reduced compared to the current state of the art. With this, the possibility of cracks developing in inner liners during lifetime of refrigerators are also reduced, preventing costly customer refrigerator replacements.

With this invention, plastic material is not stretched and does not undergo large deformations and 5¾ strains. Therefore, loss of surface luster and whitening in the corner areas of inner liners are no longer a problem. As a result, a variety of different plastic materials such as polypropylene and ABS could be used for inner liner manufacturing and inner liners with different colors instead of just white could be manufactured.

With this invention, being a single step process, plastic material is heated from ambient i l temperatures to process temperatures only once compared to twice with the current state of the art. Therefore, considering the large amount of material being processed, significant energy savings are achieved.

With this invention, part thicknesses, being completely under control, are locally increased or decreased as desired, or even various rib patterns could be formed throughout the part in order t& to increase stiffness and strength or to save material.

With this invention where plastic material is deposited over mold surface by multiple thermal spray nozzles in a layer-by-layer fashion, different layers could be sprayed with different or recycled materials for cost saving purposes. Also, various components such as sensors, heat exchangers, and fiber optic or led lights could be placed between layers during manufacturing. ttl With this invention, cycle times for manufacturing inner liners could be reduced compared to current state of the art by increasing the number of thermal spray nozzles working in parallel so that more material will be deposited over the mold surface at a given time period. Decreased cycle times will result in increase in productivity.

As an alternative to using thermal spray nozzles, plastic material in powder form could be sprayed ¾ onto the mold surface without melting as in powder painting process. Powder material and the mold is charged with different electrical polarities, material plus, mold minus polarity for example, so that powder material stays on the mold surface. After, mold with the powder material on it is placed on a oven where plastic material melts and fuses. F inally, mold is taken out of the oven and melted material cools and solidifies. F inally, solidified material is seperated from the mold 3 and the final part is formed.

Desc ription of figures :

Invention will be explained with reference to the figures which are enclosed in this document so that details of the invention could be understood more clearly. But, it is not intended to limit scope of the invention with these figures. On the contrary, it is intended to include all the 5¾ alternatives, changes, modifications, and equivalencies that are covered by the claims section of this document. Designs and concepts shown in the figures are only a particular manifestation of the invention. They do not exclude other possible concepts and designs and are used only to convey ideas and concepts behind the invention. E xplanations about the figures are given below. i l F igure - 1 Perspective view of the manufacturing equipment subject to the invention.

F igure - 2 View showing horizontal motion of the gantry, which holds multiple thermal

spray nozzles, on the rails.

F igure - 3 View showing continuation of the horizontal motion of the gantry.

F igure - 4 View showing completion of the horizontal motion of the gantry. t& F igure - 5 View showing seperation of the manufactured inner liner from the mold.

F igure - 6 Perpective view showing an alternative manufacturing equipment which

includes an oven.

F igure - 7 View showing spraying of powder material onto the mold surface in the

gantry section of the alternative manufacturing equipment. F igure - 8 View showing melting of powder material in the oven section of the alternative manufacturing equipment.

F igure - 9 View showing cooling phase after powder material is melted in the oven using altenative manufacturing equipment.

F igure - 10 View showing seperation of the manufactured inner liner from the mold using altenative manufacturing equipment.

F igure - 1 1 View of the final part, a household refrigerator inner liner, using the invention.

¾ Contents of the figures are numbered as explained below. E xplainations of the number references :

1. Manufacturing equipment

2. C hasis

3. Horizontal movement rail

5¾ 4. Horizontal movement carriage

5. Column

6. Vertical movement rail

7. Vertical movement carriage

8. Thermal spray nozzle holder t l 8.1 Thermal spray nozzle

9. Rotating shaft

10. Mold

1 1. Termal spray gantry 20. P roduction line 21. Oven

H. Raw material layer

U. F inal product (household refrigerator inner liner)

¾ Desc ription of invention:

Manufacturing equipment(1 ) which is the subject of this invention consists of a chassis(2), and, placed on top of the chassis(2), a mold(10) which gives the final product(U) its final shape, two horizontal movement rails(3) each placed such that they are along and near the long edges of the chassis(2) and the mold(10) is between them, and a thermal spray gantry(1 1 ) which is 3 connected to the horizontal movement rails(3) via horizontal movement carriages(4) and moves back and forth along the horizontal movement rails(3) on top of the mold(10), spraying raw material onto it(F igure - 1 ).

Thermal spray gantry(11 ) consists of two vertical columns(5) fixed onto the horizontal movement carriages(4). Two vertical movement rails(6) are placed on each column such that they face

5¾ each other. Two vertical movement carriages(7) are placed on each vertical movement rails(6) and they are connected by a rotating shaft(9). Thermal spray nozzle holders(8) are placed on the rotating shaft(9) and column(5) surfaces facing each other. The linear and rotational movements of the thermal spray nozzle holders(8) are such that they move over the mold(10) with desired trajectories and cover the whole mold(10) area. Multiple thermal spray nozzles(8.1 ) i l are placed on the thermal spray nozzle holders(8). The numbers and the orientations of the thermal spray nozzles(8.1 ) are such that they spray raw material evenly over the whole mold surface within desired cycle time(F igure - 1 ). S ome of the thermal spray nozzles(8.1 ) could be inactivated temporarily depending on the position of the thermal spray gantry(1 1 ) over the mold(10). Multiple thermal spray gantries(1 1 ) could be used on the same horizontal movement t& rails(3) in order to increase the number of thermal spray nozzles(8.1 ), therefore decreasing cycle time of production. Also, intead of using thermal spray gantries( 11 ), alternatives such as multiple robotic arms with high degrees of freedom could be used move thermal spray nozzles over the mold surfaces using desired trajectories.

Invention consists of the manufacturing equipment(l ) which manufactures household refrigerator ttl inner liners by spraying melted plastic material onto a mold(10). Is is differentiated from the current state of the art which is based on extrusion and thermoforming processes, by its use of thermal spraying of melted plastic material with a single and multiple thermal spray gantries(1 1 ), moving back and forth over the mold(10) on two horizontal movement carriages(4) and rails(3) that are placed on top of a chassis(2) along and near the long edges, on each side of the ¾ mold(10)(F igure - 1 ).

Detailed desc ription of the invention:

Invention is about a manufacturing equipment(1 ) and process for manufacturing household refrigerator inner liners. Manufacturing inner liners is done by thermal spray gantry(1 1 ) spraying melted plastic material onto a mold(10), followed by cooling of the plastic material on the mold(10), 3 and, finally, seperation of the cooled and solidified inner liner from the mold(10).

Household refrigerator inner liner manufacturing process which is subject to the invention, is realized by the manufacturing equipment(1 ). There are one or multiple thermal spray gantry units(1 1 ) placed on the horizontal movement rails(3) on the manufacturing equipment(1 ). Thermal spray gantry is fixed to the horizontal movement rails(3) with horizontal movement 5¾ carriages(4) and moves back and forth on the horizontal movement rails(3). The movement of the thermal spray gantry(1 1 ) could be realized by using pneumatic, hydraulic, or electro-mechanic systems.

Thermal spray gantry(11 ) which is a part of the invention, manufactures household refrigerator inner liner which is the final product(U), by spraying melted plastic material onto a mold. Melted i l plastic material is sprayed by multiple thermal spray nozzles(8.1 ) which are attached on thermal spray nozzle holder(8). There are vertical movement rails(6) placed on the surfaces of the columns(5) of the thermal spray gantry(1 1 ) facing each other. Vertical movement carriages(7) are placed on each vertical movement rails(6) and carriages(7) are connected to each other by a rotating shaft(9). Vertical movement carriages(7) could move up and down together on the t& vertical movement rails(6). T he rotating shaft(9) and the thermal spray nozzle holder(8) which is attached to the rotating shaft(9) also moves up and down with the vertical movement carriages(7). All the top horizontal surfaces of the mold(10) which could be at different heights and front and rear vertical surfaces of the mold(10) are covered with melted plastic material evenly with desired thickness by the up and down, rotational, and horizontal movement of the thermal spray ttl gantry(1 1 ). The remaining vertical surfaces of the mold(10) on each side along the horizontal movement rails(3) are covered with melted plastic material evenly with desired thickness by only the horizontal movement of the thermal spray gantry(1 1 ). During the horizontal movement of the thermal spray gantry(1 1 ), a number of thermal spray nozzles(8.1 ) which are attached to the thermal spray nozzle holders on vertical columns on each side, could be turned on and off in order to cover vertical surface regions with different heights on each side of the mold(10) along the horizontal movement rails(3). In F igure - 2, thermal spray gantry(1 1 ) could be seen to have ¾ progressed about one fourth the total distance along the horizontal movement rails(3) and deposited a plastic raw material layer(U) on the mold(10) surface. In F igure - 3, thermal spray gantry(1 1 ) could be seen to have progressed about midway along the horizontal movement rails(3) and deposited a plastic raw material layer(U) on the mold(10) surface. In transition from F igure - 2 to Figure - 3, vertical movement of the thermal spray nozzle holder(8) attached to the

3 rotating shaft(9) which, in turn, is attached to the vertical movement rails(6) via vertical movement carriages(7), could be seen. This is due to the height difference of the mold(10) surfaces between two thermal spray gantry(1 1 ) pozitions in F igures 2 and 3. All the necessary linear and rotational movement capabilities of the thermal spray gantry(11 ) should be provided so that thermal spray nozzles(8.1 ) are kept at desired trajectories with respect to the mold(10) surface

5¾ during the full range of movement of the thermal spray gantry(1 1 ). This way, a final product with desired thickness qualities could be achiewed. Above mentioned movement capability of the thermal spray gantry(1 1 ) could be seen in transition from F igure - 1 to F igure - 4 where rotational movement of the horizontal thermal spray nozzle holder is shown.

Working principle of the invention is as follows: At the beginning, thermal spray gantry(1 1 ) stays i l stationary at a predetermined horizontal position with respect to the front vertical surface of the mold(10) with horizontal thermal spray nozzle holder(8) at the bottom position and rotated so that the nozless(8.1 ) are facing the front vertical surface of the mold(10). Then, as thermal spray gantry stays at its horizontal position, the horizontal thermal spray nozzle holder(8) starts moving upward from its initial bottom position up to the top of the front vertical surface of the mold(10), t& spraying melted plastic material on the surface. At this stage, the thermal spray nozzles(8.1 ) located on the columns on each side are turned off. As the horizontal thermal spray nozzle holder(8.1 ) reaches the top of the front vertical surface of the mold(10), it rotates so that the thermal spray nozzles are now facing downward toward the horizontal surface of the mold(10) and thermal spray gantry(1 1 ) starts moving horizontally with thermal spray nozzles(8.1 ) located ttl on the vertical columns(5) on each side now turned on. It should be noted that, among the thermal spray nozzles(8.1 ) located on the vertical columns(5), only the ones facing mold(10) surfaces are turned on while others are kept turned off. As it can be seen in transition from F igure- 1 to F igure - 2, thermal spray gantry moves horizontally, spraying melted plastic material on both horizontal and vertical surfaces of the mold(10). In F igure -2, about one fourth of the mold(10) surface has been covered with raw material layer(H). Then, as it can be seen in transition from F igure - 2 to F igure - 3, the horizontal thermal spray nozzle holder rotates again so that the nozzles now face the intermediate vertical surface of the mold(10) and starts moving ¾ vertically up, spraying the intermediate vertical surface while thermal spray gantry(11 ) stops moving horizontally and thermal spray nozzles(8.1 ) on the vertical columns(5) are turned off. As the horizontal thermal spray nozzle holder(8) reaches the top of the intermediate vertical surface of the mold(10), the horizontal thermal spray nozzle holder(8) once again rotates so that the nozzles(8.1 ) are facing toward the horizontal mold(10) surface, horizontal movement of the

3 thermal spray gantry(10) resumes, more of the thermal spray nozzles(8.1 ) located on the vertical columns(5) are turned on again to accommodate increased vertical side surface height, and thermal spraying continues. In F igure - 3, sprayed raw material layer(H) could be seen. In F igure - 4, the horizontal thermal spray nozzle holder(8) rotates again so that the nozzles(8.1 ) now face the rear vertical surface of the mold(10), thermal spray gantry stops moving horizontally, the

5¾ thermal spray nozzles(8.1 ) located on the vertical columns(5) are turned off, and the horizontal thermal spray nozzle holder(8) moved vertically down spraying the rear vertical surface of the mold(10). This completes the thermal spraying stage of the manufacturing process. F inally, in F igure - 5, cooled and solidified final product(U) is seperated from the mold(10) and this completes the manufacturing process. i l If needed, the thermal spraying stage of the manufacturing process could be repeated as many times as wanted, in order to increase raw material layer thickness. In each stage, different or recycled materials could be used. Different or recycled materials could also be used locally in the same stage in orderto obtain different local properties such as thermal conductivity coefficient in the final product. Various rib patterns could be formed locally in desired areas on the final t& stage in order to increase stiffness and strength. Various components such as sensors, heat exchangers, and fiber optic or led lights could be placed between layers. Also, void areas with desired geometries could be created in the final product(U) by selectively turning off the thermal spray nozzles(8.1 ) so that various components such as sensors or thermostats could be installed on these void areas in later stages of the refrigerator manufacturing. The edges of these created ttl void areas could be nonuniform due to the nature of the thermal spraying process so that a cutting capability which will not harm the mold surface such as water jet nozzles could be integrated into the thermal spray gantries(1 1 ) in order to to trim the edges of the void areas. This cutting capability could also be used to trim the outside edges of the final product(U). In order to speed up cooling of the final product(U) after the thermal spraying stage is completed, multiple nozzles supplying cooling air or water mist at desired temperatures, pressures, and flow rates could be integrated into the thermal spray gantries(11 ). Or seperate gantries could be added to the manufacturing equipment(l ) for cooling purposes. This cooling capacity could also be ¾ used to cool the mold(10) if needed between the production cycles.

The mold(10) surface could be coated with various materials such as teflon in order to aid seperation of the final product(U) from the mold(10). Additionally, a vibrational excitation with desired frequency and amplitude could be applied to the mold(10), the final product(U), or both in order to aid the seperation. Also, multiple nozzles spraying various materials such as silicon 3 onto the mold surface between the production cycles in orderto aid seperation could be integrated into the thermal spray gantries(11 ). Or seperate gantries could be added to the manufacturing equipment(l ) for this purpose.

Alternative manufacturing equipment and process :

As an alternative to the manufacturing equipment(1 ), a production line(20) is placed on a 5¾ chassis(2). A spray gantry(1 1 ) followed by an oven(21 ) are attached to the chassis(2) such that the production line(20) moves through them. A mold(10) is attached to the production line(20) such that the mold(10) moves with the production line(20). The spray gantry(11 ) is exactly the same as the one in the previously detailed manufacturing equipment(1 ) except that the spray gantry(1 1 ) in this alternative does have powder paint nozzles instead of thermal spray nozzles. i l Therefore, in this alternative, plastic raw material in powderform is cold sprayed onto the mold(10) surface without getting melted(F igure - 6).

In this altenative manufacturing equipment and process, the mold(10) passes through the stationary spray gantry once orseveral times back and forth with the movement ofthe production line(20) while all the mold surfaces are coated with plastic powder material by powder paint t& nozzles(8.1 ) until desired thickness is obtained(F igure - 7). S ince, at this stage, powder material is not heated and melted and still in powder form, adhesion to the mold(10) surface is achieved by charging the mold(10) and the powder material with opposite polarities similar to powder painting process. For example, the mold(10) could be charged pozitive electrically, while the powder material could be charged negative. Then, the mold(10) coated with the powder material ttl is moved inside the oven(21 ) by the product line(20) where heat is applied to the powder material coating on the mold(10) and powder material melts and fuses(F igure - 8). Then, the mold(10) is moved out of the oven(21 ) by the production line(20) for cooling(F igure 9). To speed up the cooling, various methods such as fans and air nozzles could be used at this stage. F inally, cooled final product(U) is seperated from the mold(10)(F igure - 10). Once again, all the methods for aiding the seperation such as coatings, vibration application, and non-stick sprey materials could also be used in this alternative manufacturing equipment and process.