METHOD FOR COATING A MATTRESS AND APPARATUS FOR COATING A MATTRESS

Abstract: The invention relates to a method for placing a mattress (1) into the inner volume formed by a coating (8), the coating (8) having a feeding opening (9). The method uses mattress transportation means (4, 5) for moving the mattress (1) into the inner volume. The mattress transportation means (4, 5) are placed partly into the inner volume of the coating (8). The transportation means (4, 5) reduce the perimeter of the mattress (1) in a direction perpendicular to the direction of moving the mattress (1) at least at the feeding opening (9), whereby the perimeter of the mattress is preferably smaller than or equal to the perimeter of the feeding opening.

Description: Method for coating a mattress and apparatus for coating a mattress The invention relates to a method for coating a mattress presented in the introductory part of Claim 1. The invention relates also to an appa¬ ratus for coating a mattress according to the method. Particularly mattresses made of cellular plastic and raw rubber are coated with a fabric or a corresponding coating, inter alia for improving the comfort of use and appearance of the mattress. The coating is usually releasable, bag-like, wherein the mattress can be placed in the inner volume of the coating. Further, the coating is provided with a sealable opening which is preferably slightly smaller than the cross- sectional surface of the mattress, whereby the mattress can be inserted to the coating through this opening. At times, the coating must be re¬ moved from above the mattress for cleaning. Thus the means for clos¬ ing the opening formed in the coating, for example a zipper, is opened, whereby the mattress can be drawn out. The placement of the mattress back into the coating is often difficult, because the perimeter of the opening is often smaller than the perimeter of the cross-section of the mattress in the direction of inserting the mattress. Mattresses of cellular plastic and raw rubber are resilient, but their sur¬ face is poorly slipping, whereby drawing the coating on top of the mat- tress is difficult and thus also time-consuming. Methods have been de¬ veloped for inserting the mattress into the coating in an easier and quicker way. One such method is presented in British patent GB- 1 483 185. By this method, the mattress is placed inside a plastic bag which is connected to a suction apparatus. After that, the suction appa- ratus is turned on, whereby when the air is removed, the volume of the plastic bag is reduced and the mattress is thus partly compressed. Fol¬ lowing this, the plastic bag is closed. Because the volume of the mat¬ tress is reduced, it is possible to place the mattress within the plastic bag more easily into the coating. Furthermore, the plastic bag reduces the surface friction between the coating and the mattress, which will also make it easier to place the mattress into the coating. When the mattress is inside the coating, the plastic bag is opened, whereby air is allowed to flow into the plastic bag and the mattress returns substan¬ tially to its original size. This method has e.g. the disadvantage that the suction device is com- plicated and makes noise at the suction stage. Installation of the plastic bag in the coating device and placing the mattress into the plastic bag increase the work stages required for coating the mattress and prolong the time of coating the mattress. The plastic bag makes the surface of the mattress harder and causes a sweaty feeling. Further, the possible rustling sound produced by the plastic bag may cause an uncomfort¬ able feeling. Also, returning of the compressed mattress into its original size may take a relatively long time, which is not desirable in view of usability of the mattress. German application publication DE-14 85 526 presents a method and an apparatus for coating a mattress, whereby the mattress is moved with band-like conveyors in the horizontal direction. The band-like con¬ veyors are arranged in a wedge-like relation to each other, whereby they form a shaφ angle and thus induce a contraction of the mattress in the cross-sectional direction. Following this, the mattress is led into the inner volume of a bag-like coating. As extensions of the vertical conveyors, there are stationary guide means which keep the mattress compressed at the stage when the mattress is led into the inner volume of the bag-like coating. During coating of the mattress, the bag-like coating is situated outside these guide means. A disadvantage in this solution is the fact that the friction between the mattress and the guide means will considerably increase the force required for transportation of the mattress. Another disadvantage in the apparatus presented in this German application publication is the fact that it can only be used for coating mattresses of substantially uniform size. If there is a need to coat mattresses of different sizes, a different apparatus must be built for each mattress size. Also other methods are known for coating a mattress, which are based largely on the use of a suction apparatus or the like. Also these meth¬ ods have the disadvantages described above, such as complicated construction and noise of the apparatus. The purpose of the present invention is to eliminate the above-men¬ tioned disadvantages to a large extent and to provide a practical and quick method and apparatus for coating a mattress. The invention is characterized in what will be presented in the characterizing part of the appended Claim 1. The invention gives considerable advantages to the methods and appa¬ ratuses of prior art. The method according to the invention is quick and it can be implemented with a relatively inexpensive apparatus, whereby the use of the method and apparatus of the invention is inexpensive also when coating in smaller scale. The steplessly adjustable coating apparatus of the invention makes it possible to coat easily mattresses of different sizes. Furthermore, by using the method of the invention, the use of various plastic bags and other auxiliary means is avoided. Thus, the properties of the coated mattress are not impaired. Another advantage is that by using the method of the invention, the coating of the mattress can be conducted quickly, whereby the coating costs will be reduced. The coating device of the invention is almost noiseless and does not raise dust. In the following, the invention will be described in more detail with ref¬ erence to the appended drawings, in which Fig. 1 shows the apparatus according to an advantageous em- bodiment of the invention seen from above, and Fig. 2 shows a detail in cross-section at point 1 — I in Fig. 1. The placement of a mattress 1 into the inner volume of a coating 8 can be conducted according to a coating apparatus 2 according to an ad¬ vantageous embodiment shown in Fig. 1 for example in a way that the mattress 1 to be coated is placed on a mattress feeding conveyor 3. The mattress feeding conveyor 3 consists advantageously of two con¬ veyor belts 3a, 3b known as such. Rollers are provided at both ends of the conveyor belt and, if necessary, also auxiliary rollers in the inter¬ mediate section of the conveyor belt. Power transmission is advanta¬ geously coupled to a roller placed at one end of the conveyor belt 3a, 3b and whose rotation makes the conveyor belt 3a, 3b move. Next, the distance d1 between horizontal transportation means 4 is ad¬ justed in a way that the distance d1 is slightly smaller than the thickness of the mattress 1 (Fig. 2). In a corresponding way, the distance d2 be- tween vertical transportation means 5 is adjusted in a way that the dis¬ tance d2 is slightly smaller than the width of the mattress 1. The dis¬ tance d1 between the horizontal transportation means 4 can be ad¬ justed advantageously by turning on a first electric motor (not shown) coupled via a first transmission mechanism (not shown) to the support means of the horizontal transportation means 4. The first transmission mechanism can comprise e.g. a first screw arm, wherein the support means of the horizontal transportation means 4 are provided with re¬ spective first screw means fitting to the first screw arm, whereby upon turning the first screw arm in the first direction, the screw means move the upper horizontal transportation means 4a upwards and the lower horizontal transportation means 4b downwards, wherein the dis¬ tance d1 will increase. In a corresponding manner, when turning the first screw arm in the opposite direction, the distance d1 will decrease. The implementation of the transmission mechanism is obvious to a man skilled in the art, whereby its further explanation in this context will be unnecessary. The adjustment of the distance d2 between the vertical transportation means 5 is advantageously conducted with a second motor 10. The second motor 10 is coupled to a second transmission mechanism, such as a second screw arm 11. Thus, the frame parts 12a, 12b of the coat¬ ing apparatus 2 are provided with second screw means fitting to the threading of the screw arm. When the second motor 10 revolves the screw arm 10 in the first direction, the second screw means make the frame parts 12a, 12b move farther apart from each other. The first ver¬ tical transportation means 5a move along with the first frame part 12a, and the second vertical transportation means 5b move along with the second frame part 12b, wherein the distance d2 between the vertical transportation means 5a, 5b will increase. In a corresponding manner, when the motor 10 revolves the screw arm 11 in the opposite direction, the frame parts 12a, 12b will move closer to each other, wherein the distance d2 between the vertical transportation means 5a, 5b will be reduced. In the upper section of the frame parts 12a, 12b, there is a support means 13 for supporting the top of the frame parts 12a, 12b when adjusting the distance d2. The conveyor means 4, 5 consist preferably of conveyor belts. The conveyor means are advantageously elongated, wherein the conveyor means 4, 5 are at their both ends provided with a roller or the like for generating the movement of the conveyor belt. Thus that section of the conveyor belt which is between the end rollers at each time, against the surface of the mattress 1, moves in the direction of transferring the mattress, wherein also the mattress will move in this direction. In a cor¬ responding way, the other section of the conveyor belts, which is be¬ tween the end rollers on the other side at the time, moves in the oppo¬ site direction. Furthermore, the conveyor means 4, 5 are arranged in relation to each other advantageously so that when the mattress 1 is moved on the feeding conveyor 3 towards the transportation means 4, 5, the mat¬ tress 1 is first subjected to the effect of the vertical transportation means 5 before the horizontal transportation means 4. After the distances d1 , d2 of the horizontal 4 and vertical transportation means 5 have been adjusted suitable, the coating 8 is placed in the coating apparatus 2. Also coating support means 7 are fixed to the transportation means 4, 5, whereby the coating 8 can be placed around the support means 7. The coating support means 7 make the feeding opening 9 of the coating open preferably to its maximum size. At this stage, the coating 8 is placed advantageously so that the transportation means 4, 5, are partly within the inner volume of the coating, at least one end of the transportation means 4, 5. By the effect of the move- ment of the transportation means 4, 5, the mattress 1 moves gradually towards the other end of the transportation means 4, 5. Simultaneously the other end of the transportation conveyors, moving in a direction opposite to the transportation direction of the mattress, makes the coating 8 move in this direction, which will facilitate the coating 8 to re- main in its position during coating. Following this, the feeding con¬ veyor 3 and the transportation means 4, 5 can be started. Thus the mattress 1 begins to move towards the feeding opening 6 formed by the frame parts 12a, 12b. The coating 8 can also be supported manu- ally at the support means 7 to secure that the coating 8 will not disen¬ gage too early from the coating apparatus 2. Consequently, the transportation means 4, 5 reduce the perimeter of the mattress to some extent at least at the transportation means 4, 5. This situation is illustrated in Fig. 2, in which the cross-section of the mattress is shown by broken lines as an example. Because the perime¬ ter of the mattress 1 is at this stage smaller than the perimeter of the feeding opening 9 of the coating 8, the mattress 1 is gradually moved inside the coating 8. At the stage when the front end of the mattress in the direction of moving is at the second end of the transportation means 4, 5, this part of the mattress begins to return to its original shape. The transportation means 4, 5 keep on pushing the mattress forward. In the end, the mattress 1 is wholly inside the inner volume of the coating 8, after which the mattress 1 and the coating 8 disengage from the coating apparatus 2 and the mattress fills substantially the whole inner volume of the coating 8. Following this, the feeding open¬ ing 9 can be closed. Because the distance d1 , d2 between the transportation means 4, 5 can be adjusted in a stepless manner, it is possible to use the coating apparatus of the invention for coating mattresses of different sizes. Tests on the mattress coating apparatus according to the invention have shown e.g. that the vertical transportation means 5 must be placed as precisely as possible parallel to each other and to the direc¬ tion of movement of the mattress. Thus, the mattress 1 will be sub¬ jected to a minimum number of torsional moments disturbing the movement of the mattress. It is also possible to connect a formula control device to the coating ap¬ paratus according to the invention. The most common mattress sizes, particularly cross-sectional sizes, can be stored in the memory of the formula control device, whereby the size of the mattress to be coated can be selected advantageously by pressing one button. Thus, the for¬ mula control device will identify which button was pressed and will ad¬ just the distance d1 , d2 between the transportation means to corre¬ spond to the selected mattress size. Mattress sizes which are not stored in the memory of the formula control device can be coated e.g. by entering the readings corresponding to the thickness and width of the mattress via the keyboard of the formula control device. Furthermore, the coating apparatus 2 comprises support strips 14 coated preferably with Teflon, whereby the mattress to be coated is better kept in its shape in the area between the horizontal transporta¬ tion means 4. Moreover, the support strips 14 reduce the surface fric¬ tion between the mattress 1 and the coating 8, facilitating the place- ment of the mattress 1 in the inner volume of the coating 8. The density/weight ratio of mattresses 1 can vary to a great extent, the resiliency and compressibility of the mattress varying accordingly. Thus, the user of the mattress can select a mattress most suitable to his/her weight. By means of the coating apparatus 2 of the invention, it is pos¬ sible to use mattresses having different density/weight ratios. If neces¬ sary, it is possible to reduce the diminishing of the perimeter of mat¬ tresses with a higher density/weight ratio in the apparatus, taking into account the perimeter of the feeding opening 9 of the coating 8. Thus, the density/weight ratio of the mattress can be used as one parameter in the formula control device. Further, it is possible to use a mattress manipulator in connection with the coating apparatus 2 of the invention, whereby stacks of mattresses are placed in the manipulator, preferably mattresses of equal size in the same stack. Thus the manipulator takes one stack at a time for proc¬ essing. The manipulator moves one mattress at a time from the stack to the feeding conveyor 3 of the coating apparatus 2. The operator of the coating apparatus 2 puts a coating 8 fitting the mattress 1 in its place and turns on the coating apparatus 2, as described above in the de¬ scription. After processing one stack of mattresses, the manipulator will take the next stack of mattresses for processing, and the operator will set the distances d1 , d2 of the transportation means 4, 5 of the coating apparatus 2 to correspond to the mattress size to be processed. Although the invention has been described above in connection with coating a mattress, the invention can also be applied for coating other pieces preferably made of a resilient material, with a coating 8. For ex- ample, coatings of sofa cushions and seat cushions are designed to be baggy, and they have a feeding opening 9 for removing the cushion from the coating 8 e.g. to be washed and placed back in the cushion 8. It is specific also to these kinds of cushions that the inner volume of the coating 8 is advantageously slightly smaller than the free volume of the cushion and that the perimeter of the feeding opening 9 is smaller than the perimeter of the cushion in a direction perpendicular to the direction of feeding. The invention is not limited solely to the embodiments presented above, but it can be modified within the scope of the appended claims.

Claims: Claims: 1. Method for coating a piece manufactured of a resilient material, such as a mattress (1), preferably with a baggy coating (8) forming an inner volume, the coating (8) having a feeding opening (9), whereby the method uses transportation means (4, 5) for moving the piece (1) into the inner volume and the transportation means (4, 5) reduce the pe¬ rimeter of the piece (1) in a direction perpendicular to the direction of moving the piece (1) at least in that part of the piece (1) which is at the feeding opening (9) at the time, characterized in that the transporta¬ tion means (4, 5) are partly placed into the inner volume. 2. Method according to Claim 1, characterized in that the transpor¬ tation means (4, 5) consist of horizontal transportation means (4) and vertical transportation means (5), wherein the horizontal transportation means (4) are placed close to the end portions of the piece in a cross- section perpendicular to the direction of moving the piece (1). 3. Method according to Claim 1 or 2, characterized in that the trans- portation means (4, 5) consist of conveyor belts (4a, 5a). 4. Coating apparatus (2) for coating a piece manufactured of a resil¬ ient material, such as a mattress (1), preferably with a baggy coating (8) comprising an inner volume, the coating (8) having a feeding open- ing (9), whereby the coating apparatus (2) comprises transportation means (4, 5) for moving the piece (1) into the inner volume and the transportation means (4, 5) are arranged to reduce the perimeter of the piece (1) in a direction perpendicular to the direction of moving the piece (1) at least in that part of the piece (1) which is at the feeding opening (9) at the time, characterized in that the transportation means (4, 5) are arranged to be placed partly into the inner volume dur¬ ing the stage of coating the piece. 5. Coating apparatus (2) according to Claim 4, characterized in that the transportation means (4, 5) consist of horizontal transportation means (4) and vertical transportation means (5), wherein the horizontal transportation means (4) are arranged to be placed close to the end portions of the piece in a cross-section perpendicular to the direction of moving the piece (1 ). 6. Coating apparatus (2) according to Claim 4 or 5, characterized in that the horizontal transportation means comprise lower horizontal transportation means (4a) and upper horizontal transportation means (4b), and that the vertical transportation means comprise first vertical transportation means (5a) and second vertical transportation means (5b). 7. Coating apparatus (2) according to Claim 6, characterized in that the coating apparatus (2) comprises adjusting members, whereby the distance (d1) between the horizontal transportation means (4a, 4b) and the distance (d2) between the vertical transportation means (5a, 5b) can be adjusted. 8. Coating apparatus (2) according to any of the Claims 4 to 7, char¬ acterized in that the transportation means (4, 5) comprise conveyor belts. 9. Coating apparatus (2) according to any of the Claims 4 to 6, char¬ acterized in that the coating apparatus (2) comprises further a feeding conveyor (3) for moving the piece (1) to the coverage area of the trans¬ portation force generated by the transportation means (4, 5). 10. Coating apparatus (2) according to any of the Claims 4 to 9, char¬ acterized in that the coating apparatus (2) comprises further a formula control device, whereby the formula control device is provided with means for storing different piece sizes, - means for selecting a stored mattress size, and means for adjusting the transportation means (4, 5) to correspond to the selected mattress size.

Inventors: NIEMELAE JOUKO, NIEMELAE, JOUKO
Applicants: NIEMELAE JOUKO, ROBONIC LTD OY, NIEMELAE, JOUKO, OY ROBONIC LTD.
Application year: 1997
Main classification: B68G7
IPC codes: B68G7