Description:FIELD OF THE INVENTION
[001] The present invention relates to a coating thickness adjustment mechanism for a coating machine, including apparatus and more particularly, to precisely apply a coating over a web of flexible film or laminate.
BACKGROUND OF THE INVENTION
[002] Traditionally, coating machines use handwheels on both the ends of the nip roller to rotate the swing arm to adjust the distance between the nip roller and the coating roller to achieve the required thickness of the coating for a uniform coating on the surface of web of film or laminate. The gap between the nip roller and the coating roller is measured manually and validated against the thickness achieved on the web surface. This setup essentially requires specific technical expertise of the operator to precisely set the machine for production without wasting much time in hit and trials.
[003] In another prior arts nip roller is pressed at both the ends by a pair of pneumatic cylinders. The thickness of the coating on the web of flexible film or laminate is optionally controlled by CAM follower, taper wedge with calibrated rotary knob. This system may work satisfactorily when the web of flexible film or laminate thickness is uniform. In case the thickness of webs is slightly varying the pneumatic cylinder continuously presses the nip roller which in turn presses film or laminate against the coating roller, without any control on gap between coating roller and nip roller. The only control in this system is compressed air pressure provided to the pressing cylinder. This may result in film or laminate either getting stretched during the pulling through the rollers or even tear sometimes.
OBJECT OF THE INVENTION
[004] Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
[005] An object of the present invention is to provide a digitally controlled automatic servo driven coating thickness adjustment mechanism for web coating head on coating machines.
[006] Another object of the present invention is to quick and precise thickness adjustment and achieve uniform thickness of coating over web surface.
[007] Another object of the present invention is to achieve the predefined coating thickness by lowering or moving up the nip roller separately or synchronously for both the ends of nip roller according to the thickness variation in the web of film or laminate.
SUMMARY OF THE INVENTION
[008] In view of the foregoing limitations inherent in the prior art, the present invention provides a technical solution for precise and easy coating thickness adjustment mechanism on the coating machine.
[009] The present invention is realized through the following technical solutions: a coating thickness adjustment mechanism on a coating machine, comprising of a coating roller, a nip roller, a pair of linear guides and runner block sets are arranged just above the nip roller on both the side frames of the coating machine, a pair of mounting brackets, a pair of servo motors, a pair of gearboxes, a pair of linear actuators coupled with mounting brackets with floating joints. The linear actuator actuates the floating joint up and down for coating thickness adjustment by varying the gap between nip roller and the coating roller. A pneumatic cylinder is also present on any one side of the machine frame for nip roller changeover or rubber sleeve changeover and initial position locking of the nip roller. The runner block sets, and the supporting block move together on Linear motion guide.
[0010] The electrical linear actuator may be an in-line electrical linear actuator or parallel electrical linear actuator. In the in-line electrical linear actuator, the servo motor is coupled in-line with the gear box and the linear actuator. In the parallel electrical linear actuator, the servo motor is mounted on gear box, configured parallel to the linear actuator and the gear box shaft is connected with the linear actuator via a mounting block. The gear box shaft at one end and on the other end the linear actuator shaft is coupled with the timing belt and pulley arrangement housed inside the mounting block.
[0011] Compared with the prior art, the coating thickness adjustment mechanism on the coating machine of the present invention has the following benefits:
a. The coating thickness adjustment mechanism drives the floating joints up or down through the rotation of servo motor driving the gearbox and gearbox shaft then rotates the spindle of the linear actuator and provided linear up or down movement of actuator shaft. This calibrated rotation of servo motor and linear movement of actuator realizes the automation of thickness adjustment. This improves quality of thickness, efficiency and reduces skill and labour requirement.
b. The coating thickness adjustment mechanism of the present invention can offer an accuracy of 1 micron to 500 micron on any side of the nip roller. Further, both sides of the nip roller separately or synchronously can achieve the gap setting ranging from 1 micron to 500 microns. This allows to remain close to the predefined required thickness of the coating taking consideration of the web thickness variation across the width of the web and thus becomes economical by preventing wastage by coating more than the required.
[0012] The best mode for conducting the present invention will be described below with reference to the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] These and other advantages and features of the present invention, as well as methods of operation and economics of manufacture, will become apparent to one skilled in the art to which the present invention pertains based upon the following detailed description and the appended drawings, all of which form a part of this application.
[0014] FIG. 1 is the isometric view of one of the prior arts.
[0015] FIG. 2 is a schematic structural diagram of a coating thickness adjustment mechanism and apparatus of the present invention, on a coating machine.
[0016] FIG. 3 is the isometric view of a coating thickness adjustment mechanism and apparatus of the present invention, on a coating machine.
DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS
[0017] The present invention relates to a coating thickness adjustment mechanism and apparatus of coating machine and more particularly, to precisely apply a coating over a flexible film or laminate, on any side or both sides.
[0018] FIG. 1 is isometric view of one of the prior arts working on a pair of pneumatic cylinders (1) to actuate a floating joint (4) to move a runner block set on the LM guide & runner block set (5) with a supporting block (6) to lower a nip roller (7) to adjust and achieve a desired gap between the nip roller (7) and the coating roller (8) to obtain specified coating thickness on the web of flexible film or laminate present between the nip roller (7) and a coating roller (8).
[0019] FIG. 2 is a schematic structural diagram of the embodiments of a coating thickness adjustment mechanism on a coating machine of the present invention. The coating thickness adjustment mechanism on the coating machine as per the present invention includes a coating roller (8), a LM (linear motion) guide and runner block set (5) and a supporting block (6) is provided above a nip roller (7) on each of a coating machine frames (13). The linear actuator (10) is coupled with a floating joint (4) and floating joint is coupled with supporting block (6) on the other side, on each machine frames (13), and the gear box (9) is coupled with the linear actuator (10), the gear box (9) shaft can be moved clockwise or anti-clockwise by the corresponding rotation of the servo motor (2). The Nip roller (7) is permanently fixed in the supporting block (6) on any one side of the coating machine frame (13) and the other side of the nip roller (7) is fixed for initial positioning by a pneumatic cylinder (11) through a locking lever (12) for easy replacement of the nip roller (7). The floating joint (4) of any side of the nip roller (7) can be actuated through linear actuator (10) of in-line drive type to adjust the gap between the nip roller (7) and coating roller (8) to obtain the desired thickness of the coating on the web of flexible film or laminate surface. The pair of linear actuators (10) are mounted on a pair of mounting brackets (3) inside the pair of machine frames (13).
[0020] In the present invention to make the coating cylinder (8) and the nip roller assembly (7) more sensitive and accurately controlled, the pneumatic cylinders (1) are replaced with the servo motor (2) driven linear actuators (10) of high resolution wherein the pair of linear actuators (10) are controlled by a control panel having servo drives with digitally defined drive to servo motors (2). The two drives may be controlled independently or synchronized.
[0021] In the FIG 2, in an in-line electrical linear actuator (30), the servo motor (2) is coupled in-line with the gear box (9) and the linear actuator (10).
[0022] In the FIG 2, another option is shown where the in-line electrical linear actuators (30) may be replaced with parallel electrical linear actuators (20) to save vertical space on the coating machine frame. The servo motor (2) is mounted on the gear box (9), the gear box (9) is mounted on the mounting block (19). The linear actuator (10) is mounted on the other end of the mounting block (19), parallel to servo motor (2) and gearbox (9) assembly. The gearbox (9) shaft at one end and on the other end the linear actuator (10) shaft are coupled with a pair of pulleys and timing belt, enclosed inside the mounting block (19). Without departing from the scope of this invention any other design of linear actuation mechanism may also be used.
[0023] FIG. 3 is the isometric view of the coating thickness adjustment mechanism on one side of the coating machine frame.
[0024] The said arrangement provides initial zero setting by moving the linear actuators (10) downward and letting the nip roller (7) touch the coating roller (8) without any web of flexible film or laminate in between this defines the zero-gap condition and then moving the servo motors (2) upwards to obtain a gap equal to the web thickness. The fine adjustment of the gap may be required after coating and physical measurement of the coating thickness achieved and comparing it with desired coating thickness. The least count for adjustment of gap between the nip roller (7) and coating roller (8) is in the range of 1 micron to 500 micron.
[0025] The least count for the gap between the nip roller (7) and the coating roller (8) can be adjusted separately for both the ends of the nip roller (7) by actuating respective electrical linear actuator present on the side of the coating machine frame (13).
[0026] Fine adjustment of gap between nip roller (7) and coating roller (8) depending upon the thickness of the web may be done accurately by digital servo controls on HMI. This system avoids undesirable continuous pressure on the web of flexible film or laminate experienced in the prior art with pneumatic cylinders and ensures smooth movement of the web of flexible film or laminate through the coating station ensuring consistent coating uniformity and thickness.
[0027] In one of the embodiments one coating thickness adjustment mechanism is used on single head coating machine which provides coating on any one side of the film or laminate web, in one pass.
[0028] In one of the embodiments two coating thickness adjustment mechanism are used individually on double head coating machine which may provide coating on both sides of the web, one after the other in a single pass. However, such double head coating machine may also be used to coat one type of coating over another type of coating on the same side of the web.
[0029] In one of the embodiments the floating joints (4), may be suitably replaced with ball joints, knuckle joints or rod and eye ball joints.
[0030] In one of the embodiments the linear motion guide and runner block sets (5) optionally substituted with guide pillars and bushes or bearing shafts.
[0031] The foregoing descriptions of specific embodiments of the present disclosure have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present disclosure to the precise forms disclosed and obviously many modifications and variations are possible considering the above teaching. The embodiments were chosen and described in order to best explain the principles of the present disclosure and its practical application, to thereby enable others skilled in the art to best utilize the present disclosure and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omission and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the spirit or the scope of the claims of the present invention.

REFERENCE NUMERALS
1 Pneumatic Actuator
2 Servo motor
3 Mounting bracket
4 Floating joint
5 LM guide and runner block set
6 Supporting Block
7 Nip roller
8 Coating roller
9 Gear box
10 Linear Actuator
11 Pneumatic cylinder (For Holding Nip Roller)
12 Locking lever
13 Coating machine frame
19 Mounting block for gear
20 Parallel Type Electrical Linear Actuator
30 In-line Type Electrical Linear Actuator
, Claims:We Claim,
1. a coating thickness adjustment mechanism for a coating machine, comprising:
a coating roller (8);
a nip roller (7) placed above in parallel to the coating roller (8), having an adjustable gap between them for a web of film or laminate to be pressed against the coating roller (8) for coating;
the ends of the nip roller (7) are mounted on a pair of supporting blocks (6), and the pair of supporting blocks (6) are fixed on a pair of linear motion guide and runner block sets (5) fixed on a pair of machine frames (13) and connected to the supporting blocks (6);
a pair of floating joints (4) to couple a pair of electrical servo driven linear actuators (20 or 30) with the pair of supporting blocks (6); and
servo motor drive control panel with HMI.
2. The coating thickness adjustment mechanism as claimed in claim 1, wherein the supporting blocks (6) are actuated up or down by a linear actuator (10) to lift or lower the nip roller (7) towards the coating roller (8), respectively.
3. The coating thickness adjustment mechanism as claimed in claim 1, wherein the floating joints (4), is one of ball joints, knuckle joints or rod and eye ball joints.
4. The coating thickness adjustment mechanism as claimed in claim 1, wherein the Linear Motion guide and runner block sets (5) optionally substituted with guide pillars and bushes or bearing shafts.
5. The coating thickness adjustment mechanism as claimed in claim 1, wherein the supporting blocks (6) and the runner blocks set are coupled and move together.
6. The coating thickness adjustment mechanism as claimed in claim 1, wherein the servo motors (2) are configured in-line with the linear actuator (10) through the gear box (9) to form an in-line type electrical linear actuator (30).
7. The coating thickness adjustment mechanism as claimed in claim 1, wherein the servo motors (2) are configured in parallel with linear actuator (10) and coupled with a timing belt and pulley arrangement to form a parallel type electrical linear actuator (20).
8. The coating thickness adjustment mechanism as claimed in claim 1, wherein the least count for adjustment of gap between nip roller (7) and coating roller (8) is in the range of 1 micron to 500 microns.
9. The coating thickness adjustment mechanism as claimed in claim 1, wherein the gap between the nip roller (7) and the coating roller (8) can be adjusted separately for both the ends of the nip roller (7) by actuating respective electrical linear actuators (20 or 30).
10. The coating thickness adjustment mechanism as claimed in claim 1, wherein the gap between the nip roller (7) and the coating roller (8) can be adjusted by synchronous movement of electrical linear actuators (20 or 30) on both the ends of the nip roller (7).
11. The coating thickness adjustment mechanism as claimed in claim 1, wherein the zero setting is obtained by bringing down the nip roller (7) to touch the coating roller (8).
Dated this 14th day of June 2024.