Apparatus for coating products, machine provided with such apparatus and method for controlling the machine

Abstract

This invention relates to a coating apparatus for coating products. The coating apparatus has a support, a product tube disposed in the support, and a longitudinal hole defined by the support. The coating apparatus has a needle installed in the longitudinal hole. The coating apparatus has a product coating valve and a valve. The product coating valve is formed by a nozzle arranged on the support. The valve is arranged at one end of the needle located in the product tube. The needle is configured to move along a longitudinal axis between a closed position (closing the product coating valve) and an open position (opening the product coating valve). The coating apparatus is characterized by having a limiter fixed relative to the needle and a limiter fixed relative to the support. The limiter fixed relative to the support is configured to restrict the needle from returning to an intermediate position between the closed and open positions through interaction with the limiter fixed relative to the needle. Furthermore, the limiter fixed relative to the support has an adjustable position.

Description

TECHNICAL FIELD

[0001] The present invention relates to a device for coating products, a machine having such a device and a method for controlling such a machine. BACKGROUND

[0002] In the field of coating or sealing products with a robotic system, it is necessary to quickly change the coating flow in order to obtain, for example, wide or narrow lines of coated or sealed products. This change in width must be quick in order to ensure a uniform result and avoid wasting high-cost products. Because these products are adhesive, the system must be dedicated.

[0003] An electric product dosing or pressure control system is driven by an electric motor. In the case of a dosing system with little power and close to the coating, the motor speed is directly proportional to the product output. In the case of a more powerful coating, or when the coating is far from the dosing system, the dosing or pressure control system has a relatively long reaction time due to the compressibility of the product, the elasticity of the hoses and the associated high pressures.

[0004] In order to obtain a quick change in flow, it is known to use a mechanical system that forms an adjustable orifice with a moving part before the product coating nozzle. This solution has several drawbacks:

[0005] The product coating cannot be stopped quickly due to the pressure drop between the orifice and the nozzle. The ends of the coating lines are therefore not uniform.

[0006] The products are abrasive, causing wear of the moving parts, which generates leaks.

[0007] The actuator necessary for the movement of the moving part must be quick and powerful, and is therefore expensive.

[0008] A dedicated sealing gel must be used for all the moving parts, which increases the cost.

[0009] The needle and valve seat must be specially designed, which cannot use existing non-variable flow coating devices.

[0010] The present invention aims to propose a new coating device for coating products, the product coating flow of which can be quickly changed, with a lower cost and complexity of the mechanical part and better performance and reliability compared to existing solutions. SUMMARY

[0011] To this end, the application relates to a coating device for coating a product, the coating device having a support in which a product tube is arranged, the support defining a longitudinal bore, the coating device having a needle mounted in the longitudinal bore, the coating device having a product coating valve formed by a nozzle arranged on the support and a shutter arranged at one end of the needle in the product tube, the needle being configured to move along a longitudinal axis between a closed position in which the product coating valve is closed and an open position in which the product coating valve is open. The coating device is characterized in that it has a stopper fixed relative to the needle and a stopper fixed relative to the support, the stopper fixed relative to the support being configured to limit the return of the needle to an intermediate position between the closed position and the open position by interaction with the stopper fixed relative to the needle; and in that the stopper fixed relative to the support has an adjustable position.

[0012] According to the application, the needle is positioned in the intermediate position, an adjustable orifice being formed, without the need for an expensive actuator or a specific sealing solution design.

[0013] According to an advantageous but non-limiting embodiment of the application, according to any technically admissible combination, such a product coating device can have one or more of the following characteristics:

[0014] - the stopper fixed relative to the support is formed by at least one cam; and the coating device has an actuator for adjusting the position of the cam.

[0015] - the position of the cam is adjustable in rotation about an adjustment axis perpendicular to the longitudinal axis of the needle; and the profile of the cam is a surface of increasing radius.

[0016] - the position of the cam is adjustable in rotation about an adjustment axis parallel to the longitudinal axis of the needle; and the thickness of the cam increases about the adjustment axis.

[0017] - the actuator for adjusting is a rotary electric motor.

[0018] - the cam is supported by a tubular portion mounted around a portion of the needle projecting from the support; and the actuator is a hollow shaft electric motor driving the tubular portion, the angular position of the cam being adjustable about the longitudinal axis of the needle; and the thickness of the cam increases about the adjustment axis.

[0019] - the stopper fixed relative to the needle is fixed to one end of the needle projecting from the support.

[0020] - the actuator, the stopper fixed relative to the needle and the stopper fixed relative to the support form an external device configured to be fixed to and connected to the support and the needle of an existing coating device.

[0021] - The limiter fixed relative to the needle is formed by a piston, which is housed in the control chamber of the bracket; and the limiter fixed relative to the bracket is arranged in the bracket and extends into the control chamber.

[0022] - The limiter fixed relative to the needle has an inclined surface that is tilted relative to the longitudinal axis of the needle.

[0023] - The limiter fixed relative to the bracket is formed by a portion that translates along an axis parallel to the longitudinal axis of the needle; and the coating device has a linear actuator for adjusting the position of the portion that translates.

[0024] The present invention also relates to machinery for coating products, comprising: a coating apparatus as described above and a product dosing system, the dosing system being configured to deliver the product into the coating apparatus at an adjustable pressure, the dosing system having an electric motor and a control unit, the speed of the electric motor being controlled to regulate the pressure, and the control unit being configured to control the dosing system and the coating apparatus.

[0025] The present invention also relates to a control method for controlling the aforementioned machinery for coating products, characterized in that the control method comprises at least one step, the step being implemented by a control unit and the step comprising:

[0026] -a) If it is requested that the output flow rate of the nozzle of the coating device be increased to between the lower and upper limits, the output pressure of the dosage system is increased by keeping the speed of the motor at a fixed value of the speed of the motor of the dosage system and reducing the opening of the needle valve of the coating device, and then reopening the needle valve and increasing the speed of the motor to the required value to obtain a higher value of output flow rate.

[0027] -b) If a request is made to reduce the output flow rate to between the upper and lower limits or to an intermediate value between the lower and upper limits, the output pressure of the dosing system is reduced by decreasing the motor speed to a low value and decreasing the opening of the needle valve of the coating device, then the needle valve is reopened and the motor speed is increased to the value required to obtain the intermediate or lower value of the output flow rate.

[0028] According to an advantageous but non-limiting embodiment of the invention, this control method may have one or more of the following features, depending on any technically permissible combination:

[0029] - In steps a) and b), the opening of the needle valve of the coating device is reduced as follows: during the adjustment phase of the output flow, the limiter fixed relative to the support is positioned at a predetermined position, and then the needle valve is brought close to the predetermined position by positioning the limiter fixed relative to the support.

[0030] - In step b), the speed of the motor decreases to a low value that is less than zero, and the operating direction of the motor is reversed. Attached Figure Description

[0031] The invention will be better understood from the following description, with reference to the accompanying drawings, of a coating apparatus, a coating machine for a coated product, and a control method based on the principle thereof, provided as non-limiting embodiments. Other advantages will become apparent, as shown in the drawings below:

[0032] Figure 1 This is a cross-sectional schematic diagram of a coating machine for the product of the present invention, which has a coating device for the product according to a first embodiment of the present invention, wherein the coating device is in an open mode;

[0033] Figure 2 yes Figure 1 The coating device for the product shown is in a cross-sectional view in the middle position.

[0034] Figure 3 yes Figure 1 A cross-sectional view of the coating device for the product shown in the closed position.

[0035] Figure 4 yes Figure 1 A partial cross-sectional perspective view of the coating apparatus shown, illustrating the limiter in the lower position when the apparatus is closed;

[0036] Figure 5 yes Figure 1 A partial cross-sectional perspective view of the coating apparatus shown, illustrating the limiter in an intermediate configuration;

[0037] Figure 6 yes Figure 1 A partial cross-sectional perspective view of the coating apparatus shown, illustrating the limiter in its maximum opening mode;

[0038] Figure 7 This is a flowchart of the control method for the coating machinery of the present invention;

[0039] Figure 8 This is a cross-sectional schematic diagram of a coating apparatus for a product according to a second embodiment of the present invention;

[0040] Figure 9 This is a cross-sectional schematic diagram of a coating apparatus for a product according to a third embodiment of the present invention;

[0041] Figure 10 This is a cross-sectional schematic diagram of a coating apparatus for a product according to a fourth embodiment of the present invention;

[0042] Figure 11 This is a cross-sectional schematic diagram of a coating apparatus for a product according to a fifth embodiment of the present invention. Detailed Implementation

[0043] Figure 1 The diagram shows a product coating machine 1, particularly for high-viscosity products such as adhesives or sealants (tellurium, etc.). The machine 1 has a coating device 3 for coating the product and a product dosing system 5, which supplies the product from a source of the product to be coated (not shown).

[0044] The dosing system 5 has a product inlet 50, a product dosing chamber 52, and a product outlet 54 for outputting to the coating apparatus 3. The dosing system 5 has a dosing piston 56 and a motor 58, which drives the dosing piston 56 to move in the chamber 52 via a mechanical motion conversion system (e.g., a ball screw).

[0045] The dosing system 5 is configured to deliver the product to the coating apparatus 3 at adjustable pressure. The speed and torque of the motor 58 are controlled to regulate the moving speed of the dosing piston 56 and the pressure of the product output from the outlet 54.

[0046] The coating machine 1 has a control unit 7 configured to control the dosing system 5 and the coating device 3. For this purpose, the control unit 7 may be equipped with a microprocessor, a memory, a calculator, and a communication system configured to control the dosing system 5 and the coating device 3 via electrical signals.

[0047] The coating apparatus 3 has a support 30, in which a control chamber 32 and a product tube 34 are disposed. The support 30 defines a longitudinal bore 36 centered about a central axis X3, which extends longitudinally through the support 30, through the control chamber 32, and into the tube 34. The coating apparatus 3 has a needle 38 slidably mounted in the longitudinal bore 36. The coating apparatus 3 also has a piston 40 received in the control chamber 32, fixed relative to the needle 38, and also sliding along the axis X3.

[0048] The coating apparatus 3 has a needle coating valve 42 and a valve 44. The needle coating valve 42 is formed by a nozzle 43 disposed on a support 30, and the valve 44 is disposed at one end of a needle 38 located in the tube 34. The product tube 34 guides the product between the outlet 54 and the nozzle 43. The product is coated as it exits from the nozzle 43 along arrow F1. In this embodiment, the valve 44 is formed by a ball bearing; however, it can be any other shape, including a cone, etc.

[0049] Under the action of the control fluid injected into the control chamber 32, the needle 38 moves along the longitudinal axis X3. Figure 3 The closed position of the needle valve 42 shown is the same as Figure 1The needle 38 moves between the indicated open and closed positions. The coating apparatus 3 has an elastic return member, formed, for example, by a helical spring 45, which is received in the control chamber 32 to return the needle 38 to the closed position. When control fluid is injected into the control chamber 32 along arrow F2, the needle 38 overcomes the resistance of the spring 45 and moves to its open position. Control fluid can also be injected into the control chamber 32 along arrow F3, causing the needle 38 to move to its closed position. The control fluid can be compressed air.

[0050] In another embodiment, not shown, the needle 38 returns to its closed position under the sole action of the spring 45.

[0051] The coating apparatus 3 has a limiter 60 fixed relative to the needle 38 and a limiter 62 fixed relative to a support 30. The support 30 is configured to limit the needle 38 from returning to an intermediate position between the closed and open positions through interaction with the limiter 60 fixed relative to the needle 38. The limiter 60, fixed relative to the needle 38, also slides along the longitudinal axis X3. The limiter 62, fixed relative to the support 30, has an adjustable position; that is, its position along the longitudinal axis X3 is fixed relative to the needle 38, but its position along the longitudinal axis X3 is adjusted within a certain range. Adjusting the limiter 62 prevents the needle valve 42 from fully approaching, thereby reducing the product flow from the nozzle 43.

[0052] like Figure 1 As shown, limiter 62 is in the retracted position, needle 38 is also in the retracted position, and needle valve 42 is fully open. Limiters 60 and 62 are not in contact. Figure 2 As shown, in the intermediate position, limiter 60 contacts limiter 62, preventing needle 38 from returning to the lowered position and then to the intermediate position. Therefore, needle valve 42 is not fully closed, thus limiting the flow rate. Figure 3 As shown, limiter 62 is in the lowered position. This allows needle valve 38 to fully return to the lowered position, and limiter 62 no longer obstructs the downward movement of limiter 60 along axis X3. Therefore, needle valve 42 is fully closed.

[0053] according to Figures 4 to 6 In the illustrated embodiment, the limiter 60 is fixed to one end of the needle 38 extending from the bracket 30, which is relative to the valve 44. The bracket 30 has a top cover 300 with an opening 302 through which the needle 38 slides along the longitudinal axis X3. The limiter 60 is fixed to the needle 38, for example, by two screws 61.

[0054] The coating apparatus 3 has an actuator 64 for adjusting the position of a limiter 62. According to one embodiment, the limiter 62 is formed by at least one cam 63, which rotates about a rotation axis Y62 perpendicular to the longitudinal axis X3. In this case, the actuator 64 is formed by an electric motor that drives the cam 63 to rotate about the axis Y62. The rotation of the cam 63 about the axis Y62 adjusts the angular position of the cam 63, changing the positioning of the limiter 62 along the axis X3. The electric motor may be a stepper motor.

[0055] like Figures 4 to 6 As shown, the limiter 62 may consist of two parallel cams 63, which are mounted on a common shaft 630 aligned with the adjustment axis Y62.

[0056] According to one embodiment, the limiter 60 has a surface 600 for contacting the limiter 62, i.e., inclined to the longitudinal axis X3. This inclined surface 600 allows the height of the limiter 62 along the longitudinal axis X3 to change according to the angular position of the cam 63, using the limiter as consistently as possible to improve the accuracy and simplicity of controlling the cam 63 by the actuator 64. This also ensures that the contact point between the cam 63 and the inclined surface 600 is as close as possible to the longitudinal axis X3, while avoiding the need for a specially designed limiter surface 60.

[0057] In one embodiment not shown, surface 600 may be perpendicular to the longitudinal axis X3.

[0058] The limiter 60 has two parallel inclined surfaces 600, both of which interact with one of the cams 63.

[0059] Cam 63 has a curved surface with an increasing radius around axis Y62. The angular position of cam 63 around axis Y62 changes the axial position of limiter 62 along axis X3 and limits needle 38 to return to its closed position.

[0060] like Figure 4 As shown, cam 63 is in a low position, that is, an angular position that forms a low obstruction, which does not prevent limiter 60 from descending. Therefore, needle 38 can be in its closed position.

[0061] like Figure 5 As shown, cam 63 is in an intermediate position, which corresponds to a larger angular position of the surface of the cam aligned with axis X3. Cam 63 forms a... Figure 4 Compared to obstacles located at a higher position along the longitudinal axis X3. Figure 4 and Figure 5 Between, cam 63 according to Figure 5The arrow R1 in the diagram rotates. At this position of the cam 63, the limiter 60 stops at a higher position, preventing the needle valve 42 from approaching again and forming a throttle orifice in the nozzle 43.

[0062] like Figure 6 As shown, cam 63 is positioned at the angular position where the surface radius of the cam aligned with axis X3 is at its maximum. Rotation of cam 63 along Y62 continues along arrow R1. In this position, limiter 62 holds limiter 60 in the high position, where needle valve 42 is at its maximum opening.

[0063] According to one embodiment, actuator 64, limiter 60, and limiter 62 form an external device 8 configured to be fixed and connected to the bracket 30 and needle 38 of the existing coating apparatus 3. This device has a cover 80 surrounding limiters 60 and 62, secured to a top cover 300, for example, by screws 82. Actuator 64 is secured to cover 80, for example, by screws 84. In the external device 8, limiters 60 and 62, and actuator 64, are readily adaptable to existing coating apparatuses; the only limitation is the external inlet leading to needle 38. In the case of the aforementioned existing solution, this inlet limitation is minimal compared to the specific engineering solutions required to ensure sealing, needle valve modification, and actuator power.

[0064] Operating reference for Machine 1 Figure 7 This will be explained.

[0065] Figure 7 Time is shown on the x-axis and from bottom to top on the y-axis:

[0066] - The width L of the product lines coated by coating device 3;

[0067] - Output flow rate D of nozzle 43;

[0068] - The angular velocity V of the electric motor 58, which indicates the linear velocity of the piston 56;

[0069] - The position P of the needle 38, the shaded area shows the position of the limiter 62 fixed relative to the bracket 30;

[0070] - The pressure P5 of the product exiting the dosing system 5 relative to atmospheric pressure.

[0071] At time t0, this is equivalent to mechanical 1 being turned on; for example, the output flow rate D, speed V, and pressure P5 are zero, and needle 38 is in the closed position. Limiter 62 is in... Figure 3 and 4 The position shown indicates that the needle 38 is not prevented from returning to the closed position.

[0072] To obtain the initial product line, a certain pressure P5 must be present in the coating device 3, slightly higher than the required coating pressure after the needle valve 42 is opened. Therefore, an initial preload is applied for coating. This preload is obtained by a fast-start motor 58. Thus, the speed V increases at time t1 and then returns to zero at time t2, with the needle valve 38 remaining in place and the needle valve 42 remaining closed to obtain pressure P51.

[0073] At time t3, product coating begins: needle 38 moves, causing needle valve 42 to open to 100%. The speed V increases, generating a constant product pressure P52 and an output flow rate D1 equivalent to a small fraction of the maximum output flow rate D3, for example, 10%. Limiter 62 remains in the lowered position.

[0074] When the output flow rate of nozzle 43 needs to be increased or decreased, limiters 60 and 62 act during a brief phase of mechanical operation 1.

[0075] At time t6, an increase in output flow rate D is required. The flow rate must increase rapidly between D1 and D3. To this end, before time t6, the output pressure 5 is increased by maintaining the speed V at a constant value V1 and reducing the opening of the needle valve 42. To this end, the limit switch 62 gradually moves to a predetermined position, while the mechanism 1 adjusts the output flow rate D to the value D1. The positioning of the limit switch 62 begins at t3. The predetermined position of the limit switch 62 corresponds to a small opening of the needle valve 42, for example, 10% of the maximum opening.

[0076] At time t4, needle valve 42 begins to close. At time t5, limiter 62 reaches its predetermined position, and needle valve 38 is positioned to limiter 62, reaching the predetermined position. Therefore, a throttling orifice is formed in nozzle 43. The velocity V remains constant at V1, allowing pressure P5 to increase to value P53 at time t5. A second preload is required to achieve a high flow rate while simultaneously maintaining a constant output flow rate D.

[0077] At time t6, the required pressure P53 is achieved, and needle valve 42 reopens to 100%. The velocity V increases to its maximum value V3, reaching the value required to achieve the output flow rate D3. At time t7, needle valve 42 opens to 100%, achieving velocity V3, and the pressure P5 decreases to P54 due to the opening of needle valve 42, achieving flow rate D3. The time between time t6 (needle valve 42 opening) and time t7 (achieving flow rate D3) for the increase in output flow rate D is very short, for example, on the order of milliseconds, effectively increasing the line width. If this velocity were achieved by an actuator controlling the mechanical throttling orifice of nozzle 43, it would require extremely powerful functionality and would be very expensive.

[0078] Conversely, the positioning of limit switch 62 occurs during the normal control phase and can be performed during the hidden time. Therefore, a powerful motion actuator is unnecessary. Between time t3 and time t6, tens of milliseconds are sufficient for limit switch 62 to position. This is a transition time compatible with inexpensive standard stepper motors and can therefore be used for actuator 64.

[0079] Now, let's describe the brief phase of reducing the output flow rate D. The output flow rate D must be reduced to an intermediate value D2, which is lower than D3, for example, 20% of the flow rate D3. To do this, control unit 7 reduces the output pressure P5. This pressure reduction is rapid: the speed V drops rapidly to a low value. For example, the speed V drops to a low value within milliseconds. The reduction of speed V begins at time t8 and ends at time t9. The low value to which speed V drops may be zero, such as... Figure 7 As shown in time t9, if a large flow rate reduction is required, the motor 58 can run in the opposite direction. In one embodiment, for example when the required flow rate change is not too sudden, the low value can be zero, or the speed can be less than 10% of the maximum value of speed V.

[0080] Simultaneously, the opening of needle valve 42 decreases. This reduction in opening is achieved by positioning limiter 62 at a predetermined intermediate position equivalent to 20% of the total opening of needle valve 42, and by moving needle 38 towards the closed position until it is locked at the predetermined 20% position by limiter 62 at time t9, and closing needle valve 42 at time t8. The positioning of limiter 62 begins before time t8, and can begin at time t6, for example, from the 10% open position, thus giving actuator 64 sufficient time for limiter 62 to position. This causes the output flow rate D to decrease rapidly. The normal adjustment phase of output flow rate D then begins at value D2. For this purpose, needle valve 42 reopens at time t10, and speed V increases again from time t9 to the value V2 required to obtain output flow rate D2. At time t11, speed V remains stable, pressure P5 stabilizes at value P55, and needle 38 is positioned at its 100% open position.

[0081] Between time t12 and time t13, control unit 7 again executes the previously described step of increasing the output flow rate DD between D1 and D3: to restore the output flow rate D to D3, the speed V remains constant, and the pressure P5 is increased again to value P53 through the partially closed needle valve 42, until the intermediate opening value set by the positioning of the limit switch 62 is maintained. At t13, the normal control phase is determined by the output flow rate D at D3.

[0082] At times t14 and t15, the rapid decrease in speed V and the partial closure of needle valve 42 occur again, causing the output flow rate D to decrease successively to D1 and then to zero. At time t13, or slightly earlier, limiter 62 gradually lowers, setting the stop position of needle valve 38 at t14, which is approximately equivalent to the opening of needle valve 42, for example, 10%. After time t14, limiter 62 gradually lowers to its lowered position, causing needle valve 42 to close completely at t15, ending the product line. At time t15, speed V drops sharply to a negative value, equivalent to piston 56 retracting upwards, rapidly depressurizing in tube 34 of coating device 3.

[0083] Then, as at t0, the control method can restart by increasing the speed V with a new preload at t16. A new product line can then be coated at t17 with an output of D3. At time t18, the speed V abruptly reverses, and at t19, the speed is rapidly reduced and the product line ends. Because the output D does not change between t17 and t19, limiter 62 is not used during this stage. Therefore, the coating apparatus 3 equipped with limiters 60 and 62 can be operated in a normal manner.

[0084] All of the above-mentioned operating steps are controlled by the control unit 7 through control signals sent to the motor 58, to a control fluid distributor 9 (e.g., a pneumatic delivery distributor) for the movement of a control needle 38, and to the actuator 64.

[0085] The present invention has the following advantages:

[0086] When the limit switch 62 is in the lowered position, the needle valve 42 closes quickly and completely, eliminating any product flow failure between the upstream of the nozzle 43 and the nozzle 43. Therefore, the product line ends are very uniform.

[0087] There is no unique wear caused by the additional moving parts of the nozzle 43: therefore, the needle valve 42 has a normal service life.

[0088] The actuator 64 does not need to be highly functional because the pre-positioning of the limit switch 62 occurs during a hidden period, with a cycle longer than the rapid changes in product output flow. Furthermore, while the limit switch 62 is positioning, the needle valve 42 opens, thus not generating stress on the cam limit switch 62.

[0089] A standard needle valve 42 sealing system can be used; there is no need to design a special sealing system.

[0090] The limiters 60 and 62 and the actuator 64 can be adapted to existing coating apparatuses in the form of device 8 by simply providing an inlet to the needle 38 or to the piston 40.

[0091] Other embodiments of the product coating apparatus are shown inFigures 8 to 11 In these embodiments, components common to the first embodiment are labeled with the same reference numerals and serve the same function.

[0092] Figure 8 A second embodiment is shown. In this embodiment, the position of the limiter 62, fixed relative to the bracket 30, is adjustable about an adjustment axis X62 parallel to the longitudinal axis X3 of the needle 38. The limiter is formed by a cam surface 620, the height of which varies along the axis X62 depending on its angular position about the axis X62. At one angular portion, the cam surface 620 has a small-thickness step 622 that does not obstruct the downward movement of the needle 38. At an angular portion opposite to the axis X62, the cam surface has its maximum thickness, which restricts the return to the closed position of the needle 38.

[0093] Figure 9 A third embodiment is shown. In this embodiment, the actuator 64 is a hollow shaft electric motor forming a tubular member 640, which is rotatably mounted about a portion of the needle 38 extending from the bracket 30. The tubular member 640 supports the limiter 62, which has a... Figure 8 The illustrated embodiment uses a similar cam surface 620. In this case, the angular position of the cam surface 620 can be adjusted about the longitudinal axis X3 of the needle 38, with the adjustment axis X64 being the same as the longitudinal axis X3. The height of the cam surface 620 along the longitudinal axis X3 is variable about the adjustment axis X64. This embodiment ensures the radial and axial structural compactness of the coating apparatus 3.

[0094] Figure 10 A fourth embodiment is shown. In this embodiment, a limiter 62 fixed relative to the bracket 30 is arranged in the control chamber 32. A cam 63 forming the limiter 63 is rotatable about an adjustment axis Y62 perpendicular to the longitudinal axis X3. The cam 63 extends into the control chamber 32, thereby limiting the downward movement of the piston 40. In this case, the limiter fixed relative to the needle 38 is formed by the piston 40 itself. A cavity 320 is arranged in the bracket 30, allowing the cam 63 to rotate about the adjustment axis Y62.

[0095] Figure 11A fifth embodiment is shown. In this embodiment, the adjusting actuator is a linear actuator 66, i.e., it performs translational motion, such as a cylinder or a ball screw. The limiter 62, fixed relative to the bracket 30, is formed by a portion 642 that translates along the adjusting axis X62, thus the adjusting axis X62 is parallel to or coincides with the longitudinal axis X3 of the needle 38. The piston 40 has a cylindrical portion 400 extending outside the bracket 30, around which a spring 45 is wound. The cylindrical portion 400 has a cavity 402 at its upper end, in which the portion 642 is received. The cavity 402 has an inwardly oriented radial portion 404, which forms the limiter 60 fixed relative to the needle 38. When the needle 38 returns to its closed position, the portion 642, relative to the radial portion 404 along the longitudinal axis X3, restricts the closing of the needle valve 42.

[0096] Within the scope of the claims, the technical features of the above embodiments and other embodiments can be combined to form other embodiments of the present invention.

Claims

1. A coating apparatus (3) for coating a product, the coating apparatus having a support (30) in which a product tube (34) is disposed, the support (30) defining a longitudinal hole (36), the coating apparatus (3) having a needle (38) installed in the longitudinal hole (36), the coating apparatus having a product coating valve (42) and a valve (44), the product coating valve (42) being formed by a nozzle (43) arranged on the support (30), the valve being arranged at one end of the needle (38) located in the product tube (34), the needle being configured along the longitudinal axis (X3) in a closed position when the product coating valve (42) is closed and in an open position when the product coating valve is open. The coating device (3) has a limiter fixed relative to the needle (38) and a limiter fixed relative to the support (30). The limiter fixed relative to the support is configured to restrict the needle (38) from returning to an intermediate position between the closed and open positions through interaction with the limiter fixed relative to the needle (38). The limiter fixed relative to the support (30) has an adjustable position and is formed by at least one cam (63). Furthermore, the coating device (3) has an actuator (64) for adjusting the position of the cam (63). The position of the cam (63) can be adjusted by rotation about an adjustment axis (X62) parallel to the longitudinal axis (X3) of the needle (38); and the thickness of the cam increases about the adjustment axis.

2. The coating apparatus according to claim 1, characterized in that, The actuator (64) used for adjustment is a rotary electric motor.

3. The coating apparatus according to claim 1, characterized in that, The cam is supported by a tubular portion (640) which is mounted around a portion of the needle (38) extending from the bracket (30); and the actuator (64) is a hollow shaft motor that drives the tubular portion (640), and the angular position of the cam can be adjusted around the longitudinal axis (X3) of the needle (38).

4. The coating apparatus according to claim 1, characterized in that, The limiter that is fixed relative to the needle (38) is fixed to one end of the needle (38) that extends from the bracket (30).

5. The coating apparatus according to claim 4, characterized in that, The actuator (64), the limiter fixed relative to the needle (38), and the limiter fixed relative to the bracket (30) form an external device (8).

6. The coating apparatus according to claim 1, characterized in that, The limiter fixed relative to the needle (38) is formed by a piston, which is housed in the control chamber (32) of the bracket (30); and the limiter fixed relative to the bracket (30) is arranged in the bracket (30) and extends into the control chamber (32).

7. The coating apparatus according to claim 1, characterized in that, The limiter fixed relative to the needle (38) has an inclined surface (600) that is inclined relative to the longitudinal axis (X3) of the needle (38).

8. A machine (1) for coating products, characterized in that, It has: a coating device (3) according to claim 1 and a product dosing system (5), the dosing system (5) being configured to deliver the product to the coating device (3) at an adjustable pressure (P5), the dosing system (5) having a motor and a control unit (7), the speed (V) of the motor being controlled to adjust the pressure (P5), and the control unit (7) being configured to control the dosing system (5) and the coating device (3).

9. A control method for controlling the machinery (1) for coating products according to claim 8, characterized in that, The control method has at least one step, which is implemented by the control unit (7) and the step is as follows: -a) If it is requested that the output flow rate (D) of the nozzle (43) of the coating device (3) be increased to between the lower limit (D1) and the upper limit (D3), the pressure (P5) output by the dosage system (5) is increased by keeping the speed of the motor at a fixed value (V1) of the speed of the motor of the dosage system (5) and reducing the opening of the needle valve (42) of the coating device (3), and then reopening the needle valve (42) and increasing the speed of the motor to the value (V3) required to increase the output flow rate (D). -b) If it is requested that the output flow rate (D) be reduced to an intermediate value (D2) between the lower limit and the upper limit, the output pressure of the dosing system (5) is reduced by reducing the speed of the motor to a low value and reducing the opening of the needle valve (42) of the coating device (3), then the needle valve (42) is reopened and the speed (V) of the motor is increased to the value (V2) required to obtain the intermediate value of the output flow rate (D).

10. The control method according to claim 9, characterized in that, In steps a) and b), the opening of the needle valve (42) of the coating device (3) is reduced as follows: when the output flow rate (D) increases or decreases, the limiter fixed relative to the bracket (30) is positioned at a predetermined position, and then the needle valve (42) is closed to the predetermined position by positioning the limiter fixed relative to the bracket (30).

11. The control method according to claim 9 or 10, characterized in that, In step b), the speed (V) of the motor decreases to a low value that is less than zero, and the operating direction of the motor is reversed.

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