Device for applying a product, machine comprising such a device and method for controlling such a machine

Abstract

A device (3) for applying a product includes a frame (30) provided with a product conduit (34) inside, and a longitudinal bore (36) is formed in the frame (30). The application device (3) includes a needle (38) mounted within the longitudinal bore (36), and the application device includes a product application valve (42) formed by a nozzle (43) provided in the frame (30) and a shutter (44) provided at the end of the needle (38) located within the product conduit (34). The needle is configured to move along a longitudinal axis (X3) between the closed and open positions of the application valve (42). The device comprises a stop (60) fixed to the needle (38) and a stop (62) fixed to the frame (30), wherein the stop (62) is configured to limit the return of the needle (38) toward a closed position to an intermediate position between a closed position and an open position through interaction with the stop (60) fixed to the needle (38), and the stop (62) fixed to the frame (30) has an adjustable position.

Description

Technology Field

[0001] The present invention relates to a device for applying a product, a machine including such a device, and a method for controlling such a machine. Background Technology

[0002] In the field of dispensing adhesive or sealant products using robotic systems, it may be necessary to rapidly adjust the dispensing speed, for example, to obtain wider or narrower adhesive or sealant beads. Such width adjustments must be rapid to ensure clean results and avoid costly product waste. Since these products are viscous, systems must be specially designed for them.

[0003] Electrically operated product dosing or pressure control systems are driven by motors. For less dynamic applications and dispensing close to the dosing system, the motor speed is proportional to the product output. For more dynamic applications, or when dispensing is far from the dosing system, the dosing or pressure control systems have relatively long response times due to the compressibility of the products, the elasticity of the hoses, and the associated high pressures.

[0004] To achieve rapid flow changes, it is known to use mechanical systems that create adjustable restrictions prior to product dispensing nozzles via moving parts. These solutions have several disadvantages, as follows:

[0005] - Due to the volume reduction between the pharmaceutical and the nozzle, it is not possible to quickly stop the product application. Consequently, the edges of the applied bead are not clean.

[0006] - The products are rough and cause wear and leakage in the moving parts.

[0007] - The actuators required to move moving parts must be fast and powerful, and consequently, expensive.

[0008] - Special sealants must be designed for all moving parts, which adds to the cost.

[0009] - The needle and valve seat must be specially designed, which does not allow the use of existing non-variable flow dispensing devices. The problem to be solved

[0010] The object of the present invention is to propose a new product dispensing device that allows for rapid changes in product dispensing speed and has mechanical parts with lower cost and complexity compared to existing solutions, as well as better performance and better reliability. means of solving the problem

[0011] For this purpose, the present invention relates to a product application device comprising a frame provided with a product conduit therein, wherein a longitudinal bore is formed in the frame, and the application device comprises a needle mounted within the longitudinal bore, and the application device comprises a product application valve formed by a nozzle provided in the frame and a shutter provided at the end of the needle located within the product conduit, wherein the needle is configured to move along a longitudinal axis between a closed position and an open position of the application valve. The application device comprises a stop fixed to the needle and a stop fixed to the frame, wherein the stop is configured to limit the return of the needle toward a closed position to an intermediate position between a closed position and an open position by means of interaction with the stop fixed to the needle, and the stop fixed to the frame is characterized by having an adjustable position.

[0012] According to the present invention, the placement of needles at intermediate positions makes it possible to create adjustable constraints that do not require expensive actuators or specialized sealing solution designs.

[0013] According to the advantageous but non-compulsory aspects of the present invention, such a product application device may incorporate one or more of the following features in any technically acceptable combination.

[0014] - A fixed stop portion with respect to the above frame is formed by at least one cam, and the dispensing device includes an actuator for adjusting the position of the cam.

[0015] - The position of the cam is rotatable along the circumference of an adjustment axis perpendicular to the longitudinal axis of the needle, and the profile of the cam forms a surface of increasing radius.

[0016] - The position of the cam is rotatable along the circumference of the adjustment axis parallel to the longitudinal axis of the needle, and the thickness of the cam increases along the circumference of the adjustment axis.

[0017] - The above-mentioned control actuator is a rotary electric motor.

[0018] - The cam is formed by a tubular member mounted around the portion of the needle protruding from the frame, and the actuator is a hollow shaft motor that drives the tubular member, and each position of the cam is adjustable along the longitudinal axis of the needle, and the thickness of the cam increases along the adjustment axis.

[0019] - A fixed stop for the above needle is attached to the end of the needle protruding from the frame.

[0020] - The above-mentioned control actuator, the above-mentioned needle stop member, and the above-mentioned frame stop member form an external assembly configured to be attached to and connected to the frame and the needle of the existing dispensing device.

[0021] - A fixed stop portion for the above needle is formed by a piston accommodated within the pilot chamber of the frame, and the frame stop portion is provided within the frame and protrudes into the pilot chamber.

[0022] - The fixed stationary zone for the above needle has a surface inclined with respect to the longitudinal axis of the above needle.

[0023] - A stationary zone fixed to the above frame is formed by a component capable of translational movement along an axis parallel to the longitudinal axis of the needle, and the dispensing device includes a linear actuator for controlling the position of the component capable of translational movement.

[0024] The present invention also relates to a product dispensing machine comprising the above-mentioned dispensing device and a dosing system for a product, wherein the dosing system is configured to send a product into the dispensing device at an adjustable pressure, and the dosing system comprises a motor and a control unit configured to control the dosing system and the dispensing device, and the speed of the motor is controlled to regulate the pressure.

[0025] The present invention also relates to a method for controlling a product dispensing machine mentioned above, comprising the following steps performed by the control unit:

[0026] - a) in the case of a request to increase the nozzle output flow rate of the dispensing device between a low value and a high value, the step of causing an increase in the output pressure of the dispensing system by maintaining the motor speed of the dispensing system at a constant value and reducing the opening of the needle valve of the dispensing device, and then opening the needle valve and increasing the motor speed to a value necessary to obtain a high value of the output flow rate; and

[0027] - b) in the case of a request to reduce the output flow rate from a high value to a low value or to an intermediate value between a low value and a high value, a reduction in the output pressure of the injection system is caused by reducing the motor speed to a low value and reducing the opening of the needle valve of the dispensing device, and then the needle valve is reopened and the motor speed is increased to a value required to achieve an intermediate or low output flow rate value; characterized by including at least one of these steps.

[0028] According to the advantageous but non-compulsory aspects of the present invention, such a control method may incorporate one or more of the following features in any technically permissible combination.

[0029] - In steps a) and b), the reduction in the opening of the needle valve of the dispensing device is achieved by positioning the stop hole fixed to the frame at a predetermined position during the output flow control step, and then closing the needle valve to a predetermined position by positioning the stop hole fixed to the frame.

[0030] - b) In step, the low value at which the motor speed is reduced is less than 0, and the motor direction is reversed. Brief explanation of the drawing

[0031] In light of the following description of a product dispensing device, a product dispensing machine, and a control method according to the principles of the present invention, made as a non-limiting example in relation to the attached drawings, the present invention will be better understood and other advantages of the present invention will become apparent. FIG. 1 is a schematic cross-sectional view of a product coating machine according to the present invention, comprising a product coating device according to a first embodiment of the present invention, wherein the product coating device is in an open arrangement; FIG. 2 is a schematic cross-sectional view of the product dispensing device of FIG. 1 in an intermediate arrangement; FIG. 3 is a schematic cross-sectional view of the product dispensing device of FIG. 1 in a closed arrangement; FIG. 4 is a partial cross-sectional perspective view of the coating device of FIG. 1 showing a stop zone of a lower arrangement in a closed arrangement of the device; FIG. 5 is a partial cross-sectional perspective view of the coating device of FIG. 1 showing a stop section of an intermediate arrangement type; FIG. 6 is a partial cross-sectional perspective view of the coating device of FIG. 1 showing a stop zone in a maximum open arrangement configuration; FIG. 7 is a flowchart of a method for controlling a coating machine according to the present invention; FIG. 8 is a schematic cross-sectional view of a product coating device according to a second embodiment of the present invention; FIG. 9 is a schematic cross-sectional view of a product coating device according to a third embodiment of the present invention; FIG. 10 is a schematic cross-sectional view of a product coating device according to a fourth embodiment of the present invention; FIG. 11 is a schematic cross-sectional view of a product coating device according to the fifth embodiment of the present invention. Specific details for implementing the invention

[0032] FIG. 1 shows an application machine (1) for products, particularly high-viscosity products such as adhesives or sealants (mastic, etc.). The machine (1) includes a product dosing device (3) and a product dosing system (5) supplied by a product source (not shown) to be applied.

[0033] The above-described input system (5) includes a product input port (50), a product dosage chamber (52), and a product outlet port (54) to the dispensing device (3). The above-described input system (5) includes an input piston (56) and a motor (58) that operates the movement of the input piston (56) within the chamber (52) through a mechanical motion conversion system (e.g., a ball screw).

[0034] The above-described input system (5) is configured to send the product into the dispensing device (3) by an adjustable pressure. The speed and torque of the motor (58) are controlled to control the movement speed of the input piston (56) and the pressure of the product output from the output port (54).

[0035] The above-described coating machine (1) includes a control unit (7) configured to control an input system (5) and a coating device (3). For this purpose, the control unit (7) is equipped with a microprocessor, memory, a calculator, and a communication system configured to control the input system (5) and the coating device (3) by means of electrical signals.

[0036] The dispensing device (3) comprises a frame (30), and within the frame (30) are provided a control chamber (32) and a product conduit (34). A longitudinal bore (36) is formed in the frame (30), and the bore (36) is centered on a central axis (X3) and extends longitudinally through the frame (30) into the conduit (34) through the pilot chamber (32). The dispensing device (3) comprises a needle (43) slidably mounted within the longitudinal bore (36). The dispensing device (3) also comprises a piston (40) that is received within the control chamber (32) and fixed to the needle (38) when the needle (38) slides along the axis (X3).

[0037] The above dispensing device (3) includes a needle dispensing valve (42) formed by a nozzle (43) provided in the frame (30) and a shutter (44) provided at the end of a needle (38) disposed within a conduit (34). The product conduit (34) guides the product between the exit port (54) and the nozzle (43). The product exits the nozzle (43) along the arrow (F1) and is dispensed. The shutter (44) is formed by a ball in this example, but may be any other shape including a cone, etc.

[0038] The needle (38) moves along the longitudinal axis (X3) between the closed position of the needle valve (42) shown in FIG. 3 and the open position shown in FIG. 1 under the action of a pilot fluid injected into the pilot chamber (32). The dispensing device (3) includes an elastic return element for the needle (38) in the closed position, for example, formed by a helical spring (45) housed within the control chamber (32). When the control fluid is injected into the control chamber (32) along the arrow (F2), the needle (38) moves toward the open position against the force of the spring (45). Additionally, to move the needle (38) to the closed position, the pilot fluid may be injected into the pilot chamber (32) along the arrow (F3). The control fluid may be compressed air.

[0039] In an alternative embodiment not shown, the needle (38) returns to a closed position under the sole action of the spring (45).

[0040] The above-described dispensing device (3) includes a stop (60) fixed to the needle (38) and a stop (62) fixed to the frame (30), wherein the stop (62) is configured to limit the return of the needle (38) toward the closed position to an intermediate position between the closed position and the open position through interaction with the stop (60) fixed to the needle (38). The stop (60) is fixed to the needle (38) when the needle (38) slides along the longitudinal axis (X3). The stop (62) fixed to the frame (30) has an adjustable position, that is, the position of the stop (62) along the longitudinal axis (X3) is fixed to the needle (38), except for a gap for adjusting the position of the stop (62) along the longitudinal axis (X3). The control of the above stop zone (62) prevents the needle valve (42) from being completely closed, thereby reducing the flow of product out of the nozzle (43).

[0041] In FIG. 1, the stopper (62) is set to an up position, and the needle (38) is also in an up position, so the needle valve (42) is fully open. The stopper (60 and 62) are not in contact. In FIG. 2, the stopper (60) is in contact with the stopper (62) in an intermediate position, which limits the return of the needle (38) to a down position to the intermediate position, thereby preventing the needle valve (42) from being fully closed and thus restricting the flow. In FIG. 3, the stopper (62) is set to a down position. This allows the needle valve (38) to fully return to a down position because the stopper (62) no longer forms an obstacle to the downward movement of the stopper (60) along the axis (X3).

[0042] According to the embodiment illustrated in FIG. 4-6, the stopper (60) is fixed to the end of the needle (38) protruding out of the frame (30), and this end is on the opposite side of the shutter (44). The frame (30) includes an upper cover (300) perforated by an opening (302), through which the needle (38) slides along the longitudinal axis (X3). The stopper (60) is fixed to the needle (38), for example, by two screws (61).

[0043] The above-described coating device (3) includes an actuator (64) for adjusting the position of a stopper (62). According to one embodiment, the stopper (62) is formed by at least one cam (63) rotatable around 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 around the axis (Y62). Rotation of the cam (63) around the axis (Y62) allows the angular position of the cam (63) to be adjusted and allows the position of the stopper (62) along the axis (X3) to be modified. The electric motor may be a stepper motor.

[0044] As illustrated in FIGS. 4 to 6, the stop zone (62) may include two parallel cams (63) mounted on a common shaft (630) aligned with the control axis (Y62).

[0045] According to one embodiment, the stop member (60) has a surface (600) for contacting the stop member (62), and this surface (600) is inclined with respect to the longitudinal axis (X3). This inclined surface (600), together with the stop member, improves the accuracy and simplicity of controlling the cam (63) by the actuator (64) and allows the height of the stop member (62) to vary as consistently as possible along the longitudinal axis (X3) based on each position of the cam (63). This also ensures that the point of contact between the cam (63) and the inclined surface (600) is as close as possible to the longitudinal axis (X3) while avoiding the design of a special stop surface (60).

[0046] In an unillustrated variant, the surface (600) may be perpendicular to the longitudinal axis (X3).

[0047] The above stationary zone (60) has two parallel inclined surfaces (600), each of which interacts with one of the cams (63).

[0048] The cam (63) forms a curved surface with increasing radius along the axis (Y62). Each position of the cam (63) along the axis (Y2) changes the intermediate position where the return of the needle (38) to the axial position and the closed position along the axis (X3) of the stop zone (62) is restricted.

[0049] In FIG. 4, the cams (63) are in a low position, that is, at each position where the cams form a low obstacle, which does not oppose the descent of the stop zone (60). Thus, the needle (38) may be in a closed position.

[0050] In FIG. 5, the cams (63) are in an intermediate position corresponding to an angle position where the surface radius of the cam aligned with the axis (X3) is larger. The cams (63) form an obstacle located higher along the longitudinal axis (X3) compared to FIG. 4. Between FIG. 4 and FIG. 5, the cams (63) are rotated along the arrow (R1) in FIG. 5. At this position of the cams (63), the stop (60) stops at a higher position, preventing the needle valve (42) from closing again and creating a restriction on the flow in the nozzle (43).

[0051] In FIG. 6, the cams (63) are positioned at each position where the surface radius of the cam aligned with the axis (X3) is maximum. The rotation of the cams (63) along the axis (Y62) continues along the arrow (R1). At this position, the stop (62) maintains the stop (60) in a high position where the needle valve (42) is maximally open.

[0052] According to one embodiment, the actuator (64), stop member (60), and stop member (62) form an external assembly (8) configured to be connected and attached to the needle (38) and frame (30) of a conventional dispensing device (3). This assembly includes a cover (80) that surrounds the stop member (60) and the stop member (62) and is attached to the upper cover (300), for example, by screws (82). The actuator (64) is attached to the cover (80), for example, by screws (84). In the form of the external assembly (8), the stop members (60, 62) and the actuator (64) can be easily adapted to a conventional dispensing device, with the only constraint being external access to the needle (38). This access is a minor limitation compared to the specific engineering solutions required to ensure sealing, needle valve modification, and actuator power in the case of the current solutions mentioned above.

[0053] The operation of the above machine (1) is explained with reference to FIG. 7.

[0054] Figure 7 shows time on the x-axis, and on the y-axis, from bottom to top:

[0055] - Width (L) of the product bead applied by the application device (3);

[0056] - Output flow rate (D) of the nozzle (43);

[0057] - Angular velocity (V) of the motor (58) showing the linear speed of the piston (56);

[0058] - The position (P) of the needle (38) and the position of the fixed stop (62) with respect to the frame (30) in the form of a hatched area; and

[0059] - Shows the pressure (P5) relative to atmospheric pressure of the product present at the outlet of the input system (5).

[0060] For example, at time t0, corresponding to the switching on of the machine (1), the output flow rate (D), velocity (V), and pressure (P5) are 0, and the needle (38) is in the closed position. The stop zone (62) is in the position shown in FIGS. 3 and 4, that is, it does not prevent the needle (38) from returning to the closed position.

[0061] First, to obtain the product bead, it is necessary to have a constant pressure (P5) slightly higher than the desired application pressure within the application device (3) after the opening of the needle valve (42). Accordingly, an initial pre-charge is applied. This pre-charge is obtained by rapidly operating the motor (58). Thus, the speed (V) is increased at time t1 and then returned to 0 at time t2, the needle (38) is kept in place, and the needle valve (42) is kept closed to obtain the pressure (P51).

[0062] At time t3, product deposition begins: the needle (38) is moved to open the needle valve (42) 100%. The speed (V) is increased to generate a constant product pressure (P52), and the output flow rate (D1) corresponds to a portion of the maximum value (D3) of the output flow rate (D), for example, 10%. The stop zone (62) is maintained in a low position.

[0063] When an increase or decrease in the output flow rate from the nozzle (43) is to be obtained, the stop zones (60 and 62) are implemented in the transient phases of the operation of the machine (1).

[0064] At time t6, a request is made to increase the output flow rate (D). The flow rate must be rapidly increased between D1 and D2. To this end, prior to time t6, an increase in output pressure (P5) occurs by maintaining the velocity (V) at a constant value (V1) and reducing the opening of the needle valve (42). To this end, the stop zone (62) is gradually moved to a predetermined position, while the machine (1) regulates the output flow rate (D) to a value (D1). At time t3, the positioning of the stop zone (62) begins. The predetermined position of the stop zone (62) may correspond to a small opening of the needle valve (42), for example, 10% of the maximum opening.

[0065] At time t4, the closure of the needle valve (42) begins. At time t5, the stop zone (62) reaches a predetermined position, and the needle valve (38) reaches a predetermined position based on the position setting of the stop zone (62). Thus, a flow restriction is formed in the nozzle (43). Due to the velocity (V) maintained at a constant value (V1), the pressure (P5) at time t5 has the effect of increasing to a value (P53). Obtaining a higher flow rate requires a second pre-charge while maintaining the output flow rate (D) constant.

[0066] At time t6, the required pressure (P53) is obtained, and the needle valve (42) is opened again to 100%. The velocity (V) is increased to a maximum value (V3) to reach the value required to obtain the output flow rate (D3). At time t7, the needle valve (42) is opened to 100%, the velocity (V3) is obtained, and due to the opening of the needle valve (42), the pressure (P5) is reduced to a value (P54), and the flow rate (D3) is obtained. The time required to obtain the increase in output flow rate (D) between time t3 (opening of the needle valve (42)) and t7 (obtaining of the flow rate (D3)) is short, for example, by approximately a few ms, which allows for a net increase in bead width. If such a velocity is obtained by actuators controlling the mechanical constraints in the nozzle (43), they must be very powerful and expensive.

[0067] Conversely, the positioning of the stop zone (62) can be performed within a hidden time during the normal control phase. Accordingly, there is no need to provide a powerful actuator for the movement of the stop zone (62). Between time t3 and time t6, tens of milliseconds may be sufficient to position the stop zone (62). This is a transition time that maintains compatibility with standard, inexpensive stepper motors and can therefore be used for the actuator (64).

[0068] Now, a transition step for reducing the output flow rate (D) is described. The output flow rate (D) should be reduced to an intermediate value (D2) lower than D3, for example, 20% of the flow rate (D3). To this end, the control unit (7) causes a reduction in the output pressure (P5). This pressure reduction is rapid: the speed (V) is rapidly reduced to a low value. For example, the speed (V) is reduced to a low value within a few milliseconds. The reduction in speed (V) begins at time t8 and ends at time t9. If a large reduction in flow rate is desired, the speed (V) can be reduced to a value lower than 0 by reversing the rotation direction of the motor (8), as shown at time t9 in FIG. 9. In a variation, the low value may be 0, or, for example, a speed lower than 10% of the maximum value of speed (V), such as when the desired change in flow rate is less abrupt.

[0069] At the same time, the opening of the needle valve (42) is reduced. This reduction in opening is achieved by positioning the stop zone (62) at a predetermined intermediate position, for example, corresponding to 20% of the total opening of the needle valve (42), and closing the needle valve (42) by moving the needle (38) toward the closed position until it is blocked by the stop zone (62) at the predetermined 20% position at time t9. The initiation of positioning the stop zone (62) occurs before time t8 so that the actuator (64) has sufficient time to position the stop zone (62), and can start at time t6, for example, from the 10% open position. This achieves a rapid reduction in the output flow rate (D). Then, at value (D2), the normal regulation phase of the output flow rate (D) begins. To this end, the needle valve (42) is opened again at time t10, and the velocity (V) is increased again from time t9 to the required value (V2) to obtain the output flow rate (D2). At time t11, the velocity (V) is stabilized, the pressure (P5) is stabilized at the value (P55), and the needle (38) is positioned at the 100% open position.

[0070] Between times t12 and t13, the control unit (7) repeats the steps already described to increase the output flow rate (D) between D1 and D3: to restore the output flow rate (D) to D3, the velocity (V) is kept constant, and the pressure (P5) is increased again to the value of P53 by partially closing the needle valve (42) to an intermediate opening value set by the positioning of the stop zone (62) that is kept in place. At t13, a normal control step is established with the output flow rate (D) of D3.

[0071] At the subsequent times t14 and t15, a rapid reduction of the velocity (V) and partial closure of the needle valve (42) are performed again to continuously reduce the output flow rate (D) to D1 and then to 0. At time T13, or slightly earlier, the stop zone (62) is gradually lowered to set a stop position of the needle valve (38) corresponding to opening the needle valve (42) slightly, for example, 10%, at time t14. After time t14, the stop zone (62) is gradually lowered to a lower position to allow the needle valve (42) to be completely closed and the product bead to be terminated at time t15. At time t15, to achieve rapid depressurization within the conduit (34) of the dispensing device (3), the velocity (V) is rapidly reduced to a negative value, which is equivalent to the piston (56) retracting upward.

[0072] The above control method can then be resumed as it was started at time t0 by a new pre-charge by increasing the speed (V) at time t16. Then, at time t17, a new product bead can be deposited with an output flow rate D3. At time t18, the speed (V) is abruptly reversed to obtain a rapid reduction in pressure, and the product bead is terminated at time t19. Since there is no change in the output flow rate (D) between the intermediate values ​​between time t17 and t19, the stop zone (62) is not used at this stage. Accordingly, the coating device (3) equipped with the stop zones (60 and 62) can be operated in a conventional manner.

[0073] All of the operation steps described above are triggered by control signals transmitted from the control unit (7) to the control fluid distributor (9), e.g., pneumatic distributor, and actuator (64), which control the movement of the motor (58), needle (38).

[0074] The present invention provides the following advantages:

[0075] - The complete closure of the needle valve (42) is rapid when the stop zone (62) is in a low position, and no dead product volume is created between the upstream and the nozzle (43). Accordingly, the ends of the product beads are clean.

[0076] - No specific wear occurs in the nozzle (43) due to additional moving parts.

[0077] - Since the pre-positioning of the stop zone (62) is performed within a hidden time that is longer than the sudden change in the product output flow rate, the actuator (64) does not need to be powerful. Additionally, the positioning of the stop zone (62) occurs while the needle valve (42) is open, which does not generate stress on the cam stop zone (62).

[0078] - Conventional needle valves (42) can use a sealing system, and thus there is no need to design a special sealing system.

[0079] - The above stop zones (60 and 62) and actuator (64) can be applied to an existing coating device in the form of an assembly (8) by providing access only to the needle (38) or piston (40).

[0080] Other embodiments of a product dispensing device are illustrated in FIGS. 8 to 11. In these embodiments, elements common to the first embodiment have the same reference numerals and function in the same way.

[0081] A second embodiment is illustrated in FIG. 8. In this embodiment, the position of the stop (62) fixed to the frame (30) is adjustable around an adjustment axis (X62) parallel to the longitudinal axis (X3) of the needle (38). The stop is formed by a cam surface (620) whose height can vary along the axis (X62) based on each position around the axis (X62). At one position, the cam surface (620) has a small step (622) that does not prevent the needle (38) from descending. At each position opposite to the axis (X62), the cam surface (620) has a maximum thickness, which limits the return of the needle (38) to the closed position.

[0082] A third embodiment is illustrated in FIG. 9. In this embodiment, the actuator (64) is a hollow shaft motor forming a tubular member (640) that is rotatably mounted around a portion of the needle (38) protruding from the frame (30). This tubular member (640) has a stop portion (62), said stop portion (62) has a cam surface (620) similar to the embodiment of FIG. 8. In this case, each position of the cam surface (620) is adjustable around the longitudinal axis (X3) of the needle (38), and the adjustment axis (X64) coincides with the longitudinal axis (X3). The height of the cam surface (620) along the longitudinal axis (X3) can be varied around the adjustment axis (X64). This embodiment ensures radial and axial compactness of the dispensing device (3).

[0083] A fourth embodiment is illustrated in FIG. 10. In this embodiment, a stopper (62) fixed to the frame (30) is provided within the control chamber (32). A cam (63) forming the stopper (63) can rotate around a control axis (Y62) oriented perpendicularly to the longitudinal axis (X3). The cam (63) protrudes into the control chamber (32) in a manner that restricts downward movement of the piston (40). In this case, the stopper fixed to the needle (38) is formed by the piston (40) itself. A cavity (320) is provided within the frame (30) to allow rotation of the cam (63) around the control axis (Y62).

[0084] A fifth embodiment is illustrated in FIG. 11. In this embodiment, the control actuator is a linear actuator (66), that is, it applies translational motion, and is, for example, a cylinder or a ball screw. A stop member (62) fixed to the frame (30) is formed by a part (642) that can translate along a control axis (X62) that is parallel to or coincides with the longitudinal axis (X3) of the needle (38). The piston (40) includes a cylindrical part (400) extending outside the frame (30), and a spring (45) is wound around the cylindrical part (400). The cylindrical part (400) includes a cavity (402) at its upper end, and the part (642) is received within the cavity (402). The cavity (402) includes an inwardly oriented radial portion (404), which forms a fixed stop portion (60) for the needle (38). When the needle (38) returns to the closed position, the part (642) opposes the radial portion (404) along the longitudinal axis (X3) and limits the closing of the needle valve (42).

[0085] The technical features of the embodiments and variations described above may be combined to form other embodiments within the scope of the claims.

Claims

Claim 1 A device (3) for applying a product, comprising a frame (30) provided with a product conduit (34) inside, wherein a longitudinal bore (36) is formed in the frame (30), and the application device (3) comprises a needle (38) mounted within the longitudinal bore (36), and the application device comprises a product application valve (42) formed by a nozzle (43) provided in the frame (30) and a shutter (44) provided at one end of the needle (38) located within the product conduit (34), wherein the needle is configured to move along a longitudinal axis (X3) between a position where the application valve (42) is closed and a position where the application valve (42) is open, and the application device (3) comprises a stop (60; 40) fixed to the needle (38) and a stop (62) fixed to the frame (30), wherein the stop (62) comprises A coating device configured to limit the return of the needle (38) toward a closed position to an intermediate position between a closed position and an open position by means of interaction with a stop member (60; 40) fixed to the needle (38), wherein the stop member (62) fixed to the frame (30) has an adjustable position, wherein the stop member (62) fixed to the frame (30) is formed by at least one cam (63), wherein the coating device (3) includes an actuator (64) for adjusting the position of the cam (63), wherein the position of the cam (63) is rotatable along a control axis (X62) parallel to the longitudinal axis (X3) of the needle (38), and the thickness of the cam increases along the control axis. Claim 2 A coating device according to claim 1, characterized in that the control actuator (64) is a rotary electric motor. Claim 3 In paragraph 2, the cam is formed by a tubular member (640) mounted around a portion of the needle (38) protruding from the frame (30), the actuator (64) is a hollow shaft motor that drives the tubular member (640), each position of the cam is adjustable along the longitudinal axis (X3) of the needle (38), and the thickness of the cam increases along the adjustment axis. Claim 4 A coating device according to claim 1, wherein the stopper (60) fixed to the needle (38) is fixed to the end of the needle (38) protruding from the frame (30). Claim 5 In claim 4, the actuator (64), the stop member (60) fixed to the needle (38), and the stop member (62) fixed to the frame (30) form an external assembly (8) configured to be fixed and connected to the frame (30) and the needle (38) of the existing coating device (3). Claim 6 A coating device according to claim 1, wherein the stop portion fixed to the needle (38) is formed by a piston (40) received within the control chamber (32) of the frame (30), and the stop portion (62) fixed to the frame (30) is provided within the frame (30) and protrudes into the control chamber (32). Claim 7 A coating device according to claim 1, wherein the stopper (60) fixed to the needle (38) has a surface (600) inclined with respect to the longitudinal axis (X3) of the needle (38). Claim 8 A machine (1) for applying a product, comprising: a dosing device (3) according to claim 1 and a dosing system (5) for the product, wherein the dosing system (5) is configured to send the product into the dosing device (3) at an adjustable pressure (P5), and the dosing system (5) comprises a motor (58) and a control unit (7) configured to control the dosing system (5) and the dosing device (3), wherein the speed (V) of the motor (58) is controlled to adjust the pressure (P5). Claim 9 A method for controlling a product dispensing machine (1) according to claim 8, wherein the following steps are performed by the control unit (7): - a) in the case of a request to increase the output flow rate (D) of the nozzle (43) of the dispensing device (3) between a low value (D1) and a high value (D3), the speed of the motor (58) is maintained at a constant value (V1, V2) of the speed of the motor (58) of the dispensing system (5), and the opening of the needle valve (42) of the dispensing device (3) is reduced to cause an increase in the output pressure (P5) of the dispensing system (5), and then the needle valve (42) is reopened and the speed of the motor (58) is increased to a value (V3) required to obtain a high value of the output flow rate (D); and - b) in the case of a request to reduce the output flow rate (D) to a value between a high value (D3) and a low value (D1) or to an intermediate value (D2) between a low value and a high value, a reduction in the output pressure (P5) of the injection system (5) is caused by reducing the speed of the motor (58) to a low value and reducing the opening of the needle valve (42) of the application device (3), and then opening the needle valve (42) and increasing the speed of the motor (58) to a value (V2) required to achieve an intermediate or low value of the output flow rate (D); the control method is characterized by comprising at least one of these steps. Claim 10 A control method according to claim 9, wherein in steps a) and b), the reduction of the opening of the needle valve (42) of the coating device (3) is achieved by positioning the stop member (62) fixed to the frame (30) at a predetermined position during the control step of the output flow rate (D), and then closing the needle valve (42) to a predetermined position by positioning the stop member (62) fixed to the frame (30). Claim 11 A control method according to claim 9 or 10, wherein in step b), the lower value at which the speed (V) of the motor (58) is reduced is less than 0, and the operating direction of the motor (58) is reversed. Claim 12 delete Claim 13 delete Claim 14 delete Claim 15 delete

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