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

Abstract

To provide a device for applying a product, a machine including such a device, and a method for controlling such a machine.SOLUTION: The invention provides a device for applying a product (3), including a frame (30) in which a product conduit (34) is provided, the frame (30) defining a longitudinal bore (36). The device includes a needle (38) installed in the longitudinal bore (36). The device includes a product application valve (42) formed by a nozzle (43) provided on the frame (30) and a shutter (44) provided at an end of the needle (38) in the product conduit (34). The needle is configured to be moved along a longitudinal axis (X3) between a closed position and an open position of the valve (42). The device includes a stopper (60) fixed in relation to the needle (38), and a stopper (62) fixed in relation to the frame (30). The stopper (62) fixed in relation to the frame (30) has an adjustable position.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] In the field of adhesive or sealant product application by robotic systems, it may be necessary to quickly change application speed, for example, to obtain a wider or narrower bead of adhesive or sealant. This width change must be rapid to ensure a clean result and avoid costly product waste. Because these products are viscous, systems must be designed specifically for them.

[0003] Electrically operated product dosing or pressure control systems are driven by a motor. For applications that are not dynamic and are close to the dosing system, the motor speed is proportional to the product output. For more dynamic applications, or applications farther away from the dosing system, the response time of the dosing or pressure control system will be relatively long due to the compressibility of the product, the elasticity of the hose, and the high pressures involved.

[0004] To achieve fast flow changes, it is known to use mechanical systems that have moving parts in front of the product application nozzle to create an adjustable restriction. Such solutions have several drawbacks. Due to the volume being reduced between the restriction and the nozzle, the product application cannot be stopped quickly enough, and therefore the edge of the applied bead is not clean. -Product is abrasive and can cause wear and tear on moving parts and leaks. The actuators required to move the moving parts must be fast and powerful, and therefore expensive. -Adds cost as special seals must be designed for all moving parts. -Needles and valve seats must be specially designed, making existing non-variable flow application equipment incompatible. Summary of the Invention

[0005] The object of the present invention is to propose a new product application device that allows rapid changes in product application speed to be obtained using mechanical parts that are less costly and complex than existing solutions, have better performance and are more reliable.

[0006] To this end, the invention relates to a product application device comprising a frame provided with a product conduit, the frame defining a longitudinal bore, the application device comprising a needle mounted in the longitudinal bore, a product application valve formed by a nozzle provided in the frame and a shutter provided at the end of the needle arranged in the product conduit, the needle being configured to move along a longitudinal axis between a closed position and an open position of the application valve, the application device being characterized in that it comprises a stopper fixed relative to the needle and a stopper fixed relative to the frame configured to limit the return of the needle to the closed position to an intermediate position between the closed and open positions by interaction of the stopper fixed relative to the needle, and the stopper fixed relative to the frame having an adjustable position.

[0007] The present invention allows for the needle to be placed in an intermediate position, creating an adjustable restriction that does not require the design of expensive actuators or specific sealing solutions.

[0008] According to advantageous but non-essential aspects of the invention, such a product application device may incorporate one or more of the following features, taken in any technically permissible combination: the stop fixed relative to the frame is formed by at least one cam, the application device comprising an actuator for adjusting the position of the cam; The position of the cam is adjustable by rotation about an adjustment axis perpendicular to the longitudinal axis of the needle, and the profile of the cam describes a surface of increasing radius. The position of the cam is rotatably adjustable about an adjustment axis parallel to the longitudinal axis of the needle, and the thickness of the cam increases about the adjustment axis. -The adjustment actuator is a rotary electric motor. -The cam is carried by a tubular section mounted around the part of the needle protruding from the frame, the actuator is a hollow shaft motor which drives the tubular section, the angular position of the cam is adjustable around the longitudinal axis of the needle, and the thickness of the cam increases around the adjustment axis. A stopper fixed relative to the needle is attached to the end of the needle protruding from the frame. The adjustment actuator, needle stopper, and frame stopper form an external assembly configured to be attached to and connected to the frame and needle of an existing application device. The stopper fixed relative to the needle is formed by a piston accommodated in a pilot chamber of the frame, and a frame stopper is provided on the frame and projects into the pilot chamber. The stopper fixed relative to the needle has an inclined surface relative to the longitudinal axis of the needle. The stopper, fixed relative to the frame, is formed by a part that can move in translation along an axis parallel to the longitudinal axis of the needle, and the application device comprises a linear actuator for adjusting the position of the part that can move in translation.

[0009] The present invention also relates to a product applicator including an application device as described above, and to a dosing system for the product, the dosing system being configured to deliver the product to the application device at an adjustable pressure, the dosing system comprising a motor controlled to adjust the pressure, and a control unit configured to control the dosing system and the application device.

[0010] The present invention also relates to a method for controlling a product applicator as described above, characterized in that the method is carried out by a control unit and comprises at least one of the following steps: -a) when there is a demand to increase the nozzle output flow rate of the applicator between a lower limit and an upper limit, maintaining the motor speed of the dosing system at a constant value, reducing the opening of the needle valve of the applicator, then reopening the needle valve and increasing the motor speed to the value required to obtain the upper limit of the output flow rate, thereby causing an increase in the output pressure of the dosing system. -b) If there is a request to reduce the output flow rate from the upper limit to the lower limit, or to a value intermediate between the lower and upper limits, causing a decrease in the output pressure of the dosing system by reducing the motor speed to a lower value, reducing the opening of the applicator needle valve, and then reopening the needle valve and increasing the motor speed to the value necessary to reach the intermediate or lower output flow rate value.

[0011] According to advantageous but non-essential aspects of the invention, such a control method may incorporate one or more of the following features, taken in any technically permissible combination: In steps a) and b), the reduction in the opening of the needle valve of the application device is achieved by placing a stopper fixed to the frame in a predetermined position during the output flow control phase and then closing the needle valve to a predetermined position by placing the stopper fixed to the frame. In step b), the motor speed is reduced to a lower value below zero, and the motor direction is reversed. [Brief explanation of the drawings]

[0012] The invention will be better understood and other advantages will become more apparent in the light of the following description of a product application device, a product applicator and a control method according to the principles thereof, given by way of non-limiting example with reference to the accompanying drawings, in which: [Figure 1] FIG. 1 is a schematic cross-sectional view of a product applicator according to the present invention, including a product application device according to a first embodiment of the present invention, the product application device being in an open configuration. [Figure 2] FIG. 2 is a schematic cross-sectional view of the product application device of FIG. 1 in an intermediate configuration. [Figure 3] FIG. 3 is a schematic cross-sectional view of the product application device of FIG. 3 in a closed configuration. [Figure 4] 4 is a partial cross-sectional perspective view of the applicator device of FIG. 1, showing the stopper in a closed configuration in the lowered configuration of the device. [Figure 5] FIG. 5 is a partial cross-sectional perspective view of the applicator of FIG. 1 showing the stopper in an intermediate configuration. [Figure 6] FIG. 6 is a partial cross-sectional perspective view of the applicator device of FIG. 1 showing the stopper in a maximum open configuration. [Figure 7] FIG. 7 is a flow chart of a method for controlling an applicator according to the present invention. [Figure 8] FIG. 8 is a schematic cross-sectional view of a product application device according to a second embodiment of the present invention. [Figure 9] FIG. 9 is a schematic cross-sectional view of a product application device according to a third embodiment of the present invention. [Figure 10] FIG. 10 is a schematic cross-sectional view of a product application device according to a fourth embodiment of the present invention. [Figure 11] FIG. 11 is a schematic cross-sectional view of a product application device according to a fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] 1 shows a machine 1 for applying products, in particular high-viscosity products such as adhesives and sealants (such as mastics). The machine 1 comprises a product application device 3 and a product dosing system 5 supplied by a source (not shown) of the product to be applied.

[0014] The dosing system 5 comprises a product input port 50, a product dosing chamber 52, and a product exit port 54 to the applicator 3. The dosing system 5 comprises a dosing piston 56 and a motor 58 that actuates the movement of the dosing piston 56 in the chamber 52 via a mechanical motion conversion system (e.g., a ball screw).

[0015] The dosing system 5 is configured to deliver product to the applicator 3 at an adjustable pressure. The speed and torque of the motor 58 are controlled to adjust the speed of movement of the dosing piston 56 and the pressure of the product output from the outlet port 54.

[0016] The applicator 1 comprises a control unit 7, which is configured to control the dosing system 5 and the applicator device 3. To this end, the control unit 7 may comprise a microprocessor, a memory, a calculator and a communication system configured to control the dosing system 5 and the applicator device 3 by means of electrical signals.

[0017] The applicator 3 includes a frame 30 in which a control chamber 32 and a product conduit 34 are provided. The frame 30 defines a longitudinal bore 36 about a central axis X3, the bore extending longitudinally through the frame 30, through the pilot chamber 32, and into the conduit 34. The applicator 3 includes a needle 38 slidably mounted in the longitudinal bore 36. The applicator 3 also includes a piston 40 housed in the control chamber 32 and fixed relative to the needle 38 as it slides along the axis X3.

[0018] The applicator 3 comprises a needle applicator 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 in a conduit 34. The product conduit 34 guides the product between an outlet port 54 and the nozzle 43. The product is applied as it leaves the nozzle 43 along arrow F1. In this example, the shutter 44 is formed by a ball, but it may have any other shape, including a cone, etc.

[0019] The needle 38 can move along a 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 application device 3 includes a resilient return element for the needle 38 in the closed position, formed, for example, by a helical spring 45 housed in the control chamber 32. When control fluid is injected into the control chamber 32 along arrow F2, the needle 38 is directed toward its open position against the force of the spring 45. Pilot fluid can also be injected into the pilot chamber 32 along arrow F3 to direct the needle 38 toward its closed position. The control fluid can be compressed air.

[0020] In an alternative embodiment not shown, the needle 38 returns to its closed position under the sole action of the spring 45 .

[0021] The application device 3 includes a stopper 60 fixed relative to the needle 38 and a stopper 62 fixed relative to the frame 30 configured to interact with the stopper 60 fixed relative to the needle 38 to limit return of the needle 38 toward the closed position to an intermediate position between the closed positions. The stopper 60 is fixed relative to the needle 38 when the needle 38 slides along the longitudinal axis X3. The stopper 62 fixed relative to the frame 30 has an adjustable position; that is, its position along the longitudinal axis X3 is fixed relative to the needle 38 except when it is at an interval for adjusting its position along the longitudinal axis X3. Adjusting the stopper 62 prevents the needle valve 42 from completely closing, thereby reducing the flow of product from the nozzle 43.

[0022] In FIG. 1, stopper 62 is set in the up position, and needle 38 is also in the up position with needle valve 42 fully open. Stoppers 60 and 62 are not in contact. In FIG. 2, stopper 60 is in contact with stopper 62 in an intermediate position, which limits the return of needle 38 to the down position to the intermediate position, so that needle valve 42 is not fully closed and therefore flow is restricted. In FIG. 3, stopper 62 is set in the down position, which allows needle valve 38 to return to the fully down position because stopper 62 no longer forms an obstacle to the descent of stopper 60 along axis X3.

[0023] According to the embodiment shown in Figures 4 to 6, the stopper 60 is fixed to the end of the needle 38 that protrudes from the frame 30, this end being opposite the shutter 44. The frame 30 comprises a top cover 300 pierced by an opening 302 through which the needle 38 slides along a longitudinal axis X3. The stopper 60 is fixed to the needle 38, for example, by means of two screws 61.

[0024] The application device 3 comprises an actuator 64 for adjusting the position of the stopper 62. According to one embodiment, the stopper 62 is formed by at least one cam 63 rotatable about a rotation axis Y62 perpendicular to the longitudinal axis X3. The actuator 64 in this case is formed by an electric motor which drives the cam 63 to rotate about the axis Y62. The rotation of the cam 63 about the axis Y62 makes it possible to adjust the angular position of the cam 63 and thus to correct the position of the stopper 62 along the axis X3. The electric motor can be a stepper motor.

[0025] As can be seen in Figures 4 to 6, the stopper 62 may comprise two parallel cams 63 mounted on a common shaft 630 aligned with the adjustment axis Y62.

[0026] According to one embodiment, the stopper 60 has a surface 600 for contacting the stopper 62 that is inclined with respect to the longitudinal axis X3. This inclined surface 600 allows the height of the stopper 62 to be as regular as possible with the stopper varying along the longitudinal axis X3 based on the angular position of the cam 63, improving the accuracy and simplicity of the control of the cam 63 by the actuator 64. This also avoids the design of a specific stopper surface 60, while ensuring that the contact point between the cam 63 and the inclined surface 600 is as close as possible to the longitudinal axis X3.

[0027] In a variant not shown, the surface 600 may be perpendicular to the longitudinal axis X3.

[0028] The stopper 60 has two parallel inclined surfaces 600 each of which interacts with one of the cams 63 .

[0029] The cam 63 describes a curved surface of increasing radius about the axis Y62. The angular position of the cam 63 about the axis Y62 varies the axial position along the axis X3 of the stopper 62 and the intermediate position at which the needle 38 is limited to return to the closed position.

[0030] 4, the cam 63 is in a low position, i.e., an angular position in which the cam 63 forms a low obstruction, which does not oppose the descent of the stopper 60. The needle 38 can therefore be in a closed position.

[0031] In Figure 5, the cam 63 is in an intermediate position corresponding to an angular position where the cam surface radius aligned with the axis X3 is larger. The cam 63 forms an obstacle that is higher along the longitudinal axis X3 compared to Figure 4. Between Figures 4 and 5, the cam 63 has been rotated according to the arrow R1 in Figure 5. In this position of the cam 63, the stopper 60 is stopped at a higher position, preventing the needle valve 42 from closing again and creating a restriction in the flow at the nozzle 43.

[0032] In Figure 6, cam 63 is positioned at an angular position where the cam's surface radius, aligned with axis X3, is at its maximum. Rotation of cam 63 along axis Y62 continues along arrow R1. In this position, stop 62 holds stop 60 in its high position, where needle valve 42 is fully open.

[0033] According to one embodiment, actuator 64, stopper 60, and stopper 62 form an external assembly 8 configured to be attached to and connected to frame 30 and needle 38 of an existing applicator 3. This assembly includes a cover 80 that surrounds stopper 60 and stopper 62 and is attached to top cover 300, e.g., by screws 82. Actuator 64 is attached to cover 80, e.g., by screws 84. In the form of external assembly 8, stoppers 60 and 62 and actuator 64 can be easily adapted to existing applicator devices, with the only limitation being external access to needle 38. This access is much less restrictive than the specific engineering solutions required to ensure sealing, needle valve modifications, and actuator output in the case of the current solutions described above.

[0034] The operation of the applicator 1 will now be explained with reference to FIG.

[0035] Figure 1 shows time on the x-axis and, from bottom to top, the following on the y-axis: - width L of the product bead deposited by the application device 3; - output flow rate D of nozzle 43; - the angular velocity V of the motor 58, which indicates the linear velocity of the piston 56; - the position P of the needle 38 with the position of the stopper 62 fixed relative to the frame 30 in the form of a hatched area; - pressure of the product present at the outlet of the dosing system 5 relative to atmospheric pressure P5.

[0036] At time t0, which corresponds to switching on of the applicator 1, for example, the output flow rate D, velocity V and pressure P5 are zero and the needle 38 is in the closed position. The stopper 62 is in the position shown in Figures 3 and 4, i.e. does not prevent the needle 38 from returning to the closed position.

[0037] To obtain the first product bead, a certain pressure P5 in the applicator 3 needs to be slightly higher than the desired application pressure after opening the needle valve 42. Therefore, an initial precharge is applied. This precharge is obtained by rapidly activating the motor 58. Thus, to obtain the pressure P51, the velocity V increases at time t1 and then returns to zero at time t2, while the needle valve 38 does not move and the needle valve 42 remains closed.

[0038] At time t3, product deposition begins: needle 38 is moved to open needle valve 42 to 100%. Speed ​​V is increased to produce a constant product pressure P52 and an output flow rate D1 corresponding to a percentage, e.g., 10%, of the maximum value D3 of output flow rate D. Stopper 62 remains in the low position.

[0039] Stoppers 60 and 62 are implemented during transient stages of operation of applicator 1 when an increase or decrease in output flow rate from nozzle 43 must be obtained.

[0040] At time t6, a request is made to increase the output flow rate D. The flow rate must increase quickly between D1 and D3. For this purpose, before time t6, an increase in output pressure P5 is generated by maintaining the speed V at a constant value V1 and reducing the opening of the needle valve 42. For this purpose, the stopper 62 is moved progressively to a predetermined position while the applicator 1 adjusts the output flow rate D to the value D1. The positioning of the stopper 62 begins at t3. The predetermined position of the stopper 62 may correspond to a small opening of the needle valve 42, for example, 10% of the maximum opening.

[0041] At time t4, needle valve 42 begins to close. At time t5, stopper 62 reaches a predetermined position and needle valve 38 reaches a predetermined position due to the positioning of stopper 62. Thus, a flow restriction is formed at nozzle 43. If velocity V is held constant at V1, this has the effect of increasing pressure P5 to a value P53 at time t5. To obtain a higher flow rate, a second precharge is required, while keeping output flow rate D constant.

[0042] At time t6, once the required pressure P53 has been achieved, the needle valve 42 is again opened to 100%. The speed V is increased to a maximum value V3 until it reaches the value required to obtain the output flow rate D3. At time t7, the needle valve 42 is opened to 100%, the speed V3 is obtained, and the pressure P5 decreases to a value P54 due to the opening of the needle valve 42, obtaining the flow D3. The time required to obtain the increase in the output flow rate D between time t6 (opening of the needle valve 42) and time t7 (obtaining the flow D3) is, for example, shorter than the order of a few milliseconds, which allows a net increase in the bead width. If such speeds were to be obtained by actuators controlling the mechanical limits in the nozzle 43, these would have to be very powerful and expensive.

[0043] Conversely, the positioning of stopper 62 can be performed in hidden times between the normal control phases. Therefore, it is not necessary to provide a powerful actuator for its movement. Between times t3 and t6, a few tens of milliseconds may be sufficient to position stopper 62. This is a switching time that maintains compatibility with standard, inexpensive stepper motors, which can therefore be used as actuators 64.

[0044] Next, the transient phase of decreasing the output flow rate D will be described. The output flow rate D must be decreased to an intermediate value D2 lower than D3, for example, 20% of the flow rate D3. To this end, the control unit 7 generates a decrease in the output pressure P5. This pressure decrease is fast. The speed V decreases to a low value immediately. For example, the speed V decreases to a low value in a few milliseconds. The decrease in speed V begins at time t8 and ends at time t9. As shown at time t9 in FIG. 7, the low value to which the speed V is reduced can be less than zero, so that the direction of travel of the motor 58 can be reversed if a large flow rate decrease is desired. In a variant, the low value can be zero or less than 10% of the maximum value of speed V, for example, if the desired flow change is not too abrupt.

[0045] At the same time, the opening of the needle valve 42 is reduced. This reduction in opening is achieved, for example, by placing the stopper 62 at a predetermined intermediate position corresponding to 20% of the needle valve 42's full opening, and by closing the needle valve 42 at time t8 by moving the needle 38 toward the closed position until it is blocked by the stopper 62 at the predetermined 20% position at time t9. The start of positioning the stopper 62 can occur before time t8, for example, starting from the 10% open position at time t6, so that the actuator 64 has sufficient time to position the stopper 62. In this way, a rapid reduction in the output flow rate D is achieved. The normal adjustment phase of the output flow D then begins, starting at value D2. For this purpose, the needle valve 42 is reopened at time t10, and the speed V is increased again from time t9 to the value V2 required to obtain the output flow rate D2. At time t11, the speed V stabilizes, the pressure P5 stabilizes at the value P55, and the needle 38 is positioned in the 100% open position.

[0046] Between times t12 and t13, the control unit 7 again carries out the steps already described to increase the output flow rate D between D1 and D3: to restore the output flow D to D3, the velocity V is kept constant and the pressure P5 is increased again to a value P53 by partially closing the needle valve 42, and to an intermediate opening value set by the positioning of the stopper 62, which remains in place. At t13, the normal control phase is established with the output flow D at D3.

[0047] Thereafter, at t14 and t15, a rapid decrease in velocity V and partial closure of needle valve 42 is again performed to successively decrease output flow rate D to D1 and then to zero. At time t13, or slightly earlier, stopper 62 was progressively lowered to set a stop position for needle valve 38 at t14, corresponding to slightly opening needle valve 42, e.g., 10%. After time t14, stopper 62 was gradually lowered to its lowered position so that needle valve 42 fully closed at t15 and the product bead could be terminated. At time t15, velocity V was suddenly reduced to a negative value, corresponding to withdrawing piston 56 upward, achieving a rapid decompression within conduit 34 of applicator 3.

[0048] The control method can be resumed as started at t0 with a new precharge by increasing the velocity V at t16. A new product bead can then be deposited at output rate D3 at t17. At time t18, velocity V is suddenly reversed, resulting in a rapid decompression and termination of the product bead at t19. Since there is no variation in output rate D between the intermediate values ​​between t17 and t19, stopper 62 is not used at this stage. Applicator 3 with stoppers 60 and 62 can therefore be operated in a conventional manner.

[0049] All the above operating steps are initiated in the control unit 7 by control signals sent to the motor 58, the control fluid distributor 9, e.g. a compressed air distributor, which controls the movement of the needle 38, and the actuator 64.

[0050] The present invention provides the following advantages: When the stopper 62 is in the down position, the complete closure of the needle valve 42 is quick and there is no dead product volume created between the nozzle 43 and the nozzle 43. Therefore, the edge of the product bead is clean. No additional moving parts in the nozzle 43 cause no particular wear: the needle valve 42 therefore has a normal lifespan. The actuator 64 does not need to be powerful because the pre-positioning of the stopper 62 occurs over a period of time that is hidden from the sudden change in product output flow. Furthermore, the positioning of the stopper 62 occurs while the needle valve 42 is open, which does not create stress on the cam stopper 62. - Conventional needle valve 42 sealing system can be used, no need to design a specific sealing system. The stoppers 60 and 62 and the actuator 64 can be adapted in the form of an assembly 8 to existing application devices by simply providing access to the needle 38 or piston 40 .

[0051] Other embodiments of the product application device are shown in Figures 8 to 11. In these embodiments, elements common to the first embodiment have the same reference numbers and function in the same manner.

[0052] A second embodiment is shown in Figure 8. In this embodiment, the position of a stopper 62, which is fixed relative to the frame 30, is adjustable about an adjustment axis X62 parallel to the longitudinal axis X3 of the needle 38. The stopper is formed by a cam surface 620 whose height along the axis X62 varies depending on the angular position about the axis X62. At one angular portion, the cam surface 620 has a step 622 of small thickness that does not prevent the needle 38 from descending. At the opposite angular portion relative to the axis X62, the cam surface 620 has a maximum thickness, which limits the return of the needle 38 to the closed position.

[0053] A third embodiment is shown in Figure 9. In this embodiment, the actuator 64 is a hollow shaft motor forming a tubular member 640 rotatably mounted around the portion of the needle 38 that protrudes from the frame 30. This tubular member 640 carries a stopper 62 having a cam surface 620 similar to that of the embodiment of Figure 8. In this case, the angular position of the cam surface 620 is adjustable about the longitudinal axis X3 of the needle 38, with the adjustment axis X64 coinciding with 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 radial and axial compactness of the application device 3.

[0054] A fourth embodiment is shown in Figure 10. In this embodiment, a stopper 62 fixed relative to the frame 30 is provided in the control chamber 32. A cam 63 forming the stopper 62 is rotatable about an adjustment axis Y62 oriented perpendicular to the longitudinal axis X3. The cam 63 protrudes into the control chamber 32 so as to limit the downward movement of the piston 40. In this case, the stopper fixed relative to the needle 38 is formed by the piston 40 itself. A cavity 320 is provided in the frame 30 to allow rotation of the cam 63 about the adjustment axis Y62.

[0055] A fifth embodiment is shown in FIG. 11. In this embodiment, the adjustment actuator is a linear actuator 66, i.e., it exerts a translational movement, e.g., a cylinder or ball screw. The stopper 62 fixed to the frame 30 is formed by a member 642 translatable along an adjustment axis X62 parallel to or coincident with the longitudinal axis X3 of the needle 38. The piston 40 includes a cylindrical portion 400 extending outside the frame 30 and around which the spring 45 is wound. The cylindrical portion 400 includes a cavity 402 at its upper end, in which the member 642 is received. The cavity 402 includes an inwardly directed radial portion 404, which forms the stopper 60 fixed to the needle 38. When the needle 38 returns to the closed position, the member 642 opposes the radial portion 404 along the longitudinal axis X3 and limits the closure of the needle valve 42.

[0056] The technical features of the above embodiments and variants may be combined to form the present invention within the scope of the claims. Clearly other embodiments can be formed. The present invention can be embodied in the following manner. <Aspect 1> A device (3) for applying a product, comprising a frame (30) provided with a product conduit (34), the frame (30) defining a longitudinal bore (36), the applicator (3) comprising a needle (38) mounted in the longitudinal bore (36), the applicator comprising 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) disposed in the product conduit (34), the needle being movable along a longitudinal axis (X3) such that the application valve (42) is in a closed position. a stopper (60; 40) fixed relative to the needle (38), configured to move between a closed position and an open position, and a stopper (62) fixed relative to the frame (30) configured to limit the return of the needle toward the closed position to an intermediate position between the closed and open positions by interacting with the stopper (60; 40) fixed relative to the needle (38), and the stopper (62) fixed relative to the frame (30) has an adjustable position. <Aspect 2> The application device according to aspect 1, characterized in that the stopper (62) fixed to the frame (30) is formed by at least one cam (63), and the application device (3) comprises an actuator (64) for adjusting the position of the cam (63). <Aspect 3> 3. The application device of claim 2, wherein the position of the cam (63) is rotatably adjustable around an adjustment axis (Y62) perpendicular to the longitudinal axis (X3) of the needle (38), and wherein the profile of the cam describes a surface of increasing radius. <Aspect 4> 3. The application device of claim 2, wherein the position of the cam (63) is rotatably adjustable around an adjustment axis (X62) parallel to the longitudinal axis (X3) of the needle (38), and wherein the thickness of the cam increases around the adjustment axis. <Aspect 5> 5. The application device according to any one of aspects 3 and 4, wherein the adjustment actuator (64) is a rotary electric motor. <Aspect 6> The application device of aspect 5, characterized in that the cam is supported 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), the angular position of the cam is adjustable around the longitudinal axis (X3) of the needle (38), and the thickness of the cam increases around the adjustment axis. <Aspect 7> The applicator according to any one of aspects 1 to 6, wherein a stopper (60) fixed to the needle (38) is fixed to the end of the needle (38) protruding from the frame (30). <Aspect 8> The application device of aspect 7, wherein the actuator (64), the stopper (60) fixed to the needle (38), and the stopper (62) fixed to the frame (30) form an external assembly (8) configured to be fixedly connected to the frame (30) and needle (38) of an existing application device (3). <Aspect 9> The applicator of any one of aspects 1 to 6, wherein the stopper fixed to the needle (38) is formed by a piston (40) housed in a control chamber (32) of the frame (30), and the stopper (62) fixed to the frame (30) is provided on the frame (30) and protrudes into the control chamber (32). <Aspect 10> 10. The applicator device according to any one of the preceding aspects, wherein the stopper (60) fixed relative to the needle (38) has a surface (600) that is inclined relative to the longitudinal axis (X3) of the needle (38). <Aspect 11> The application device according to aspect 1, characterized in that the stopper (62) fixed relative to the frame (30) is formed by a member (642) movable in translation along an axis (X62) parallel to the longitudinal axis (X3) of the needle (38), and the application device (3) comprises a linear actuator (66) for adjusting the position of the movable member (642). <Aspect 12> 10. A machine (1) for applying a product, comprising: an application device (3) according to any one of aspects 1 to 9; a dosing system (5) for the product configured to feed the product into the application device (3) with an adjustable pressure (P5), the dosing system (5) comprising a motor (58) whose speed (V) is controlled to adjust the pressure (P5); and a control unit (7) configured to control the dosing system (5) and the application device (3). <Aspect 13> A method for controlling a machine (1) for applying a product according to aspect 12, characterized in that it comprises at least one of the following steps, the method being carried out by a control unit (7) and consisting of: -a) when there is a demand to increase the output flow rate (D) of the nozzle (43) of the applicator (3) between a lower limit (D1) and an upper limit (D3), maintaining the speed of the motor (2) at a constant value (V1, V2) of the speed of the motor (58) of the dosing system (5), reducing the opening of the needle valve (42) of the applicator (3), then reopening the needle valve (42) and increasing the speed of the motor (58) to the value (V3) required to obtain the higher value of the output flow (D), thereby causing an increase in the output pressure (P5) of the dosing system (5); -b) if there is a demand to reduce the output flow rate (D) between an upper limit (D3) and a lower limit (D1), or to an intermediate value (D2) between the lower and upper limits, the speed of the motor (58) is reduced to a lower value, the opening of the needle valve (42) of the applicator (3) is reduced, and then the needle valve (42) is opened again and the speed (V) of the motor (58) is increased to the value (V2) required to reach the intermediate or lower value of the output flow rate (D), thereby causing a reduction in the output pressure (P5) of the dosing system (5). <Aspect 14> 14. The method for controlling according to claim 13, wherein in steps a) and b), the reduction of the opening of the needle valve (42) of the application device (3) is achieved by placing a stopper (62) fixed relative to the frame (30) in a predetermined position during the phase of adjusting the output flow rate (D), and then closing the needle valve (42) in a predetermined position by placing the stopper (62) fixed relative to the frame (30). <Aspect 15> 15. The method for controlling according to claim 13 or 14, wherein in step b), the low value to which the speed (V) of the motor (58) is reduced is less than zero and the direction of operation of the motor (58) is reversed.

Claims

1. An apparatus (3) for applying a product, comprising a frame (30) provided with a product conduit (34), the frame (30) defining a longitudinal bore (36), the applicator (3) comprising a needle (38) mounted in the longitudinal bore (36), the applicator comprising 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) arranged in the product conduit (34), the needle being configured to move along a longitudinal axis (X3) between a position in which the application valve (42) is closed and a position in which it is open, the applicator (3) comprising a stopper (60; 40) fixed relative to the needle (38) and a stopper (44) fixed relative to the needle (38). the stopper (62) fixed relative to the frame (30) is configured to limit the return of the needle towards the closed position to an intermediate position between the closed position and the open position by interaction with a stopper (60; 40), the stopper (62) fixed relative to the frame (30) has an adjustable position, the stopper (62) fixed relative to the frame (30) is formed by at least one cam (63), the application device (3) comprises an actuator (64) for adjusting the position of the cam (63), the position of the cam (63) is rotatably adjustable around an adjustment axis (X62) parallel to the longitudinal axis (X3) of the needle (38), and the thickness of the cam increases around the adjustment axis.

2. 2. The application device of claim 1, wherein the adjustment actuator (64) is a rotary electric motor.

3. 3. The application device of claim 2, wherein the cam is supported 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), the angular position of the cam is adjustable around the longitudinal axis (X3) of the needle (38), and the thickness of the cam increases around the adjustment axis.

4. 4. The application device according to claim 1, wherein a stopper (60) fixed relative to the needle (38) is fixed to the end of the needle (38) protruding from the frame (30).

5. 5. The application device of claim 4, wherein the actuator (64), the stopper (60) fixed to the needle (38), and the stopper (62) fixed to the frame (30) form an external assembly (8) configured to be fixedly connected to the frame (30) and needle (38) of an existing application device (3).

6. 6. The application device according to claim 1, wherein the stop fixed relative to the needle (38) is formed by a piston (40) accommodated in a control chamber (32) of the frame (30), and the stop (62) fixed relative to the frame (30) is provided on the frame (30) and protrudes into the control chamber (32).

7. 7. The application device according to claim 1, wherein the stopper (60) fixed relative to the needle (38) has a surface (600) inclined relative to the longitudinal axis (X3) of the needle (38).

8. 10. A machine (1) for applying a product, comprising: an application device (3) according to any one of claims 1 to 7; a dosing system (5) for the product configured to feed the product into the application device (3) with an adjustable pressure (P5), the dosing system (5) comprising a motor (58), the speed (V) of which is controlled to adjust the pressure (P5); and a control unit (7) configured to control the dosing system (5) and the application device (3).

9. A method for controlling a machine (1) for applying a product according to claim 8, characterized in that it comprises at least one of the following steps, carried out by a control unit (7) and consisting of: a) when there is a demand to increase the output flow rate (D) of the nozzle (43) of the application device (3) between a lower limit (D1) and an upper limit (D3), maintaining the speed of the motor (58) at a constant value (V1, V2) of the speed of the motor (58) of the dosing system (5) and reducing the opening of the application valve (42) of the application device (3), then opening the application valve (42) again and increasing the speed of the motor (58) to the value (V3) required to obtain the higher value of the output flow rate (D), thereby causing an increase in the output pressure (P5) of the dosing system (5); -b) when there is a demand to reduce the output flow rate (D) between an upper limit (D3) and a lower limit (D1) or to an intermediate value (D2) between the lower and upper limits, the speed of the motor (58) is reduced to a lower value, the opening of the application valve (42) of the application device (3) is reduced, and then the application valve (42) is opened again and the speed (V) of the motor (58) is increased to the value (V2) required to reach the intermediate or lower value of the output flow rate (D), thereby causing a reduction in the output pressure (P5) of the dosing system (5).

10. 10. The method for controlling according to claim 9, characterized in that in steps a) and b) the reduction of the opening of the application valve (42) of the application device (3) is achieved by placing a stopper (62) fixed relative to the frame (30) in a predetermined position during the phase of adjusting the output flow rate (D) and then closing the application valve (42) in a predetermined position by placing the stopper (62) fixed relative to the frame (30).

11. 11. A method for controlling according to claim 9 or 10, characterized in that in step b), the low value to which the speed (V) of the motor (58) is reduced is less than zero and the direction of movement of the motor (58) is reversed.

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