Dispenser

Abstract

To provide a dispenser that can shorten the cycle time of the viscous material coating process. [Solution] The first cylinder 51 has a filling port 52 in front of the discharge nozzle 54. The second cylinder 31 has a supply port 32 from which viscous material is supplied from the liquid storage tank 10, and is connected to the filling port 52 of the first cylinder 51 via a connecting passage 40 connected to a branching section 33. The first plunger 55 fills the filling port 52 with viscous material when retracted and discharges the viscous material from the discharge nozzle 54 when moving forward. The second plunger 35 supplies viscous material from the supply port 32 when retracted and fills the first cylinder 51 with viscous material via the connecting passage 40 when moving forward. The first switching valve 56 blocks the flow path to the discharge nozzle 54 when filling the first cylinder 51 and prevents backflow to the filling port 52 when discharging. The second switching valve 36 blocks the connecting passage 40 when supplying to the second cylinder 31 and prevents backflow to the supply port 32 when filling the first cylinder 51.

Description

Technical Field

[0001] The present invention relates to a dispenser.

Background Art

[0002] Conventionally, a discharge device (dispenser) for discharging a viscous material such as a sealing material or a heat dissipation material and applying it to a workpiece has been known. For example, Patent Document 1 discloses a sealing material application device that applies a high-viscosity sealing material to a workpiece by discharging it with compressed air.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Dispensers include methods such as the mono type, the plunger type, and the jet type, and are selected according to the viscosity of the viscous material to be used and the application flow rate. For high-viscosity materials with a viscosity of 100 [Pa·s] or more, the mono type or the plunger type is generally adopted. For example, in the manufacture of electronic devices incorporating circuit boards, shortening the cycle time of the application process for applying viscous materials such as sealing materials and heat dissipation materials is required. However, even if an attempt is made to speed up the discharge operation, there are limitations in the structure of conventional dispensers due to the characteristics of the viscous material and the pressure resistance of the discharge part.

[0005] The present invention has been created in view of such points, and an object thereof is to provide a dispenser capable of shortening the cycle time of the viscous material application process.

Means for Solving the Problems

[0006] The present invention relates to a dispenser for dispensing a viscous material and applying it to a workpiece, comprising a first cylinder (51), a second cylinder (31), a first plunger (55), a second plunger (35), a first valve mechanism (56), and a second valve mechanism (36).

[0007] The first cylinder has a discharge nozzle (54) at its tip and a filling port (52) in front of the discharge nozzle. The second cylinder has a branch section (33) at one end in the axial direction, and a supply port (32) on one side of the branch section from which viscous material is supplied from a liquid storage tank (10), and is connected to the filling port of the first cylinder via a connecting passage (40) that connects to the other side of the branch section.

[0008] The first plunger is reciprocable in a first operating region (Ar1) in the first cylinder, opposite to the discharge nozzle relative to the filling port. When the first plunger retracts, viscous material is filled into the first cylinder from the filling port, and when it moves forward, the viscous material is discharged from the discharge nozzle. The second plunger is reciprocable in a second operating region (Ar2) in the second cylinder, excluding the branching section. When the second plunger retracts, viscous material is supplied into the second cylinder from the supply port, and when it moves forward, viscous material is filled into the first cylinder via the connecting passage.

[0009] The first valve mechanism blocks the flow path to the discharge nozzle when the viscous material is being filled into the first cylinder, preventing backflow to the filling port when the viscous material is being discharged. The second valve mechanism blocks the communication passage when the viscous material is being supplied to the second cylinder, preventing backflow to the supply port when the viscous material is being filled from the second cylinder to the first cylinder.

[0010] In this invention, the cycle time of the entire coating process can be shortened by separating the first plunger for dispensing and the second plunger for filling and supplying, and configuring the system so that the next viscous material is supplied to the second plunger while the first plunger is dispensing.

[0011] Preferably, in a filling step in which the viscous material supplied to the second cylinder is filled into the first cylinder via a connecting passage and a filling port, the first plunger retracts while the second plunger advances. In a discharge and supply step in which the viscous material is discharged from a discharge nozzle and the viscous material is supplied to the second cylinder from a supply port, the first plunger advances while the second plunger retracts. [Brief explanation of the drawing]

[0012] [Figure 1] Operation diagram 1 of the dispenser of the first embodiment (initial material supply start). [Figure 2] Operation diagram 2 of the dispenser of the first embodiment (completion of initial material supply). [Figure 3] Operation diagram 3 of the dispenser of the first embodiment (start of filling). [Figure 4] Operation diagram 4 of the dispenser of the first embodiment (filling complete). [Figure 5] Operation diagram 5 of the dispenser of the first embodiment (dispensing and supply start). [Figure 6] Operation diagram 6 of the dispenser of the first embodiment (dispensing and supply completed). [Figure 7] Operation diagram of a single-plunger dispenser in a comparative example (filling complete). [Figure 8] Operation diagram of a single-plunger dispenser in a comparative example (dispensing complete). [Figure 9] A diagram illustrating the cycle time for a viscous material coating process. [Figure 10] A diagram showing the configuration of the dispenser according to the second embodiment. [Modes for carrying out the invention]

[0013] Dispensers according to several embodiments of the present invention will be described with reference to the drawings. This dispenser dispenses a viscous material supplied from a liquid tank and applies it to a workpiece. For example, in the manufacture of an electronic device containing a circuit board, sealing material for sealing and heat dissipation material for heat dissipation are applied to the workpiece (a semi-finished product of the electronic device).

[0014] Hereinafter, including the first and second embodiments, it is referred to as "this embodiment". The dispenser of this embodiment is characterized by adopting a "series double plunger method" in which two plungers are connected in series. In the first embodiment and the second embodiment, only the connection configuration between the liquid storage tank and the dispenser is different. The same components in the first and second embodiments are denoted by the same reference numerals, and redundant descriptions are omitted.

[0015] (Problem) The sealing material and heat dissipation material to be applied are high-viscosity materials with a viscosity of 100 [Pa·s] or more. In order to shorten the cycle time of the coating process of these high-viscosity materials, an increase in the discharge flow rate, in other words, an increase in the speed of the discharge operation, is considered. Theoretically, the discharge flow rate is expressed by the Hagen-Poiseuille equation.

[0016] [Number]

[0017] Q: Flow rate ν: Kinematic viscosity coefficient Δp: Pressure loss L: Pipe length a: Pipe radius ρ: Density

[0018] In order to increase the flow rate Q, whether the kinematic viscosity coefficient ν can be decreased by temperature control depends on the material properties. Whether the pipe length L can be shortened to form a short nozzle depends on the conditions of the equipment and the workpiece. Whether the pressure p can be increased depends on the structure. Referring to FIGS. 7 and 8, for the single plunger type dispenser of the comparative example, the possibility of increasing [1] the discharge pressure, [2] the filling pressure, and [3] the supply pressure is examined. Also, for reference, the Mono type dispenser that rotates a screw with a motor is also supplemented.

[0019] As shown in Figures 7 and 8, the comparative example dispenser 90 has a filling port 92 and a discharge nozzle 94 in a single cylinder 91. The plunger 95 is reciprocally movable in the operating region Ar0 opposite to the discharge nozzle 94 relative to the filling port 92 in the cylinder 91. In Figure 8, [1] the discharge pressure cannot be raised above the pressure resistance of the cylinder 91 or the discharge nozzle 94. Also, in Figure 7, [2] if the filling pressure (amount) is less than the discharge pressure (amount), there will be insufficient material in the cylinder. In a mono type, air may be drawn in, potentially causing motor overload.

[0020] The liquid storage tank 10 is a cartridge type that can be replaced when the material is used up. The lid 13, which is placed on the liquid surface of the material, is pushed down by a pressurizing cylinder (not shown). In addition, a pressurized air inlet 11 is provided at the top of the liquid storage tank 10, through which pressurized air flows into the pressurizing chamber 12, which is the space above the material. The lid 13 is pushed down by the air pressurization in the pressurizing chamber 12 in addition to the cylinder pressurization. [3] The supply pressure is the sum of the cylinder pressurization and the air pressurization, but there is a limit to how much pressure can be increased.

[0021] Thus, with the conventional single-plunger and mono-type dispenser structures, there are limitations to how quickly the dispensing operation can be increased. Therefore, in this embodiment, instead of increasing the speed of the dispensing operation itself, a double-plunger structure is adopted in which the roles of the dispensing plunger and the supply / filling plunger are separated, thereby shortening the cycle time of the coating process.

[0022] (First Embodiment) Referring to Figures 1 to 6, the configuration and operation of the dispenser 60 of the first embodiment will be described. Figures 1 and 2 show the operation of the initial material supply process, Figures 3 and 4 show the filling process, and Figures 5 and 6 show the operation of the dispensing and supply process. The vertical direction on the paper in Figures 1 to 6 corresponds to the vertical direction. When the first plunger 55 and the second plunger 35 move downward within the operating areas of the first cylinder 51 and the second cylinder 31, respectively, this is referred to as "forward movement," and when they move upward within the operating area, this is referred to as "backward movement."

[0023] The dispenser 60 includes a first cylinder 51, a second cylinder 31, a first plunger 55, a second plunger 35, a first switching valve 56 as a "first valve mechanism", a second switching valve 36 as a "second valve mechanism", and the like. The first cylinder 51, the first plunger 55, and the first switching valve 56 constitute the discharge section 50, while the second cylinder 31, the second plunger 35, and the second switching valve 36 constitute the supply / filling section 30.

[0024] In this embodiment, "supply" means the operation of introducing the viscous material stored in the liquid storage tank 10 into the second cylinder 31. "Filling" means the operation of introducing the viscous material to be discharged in the next cycle into the first cylinder 51. In this embodiment, the viscous material from the liquid storage tank 10 is introduced into the first cylinder 51 through two stages: "supply" and "filling". Hereafter, when referring to "material supply," "viscous material" will be appropriately abbreviated to "material."

[0025] The names "No. 1" and "No. 2" refer to the side related to the dispensing function, which is the main function of the dispenser, as "No. 1," and the side related to the supply and filling function, which is the preparation operation for dispensing, as "No. 2." On the other hand, the symbols for each part are assigned such that the first digit increases from the upstream side to the downstream side of the viscous material. For example, the first digit of the symbol for the upstream No. 2 cylinder, etc., is set to "3," and the first digit of the symbol for the downstream No. 1 cylinder, etc., is set to "5."

[0026] In this embodiment, the liquid storage tank 10 is of the cartridge type, similar to the single-plunger dispenser in the comparative example, and the cylinder pressurization and air pressurization configurations are also the same as in the comparative example. In the first embodiment, the liquid storage tank 10 is connected to the dispenser 60 via a relatively short supply channel 20.

[0027] The first cylinder 51 and the second cylinder 31 are arranged parallel to each other along the vertical direction, and the lower parts of each cylinder 51 and 31 are connected via a connecting passage 40. The first cylinder 51 has a discharge nozzle 54 at its tip and a filling port 52 in front of (i.e., above) the discharge nozzle 54. The area in the first cylinder 51 opposite the discharge nozzle 54 to the filling port 52 is defined as the first operating region Ar1 (see Figures 4 and 5).

[0028] A T-shaped branch section 33 is provided at one axial end (i.e., the lower end) of the second cylinder 31. The second cylinder 31 has a supply port 32 on one side of the branch section 33 through which viscous material is supplied from the liquid storage tank 10. The second cylinder 31 is also connected to the filling port 52 of the first cylinder 51 via a connecting passage 40 that connects to the other side of the branch section 33. The area of ​​the second cylinder 31 other than the branch section 33 is defined as the second operating area Ar2 (see Figures 2, 3, and 6).

[0029] The outer diameter of the first plunger 55 is set to be slightly smaller than the inner diameter of the first cylinder 51, and the first plunger 55 is reciprocating within the first operating region Ar1 of the first cylinder 51. When the first plunger 55 retracts, viscous material is filled into the first cylinder 51 from the filling port 52, and when it moves forward, viscous material is discharged from the discharge nozzle 54.

[0030] The outer diameter of the second plunger 35 is set to be slightly smaller than the inner diameter of the second cylinder 31, and the second plunger 35 is reciprocating within the second operating region Ar2 of the second cylinder 31. When the second plunger 35 retracts, viscous material is supplied to the second cylinder 31 from the supply port 32, and when it advances, viscous material is filled into the first cylinder 51 via the communication passage 40.

[0031] Here, we assume that the first plunger 55 and the second plunger 35 have the same diameter, and that the stroke of the first plunger 55 in the first operating region Ar1 and the stroke of the second plunger 35 in the second operating region Ar2 are set to be the same. In this case, for example, a rack and pinion mechanism may be used as the drive mechanism for the first cylinder 51 and the second cylinder 31, and the pinion gear may be rotated to link the first cylinder 51 and the second cylinder 31, and they may be driven simultaneously in opposite directions. This will result in the same volume change within the first cylinder 51 and the second cylinder 31. Alternatively, the first plunger 55 and the second plunger 35 may be driven independently by separate actuators.

[0032] The first switching valve 56 has a wall in the circumferential direction and a plurality of passage holes that communicate with each other internally. One passage hole is always in communication with the first operating region Ar1. Depending on the rotational position of the first switching valve 56, the other passage hole opens one of the flow paths to the filling port 52 on the inlet side and the discharge nozzle 54 on the outlet side, and closes the other. The open flow path communicates with the first operating region Ar1.

[0033] The second switching valve 36 has a wall in the circumferential direction and a plurality of passage holes that communicate with each other internally. One passage hole is always in communication with the second operating region Ar2. Depending on the rotational position of the second switching valve 36, the other passage holes open one of the supply port 32 on the inlet side and the communication passage 40 on the outlet side, and close the other. The open passage is in communication with the second operating region Ar2. The detailed switching operations of the first switching valve 56 and the second switching valve 36 will be explained together with the operation of the dispenser 60.

[0034] Next, the operation of the dispenser 60 shown in Figures 1 to 6 will be explained in order. Figures 1 and 2 show the process of supplying the first material from an empty state inside the dispenser 60. From the material supply start state shown in Figure 1 to the material supply completion state shown in Figure 2, the second plunger 35 retracts. At this time, the second switching valve 36 opens the supply port 32 on the inlet side and closes the communication passage 40 on the outlet side. In other words, the second switching valve 36 shuts off the communication passage 40 when supplying viscous material to the second cylinder 31. As a result, viscous material is supplied from the supply port 32 to the second cylinder 31. In the liquid storage tank 10, the position of the lid 13 lowers according to the amount of viscous material supplied due to the supply pressure.

[0035] In the examples in Figures 1 and 2, it is assumed that the first plunger 55 and the second plunger 35 are driven individually, and the first plunger 55 is stopped while the second plunger 35 is retracting. However, if the first plunger 55 and the second plunger 35 are driven in conjunction, the first plunger 55 may move forward without load at the same time as the second plunger 35 retracts.

[0036] Figures 3 and 4 show the filling process. From the filling start state shown in Figure 3 to the filling completion state shown in Figure 4, the first plunger 55 retracts while the second plunger 35 advances. At this time, the second switching valve 36 opens the communication passage 40 on the outlet side and closes the supply port 32 on the inlet side. In other words, the second switching valve 36 prevents backflow to the supply port 32 when the viscous material is being filled from the second cylinder 31 to the first cylinder 51. The first switching valve 56 opens the filling port 52 on the inlet side and closes the flow path to the discharge nozzle 54 on the outlet side. In other words, the first switching valve 56 blocks the flow path to the discharge nozzle 54 when the viscous material is being filled into the first cylinder 51. As a result, the viscous material supplied to the second cylinder 31 is filled into the first cylinder 51 via the communication passage 40 and the filling port 52.

[0037] Figures 5 and 6 show the discharge and supply process. From the discharge and supply start state shown in Figure 5 to the discharge and supply completion state shown in Figure 6, the first plunger 55 moves forward while the second plunger 35 retracts. At this time, the second switching valve 36 opens the supply port 32 on the inlet side and closes the communication passage 40 on the outlet side. In other words, the second switching valve 36 blocks the communication passage 40 when supplying viscous material to the second cylinder 31. The first switching valve 56 opens the flow path to the discharge nozzle 54 on the outlet side and closes the filling port 52 on the inlet side. In other words, the first switching valve 56 prevents backflow to the filling port 52 when discharging viscous material. As a result, viscous material is discharged from the discharge nozzle 54 and supplied to the second cylinder 31 from the supply port 32.

[0038] The positions of the first plunger 55 and the second plunger 35 in Figure 6 are the same as in Figure 2. The difference in Figure 6 compared to Figure 2 is that the communication passage 40 and the discharge nozzle 54 are filled with viscous material. Subsequently, the filling process and discharge / supply process shown in Figures 3 to 6 are repeated. In the filling process from the second cycle onward, the discharge nozzle 54 is filled with viscous material, as in Figures 3 and 4.

[0039] Referring to Figures 7 to 9, the cycle times of the viscous material application process between the comparative example single-plunger dispenser and the double-plunger dispenser according to this embodiment will be compared and explained. Here, the "application process" includes the material supply, filling, and dispensing processes, and refers to the entire process for applying the viscous material to the workpiece. The time it takes for the material to actually be dispensed from the dispensing nozzle 54 and applied is referred to as the "dispensing" process time.

[0040] As shown in Figures 7 and 8, the comparative example dispenser 90 has a filling port 92 and a discharge nozzle 94 in a single cylinder 91. The plunger 95 is reciprocally movable in the operating region Ar0 opposite to the discharge nozzle 94 relative to the filling port 92 in the cylinder 91. As shown in Figure 7, when the plunger 95 retracts, viscous material is filled from the storage tank 10 through the filling port 92. As shown in Figure 8, when the plunger 95 advances, viscous material is discharged from the discharge nozzle 94. These two modes are repeated.

[0041] Figure 9 shows an image of the cycle time for the viscous material application process in the dispensers of the comparative example and this embodiment. In the figure, the dashed hatching in the "filling," "dispensing," and "supplying" areas corresponds to the dashed hatching of the viscous material in the respective parts of Figures 1 to 8. It is assumed that the dispensing volume per cycle and the operating speed of the plunger are the same in the comparative example and this embodiment.

[0042] In the comparative example, after filling one cylinder 91 with viscous material, the dispensing process is performed, and the overall cycle time is Ts. Workpiece replacement is performed concurrently with material filling. In this embodiment as well, the time for workpiece replacement is the same as in the comparative example and does not affect the overall cycle time.

[0043] In the filling process of this embodiment (see Figures 3 and 4), the second plunger 35 and the first plunger 55 work together. The viscous material supplied to the second cylinder 31 is pushed in by the forward movement of the second plunger 35, and at the same time drawn into the first cylinder 51 by the backward movement of the first plunger 55. In other words, the relative velocity of the force acting on the viscous material due to the cooperative action of the second plunger 35 and the first plunger 55 is twice that of the comparative example. Therefore, the same amount of viscous material is filled into the first cylinder 51 in half the time compared to the comparative example.

[0044] In this embodiment, the first plunger 55 advances and discharges, while the second plunger 35 retracts and supplies the viscous material to the second cylinder 31 (see Figures 5 and 6). As a result, the overall cycle time in this embodiment is Tw. Therefore, the cycle time of the viscous material coating process can be shortened by ΔT compared to the comparative example.

[0045] (Second Embodiment) As shown in Figure 10, in the second embodiment, the dispenser 60 is configured separately from the liquid storage tank 10 and connected via a hose 24, for example, about 1 to 2 m in length. The liquid storage tank 10 is installed in a fixed position. The dispenser 60 is attached to an XYZ axis loader 70 provided on a line through which workpieces to be coated with viscous material are transported, and is capable of horizontal and vertical movement depending on the coating position.

[0046] By fixing the heavy liquid storage tank 10 to the outside, away from the movable parts of the XYZ-axis loader 70, the work efficiency of setup operations is improved and the load on the XYZ-axis loader 70 is reduced. However, since the supply path is extended, an increase in supply capacity is necessary, and simply increasing the flow path diameter is insufficient.

[0047] Therefore, a screw supply unit 22 is provided in the supply channel 20 from the liquid storage tank 10 to the supply port 32 to agitate the viscous material and reduce its viscosity. For example, the screw supply unit 22 is located at the bottom of the liquid storage tank 10, and when the screw rotates and agitates the viscous material, shear stress is applied, which reduces the viscosity due to the thixotropy of the viscous material. The screw supply can increase the supply flow rate of the viscous material. For example, it is expected that the flow rate will approximately double if the viscosity is reduced to (1 / 2).

[0048] While temperature control (heating) does slightly reduce the viscosity of viscous materials, the reduction is small, and temperature control alone is not sufficient to increase the flow rate. However, combining temperature control with screw feeding may allow for a further reduction in viscosity.

[0049] (Other embodiments) (a) In the filling process of the above embodiment, the first plunger 55 retracts and the second plunger 35 advances. In the discharge and supply process, the first plunger 55 advances and the second plunger 35 retracts. However, the timing is not necessarily to be perfectly "simultaneous," and depending on the compression characteristics of the viscous material, for example, a slight time difference may be set between the start of advancement of one plunger and the start of retraction of the other plunger.

[0050] Including cases where a time difference is introduced, the relationship between the operation of the first plunger 55 and the operation of the second plunger 35 is described as follows: "In at least part of the filling process, the first plunger 55 retracts while the second plunger 35 advances, and in at least part of the discharge and supply process, the first plunger 55 advances while the second plunger 35 retracts."

[0051] (b) The first plunger 55 and the second plunger 35 are not limited to having the same diameter and moving the same stroke, but may be configured to have different diameters and move different strokes so that the volume change is equivalent.

[0052] (c) The "first valve mechanism" of the discharge section 50 and the "second valve mechanism" of the supply / filling section 30 are not limited to the first switching valve 56 and the second switching valve 36 of the above embodiment, but may be any valve mechanism that has the function of "opening and closing the flow path on the outlet side and preventing backflow to the inlet side when the flow path on the outlet side is closed". Each valve mechanism is not limited to being composed of a single valve, but may be composed of a combination of an outlet valve and an inlet valve. For example, a flow path opening / closing valve may be provided on the outlet side and a check valve may be provided on the inlet side.

[0053] The present invention is not limited in any way to the embodiments described above, and can be implemented in various forms without departing from its spirit. [Explanation of symbols]

[0054] 10...liquid storage tank, 31...Second cylinder, 32...Branch section, 33...Supply port, 35...Second plunger, 36...Second switching valve (second valve mechanism), 40...Communication path, 51...First cylinder, 52...Filling port, 54...Discharge nozzle, 55...First plunger, 56...First switching valve (first valve mechanism), 60 dispensers.

Claims

1. A dispenser that dispenses a viscous material and applies it to a workpiece, A first cylinder (51) having a discharge nozzle (54) at its tip and a filling port (52) in front of the discharge nozzle, A branch section (33) is provided at one end in the axial direction, and a supply port (32) is provided on one side of the branch section for supplying viscous material from a liquid storage tank (10), and a second cylinder (31) is connected to the filling port of the first cylinder via a connecting passage (40) that is connected to the other side of the branch section. A first plunger (55) is reciprocally movable in a first operating region (Ar1) opposite to the discharge nozzle with respect to the filling port in the first cylinder, and when retracted, a viscous material is filled into the first cylinder from the filling port, and when advanced, the viscous material is discharged from the discharge nozzle, A second plunger (35) is capable of reciprocating movement in a second operating region (Ar2) within the second cylinder other than the branching portion, and when retracted, a viscous material is supplied to the second cylinder from the supply port, and when advanced, the viscous material is filled into the first cylinder via the connecting passage, A first valve mechanism (56) that blocks the flow path to the discharge nozzle when the viscous material is filled into the first cylinder and prevents backflow to the filling port when the viscous material is discharged, A second valve mechanism (36) that blocks the communication passage when supplying viscous material to the second cylinder and prevents backflow to the supply port when filling the first cylinder from the second cylinder with viscous material, A dispenser equipped with the following features.

2. In the filling process in which the viscous material supplied to the second cylinder is filled into the first cylinder via the communication passage and the filling port, the first plunger retracts and the second plunger advances simultaneously. The dispenser according to claim 1, wherein in a discharge and supply step in which a viscous material is discharged from the discharge nozzle and the viscous material is supplied to the second cylinder from the supply port, the first plunger moves forward and the second plunger moves backward at the same time.

3. The dispenser according to claim 1 or 2, wherein a screw supply unit (22) for stirring a viscous material to reduce its viscosity is provided in the supply channel (20) from the liquid storage tank to the supply port.

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