JP5776646B2 - Release agent coating apparatus and coating method - Google Patents

Description

  The present invention relates to a coating apparatus and a coating method for a release agent that is applied to a mold.

  Conventionally, a technique for applying a release agent to a die casting die is known in order to normally release the molded die cast product from the die (see, for example, Patent Document 1).

  In patent document 1, the spray apparatus for spraying a mold release agent on mold surfaces, such as a die-casting apparatus, is disclosed. Specifically, in Patent Document 1, in a die casting apparatus including a fixed mold and a movable mold, a spray head in which a spray nozzle for spraying a release agent is fixed to a manipulator provided along with the die casting apparatus is held. A spray device that enables spraying of a release agent to an appropriate position on the mold casting surface of a fixed mold and a movable mold by moving a spray head in a three-dimensional direction by operating a manipulator Is disclosed. In particular, in this spray device, the spray nozzle is a manipulator capable of position movement control and rotation angle control in three axis directions (X, Y, Z) including the width direction and three rotation axis directions (Θx, Θy, Θz). Is held in.

JP 2006-334646 A

  However, when a liquid release agent such as a water-soluble release agent or an oil release agent is sprayed onto a high-temperature mold by the spray device described in Patent Document 1, the solvent component of the release agent is vaporized and vapor is generated. Occurrence or part of the release agent that has reached the mold surface rebounds to block the subsequent spraying, thereby inhibiting adhesion of the release agent to the mold surface. That is, no consideration is given to the fact that the adhesion of the release agent to the mold surface is inhibited by the generation of steam or the rebound of a part of the release agent. Therefore, it is possible to apply the release agent close to the mold surface with complex irregularities, and even when the release agent is sprayed close to the mold surface, generation of vapor or release agent There is a demand for a technique that can apply an optimal amount of a release agent to an optimal position without being affected by the rebound of the sheet.

  Accordingly, the present invention has been made in view of the above problems, and a release agent coating technique capable of applying an optimal amount of a release agent to an optimal position even on a mold surface with complex irregularities. The purpose is to provide.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

In order to apply the mold release agent to the mold surface, the robot arm is provided with a spray nozzle provided with a spray agent,
The robot arm rotatably holds a spray nozzle capable of intermittently spraying a release agent on the mold surface ,
The valve for controlling the hydraulic pressure of the release agent sent to the spray nozzle is a release agent application device directly connected to the upstream end of the spray nozzle .

In claim 2,
A controller for controlling the ratio t / T when the period of intermittent spraying is T and the spraying time of the period T is t;
The controller controls the ratio t / T so that the total kinetic energy of the release agent sprayed per unit time on a unit area of the mold surface is equal to or lower than a predetermined upper limit value. It is.

In claim 3,
A release agent coating method using the release agent coating apparatus according to claim 1,
The spray nozzle is rotated by the robot arm, and a release agent is intermittently sprayed from the spray nozzle to the mold surface ,
In this method, the release agent is applied by directly connecting a valve for controlling the hydraulic pressure of the release agent sent to the spray nozzle to the upstream end of the spray nozzle .

In claim 4,
The release agent coating apparatus includes a controller that controls a ratio t / T when a period of intermittent spraying is T and a spray time of the period T is t.
A mold release agent coating method in which the ratio t / T is controlled by the controller so that the total kinetic energy of the mold release agent sprayed per unit time on a unit area of the mold surface is equal to or lower than a predetermined upper limit value. is there.

  According to the present invention, an optimal amount of a release agent can be applied to an optimal position even on a mold surface with complex irregularities.

It is a schematic diagram which shows the whole structure of the coating device which concerns on the Example of this invention. It is a schematic diagram which shows the metal mold | die used as the object sprayed with the mold release agent in an Example. It is explanatory drawing explaining the effect of this invention, (a) is a figure explaining the problem of a prior art, (b) is a figure explaining the effect of this invention. It is explanatory drawing explaining the relationship between the valve position with respect to a nozzle, and the flow velocity responsiveness of a mold release agent, (a) is a figure explaining the case where a valve is arrange | positioned in the position far from a nozzle, (b) is a nozzle and valve | bulb. It is a figure explaining the case where these are directly connected. It is explanatory drawing explaining application | coating of the mold release agent by a spray cassette. It is explanatory drawing explaining the case where it apply | coats to a metal mold | die with the conventional coating device. It is explanatory drawing explaining the case where it apply | coats to a metal mold | die with the coating device which concerns on an Example. It is a figure explaining the relationship between an application range and a nozzle moving speed (1). It is a figure explaining the relationship between an application range and a nozzle moving speed (2). It is a figure explaining unit spray energy. It is a figure which shows the calculation result of unit spray energy. It is a table | surface which shows the influence on the coating amount waste by the coating distance and the kind of nozzle. It is a figure which shows the relationship between application distance and application amount waste. It is a graph which shows the relationship between responsiveness and application amount waste. It is a graph which shows the relationship between application distance and unit spray energy. It is a graph which shows the result of a mold release resistance test (1). It is a graph which shows the result of a mold release resistance test (2).

Next, embodiments of the invention will be described.
One embodiment of a coating apparatus according to the present invention is a release agent coating apparatus in which a spray nozzle is provided on a robot arm in order to apply a release agent to a mold surface. And a robot arm that rotatably holds the spray nozzle. The robot arm is characterized in that a spray nozzle (hereinafter also referred to as a nozzle) capable of intermittently spraying a release agent on the mold surface is rotatably held.

  Further, the coating apparatus includes a controller that controls the ratio t / T of the spray time t in the period T, where T is the period of intermittent spraying by the spray nozzle. The controller has a rate t / T such that the kinetic energy of the release agent sprayed from the nozzle and sprayed per unit time on a unit area of the mold surface is less than or equal to a predetermined upper limit value. It is characterized by controlling. Hereinafter, for the sake of simplicity, “kinetic energy possessed by the release agent sprayed from the nozzle and sprayed per unit time on a unit area of the mold surface” will be referred to as “unit spray energy”. . The release agent may be either aqueous or oily. Alternatively, the release agent may be an emulsion (a dispersion solution in which both the dispersoid and the dispersion medium are liquid).

  Qualitatively, the smaller the distance between the nozzle and the mold surface (coating distance), the smaller the coating area. Therefore, when the distance between the nozzle and the mold surface is less than a predetermined distance, the controller It is preferable to reduce the ratio t / T as the distance decreases.

According to the inventors' investigation, the upper limit value of the unit injection energy is specifically 3000 × 10 ^3.
It was found that [g · (cm / sec) ² / (cm) ² / sec] is preferable. In addition, since the ratio of the mold release agent which does not reach a metal mold | die will increase when unit spray energy is too low, it is also preferable to set the minimum value of unit spray energy. According to the inventors' investigation, the lower limit is 70 × 10
³ [g · (cm / sec) ² / (cm) ² / sec] was found to be preferable. That is, it is preferable that the coating apparatus controls the ratio t / T so that the unit spray energy is in a range between the upper limit value and the lower limit value.

  The phrase “spraying the release agent intermittently” can be said to spray the release agent in pulses. Therefore, in other words, the above-described coating apparatus includes a spray nozzle capable of spraying the release agent in a pulsed manner, a robot arm that rotatably holds the spray nozzle, and a cycle of the pulsed spraying by the spray nozzle. Is provided with a controller for controlling t / T where T is T and the pulse width is t. Further, from this, “the ratio t / T of the spraying time t to the intermittent spraying period T” corresponds to a so-called duty ratio. The fact that a suitable coating can be obtained within the above range will be specifically described in Examples.

  The robot arm is a driving means that holds the nozzle rotatably and moves the nozzle to an optimum position for applying the release agent. The robot arm can move the nozzle in a three-dimensional direction. When applying a release agent to the surface of the mold, the robot arm can spray while rotating the nozzle and moving the nozzle. That is, the robot arm can operate the nozzle according to a control program preset in the controller when applying the release agent to the surface of the mold. At this time, the controller appropriately rotates the nozzle and appropriately moves the nozzle relative to the mold while adjusting the ratio t / T so that the unit spray energy is between the upper limit value and the lower limit value. It is preferable to control.

  The robot arm is connected to the controller via the controller with the nozzle rotation speed, the nozzle rotation direction, the spray speed of the release agent from the nozzle (injection speed), the spray angle, and the nozzle movement speed (the mold movement speed). Parameter) such as the distance from the nozzle to the mold can be set in advance. The unit spray energy is determined from these parameters. Therefore, the spray speed, spray angle, and arm tip trajectory (ie, nozzle rotation speed, nozzle rotation direction, nozzle movement speed, and nozzle and mold so that the unit spray energy is within the above range. Is set in advance as a control program, and the arm and the nozzle are operated in accordance with the setting.

  The technology disclosed in this specification is also embodied in a method for applying a release agent. The method is a method for applying a release agent using the above-described application device, wherein the spray nozzle is rotated by the robot arm, and the release agent is intermittently applied to the mold surface from the spray nozzle. It is to spray. Furthermore, the ratio t when the period is T and the spray time of the period T is t so that the unit spray energy of the release agent sprayed from the spray nozzle is equal to or less than a predetermined upper limit value. / T is determined and the release agent is intermittently sprayed. Further, it is preferable to spray intermittently so that the unit spray energy is between the above upper limit value and lower limit value.

Next, the function and effect of the present invention will be described.
As shown in FIG. 3A, when a liquid release agent such as a water-soluble release agent or an oil release agent is sprayed onto a high-temperature mold, the solvent component of the release agent is vaporized to generate its vapor. Then, it is assumed that the subsequent release agent reaches the mold surface. In other words, it is presumed that the adhesion of the release agent to the mold surface is inhibited. In this case, it is considered that avoiding vaporized vapor contributes to applying an optimum amount of a release agent to the mold. As one way of thinking, as shown in FIG. 3B, if spraying is temporarily stopped when the sprayed release agent is vaporized, arrival of the subsequent release agent on the mold surface is hindered. Can be suppressed. That is, by switching ON / OFF of the spraying by the nozzle and appropriately controlling the ON / OFF switching interval, it is possible to prevent the subsequent release agent from being blocked from reaching the mold surface. From this, the inventor has found that by intermittently spraying the release agent, inhibition of the arrival of the subsequent release agent on the mold surface by the vaporized vapor can be suppressed.

In addition, when the mold release agent is continuously sprayed, it is assumed that a part of the mold release agent that has previously reached the mold surface rebounds, thereby preventing the subsequent mold release agent from reaching the mold surface. The In other words, it is presumed that the adhesion of the release agent to the mold surface is inhibited. Therefore, it is considered that suppressing the rebound contributes to the efficient application of the release agent. As one way of thinking, if the size (particle diameter) of the sprayed release agent is reduced, the rebound can be suppressed. As another way of thinking, even if the spraying speed is slowed down, the rebound can be suppressed. From these facts, the inventor paid attention to the kinetic energy of the release agent sprayed per unit time on the unit area of the mold surface as a parameter depending on the size of the grain and the spraying speed. Kinetic energy depends on spray speed and grain size. Therefore, the spray state for efficiently applying the release agent to the mold surface can be specified based on one index of kinetic energy of the release agent. In other words, efficient application is achieved by limiting the kinetic energy of the release agent sprayed per unit time to a unit area of the mold surface to be equal to or lower than a predetermined upper limit value.
In addition, when it is desired to apply an optimal amount of the release agent to the mold surface with complex irregularities, it is preferable to spray the mold surface in a direction perpendicular to the mold surface and at a close distance. It is presumed that the amount increases and the subsequent release agent reaches the mold surface further.
Therefore, in the coating apparatus of the present invention, when a release agent is applied to a mold surface with complicated irregularities, the robot arm can apply the release agent by bringing the nozzle close to the mold surface, and As described above, by suppressing the influence of the generation of vapor and the rebound of the release agent, the optimal amount of the release agent can be applied to the optimal position even on the mold surface with complex irregularities.

Next, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the coating device 20 is a device that is provided with a spray nozzle 12 at the tip of the robot arm 14 and applies a release agent to the surface of the mold 50. Specifically, the coating apparatus 20 includes an articulated robot 11 having a robot arm 14, spray nozzles 12 and 12 attached to the tip of the robot arm 14, an actuator 15 that rotates the spray nozzles 12 and 12, A supply device 16 for supplying a release agent to the spray nozzles 12 and 12 and a controller 18 are provided.

  As shown in FIG. 2, the mold 50 is a die-cast movable mold to be sprayed with a release agent in the present embodiment, and includes four slide inserts C <b> 1 and C <b> 2 as mold elements that form the cavity 51. C3 and C4 are provided. Each surface of the slide inserts C1, C2, C3, and C4 (surface that forms a part of the cavity 51) has a concavo-convex shape, and in this embodiment, the surface of the mold that is the target to be sprayed with the release agent ( Cavity surface).

The multi-joint robot 11 is a robot having a plurality of joints (six in this embodiment) and including a plurality of robot arms 14a and 14b, and is a so-called six-axis robot. The articulated robot 11 operates the two spray nozzles 12 and 12 attached to the distal end side of the robot arm 14 b, which is the distal end portion of the robot arm 14, via the joints of the articulated robot 11. Thus, the spray nozzles 12 and 12 can be moved in a three-dimensional direction, the spray nozzles 12 and 12 can be positioned at arbitrary positions in the cavity 51 of the mold 50, and a predetermined distance can be set between arbitrary positions in the cavity 51. It is possible to move the spray nozzles 12 and 12 at a speed. The articulated robot 11 is controlled by a controller 18.
In this embodiment, two spray nozzles are used, but there is no particular limitation.

The actuator 15 is a rotation driving means (rotating shaft mechanism) of the robot arm 14 provided at a connecting portion between the robot arm 14a and the robot arm 14b. Specifically, one end of the actuator 15 is fixed to one end of the robot arm 14a, and the robot arm 14b is rotatably supported in the circumferential direction. It is possible to rotate 14b in the circumferential direction of the robot arm 14b. That is, the actuator 15 can rotate the spray nozzles 12 and 12 attached to the distal end side of the robot arm 14a in the circumferential direction of the robot arm 14a by rotating the robot arm 14b in the circumferential direction. The actuator 15 is controlled by the controller 18.
In the present embodiment, the spray nozzles 12 and 12 are held side by side at the tip of the rod-like robot arm 14b, but there is no particular limitation. The shape of the robot arm, the number of nozzles, and the holding position of the nozzle on the robot arm may be appropriately set according to the shape of the mold surface (the surface to which the release agent is applied). The shape may be branched.

  Usually, a release agent is applied to a high-temperature mold used for casting. That is, the mold release agent also serves as a mold cooling. The mold temperature when applying the release agent is 100 ° C. or higher.

  The supply device 16 can control the hydraulic pressure of the release agent sent to the nozzle 12. The nozzle 12 can spray the liquid release agent sent from the supply device 16, that is, inject in a mist form. Moreover, the nozzle 12 can spray a mold release agent intermittently. The nozzle 12 is moved with respect to the mold 50 by the robot arm 14 and is rotated in the circumferential direction of the robot arm 14 b by driving the actuator 15. The controller 18 controls the liquid pressure of the release agent, the duty ratio of intermittent spraying (described later), the moving path and moving speed of the tip of the robot arm 14b. Moreover, the liquid pressure of the mold release agent sent to the nozzle 12 is controlled by opening and closing a valve disposed between the nozzle 12 and a pressure pump provided in the supply device 16 (see FIG. 4). As shown in FIG. 4A, when the valve is provided at a position farther than the nozzle 12, the mold release sprayed from the nozzle 12 at the time of applying the release agent shown in the right side of FIG. 4A. As shown in the relationship between the flow rate of the agent and the elapsed time, even if the valve is opened, the rise of the flow rate is slow and the response of the flow rate is poor. Therefore, when it is desired to obtain the responsiveness of the flow rate of the release agent so as to follow the robot operation speed, for example, as shown in the left diagram of FIG. 4B, when a plurality of nozzles are arranged, What is necessary is just to connect a valve | bulb directly to the upstream edge part of each nozzle. In this way, when the valve is opened, as shown in the right side of FIG. 4 (b), the rise of the flow rate is accelerated, and the relationship between the flow rate of the release agent and the elapsed time when the release agent is applied. Therefore, when the spray amount of the release agent emitted from the nozzle is increased or decreased, the response is good, and the release agent flow rate response that follows the robot operation speed can be obtained.

The nozzle 12 can be exchanged between a type that sprays one fluid and a type that sprays two fluids. Here, “a type in which two fluids are sprayed” means a type in which two different types of fluids (for example, oil and air) are mixed and ejected.
Further, the nozzle 12 can be rotated and rotated like a pendulum by a driving means (not shown) as shown in FIG. 7B.

  In the following, the application techniques using the articulated robot 11 and the actuator 15 (rotating shaft mechanism), the pulse application technique, and the kinetic energy optimization technique of the release agent to be sprayed, which are the main techniques characterizing the present invention, will be described. I will explain it.

(About coating technology using articulated robot and actuator (rotary shaft mechanism))
By comparing the mold release agent coating method according to the present invention using the coating apparatus 20 of the embodiment and the conventional mold release agent coating method, the effect of the mold release agent coating method according to the present invention is concretely demonstrated. Explained.

  FIG. 5 is a diagram for explaining a method (Example 1) for applying a release agent to the mold 50 by a conventional spray device (also referred to as a spray cassette) in which a plurality of nozzles are arranged. In such a box-shaped spray cassette, a large number of spray nozzles are formed in multiple directions (four directions in the up, down, left and right directions in FIG. 5), and there are some in which the number of nozzles is 100 or more. When such a spray cassette having a large number of nozzles is used, a loss associated with maintenance such as handling nozzle clogging (decrease in device operation rate, increase in maintenance costs, etc.) is large. In addition, vapor is generated by the vaporization of the solvent component of the release agent, and the adhesion of the release agent to the mold surface is inhibited.

  The conventional coating apparatus shown in FIG. 6 operates a robot arm with a six-axis robot. However, unlike the coating apparatus 20 shown in this embodiment, the robot arm does not include an actuator 15. When such a conventional coating apparatus is used, steam is generated due to the vaporization of the solvent component of the release agent, and the adhesion of the release agent to the mold surface is hindered. In addition, when the release agent is sprayed around the convex protrusion in the part surrounded by the circle in the left diagram of FIG. 6, as shown in the enlarged side view on the right side of FIG. The back side of the object becomes a blind spot, and the release agent is not attached. Therefore, the 6-axis robot is operated (in FIG. 6, the rear end side of the robot arm is raised and the front end side of the robot arm is moved to the rear side of the mold (back side)), and the nozzle is brought close to the blind spot portion. However, since the coating apparatus interferes with the mold, the nozzle cannot be moved to an optimum position any more, and coating is difficult.

  On the other hand, the coating apparatus 20 of this embodiment shown in FIG. 7 includes an actuator 15 on the robot arm 14. When the coating apparatus 20 of the present embodiment is used, even when steam is generated by the vaporization of the solvent component of the release agent by the pulse coating technique described later, the vapor can be avoided, and the release agent on the mold surface can be avoided. Adhesion of is improved. Further, the release agent can be applied to the surfaces of the slide inserts C1, C2, C3, and C4 by appropriately rotating the nozzles 12 and 12 in the circumferential direction of the robot arm 14 by the actuator 15. By introducing this actuator 15, it is possible to apply in multiple directions (in the case of the right side of FIG. 7, four directions, up, down, left, and right) with a small number of nozzles. Since no nozzle is required, maintenance loss such as handling nozzle clogging is small. In addition, when the release agent is sprayed around the convex protrusion in the part surrounded by the dotted circle in the left side of FIG. 7, as shown in the enlarged side view on the right side of FIG. Although the back side of the protrusion becomes a blind spot part (see the enlarged side view (a) in FIG. 7), as shown in the enlarged side view (b) in FIG. 7, the tip of the robot arm 14b is placed behind the mold (the back side). ), And the nozzles 12 and 12 are rotated and rotated (in FIG. 7B, a pendulum-like rotation in the front and rear directions) so that the mold release agent is attached even at the blind spot. be able to.

(About pulse coating technology)
Next, a pulse coating technique which is one of the techniques characterizing the present invention, that is, a technique for intermittently spraying a release agent described below will be specifically described.

“Intermittently spraying” means spraying periodically and discretely in pulses. That is, after spraying the release agent continuously for t [sec (seconds)], repeating not spraying for Tt [sec]. In other words, it can be expressed that the release agent is sprayed in a pulse shape with a period T [sec] and a duty ratio t / T.
Hereinafter, “t” may be referred to as a spraying time, and “T−t” may be referred to as a non-spraying time.

  When intermittently spraying the release agent while moving the nozzle 12, if the moving speed of the nozzle is too fast or if the non-spray time (Tt) is too long, unevenness will occur in the coating. The unevenness also depends on the application range. Therefore, the relationship between the spray range, the nozzle moving speed, and the intermittent application cycle T will be described next.

  FIG. 8 shows the relationship between the application range and the nozzle moving speed. Here, the range in which the release agent is sprayed onto the mold surface by spraying while the nozzle is stationary is referred to as a coating range. The application range is assumed to be circular. C1 and C2 in FIG. 2 indicate the application range. The diameters of the application ranges C1 and C2 are denoted by reference sign DL. The application range C1 indicates a range in which the release agent is applied in a certain moment. When the release agent is intermittently sprayed at the cycle T and the application time t, the application range C2 by the next spraying is formed at a position shifted by the distance dV after being sprayed to the application range C1 for a certain moment. Assuming that the nozzle moves at a speed Vs parallel to the mold surface, the distance dV between the centers of the two coating ranges C1 and C2 is dV = Vs × (T−t). Here, (Tt) is the non-application time as described above. Empirically, coating unevenness can be eliminated if the overlapping portion (distance indicated by LAP in FIG. 8) of two adjacent coating ranges C1 and C2 is at least half the diameter DL of the coating range. Then, it can be seen from FIG. 8 that dV = LAP = DL / 2 is the limit that can eliminate coating unevenness. On the other hand, since it can be considered that the upper limit value of the non-application time is the period T, it can be seen that the relationship shown in FIG. 9 is associated with the period T, the nozzle moving speed Vs, and the application range diameter DL. FIG. 9 is a graph showing the relationship between the coating range diameter DL satisfying LAP = DL / 2 and the nozzle moving speed Vs when the period T = 0.05 [sec] is assumed to be the maximum non-application time. For example, when the nozzle movement speed Vs is 1000 [mm / sec], the nozzle movement amount dV at the maximum non-application time (period T) = 0.05 [sec] is 50 [mm]. Since DL = LAP = 2dV, if the diameter DL of the application range is 100 [mm] or more, the overlapping portion LAP of the application ranges C1 and C2 becomes more than half of the diameter DL of the application range. That is, coating unevenness can be eliminated by setting the nozzle moving speed Vs and the coating range diameter DL so as to be in the region above the graph of FIG. For example, when a nozzle having an intermittent spray period T = 0.05 [sec] is used and a release agent is sprayed onto the mold surface so that the coating range diameter DL is 100 [mm], the nozzle moving speed (metal mold) If the moving speed in the direction parallel to the mold surface (Vs) is set to 1000 [mm / sec] or less, uneven coating can be prevented.

(Technology optimization technology for sprayed release agent)
Next, unit spray energy will be described with reference to FIG. As described above, the “unit spray energy” is kinetic energy of the release agent sprayed from the nozzle 12 and is sprayed per unit time on the unit area of the surface of the mold 50. . As shown in FIG. 10, a distance (application distance) between the nozzle 12 and the surface of the mold 50 is represented by a symbol Ls. Further, the spray angle of the nozzle 12 is represented by 2θs. At this time, the radius DL / 2 of the coating range can be expressed by Ls · tan (θs). That is, the coating area S = [Ls · tan (θs)] ² · n [cm ² ]. When the spray amount per second of the release agent is represented by M [g / sec] and the spray particle velocity is represented by v [cm / sec], the unit spray energy Es can be represented by the following (Equation 1). .

  FIG. 11 shows the relationship between the application distance (Ls in FIG. 10) and the unit spray energy Es when the period T = 50, 100, and 200 [msec]. FIG. 11 shows the result calculated by Equation 1 based on the result of actually spraying the release agent from the nozzle and measuring the ejection speed of the release agent droplet at that time with a laser velocimeter. Note that the vertical axis of the figure is a logarithmic scale. It can be seen that the unit spray energy gradually increases as the application distance becomes shorter. In addition, in FIG. 11, the result in the case of 1 fluid and the case of 2 fluid is shown.

  When the release agent is sprayed without moving the nozzle 12, the release agent sprayed first from the nozzle 12 rebounds on the mold surface and affects the subsequent release agent. FIG. 12 shows the results of an experiment examining the influence of the coating distance Ls and the type of nozzle. In FIG. 12, “grain velocity” is the velocity of the sprayed release agent droplets. The grain velocity was measured with a laser velocimeter. “No rebound time” means the time until the release agent sprayed from the nozzle reaches the mold. “Response” corresponds to the period T of intermittent application. The “bounce time” means a time affected by the bounce and corresponds to “response time−droplet arrival time”. The “influenced application amount” means an application amount that is affected by rebound from the mold surface when a 20 [ml (milliliter)] release agent is applied. 12 to 14 are results obtained by simulation. The upper seven rows in the table of FIG. 12 are the calculation results when using a nozzle that sprays two fluids, and the lower seven rows are the calculation results when using a nozzle that sprays one fluid.

  A nozzle selection method obtained from the simulation result will be described. Specifically, the amount of influence applied (the amount of application affected by the rebound from the mold surface when a 20 [ml (milliliter)] release agent is applied) is regarded as a waste application amount, and waste application. The nozzle response necessary to reduce the amount will be described. As a result of the simulation, it is understood that when the responsiveness (intermittent spray cycle T) is 500 [msec], about 50% of the sprayed release agent is wasted regardless of the nozzle and application distance. On the other hand, when the responsiveness (intermittent spraying cycle T) is 10 [msec], the release agent that becomes waste is 1% or less of the amount of the sprayed release agent (20 [ml]). For example, when the upper limit of the application amount waste is 2% of the spray amount, if a nozzle that sprays the release agent at 20 [ml / sec] is used, the application amount waste needs to be suppressed within 2 [ml]. From FIG. 12, it can be said that the period T of intermittent spraying is preferably at least 10 [msec] or less.

FIG. 13 shows the relationship between the application distance and the application amount waste for some responsiveness. In FIG. 13, a nozzle having a coating amount of 20 [ml / sec] is used, and a flow rate = 50 [mm / sec].
], The relationship between the influence application amount (application amount affected by rebound) and the distance when the release agent is applied is derived from the nozzle response. From FIG. 13, it is possible to derive the responsiveness required to suppress the influence application amount to 10%, for example.

  FIG. 14 shows the relationship between the responsiveness and the influence application amount. From FIG. 14, for example, in order to keep the influence application amount within 2 [ml] (10% of the total application amount 20 [ml]) at an application distance of 50 mm, the responsiveness needs to be set to about 100 [msec] or less. I know that there is. It can be seen that in order to keep the influence coating amount within 2 [ml] at a coating distance of 350 mm, it is necessary to set the responsiveness to about 130 [msec] or less.

Next, the range of unit spray energy for efficiently applying the release agent will be described. FIG. 15 is a graph showing the relationship between unit spray energy and coating distance for each of the 1 fluid and 2 fluid. The upper limit value and the lower limit value in the graph are derived by testing with a Lub tester U (automatic tensile testing machine for aluminum die casting manufactured by MEC International Co., Ltd.). The upper limit value represents a limit at which the kinetic energy of the release agent to be sprayed is large and the solute (active ingredient) is caused to flow by the solvent, and the release agent after coating becomes thin. Specifically, the upper limit value is 3000 × 10 ³ [g · (cm / sec) ² / (cm) ² / sec]. The lower limit value represents a limit where the release agent sprayed has a small kinetic energy and does not reach the mold surface even when sprayed from the nozzle. Specifically, the lower limit is 70 × 10 ³ [g · (cm / sec) ² / (cm) ² / sec]. A square marker in FIG. 15 indicates a result (in the case of two fluids) when the unit spray energy is limited to an upper limit value or less. The upper limit value and the lower limit value are obtained from FIG. The mold release resistance when continuously applied with a certain nozzle is minimized at an energy of 500 × 10 ³ [g · (cm / sec) ² / (cm) ² / sec]. On the basis of the mold release resistance at this time, if the mold release resistance exceeds 20%, the product quality is remarkably deteriorated as a rule of thumb. From this, the upper limit value: 3000 × 10 ³ [g · (cm / sec) ² / (cm) ² / sec] and the lower limit value: 70 × 10 ³ [g · (cm / sec) ² / (cm) ² / sec] is determined.

In addition, a mold release resistance test was performed with the Lub tester U. The results are shown in FIGS. The test conditions are as follows. A nozzle for two fluids was used as a nozzle for spraying the release agent. The application conditions were 20 [ml / sec] for continuous spraying for 1 second (not intermittent spraying). The temperature of the object to be applied (metal body simulating a mold) is 100 degrees. As the release agent to be sprayed, an oily stock solution type was used. The graph of FIG. 16 has an inflection point at a coating distance of 200 [mm], and the mold release resistance increases regardless of whether the coating distance is far or near. FIG. 17 shows a comparison between the case of continuous application and the case of intermittent application. The marker marked with x indicates the case where intermittent application is performed. In intermittent application, the duty ratio was controlled so that the unit spray energy did not exceed the above-described upper limit value, that is, 3000 × 10 ³ [g · (cm / sec) ² / (cm) ² / sec]. As described above, the duty ratio here means the duty ratio when the application time at the time of continuous application = T. As shown in the graph of FIG. 16, in the continuous application, the application area becomes smaller and the unit spray energy increases as the application distance becomes smaller. In intermittent spraying, the duty ratio is reduced as the coating distance decreases to keep the unit spray energy constant. That is, when the application distance is 200 [mm] or less, the controller 18 decreases the duty ratio as the application distance decreases. In other words, when the distance between the nozzle 12 and the surface of the mold 50 (application distance Ls) is equal to or less than a predetermined distance (in this embodiment, 200 mm or less), The duty ratio is decreased as the application distance Ls is decreased. In this test, the energy increases as the coating distance becomes shorter and exceeds 500 × 10 ³ [g · (cm / sec) ² / (cm) ² / sec]. Switching to duty ratio control. If the release resistance can be allowed to deteriorate by 20%, the spraying may be switched to intermittent spraying after the energy exceeds 3000 × 10 ³ [g · (cm / sec) ² / (cm) ² / sec].

  In the case of continuous application, the reason why the release resistance increases when the application distance is 200 mm or less is estimated as follows. When an oil-based release agent is used, (a) the kinetic energy of the release agent is too large, and the solute (active ingredient) is washed away by the solvent and becomes a thin film, and (b) the solute is deposited, It is presumed that the mold release resistance increases due to vigorous gasification due to the heat of the molten metal and vacuuming of the casting interface. When a water-soluble mold release agent is used, deposition is not a problem, but it is presumed that the mold release resistance increases in the same manner because the factor (a) and vaporization are inhibited.

  As described above, in the present invention, the main techniques that characterize the present invention are the application technique using the articulated robot 11 and the actuator 15 (rotary shaft mechanism), the pulse application technique, and the kinetic energy of the release agent to be sprayed. By building each optimization technology, it is possible to apply a release agent close to the mold surface with complex irregularities, and when the release agent is sprayed close to the mold surface In this case, it is possible to provide an application technique that can apply an optimal amount of a release agent to an optimal position without being affected by the generation of steam or the rebound of the release agent.

  According to the present invention, for example, even in the case of a mold having a complicated shape having a plurality of movable cylinders, by rotating several spray nozzles, the entire surface of the mold can be evenly separated without excess or deficiency. A mold can be applied. In addition, according to the present invention, the number of nozzles can be reduced as compared with the conventional coating apparatus, and the maintainability is improved.

11 Articulated Robot 12 Spray Nozzle 14 Robot Arm 15 Actuator 18 Controller 20 Coating Device 50 Mold

Claims (4)

In order to apply the mold release agent to the mold surface, the robot arm is provided with a spray nozzle provided with a spray agent,
The robot arm rotatably holds a spray nozzle capable of intermittently spraying a release agent on the mold surface ,
A valve for controlling the hydraulic pressure of the release agent sent to the spray nozzle is directly connected to the upstream end of the spray nozzle;
A release agent coating apparatus characterized by that. A controller for controlling the ratio t / T when the period of intermittent spraying is T and the spraying time of the period T is t;
The controller controls the ratio t / T so that the total kinetic energy of the release agent sprayed per unit time on a unit area of the mold surface is equal to or lower than a predetermined upper limit value. Item 2. A release agent coating apparatus according to Item 1. A release agent coating method using the release agent coating apparatus according to claim 1,
The spray nozzle is rotated by the robot arm, and a release agent is intermittently sprayed from the spray nozzle to the mold surface ,
A valve for controlling the hydraulic pressure of the release agent sent to the spray nozzle is directly connected to the upstream end of the spray nozzle;
A method for applying a release agent. The release agent coating apparatus includes a controller that controls a ratio t / T when a period of intermittent spraying is T and a spray time of the period T is t.
The ratio t / T is controlled by the controller so that the total kinetic energy of the release agent sprayed per unit time on a unit area of the mold surface is equal to or lower than a predetermined upper limit value. 3. A method for applying a release agent according to 3.

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