Apparatus for taking out molded product

Abstract

To provide an apparatus for taking out a molded product that facilitates setting of a user-set lower limit value while maintaining on-off control.SOLUTION: A negative pressure control unit 9 includes a pressure valve resumption time period determining unit 92 for determining a pressure valve resumption time period Tv that is used to resume a suction operation such that an inflection point does not become lower than a user-set lower limit value. The negative pressure control unit 9 continues an off operation, which is performed to keep a pressure valve 34 closed until the pressure valve resumption time period Tv elapses after the suction operation is stopped, and an on operation, which is performed to open the pressure valve 34 and keep the pressure valve open until a negative pressure reaches a stable value or an upper limit set value, until suction of a molded product is canceled.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a molded product remover having a function of reducing air consumption by controlling the on / off of negative pressure applied to a suction section. [Background technology]

[0002] Japanese Patent Publication No. 4779004 discloses a conventional molded product extractor that reduces air consumption by controlling the negative pressure applied to the suction unit. The conventional molded product extractor includes an attachment with a suction unit that suctions a molded product within a mold of a molding machine, a movement mechanism that moves the attachment according to a predetermined operating sequence, an air passage between the suction unit and a vacuum generator to create a negative pressure in the space formed between the suction unit and the molded product, a negative pressure generation circuit including a pressure valve and a pressure detector disposed in the air passage, and a negative pressure control unit that controls the vacuum generator or the pressure valve to control the negative pressure. Techniques that use an upper limit instead of a stable value are also known. The negative pressure control unit is configured to open the pressure valve to start suction when it receives a suction start command, close the pressure valve to stop suction when the negative pressure of the air flowing through the air passage reaches a stable value, and then open the pressure valve to resume suction when the negative pressure reaches a user-set lower limit lower than the stable value. This on-off control is repeated until it receives a suction stop command. Here, the user-defined lower limit value is arbitrarily set by the user based on his or her own experience. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4779004 Summary of the Invention [Problem to be solved by the invention]

[0004] According to the inventor's research, when a negative pressure generating circuit with a pressure valve disposed in the air flow path between the suction unit and the vacuum generator is used, the negative pressure does not immediately increase after the pressure valve is opened. Instead, the negative pressure drops to an inflection point after the pressure valve is opened, resulting in a "drop" phenomenon in which the negative pressure begins to increase. If this phenomenon occurs, using the user-defined lower limit as the pressure valve opening timing can result in a problem where the molded product falls due to insufficient negative pressure between the time when the negative pressure reaches the user-defined lower limit and the time when the negative pressure rises. This is because the user-defined lower limit set by the operator may be too low, resulting in an insufficient pressure to maintain suction on the molded product after the pressure valve is opened. Therefore, when an operator attempts to set a user-defined lower limit that effectively utilizes on / off control to reduce air consumption and prevent the molded product from falling off, the operator often has to perform multiple setting and test runs to find a user-defined lower limit that satisfies the operator.

[0005] SUMMARY OF THE INVENTION The present invention provides a molded product remover that maintains on / off control and allows easy setting of a user-set lower limit value. [Means for solving the problem]

[0006] The molded product remover of the present invention comprises an attachment having a suction portion that sucks a molded product in a mold of a molding machine, a movement mechanism that moves the attachment according to a predetermined operation sequence, and a movement mechanism control unit that controls the movement mechanism;The present invention includes an air flow path between the suction unit and the vacuum generator to create a negative pressure in the space formed between the suction unit and the molded product, a negative pressure generating circuit including a pressure valve and a pressure detector disposed in the air flow path, and a negative pressure generating circuit having a change characteristic in which, after the pressure valve is opened, the negative pressure drops to an inflection point before starting to rise, and a negative pressure control unit that controls the vacuum generator or the pressure valve to control the negative pressure. The negative pressure control unit of the molded product extractor is configured to open the pressure valve upon receiving a suction start command to start suction, close the pressure valve to stop suction when the negative pressure of the air flowing through the air flow path reaches a stable value or an upper limit setting, and then open the pressure valve to resume suction based on a user-set lower limit that is lower than the stable value or the upper limit setting, repeating this on-off control. The negative pressure control unit used in the present invention also includes a pressure valve restart time period determination unit that determines a pressure valve restart time period Tv used to restart suction so that the inflection point does not fall below the user-set lower limit. In the on / off control, the negative pressure control unit repeats an off operation of closing the pressure valve until the pressure valve restart time period Tv has elapsed after the suction operation is stopped, and an on operation of opening the pressure valve and keeping it open until the negative pressure reaches a stable value or an upper limit setting. According to the present invention, the pressure valve restart time period Tv is determined so that the inflection point of the negative pressure change characteristic does not fall below the user-set lower limit value set by the operator, giving the operator the feeling that the user-set lower limit value is directly determining the pressure valve opening timing. This has the advantage of making the user-set lower limit value setting process easier and smoother than before.

[0007] The pressure valve reopening time period determination unit can be composed of a negative pressure change slope detection means that detects the slope A of the negative pressure change immediately after the negative pressure starts to decrease, a first calculation unit that calculates the predicted time period Tp from when the negative pressure starts to decrease until it is expected to cross the inflection point based on the negative pressure value Po when the negative pressure starts to decrease, the user-set lower limit value Pu, and the slope A, and a second calculation unit that determines the pressure valve reopening time period Tv based on the predicted time period Tp.

[0008] The formula used in the first calculation unit is not limited to one formula, but may be, for example, the formula Tp=(Po-Pu) / A. This type of formula allows for easy and quick calculation.

[0009] Furthermore, the second calculation unit calculates the pressure valve reopening time period Tv based on the predicted time period Tp and the response delay time period Tw2, where Tw2 is the response delay time period required for negative pressure to build up after the suction operation is resumed. The formula used by the second calculation unit is not limited to one formula, but for example, the pressure valve reopening time period Tv can be calculated using the formula Tv = Tp - Tw2. When using this formula, it is of course also possible to multiply the response delay time period Tw2 by a safety factor. This type of formula makes calculations easy and allows for rapid calculations.

[0010] There is no single way to define the response delay time period Tw2; it may simply be a fixed value measured in a prior test. Alternatively, the response delay time period Tw2 may be the dry suction response delay time period Td measured when dry suction is performed in a test operation or actual molding operation after replacing the suction unit. Furthermore, the response delay time period Tw2 may be defined so that the pressure valve reopening time period Tv gradually approaches the predicted time period Tp in measurements during an actual cycle.

[0011] The negative pressure control unit may be configured to select from a power reduction mode in which the power consumption of the vacuum generator is reduced by on / off controlling the pressure valve, a non-power reduction mode in which on / off control is not performed, and an intermediate power reduction mode in which on / off control of the pressure valve is variable, resulting in more power consumption than the power reduction mode but less power consumption than the non-power reduction mode. This allows the mode to be selected according to the shape of the molded product and the performance of the suction unit, thereby reducing the occurrence of molded product drop errors. Furthermore, if the control mode is selectable, the operator can choose not to perform on / off control at their own discretion, thereby respecting the wishes of experienced operators.

[0012] The control mode may be selected automatically. The negative pressure control unit includes a control mode determination unit for automatically selecting and determining the control mode. The control mode determination unit may select and determine the non-reduced power mode, reduced power mode, or intermediate reduced power mode in any manner. For example, the control mode determination unit may be configured to detect the negative pressure at the start of operation and select one of the non-reduced power mode, reduced power mode, or intermediate reduced power mode according to the slope of change in the detected negative pressure. The control mode determination unit may also be configured to select one of the non-reduced power mode, reduced power mode, or intermediate reduced power mode according to the slope of change in the negative pressure during operation. If the control mode can be changed even during operation, the control mode determination unit can select an appropriate control mode according to changes in negative pressure due to aging of the suction nozzle. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a block diagram showing the main components of a configuration of a molded product removal machine according to an embodiment of the present invention, which removes a resin molded product from a resin molding machine. [Figure 2] FIG. 10 is a diagram showing the movement path of the take-out head. [Figure 3] FIG. 10 is a diagram used to explain a change in negative pressure during a suction operation. [Figure 4] FIG. 10 is a diagram showing a change in negative pressure when on / off control is performed. [Figure 5] 10 is a flowchart showing an algorithm for performing on / off control. [Figure 6] FIG. 10 is a diagram showing changes in negative pressure under conditions in which the reduced power mode is selected, in normal operation (solid line) and when a vacuum leak occurs (dashed line). [Figure 7] 10 is a flowchart showing an algorithm for performing automatic selection. DETAILED DESCRIPTION OF THE INVENTION

[0014] An embodiment of the molded product removal machine of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram showing the main components of a molded product removal machine 1 according to an embodiment of the present invention, which removes a resin molded product from a resin molding machine 11. The molded product removal machine 1 includes a vacuum suction device 3, a movement mechanism 5, and a control device 7. The vacuum suction device 3 includes a suction nozzle 31 as a suction unit for suctioning the molded product, a vacuum generator 33 connected to the suction nozzle 31 via an air flow path 32 and applying vacuum pressure to the suction nozzle 31, a pressure valve 34 provided in the air flow path 32 between the vacuum generator 33 and the suction nozzle 31 and controlling communication between the vacuum generator 33 and the suction nozzle 31, and a pressure detector 35 for detecting the pressure in the air flow path 32 between the pressure valve 34 and the suction nozzle 31. The suction nozzle 31 is attached to a removal head 6 (attachment) that is moved by the movement mechanism 5.

[0015] When the movement mechanism 5 is a well-known three-axis movement mechanism, i.e., an XYZ-type movement mechanism, during the operation of removing a molded product as shown in Figure 2, the movement mechanism 5 moves the removal head 6 equipped with a suction nozzle 31 along the Z-axis and Y-axis in the following order: standby position (position where descent begins) → lowered position → removal position → extraction position → raised position. At the removal position, the movement mechanism 5 uses the suction nozzle 31 to suck and remove a molded product that is pushed out of the molding mold 12 of the molding machine 11 by the protruding action of the ejector pins. The movement mechanism 5 then moves the removal head 6 equipped with the suction nozzle 31 from the raised position to an open position (not shown). At the open position, suction by the suction nozzle 31 is released, and the molded product MP is released at the open position.

[0016] The control device 7 controls the operation of the vacuum generator 33 and the pressure valve 34, and controls the drive of the moving mechanism 5. As shown in Fig. 1, in this embodiment, the control device 7 includes a moving mechanism control unit 81 that controls the moving mechanism 5, a time period counting unit 82 (described later), a suction operation start time determining unit 83 that notifies the moving mechanism control unit 81 of the suction operation start time based on the output of the time period counting unit 82 so as to start the suction operation, and a negative pressure control unit 9.

[0017] The negative pressure control unit 9 , cheap The apparatus includes a constant or upper limit setting value detection unit 91, a negative pressure change gradient detection unit 92A, a pressure valve reopening time period determination unit 92 having a first calculation unit 92B and a second calculation unit 92C, a user-set lower limit value detection unit 93, a lower limit value setting unit 94, a response delay time period storage unit 95, a vacuum generation device control unit 96, a control mode determination unit 97, and a control mode selection unit 98. 8 It is prepared.

[0018] In the molded product extractor of this embodiment, a negative pressure generating circuit is configured, consisting of an air passage 32 provided between the suction nozzle 31 and the vacuum generator 33 to create a negative pressure in the space formed between the suction nozzle 31 and the molded product, a pressure valve 34 disposed in the air passage 32, and a pressure detector 35. The circuit has a change characteristic in which, after the pressure valve 34 is opened, the negative pressure drops to an inflection point and then begins to rise. The negative pressure control unit 9 controls the vacuum generator 33 or the pressure valve 34 to control the negative pressure. Upon receiving a suction start command from the suction operation start time determination unit 83, the negative pressure control unit 9 opens the pressure valve 34 to start the suction operation. When the negative pressure of the air flowing through the air passage 32 reaches a stable value or an upper limit setting, the negative pressure control unit 9 closes the pressure valve to stop the suction operation. The negative pressure control unit 9 then repeats this on / off control, opening the pressure valve 34 to resume the suction operation, until the suction of the molded product by the suction nozzle 31 is released.

[0019] In this embodiment, the negative pressure control unit 9 includes a pressure valve restart time period determination unit 92 that determines a pressure valve restart time period Tv used to restart the suction operation so that the inflection point in the characteristics of the negative pressure generating circuit does not fall below a user-set lower limit. The configuration and functions of the negative pressure control unit 9 will be described in detail after describing the operation up to the start of suction.

[0020] (Operation until suction starts) An example of the operation up to the start of suction using the movement mechanism control unit 81 will be described with reference to Figure 3. The time when the suction nozzle 31 passes a predetermined initial suction start position P0 is set to 0, and the pressure valve is opened at the initial suction start position P0 to start the suction operation by the vacuum generator 33. In the process of moving the suction nozzle 31 closer to the molded product by the movement mechanism 5, the time when the pressure detector 35 detects a predetermined pressure is changed to the time when the suction operation start pressure is detected, which indicates that the suction nozzle 31 has started the operation of suctioning the molded product. t The time period from this reference time period T0 to the total time period T1 =Ttr1+T3 [where Ttr1 is the rise time period and T3 is the settling time period] The time period obtained by subtracting the above is set as a delay time period Δt, and the timing of starting the suction operation can be determined from this delay time period Δt. The time period is counted by a time period counting unit 82.

[0021] This predetermined pressure is recognized as having been reached, and also as having been a stable pressure, when a time period (corresponding to the bias time period Tb) has passed during which the pressure in the air flow path 32 is within a small change range (Δp) from the output of the pressure detector 35.

[0022] This stabilization time period T3 varies with each extraction cycle due to variations in at least the ejector pin operation time. Therefore, the total time period T1 = Ttr1 + T3 also varies. Because the output of the pressure detector 35 fluctuates slightly, it is only after the bias time period Tb (the output of the pressure detector 35 fluctuates slightly even during this time period) has elapsed after the pressure in the air flow path 32 reaches a predetermined pressure that it is determined that the pressure has reached a stable pressure at which the suction operation start pressure can be accurately detected. In this embodiment, the suction operation start time determination unit 83 determines the suction operation start time so that the stabilization time period T3 is longer than the bias time period Tb. Therefore, if the extraction operation is performed using the suction operation start time determined by the suction operation start time determination unit 83, there is no risk of a drop error.

[0023] In this embodiment, the suction operation start time determination unit 83 of the control device 7 determines the suction operation start time so that the stable time period T3, which occurs from when the pressure detector 35 detects a predetermined pressure until the suction operation start pressure, indicating that the suction nozzle 31 has started suctioning the molded product, is longer than the bias time period Tb during the process of opening the pressure valve 34 to start the suction operation by the vacuum generator 33 and using the movement mechanism 5 to move the suction nozzle 31 closer to the molded product, is longer than the bias time period Tb. As shown in FIG. 3 , to reduce the amount of air consumed during suction, the suction operation start time determination unit 83 of the control device 7 automatically decreases the total time period Ttr1+T3 by increasing the delay time period Δti (the time period from when the suction nozzle 31 passes the initial suction start position P0 to when the suction operation starts, counting 0 as the time 0), for each take-out cycle, thereby bringing the stable time period T3 closer to the bias time period Tb (changing the suction operation start time from 0 to t1 to t2). However, this operation must be performed under the condition that the stable time period T3 is longer than the bias time period Tb. When the suction operation start timing determining unit 83 of the control device 7 determines the suction operation start timing so that the stabilization time period T3 is longer than the bias time period Tb, the operator does not need to determine by trial and error the suction operation start timing (corresponding to the delay time period Δti) at which the pressure detector 35 can operate without any problems and drop errors can be prevented.

[0024] (Configuration and Operation of Negative Pressure Control Unit 9) The following describes the change in the negative pressure characteristics after suction by the suction nozzle 31 begins and the on / off control by the negative pressure control unit 9 employed in this embodiment. Figure 4 shows the change in the negative pressure characteristics of the suction nozzle 31. During the take-out operation, suction begins (point a) before the suction pad of the suction nozzle 31 contacts the molded product. However, because a certain amount of time is required to exhaust the air in the air flow path, the negative pressure rises with a delay of time Tw1 (point b in Figure 4). This time period Tw1 is called the response period during dry suction. When the suction pad of the suction nozzle 31 contacts the molded product, the negative pressure increases further (point c). Once the negative pressure stabilizes, suction is stopped (point d). Whether the negative pressure has stabilized (reached a stable value) can be determined by whether the change in negative pressure approaches zero. Of course, an upper limit setting value may be set in advance. Whether the stable value or the upper limit setting value has been reached is detected by the stable value or upper limit setting value detection unit 91. Upon receiving this detection, the vacuum generating device control section 96 outputs a command to close the pressure valve 34, thereby stopping the suction.

[0025] Because the negative pressure gradually decreases due to a slight air leak in the air flow path, etc., the negative pressure change gradient detection unit 92A calculates the gradient A of this decrease in negative pressure at point e. Specifically, the gradient A is calculated from the pressure Po at the time (point d) when the pressure valve 34 is closed and suction is stopped (suction OFF) and the pressure Pm after a predetermined time Tm has passed. The negative pressure change gradient detection unit 92A calculates this negative pressure gradient A as A=Po-(Pm / Tm). Note that the predetermined time Tm can be set arbitrarily during the design stage.

[0026] Using the slope A, the first calculation unit 92B calculates the predicted time period Tp from point d, when suction is turned off, until the negative pressure is expected to exceed the inflection point (point g). For example, when the user-defined lower limit value Pu is used, the first calculation unit 92B can calculate the predicted time period Tp using the formula Tp = (Po - Pu) / A. The predicted time period Tp is determined by setting point d, when suction is turned off, as time 0. The user-defined lower limit value Pu is set by a lower limit value setting unit 94 implemented in a controller (not shown). When the user-defined lower limit value detection unit 93 detects that the negative pressure has reached the user-defined lower limit value Pu, the vacuum generator control unit 96 resumes suction operation by the suction nozzle 31. In this case, the pressure valve is resumed based on the user-defined lower limit value Pu set by the user, which takes precedence over the result determined by the pressure valve restart time period determination unit 92. However, since the user-set lower limit value Pu at this time is a value (high range value) within a safe range where the molded product will not fall, no problems will occur by prioritizing the user's setting. In other words, it can be said that the decision result of the pressure valve reopening time period decision unit 92 takes priority when the user-set lower limit value Pu is so low that the molded product may fall.

[0027] The second calculation unit 92C calculates and determines the pressure valve reopening time period Tv based on the predicted time period Tp. The second calculation unit 92C used in this embodiment calculates the pressure valve reopening time period Tv using the formula Tv = Tp - Tw2, where Tw2 is the response delay time period required for negative pressure to build up after the suction operation is resumed. Of course, the response delay time period Tw2 may also be multiplied by a safety factor. This type of formula makes calculation easy and allows for rapid calculation. The response delay time period is stored in the response delay time period storage unit 95.

[0028] In this embodiment, the pressure valve reopening time period Tv is determined so that the inflection point of the negative pressure change characteristic does not fall below the user-set lower limit value set by the operator, thereby giving the operator the feeling that the pressure valve opening timing is directly determined by the user-set lower limit value.

[0029] There is no single way to define the response delay time period Tw2, and it may simply be a fixed value measured in a prior test. Alternatively, the response delay time period Tw2 may be the dry suction response delay time period Tw1 measured when dry suction is performed in a test operation or actual molding operation after replacing the suction nozzle 31. Furthermore, the response delay time period Tw2 may be defined so that the pressure valve reopening time period Tv gradually approaches the predicted time period Tp in measurements during an actual cycle.

[0030] FIG. 5 shows a program algorithm used when the negative pressure control unit 9 is configured using a computer and, in particular, when on / off control is realized. flowchart In this algorithm, in step ST1, it is determined whether or not a suction start command has been input. The suction start command is output by the suction operation start time determination unit 83. When the suction start command is input, the pressure valve 34 is opened in step ST2, and the negative pressure increases (the negative pressure becomes stronger). When the pressure valve 34 is opened, it is determined in step ST3 whether the negative pressure has reached a stable value or an upper limit set value. This determination is made by the stable value or upper limit set value detection unit 91. When the negative pressure has reached the stable value or the upper limit set value, the pressure valve 34 is closed in step ST4, and the negative pressure begins to decrease (the negative pressure becomes weaker). Then, in step ST5, a pressure valve restart time period Tv is determined. This step is executed by the pressure valve restart time period determination unit 92. When it is determined in step ST6 that the pressure valve restart time period Tv has elapsed, the pressure valve 34 is restarted in step ST7. Thereafter, the negative pressure further decreases, passes an inflection point, and then increases (the negative pressure becomes stronger). Steps ST3 to ST8 are repeated until an adsorption release command is input. This allows on / off control to be performed. When an adsorption release command is output from the movement mechanism control unit 81, adsorption of the molded product is released at the release position.

[0031] 5 functions when the user's setting of the user's lower limit value would cause the molded product to drop. If the user's setting of the lower limit value is a value that would not cause the molded product to drop, when the user's setting of the lower limit value detection unit 93 detects that the negative pressure has reached the user's setting of the lower limit value, the vacuum generator control unit 96 begins to reopen the pressure valve from that point on, and thereafter, on / off control is executed based on the user's setting of the lower limit value. Of course, even after the suction release command is output, suction of the molded product may not be released immediately, but may be released after on / off control has ended.

[0032] In this embodiment, the negative pressure control unit 9 is equipped with a control mode selection unit 98 and a control mode determination unit 97, and is configured to select from a power reduction mode in which the power consumption of the vacuum generator is reduced by on / off controlling the pressure valve 34; a non-power reduction mode in which on / off control is not performed; and an intermediate power reduction mode in which on / off control of the pressure valve is variable, resulting in more power consumption than the power reduction mode but less power consumption than the non-power reduction mode. The above-described on / off control is performed when the control mode selection unit 98 selects the power reduction mode or the intermediate power reduction mode. When the selected control mode is the non-power reduction mode, the vacuum generator control unit 96 does not perform on / off control. Mode selection allows the control mode to be selected according to the shape of the molded product and the performance of the suction unit, thereby reducing the occurrence of molded product drop errors.

[0033] The control mode can be selected automatically if the control mode determination unit 97 is provided with a function to automatically determine the non-power reduction mode, power reduction mode, or intermediate power reduction mode according to the shape of the molded product and the performance of the suction part.

[0034] An example of automatically selecting the non-reduced power mode, reduced power mode, or intermediate reduced power mode by the control mode determination unit 97 is described below with reference to FIG. 6. Naturally, an operator would like to maximize energy savings if it can stably adsorb molded products. However, a "vacuum leak" can occur due to factors such as a broken suction nozzle pad. FIG. 6 illustrates the negative pressure change under conditions in which the reduced power mode is selected, under normal conditions (solid line) and when a vacuum leak occurs (dashed line). Under normal conditions (solid line), after suction is turned off, the pressure valve 34 turns on after the negative pressure reaches the user-set lower limit Pu. The pressure valve turns on again after the negative pressure exceeds the inflection point (point g). This state is then repeated for on / off operation. When a vacuum leak occurs, the negative pressure decreases more rapidly than normal, and the slope A of the negative pressure change becomes larger. The negative pressure change slope detection unit 92A calculates the slope A of the negative pressure decrease at point e'. As mentioned above, the slope A is calculated from the pressure Po at the time (point d) when the pressure valve 34 is closed and suction is stopped (suction OFF) and the pressure Pm when a predetermined time Tm has elapsed. In this case, as shown by the dashed line in Figure 6, if suction is resumed based on the user-set lower limit Pu, the pressure may reach a level at which the molded product cannot be maintained by suction until the negative pressure starts to increase. Therefore, by using the slope A of the negative pressure change to determine the occurrence of a vacuum leak and automatically switching from the reduced power mode to the intermediate reduced power mode, the negative pressure can be prevented from falling below the user-set lower limit Pu. Pressure valve reopening time periodThe negative pressure change slope A is measured after a predetermined time Tm has elapsed. When a vacuum leak occurs, the normal negative pressure Pm becomes Pm'. The negative pressure slope at this time is (P0 - Pm') / Tm. If the negative pressure change slope A exceeds a predetermined slope, suction begins before the negative pressure reaches the user-specified lower limit Pu. After this, the system can either switch to non-power reduction mode (continuous suction) until the product is released, or switch to intermediate power reduction mode (the pressure valve is turned on earlier than in power reduction mode and repeatedly turned on and off) until the product is released.

[0035] After the mode transition, the mode can remain switched to either mode, or the gradient A of the change in negative pressure drop can be detected for each cycle and the mode transition can be performed according to the detection results. If the reduced power mode is selected, stable extraction is possible even if an abnormality such as a vacuum leak occurs (or even if an abnormality has occurred from the beginning).

[0036] Furthermore, if the magnitude of the gradient A of the negative pressure change does not vary significantly from the normal value (even when taking into account the variation in the gradient of the negative pressure decrease that occurs with each adsorption), it may be determined that stable extraction is possible even if the setting is changed to the intermediate power reduction mode, and in that case, it is preferable to select the intermediate power reduction mode, which is superior to the non-power reduction mode.

[0037] Fig. 7 is a flowchart showing an algorithm for performing automatic selection. In the present embodiment, this algorithm can be executed by the control mode determination unit 97. The thresholds TH1 and TH2 in steps ST13 and ST15 in Fig. 7 may be set at the time of design, or may be the normal slope multiplied by a predetermined factor (for example, 1.2 times). Note that steps ST11 to ST17 in the automatic selection algorithm shown in Fig. 7 are merely an example, and the present invention is not limited to using the algorithm of Fig. 7.

[0038] In addition to vacuum leaks in the negative pressure equipment, other factors that can cause a significant drop in negative pressure include the way the molded product contacts the suction pad and the shape of the molded product (for example, porous or grooved parts are prone to sudden drops in negative pressure). However, it is difficult for unskilled personnel to manually select and pre-set the control mode while taking these factors into consideration. However, with automatic selection, the mode is automatically switched according to the actual state of negative pressure drop, so it is possible to achieve the maximum possible energy savings depending on the situation, and there are more opportunities to use the energy-saving function.

[0039] If the control mode can be selected manually, the operator can choose not to perform on / off control at his / her discretion, so the intention of a skilled operator can be respected. [Industrial Applicability]

[0040] According to the present invention, the pressure valve reopening time period Tv is determined so that the inflection point of the negative pressure change characteristic does not fall below the user-set lower limit value set by the operator, thereby giving the operator the feeling that the user-set lower limit value is directly determining the pressure valve opening timing, and providing the advantage that the user-set lower limit value setting work can be performed more easily and smoothly than before. [Explanation of symbols]

[0041] 1 Molded product removal machine 3 Vacuum suction device 5 Moving mechanism 7 Control Device 6 Extraction head 9 Negative pressure control section 11 Molding machine 12 Molding mold 31 Suction nozzle (suction part) 32 Air flow path 33 Vacuum Generator 34 Pressure valve 35 Pressure detector 81 Movement mechanism control unit 82 Time Period Counter 83 Suction operation start timing determining section 91 Stable value or upper limit setting value detection section 92 Pressure valve reopening time period determination unit 92A Negative pressure change gradient detector 92B First Calculation Unit 92C Second Calculation Unit 93 User-defined lower limit detector 94 Lower limit setting section 95 Response delay time period storage section 96 Vacuum generator control unit 97 Control mode determination unit 98 Control mode selection section

Claims

1. an attachment having a suction part for suctioning a molded product in a mold of a molding machine; a movement mechanism for moving the attachment according to a predetermined operation sequence; A movement mechanism control unit that controls the movement mechanism; an air flow path provided between the suction part and a vacuum generator to create a negative pressure in the space formed between the suction part and the molded product; a negative pressure generating circuit including a pressure valve and a pressure detector disposed in the air flow path, the negative pressure having a change characteristic in which, after the pressure valve is opened, the negative pressure drops to an inflection point and then starts to rise; a negative pressure control unit that controls the vacuum generating device or the pressure valve to control the negative pressure, a negative pressure control unit that, upon receiving a suction start command, opens the pressure valve to start a suction operation, closes the pressure valve to stop the suction operation when the negative pressure of the air flowing through the air flow path reaches a stable value or an upper limit setting value, and then opens the pressure valve based on a user-set lower limit value that is lower than the stable value or the upper limit setting value, thereby repeating on-off control to resume the suction operation, the negative pressure control unit includes a pressure valve restart time period determination unit that determines a pressure valve restart time period used to restart a suction operation so that the inflection point does not become lower than the user-set lower limit value, a negative pressure control unit that repeats, in the on / off control, an off operation of closing the pressure valve until the pressure valve restart time period has elapsed after the suction operation is stopped, and an on operation of opening the pressure valve and keeping the pressure valve open until the negative pressure reaches the stable value or an upper limit set value.

2. The molded product removal machine according to claim 1, characterized in that the negative pressure control unit is configured to select a power reduction mode in which power consumption in the vacuum generating device is reduced by controlling the pressure valve on and off, a non-power reduction mode in which the on-off control is not performed, and an intermediate power reduction mode in which power consumption is greater than that in the power reduction mode but less than that in the non-power reduction mode by varying the on-off control of the pressure valve.

3. 3. The molded product remover according to claim 2, wherein the negative pressure control unit further comprises a control mode determination unit that automatically determines the non-reduced power mode, the reduced power mode, or the intermediate reduced power mode.

4. The molded product removal machine according to claim 3, wherein the control mode determination unit detects the negative pressure at the start of operation and selects and determines one of the non-power reduction mode, the power reduction mode, and the intermediate power reduction mode depending on a slope of change in the detected negative pressure.

5. The molded product removal machine according to claim 3, wherein the control mode determination unit detects a change in the negative pressure during operation, and selects and determines one of the non-power reduction mode, the power reduction mode, and the intermediate power reduction mode depending on a slope of the detected change in the negative pressure.

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