Method and device for supporting resin replacement in molding machines

Abstract

To improve production efficiency and reduce production cost, and to easily and quickly obtain a stable and reliable purge resin required amount.SOLUTION: For each different resin R, a zero shear viscosity ηo of each resin is calculated from a conversion function equation with MFR and a set temperature of a heating barrel 2 as parameters, and registered. In addition, a purge resin required amount Wu corresponding to a viscosity difference ηd between a zero shear viscosity ηof of a previous resin Rf and a zero shear viscosity ηos of a next resin Rs is registered. When changing resins, the MFR of the previous resin Rf and the MFR of the next resin Rs are input into a molding machine controller 3 to obtain the zero shear viscosity ηof of the previous resin Rf and the zero shear viscosity ηos of the next resin Rs, and the viscosity difference ηd between the zero shear viscosity ηof of the previous resin Rf and the zero shear viscosity ηos of the next resin Rs is obtained. At least display processing is performed by calculating the purge resin required amount Wu at a time of changing resins.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method and device for supporting resin changeover in a molding machine when resin changeover is performed by discharging a previous resin from a heating barrel and then supplying a next resin. [Background technology]

[0002] Generally, when an injection molding machine is used to successively produce molded products with different resin types or colors, it is necessary to switch from the previous resin used in the previous production to the next resin used in the next production, so the resin is replaced in a resin change process after the previous production is completed.In the resin change process, the residual resin (previous resin) in the heating cylinder is usually discharged, and then the next resin to be used in the next production is supplied, so it is required that no residual previous resin is mixed in when the next production starts.

[0003] Conventionally, as a related technique for supporting such a resin change process, a method (support device) for supporting resin change in a molding machine proposed by the present applicant and described in Patent Document 1 is known. The method for supporting resin change in a molding machine described in Patent Document 1 aims to contribute to reducing material costs, shortening resin change time, and further suppressing the occurrence of unnecessary defective products by allowing an operator to accurately (precisely) know the necessity of intermediate materials, and specifically, when performing resin change by supplying a latter resin after discharging a former resin from a heating cylinder, an apparent viscosity having a correlation with a predetermined physical quantity of operation in the molding machine is obtained in advance for each type of resin, and the obtained apparent viscosity is set as a database, and during resin change in the molding machine, a viscosity difference index related to a viscosity difference obtained by subtracting the apparent viscosity of the former resin from the apparent viscosity of the latter resin to be changed in the database is calculated by a molding machine controller, and a positive or negative judgment is made on the obtained viscosity difference index, so that a judgment result indicating that an intermediate material is required is output at least when the judgment is negative. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-222144 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the above-mentioned conventional resin replacement techniques have the following problems to be solved.

[0006] In other words, the molding machine owned by the user must be used as a test machine to perform tests for each resin and to obtain the apparent viscosity, which is the relative viscosity. This causes problems such as the molding machine being unavailable when the tests are performed, which can cause production problems. Moreover, even if the specific calculation processing can be performed by software built into the molding machine controller, the testing work itself requires the molding machine to be operated using the resin, and the user (operator) must perform testing work at the production site similar to the resin change process, which requires a lot of labor and time.

[0007] In the end, the conventional method involving on-site testing work is not necessarily desirable for inexperienced beginners, and can lead to reduced production efficiency and increased production costs. In addition, there is a risk that the stability and reliability of the support method cannot be sufficiently ensured due to variations in the testing work.

[0008] An object of the present invention is to provide a method and device for supporting resin change in a molding machine that solves the problems existing in the background art. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems, the resin change support method for a molding machine according to the present invention, when performing resin change by discharging a front resin Rf from a heating barrel 2 and then supplying a rear resin Rs, estimates the zero shear viscosity ηo… of each resin R… in advance using a conversion function equation with the melt flow rate (MFR) and the set temperature of the heating barrel 2 as parameters for each different resin R…, registers the calculated values ​​in a molding machine controller 3 as a first database DB1, and performs a purge resin change using the rear resin Rs… corresponding to the viscosity difference ηd… between the zero shear viscosity ηof… of the front resin Rf… and the zero shear viscosity ηos… of the rear resin Rs…. The required amount Wu... is registered in the molding machine controller 3 as a second database DB2, and when changing the resin, the MFR of the previous resin Rf and the MFR of the subsequent resin Rs are input into the molding machine controller 3, the zero shear viscosity ηof of the previous resin Rf and the zero shear viscosity ηos of the subsequent resin Rs are obtained from the first database DB1, and the viscosity difference ηd between the zero shear viscosity ηof of the previous resin Rf and the zero shear viscosity ηos of the subsequent resin Rs is obtained, and the required purged resin amount Wu of the subsequent resin Rs at the time of resin change is obtained from the second database DB2, thereby performing at least display processing.

[0010] In order to solve the above-mentioned problems, the resin change support device 1 for a molding machine according to the present invention is configured as a support device for discharging a front resin Rf from a heating barrel 2 and supplying a rear resin Rs to perform resin change. The support device includes a first database DB1 in which the zero shear viscosity ηo… of each resin R… estimated by a conversion function equation using the MFR and the set temperature of the heating barrel 2 as parameters for each different resin R…, and a second database DB2 in which the required amount of purged resin Wu… using the rear resin Rs… corresponding to the viscosity difference ηd… between the zero shear viscosity ηof… of the front resin Rf… and the zero shear viscosity ηos… of the rear resin Rs… is registered. 2, an MFR input function unit Fi for inputting the MFR of the front resin Rf and the MFR of the rear resin Rs, a viscosity difference calculation function unit Fs for obtaining the viscosity difference ηd between the zero shear viscosity ηof of the front resin Rf and the zero shear viscosity ηos of the rear resin Rs from a first database DB1 based on the input MFRs, a required amount calculation function unit Fw for obtaining the required amount of purged resin Wu of the rear resin Rs at the time of resin change from a second database DB2 based on the obtained viscosity difference ηd, and a display processing function unit Fo for at least displaying the obtained required amount of purged resin Wu.

[0011] On the other hand, according to a preferred embodiment of the present invention, when the heating cylinder 2 is divided into three regions, a front portion 2f, a middle portion 2m, and a rear portion 2r in the axial direction, the set temperature of the heating cylinder 2 is preferably set to a high temperature region ZAu before the front portion 2f and a low temperature region ZAd after the middle portion 2m, and the temperature difference between the high temperature region ZAu and the low temperature region ZAd is preferably set in the range of 0-50°C. On the other hand, in the support device 1, when the zero shear viscosity ηos of the rear resin Rs is lower than the zero shear viscosity ηof of the front resin Rf, the viscosity difference calculation function unit Fs performs processing to output a message indicating that a purging agent is necessary, and the display processing function unit Fo can provide a purging agent recommendation display unit 4p on the display 4 to display that a purging agent is necessary. Note that it is preferable to apply the present invention to an injection molding machine M as a molding machine. Effect of the Invention

[0012] According to the resin change support method and device 1 for a molding machine according to the present invention, the following remarkable effects are obtained.

[0013] (1) By inputting the MFR of the front resin Rf and the MFR of the rear resin Rs into the molding machine controller 3, the zero shear viscosity ηof of the front resin Rf and the zero shear viscosity ηos of the rear resin Rs are obtained from the first database DB1, and the viscosity difference ηd between the zero shear viscosity ηof of the front resin Rf and the zero shear viscosity ηos of the rear resin Rs is obtained, and the required amount of purged resin Wu at the time of resin change is obtained from the second database DB2, so that at least the display processing is performed. Therefore, it is possible to eliminate the conventional test work using the molding machine owned by the user and the resin change process using the actual resin. As a result, it is possible to improve production efficiency (production efficiency) and reduce production costs, and it is possible to obtain the accurate required amount of purged resin Wu by a stable and reliable support method. This allows the method to be constructed as an optimal support method for inexperienced beginners, and the required amount of purged resin Wu can be easily and quickly obtained.

[0014] (2) In a preferred embodiment, by including the intermediate material Rms in the subsequent resin Rs, the required amount of purged resin Wu can be known for the intermediate material Rms as well, so that the same effect as for the subsequent resin Rs can be obtained for the intermediate material Rms.

[0015] (3) In a preferred embodiment, when the zero shear viscosity ηos of the rear resin Rs is lower than the zero shear viscosity ηof of the front resin Rf, an output process is performed to indicate that a purging agent is necessary. This allows an actual determination to be made as to whether or not a purging agent is necessary, allowing the operator to quickly know whether a purging agent is necessary, and also contributes to reducing material costs, shortening the time required to change resins, and further suppressing the occurrence of unnecessary defective products.

[0016] (4) In a preferred embodiment, when setting the temperature of the heating barrel 2, the heating barrel 2 is divided into three axial regions, a front region 2f, a middle region 2m, and a rear region 2r. The region up to the front region 2f is set as a high temperature region ZAu, and the region after the middle region 2m is set as a low temperature region ZAd. In addition, the temperature difference between the high temperature region ZAu and the low temperature region ZAd is set in the range of 0-50°C. This makes it possible to set the operating environment of the molding machine (injection molding machine) M to an efficient operating state, thereby making it possible to obtain a more efficient and accurate required amount of purged resin Wu.

[0017] (5) In a preferred embodiment, if the resin contains general-purpose resins, engineering plastics, super engineering plastics, composite materials, purging agents, or special resins other than purging agents, the method can be applied to a wide range of resin materials, making it possible to construct a highly versatile method.

[0018] (6) In a preferred embodiment, when the zero shear viscosity ηos of the rear resin Rs is lower than the zero shear viscosity ηof of the front resin Rf, the viscosity difference calculation function unit Fs of the support device 1 performs processing to output the fact that a purging agent is needed. In addition, if the display processing function unit Fo is provided with a purging agent recommendation display unit 4p on the display 4 that displays the fact that a purging agent is needed, the operator (user) can reliably confirm by visually checking the display 4 that a purging agent is needed, and therefore it is possible to quickly carry out corresponding processing such as preparations related to the purging agent.

[0019] (7) In a preferred embodiment, when the present invention is applied to an injection molding machine, the most desirable performance can be obtained since the present invention can be used in injection molding machines where there is a high demand. [Brief description of the drawings]

[0020] [Figure 1] 1 is a flowchart illustrating a process of a resin replacement support method according to a preferred embodiment of the present invention; [Diagram 2] An overall configuration diagram of an injection molding machine including a block diagram of a support device used to implement the resin change support method; [Diagram 3]FIG. 1 is a diagram showing a partially omitted setting screen displayed on a display of an assistance device used to implement the resin replacement assistance method; [Figure 4] A diagram of the condition table display screen with some parts omitted, as shown on the same display. [Diagram 5] A schematic diagram of the heating barrel to explain the set temperatures used in the test. [Figure 6] A characteristic diagram of shear rate vs. shear viscosity for explaining the coefficient of a conversion function equation for calculating zero shear viscosity in the resin replacement support method. [Figure 7] A data table showing the results of the zero shear viscosity and purge resin requirement from a test to verify the effectiveness of the resin replacement support method. [Figure 8] Graph showing the results of the test on zero shear viscosity and required amount of purge resin. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Next, preferred embodiments of the present invention will be described in detail with reference to the drawings.

[0022] First, the configuration of an injection molding machine M (molding machine) capable of implementing the resin change support method according to this embodiment will be described with reference to FIGS. 2 to 4. FIG.

[0023] 2, M denotes an injection molding machine, particularly an injection unit Mi with the clamping device omitted. In the injection unit Mi, 2 denotes a heating barrel, and a nozzle 2n is attached and fixed to the front end of this heating barrel 2 via a head portion 2h, and a hopper 11 is provided at the upper rear end of the heating barrel 2. The nozzle 2n has a function of injecting molten resin inside the heating barrel 2 into a mold (clamping device), and the hopper 11 has a function of supplying resin (molding material) R..., that is, rear resin Rs including a front resin Rf and an intermediate material Rms described later, into the inside of the heating barrel 2.

[0024] In this way, if the resin change support method according to this embodiment is applied to an injection molding machine, it can be used in injection molding machines where the need is high, and the most desirable performance can be obtained. In addition, since the intermediate material Rms can be included in the post-resin Rs, the required amount of purged resin Wu can be known for the intermediate material Rms as well. This allows the same effect as for the post-resin Rs to be obtained for the intermediate material Rms as well.

[0025] In addition, the screw 12 is loaded inside the heating barrel 2 so as to be rotatable and move forward and backward. The screw 12 includes a screw body 12m on which a spiral flight portion 12mp is formed, and a torpedo portion 12t and a screw tip portion 12s are provided at the front end of the screw body 12m. The screw body 12m has a metering zone Zm, a compression zone Zc, and a feed zone Zf from the front side to the rear side. Meanwhile, the rear end of the screw 12 is connected to a screw drive unit 13. The screw drive unit 13 includes a screw rotation mechanism 13r that rotates the screw 12 and a screw advance and retreat mechanism 13m that advances and retreats the screw 12. The drive system of the screw rotation mechanism 13r and the screw advance and retreat mechanism 13m may be a hydraulic system using a hydraulic circuit or an electric system using an electric motor, and the drive system is not limited.

[0026] Furthermore, the heating cylinder 2 has, from the front side (nozzle 2n side) to the rear side, a heating cylinder front part 2f, a heating cylinder middle part 2m, and a heating cylinder rear part 2r, and a front heating part 14f, a middle heating part 14m, and a rear heating part 14r are attached to the outer circumferential surface of each part 2f, 2m, and 2r, respectively. Similarly, a head heating part 14h is attached to the outer circumferential surface of the head part 2h, and a nozzle heating part 14n is attached to the outer circumferential surface of the nozzle 2n. Each of these heating parts 14f, 14m, 14r, 14h, and 14n can be composed of a band heater or the like.

[0027] Meanwhile, reference numeral 3 denotes a molding machine controller which controls the entire injection molding machine M. The molding machine controller 3 is provided with a controller main body 15 having a computer function incorporating hardware such as a CPU and an associated internal memory 15m, and also with a display 4 connected to the controller main body 15. Since the display 4 is provided with a touch panel, various operations such as setting, selection, input, etc. can be performed using the display 4, and various displays can also be displayed. In particular, in relation to this embodiment, a resin change setting screen Hc shown in Fig. 3 and a condition table display screen Hm shown in Fig. 4 are displayed.

[0028] Furthermore, the controller body 15 is connected to the above-mentioned screw rotation mechanism 13r and screw advance / retract mechanism 13m via a driver 16, and is also connected to each of the heating parts 14f, 14m, 14r, 14h, and 14n. This allows the controller body 15 to drive and control the screw rotation mechanism 13r and the screw advance / retract mechanism 13m via the driver 16, and also to control the energization of each of the heating parts 14f, 14m, 14r, 14h, and 14n.

[0029] Therefore, the molding machine controller 3 includes an HMI (human machine interface) control system and a PLC (programmable logic controller) control system, and the internal memory 15m stores a PLC program and an HMI program. The PLC program is software for implementing sequence operations of various processes in the injection molding machine M and monitoring of the injection molding machine M, and the HMI program is software for implementing setting and display of operation parameters of the injection molding machine M and display of operation monitoring data of the injection molding machine M. The molding machine controller 3 constitutes (serves as) the resin changing support device 1 according to this embodiment.

[0030] Next, a basic support technique of the resin replacement support method according to this embodiment will be described with reference to Tables 1 and 2 and FIGS.

[0031] This resin change support method is a technique for estimating the required amount of purged resin Wu required for resin change (including color change of the same resin) when carrying out resin change. Conventionally, the molding machine itself was used as a test machine to actually obtain the viscosity (apparent viscosity) of the resin, and the required amount of purged resin Wu was predicted from the test results. The resin change support method according to this embodiment uses the MFR value known from a catalog or the like as is, that is, it makes it possible to estimate the corresponding accurate required amount of purged resin Wu by simply inputting a numerical value.

[0032] First, in order to confirm the effectiveness, a verification test was carried out on the resin replacement support method according to the present embodiment.

[0033] In the verification test, a resin change test was performed using an injection molding machine with a φ26 standard screw. The purge processing conditions for the resin change test are shown in [Table 1].

[0034] [Table 1]

[0035] In Table 1, the temperature of the high temperature side region (ZAu in Figure 5) includes the temperatures of the nozzle 2n, head portion 2h and front portion 2f of the heating barrel 2, and the temperature of the low temperature side region (ZAd in Figure 5) includes the temperatures of the middle portion 2m and rear portion 2r of the heating barrel 2.

[0036] In the verification test, first, the front resin Rf was adjusted so that the master batch was 1 [wt%], and the heating cylinder 2 was filled with black front resin Rf. After this, the rear resin Rs (LDPE) was purged according to the purging conditions in [Table 1], the screw was pulled out, and after cooling, the resin was peeled off to visually confirm whether or not the front resin Rf remained. At this time, if the front resin Rf was confirmed, 500 [g] of the rear resin Rs was added and the purging process was continued until the front resin Rf was gone. Then, the amount of purged resin when the front resin Rf was completely gone was determined.

[0037] On the other hand, the zero shear viscosity was calculated using Equation 101 shown in [Mathematical Expression 1].

[0038]

number

[0039] In (Equation 101), η is the shear viscosity (Pa s), ηo is the zero shear viscosity (Pa s), γ is the shear rate (1 / sec), n is the viscosity index, C is the temperature constant, T is the measurement temperature (°C), and Tr is the reference temperature (°C).

[0040] The zero shear viscosity ηo of each resin R at different temperatures (200° C., 250° C.) is shown in Table 2, and the temperature range of the heating barrel 2 is shown in FIG.

[0041] [Table 2]

[0042] Then, the required amount of purged resin Wum based on these was calculated using the calculation formula (Formula 102) shown in [Mathematical formula 2].

[0043]

number

[0044] In this case, the heating barrel 2 is divided into three axial regions, a front region 2f, a middle region 2m, and a rear region 2r, and the region before the front region 2f is set as a high temperature region ZAu, and the region after the middle region 2m is set as a low temperature region ZAd. As shown in the example, if the temperature of the high temperature region ZAu is set to 250°C, and the temperature of the low temperature region ZAd is set to 200°C, the required amount of purged resin Wum, which is the amount of resin required for the rear resin Rs, is expected to be proportional to the value obtained by adding up the difference values ​​obtained from ηos, ηof, and ηofe, as shown in (Equation 102).

[0045] The temperature difference between the high temperature side area ZAu and the low temperature side area ZAd is preferably set in the range of 0-50°C. By setting it in this way, the operating environment of the molding machine (injection molding machine) M can be set to an efficient operating state, so that a more efficient and accurate required amount of purged resin Wu can be obtained.

[0046] The theory of discharge of the front resin Rf in the high temperature side area ZAu is that the greater the difference in zero shear viscosity is with respect to the rear resin Rs, which has a zero shear viscosity in the low temperature side area ZAd from the rear, the easier it is to discharge, and in the low temperature side area ZAd, the greater the difference in zero shear viscosity between the rear resin Rs and the front resin Rf at that temperature, the easier it is to discharge the front resin Rf. Note that, when changing colors between the same resins, the difference in apparent viscosity in the low temperature side area ZAd is always 0, so a larger amount of purged resin is required compared to resin change. Therefore, the more the value on the right side of (Equation 102) becomes positive, the smaller the amount of purged resin required Wum becomes.

[0047] On the other hand, the zero shear viscosity ηo of the front resin Rf and the rear resin Rs (intermediate material Rms) was predicted by calculation using the MFR value.

[0048] That is, based on the MFR value (catalog value) of each resin R..., the change characteristic of the shear viscosity and further the zero shear viscosity ηo were predicted from the functional formula (Equation 103) shown below.

[0049] ηo=f(kx, MFR value, Th) … (Equation 103)

[0050] Here, kx is a coefficient proportional to the heater barrel temperature Th and MFR value. In (Equation 103), the zero shear viscosity ηo of each resin R is set corresponding to the MFR value and heater barrel temperature Th, which are parameters that differ for each resin R, so the coefficient kx is set individually for each resin R as kx=a,b,c,d.... Due to the differences in each coefficient kx=a,b,c,d..., the relationship of shear viscosity η (Pa s) to shear rate γ (1 / sec) is as shown in Figure 6. For this reason, the coefficient value of kx can be set in advance by experiment, etc., to an appropriate value.

[0051] Then, the viscosity difference ηd of the obtained zero shear viscosity ηo, that is, the viscosity difference ηd (= ηof - ηos) between the zero shear viscosity ηof of the front resin Rf and the zero shear viscosity ηos of the rear resin Rs, was calculated. The calculated viscosity difference ηd is shown in the table in FIG.

[0052] The relationship between the amount of purged resin Wu required for the rear resin Rs when completely discharged, obtained from the verification test, was considered. Figure 8 is a correlation graph showing the relationship between the viscosity difference ηd and the amount of purged resin Wu required. Note that the amount of purged resin Wum is the amount of purged resin required for the rear resin Rs until the front resin Rs is completely discharged in the verification test described above. As is clear from Figure 8, it was confirmed that the amount of purged resin required based on the MFR has significance.

[0053] The amount of post-processing resin Wu that is actually required can be calculated using the calculation formula (Formula 104) shown in [Mathematical formula 3].

[0054]

number

[0055] (Formula 104) is a calculation (prediction) formula for the required post-resin amount Wu when formula 102 is applied to other molding machines. The coefficient values ​​in formula 104 are values ​​obtained from Figure 8, which plots the results of Figure 7, and the coefficient values ​​will change as the number of data increases.

[0056] Next, a specific configuration of the resin replacement assistance device 1 according to this embodiment will be described with reference to FIGS.

[0057] 2, the resin replacement support device 1 utilizes a controller main body 15 with an internal memory 15m provided in a molding machine controller 3, and a display 4 with a touch panel. As a basic configuration, it has a first database DB1 and a second database DB2 registered in the internal memory 15m, as well as an MFR input function unit Fi, a viscosity difference calculation function unit Fs, a required amount calculation function unit Fw, and a display processing function unit Fo that function as the molding machine controller 3.

[0058] The display 4 displays a resin change setting screen Hc shown in Fig. 3 and a condition table display screen Hm shown in Fig. 4, which are related to the present invention. The resin change setting screen Hc basically enables the user to set various operating conditions related to resin change, such as purging conditions, and the condition table display screen Hm enables the user to display a condition table related to resin change.

[0059] 3, a molding machine (screw) setting field 31 is located on the left side of the upper area Au, a temperature setting selection field 32 is located to the right of this setting field 31, and a "display condition table" key 33 is located to the right of this selection field 32. In addition, a viscosity information selection field 34 is located on the left side of the central area Am, and this viscosity information selection field 34 allows the selection of "none" in 34a, "MFR" in 34b used in the present invention, and "molding machine viscosity" in 34c.

[0060] Further, a resin selection unit 35 is disposed to the right of the selection field 34. Resin selection unit 35 has a current resin (previous resin Rf) selection field 35f disposed on the left side and a replacement resin (next resin Rs) selection field 35s disposed on the right side, with a "START" key 37 disposed between the selection fields 35f and 35s. An MFR input unit 21f for inputting the MFR value of the selected resin is provided below the current resin selection field 35f, and an MFR input unit 21s for inputting the MFR value of the selected resin is provided below the replacement resin selection field 35s. These MFR input units 21f and 21s constitute the MFR input function unit Fi described above.

[0061] In this case, the resins that can be selected include general-purpose resins, engineering plastics, super engineering plastics, composite materials, purging agents, and special resins excluding purging agents. In this way, the resin replacement support method according to the present embodiment can be applied to a wide range of various resin materials, and therefore can be constructed as a highly versatile method.

[0062] The lower area Ad is provided with a set temperature display section 38 that resembles the heater barrel of a molding machine. Therefore, this set temperature display section 38 displays, from the front, the nozzle temperature, head temperature, heater barrel front temperature, heater barrel middle temperature, and heater barrel rear temperature.

[0063] Moreover, by pressing the "display condition table" key 33 on the resin change setting screen Hc, the condition table display screen Hm shown in FIG. 4 can be displayed.

[0064] On the other hand, in the condition table display screen Hm shown in Fig. 4, a purging agent recommendation display section 4p is provided in the upper area ASu. When the zero shear viscosity ηos of the rear resin Rs is lower than the zero shear viscosity ηof of the front resin Rf, the purging agent recommendation display section 4p can output a notification that a purging agent is necessary by lighting or blinking the purging agent recommendation display section 4p using the viscosity difference calculation function section Fs. In this way, if the display processing function section Fo is provided with the purging agent recommendation display section 4p that displays that a purging agent is necessary, the operator (user) can reliably confirm that a purging agent is necessary on the display 4, and therefore can quickly make preparations related to the purging agent.

[0065] Furthermore, in the central area ASm of the condition table display screen Hm, from left to right, there are arranged a metering rotation speed display field 41, a purge speed display field 42, a back pressure display field 43, a material shortage monitoring time display field 44, and an "OK" key 45. In the lower area ASd of the condition table display screen Hm, there are provided a pre-purge condition display field 46a, a post-purge condition display field 46b, and an empty purge condition display field 46c, each of which displays the movement stroke and number of times. And at the right end of the lower area ASd, there is provided an input resin amount display section 47.

[0066] In each functional unit constituting the resin change support device 1, the zero shear viscosity ηo... of each resin R... (resin type, color) is calculated and registered in the first database DB1, which is obtained from a function equation (Equation 103) using the MFR value and the set temperature of the heater barrel 2 as parameters. The MFR value [g / 10 min] is one of the resin properties that indicates the fluidity of the molten resin, and a value listed in the catalog of the molding material (resin R) can be used.

[0067] The second database DB2 registers a required amount of purged resin Wu... corresponding to a viscosity difference ηd (=ηof-ηos)... between the zero shear viscosity ηof... of the front resin Rf... and the zero shear viscosity ηos... of the rear resin Rs....

[0068] On the other hand, the MFR input function unit Fi has the function of inputting the MFR value of the previous resin Rf and the MFR value of the next resin Rs, and is equipped with an MFR input unit 21 having an MFR input section 21f for inputting the MFR value of the current resin (previous resin Rf) in the resin change setting screen Hc displayed on the display 4 shown in Figure 3, and an MFR input section 21s for inputting the MFR value of the replacement resin (next resin Rs).

[0069] The viscosity difference calculation function unit Fs has a calculation function that reads out the zero shear viscosity ηof of the front resin Rf and the zero shear viscosity ηos of the rear resin Rs from the first database DB1 based on each MFR input from the MFR input unit 21, and calculates the viscosity difference ηd (= ηof - ηos) between the zero shear viscosity ηof of the front resin Rf and the zero shear viscosity ηos of the rear resin Rs.

[0070] Furthermore, the required amount calculation function unit Fw has a function of obtaining a required amount Wu of purged resin at the time of resin change from the second database DB2 based on the obtained viscosity difference ηd. The display processing function unit Fo has a function of displaying the obtained required amount Wu of purged resin in the input resin amount display unit 47 on the condition table display screen Hm of FIG. Next, a resin replacement assistance method using the resin replacement assistance device 1 according to this embodiment will be specifically described based on the flowchart shown in FIG. 1 and with reference to FIGS.

[0071] Assume now that a series of production runs using a given resin (previous resin Rf) has ended, and that the next production run will begin by changing to the next resin (next resin Rs). As the production run using the previous resin Rf has ended, the operator causes the resin change setting screen Hc shown in FIG. 3 to be displayed on the display 4 (step S1). Then, first, various setting items are selected or input (step S2). In the illustrated example, the model of molding machine to be used can be selected in the molding machine setting field 31 including the screw size, and the setting mode of the temperature to be used can be selected in the temperature setting selection field 32.

[0072] Next, viscosity information is selected in the viscosity information selection field 34. In this embodiment, since MFR information is used, "MFR" 34b is selected (step S3). The current resin used, i.e., the resin type related to the previous resin Rf, is selected from the current resin selection field 35f of the resin selection unit 35 (step S4). The example shows a state in which "HDPE" has been selected. Then, the MFR value of the current resin (previous resin Rf) is input into the MFR input field 21f (step S5). The example shows a state in which "10" has been input.

[0073] Furthermore, the replacement resin to be used, i.e., the resin type related to the subsequent resin Rs, is selected from the replacement resin selection field 35s (step S6). The example shows the case where "PMMA" is selected. Then, the MFR value of the replacement resin (subsequent resin Rs) is input in the MFR input field 21s (step S7). The example shows the state where "10" is input.

[0074] When the above settings are completed, the "START" key 37 is turned ON. This determines the heating temperature of the corresponding heating barrel 2 and displays it as the set temperature in the set temperature display section 38 (step S9). That is, the nozzle temperature, head temperature, heating barrel front temperature, heating barrel middle temperature, and heating barrel rear temperature are displayed in each display section of the set temperature display section 38.

[0075] Next, the "Condition table display" key 33 is turned ON (step S10). This determines the operating conditions during purging, and the purging conditions are determined, and the operating conditions and purging conditions are displayed on the condition table display screen Hm shown in FIG. 4 (steps S11, S12). The operating conditions include the metering rotation speed, purging speed, back pressure, material shortage monitoring time, etc., and the screw movement stroke and number of times are displayed as purging conditions in the pre-purge condition display field 46a, the post-purge condition display field 46b, and the empty purge condition display field 46c, respectively. Also, the amount of resin input [kg] required during purging is displayed in the input resin amount display section 47 (step S13).

[0076] On the other hand, the condition table display screen Hm is provided with a purging agent recommendation display section 4p. When the zero shear viscosity ηos of the rear resin Rs is lower than the zero shear viscosity ηof of the front resin Rf by the viscosity difference calculation function section Fs, the purging agent recommendation display section 4p outputs a message indicating that a purging agent is required, and notifies the user by lighting or blinking the purging agent recommendation display section 4p.

[0077] This allows a substantial determination as to whether or not a purging agent is necessary, and the operator (user) can quickly and reliably confirm the necessity of a purging agent by visually checking the display 4, so that the operator can quickly take appropriate measures such as preparation for the purging agent (steps S14, S15). As a result, it is possible to reduce material costs and the time required for resin replacement, and further to contribute to suppressing the occurrence of unnecessary defective products.

[0078] When the above preparations are completed, the operator performs a final check, and if it is determined that there is no problem, turns on the "OK" key 45 (step S16), which causes a series of resin change steps to be performed (step S17).

[0079] Therefore, according to the resin change support method (apparatus) of this embodiment, as a basic technique, the zero shear viscosity ηo... of each resin is obtained in advance for each type of resin R... from a conversion function equation using the melt flow rate (MFR) and the set temperature of the heater barrel 2 as parameters, and registered in the molding machine controller 3 as a first database DB1. At the same time, the required amount of purged resin Wu... corresponding to the viscosity difference ηd... between the zero shear viscosity ηof... of the previous resin Rf... and the zero shear viscosity ηos... of the subsequent resin Rs... is registered in the molding machine controller 3 as a second database DB2. By inputting the MFR of Rf and the MFR of the rear resin Rs into the molding machine controller 3, the zero shear viscosity ηof of the front resin Rf and the zero shear viscosity ηos of the rear resin Rs are obtained from the first database DB1, and the viscosity difference ηd between the zero shear viscosity ηof of the front resin Rf and the zero shear viscosity ηos of the rear resin Rs is obtained. The required amount of purged resin Wu at the time of resin change is obtained from the second database DB2, and at least the display process is performed. This makes it possible to eliminate the need for a molding machine owned by the user and a test operation similar to the resin change process using an actual resin, as in the past. As a result, it is possible to improve production efficiency (production efficiency) and reduce production costs, and it is possible to obtain an accurate required amount of purged resin Wu by a stable and reliable support method. This makes it possible to construct an optimal support method for inexperienced beginners, and to easily and quickly obtain the required amount of purged resin Wu.

[0080] Although the preferred embodiment has been described in detail above, the present invention is not limited to such an embodiment, and the detailed configuration, shape, material, ingredients, quantities, values, methods, etc. can be changed, added, or deleted as desired without departing from the gist of the present invention.

[0081] For example, resin change is a concept that includes not only changing resins of different types, but also changing the same resin with different colors. Although the MFR (MFR value) is an example that uses the catalog value of the resin, various values ​​such as values ​​from various documents and values ​​obtained by one's own experiments can be used. In addition, the intermediate material Rms can be included in the rear resin Rs. Therefore, in this case, the rear resin Rs can be replaced with the intermediate material Rms in the same way. On the other hand, when the heating cylinder 2 is divided into three regions, the front portion 2f, the middle portion 2m, and the rear portion 2r in the axial direction, the set temperature of the heating cylinder 2 is set to the high temperature side region ZAu before the front portion 2f and the low temperature side region ZAd after the middle portion 2m, and it is desirable to set the temperature difference between the high temperature side region ZAu and the low temperature side region ZAd in the range of 0-50 [℃], but this is not an essential component. Furthermore, the resin can include various resins, including general-purpose resins, engineering plastics, super engineering plastics, composite materials, purging agents, and special resins other than purging agents. In addition, an example has been given of a display processing function unit Fo having a purging agent recommendation display unit 4p provided on the display 4 to indicate that purging agent is needed, but various other means for notifying that purging agent is needed, such as voice (sound) or display means other than a display, can be used. [Industrial Applicability]

[0082] INDUSTRIAL APPLICABILITY The resin change support method and device according to the present invention can be used in various molding machines including injection molding machines that carry out a resin change process in which the resin used in molding is changed from a front resin to a different rear resin. [Explanation of symbols]

[0083] 1: Resin change support device, 2: Heating barrel, 2f: Front, 2m: Middle, 2r: Rear, 3: Molding machine controller, 4: Display, 4p: Purge agent recommendation display section, R: Resin, Rf: Front resin, Rs: Rear resin, Rms: Intermediate material, ηo: Zero shear viscosity, DB1: First database, DB2: Second database, Wu: Purge resin requirement, Fi: MFR input function section, Fs: Viscosity difference calculation function section, Fw: Requirement calculation function section, Fo: Display processing function section, ZAu: High temperature side area, ZAd: Low temperature side area, M: Injection molding machine

Claims

1. a first database for estimating a zero shear viscosity of each resin from a conversion function equation having a melt flow rate (MFR) and a set temperature of the heating barrel as parameters for each different resin, and registering the estimated zero shear viscosity in a molding machine controller as a first database; and a required amount of purged resin using the rear resin, which corresponds to a viscosity difference between the zero shear viscosity of the front resin and the zero shear viscosity of the rear resin, as a second database for registering the estimated zero shear viscosity in a molding machine controller. When performing resin change, the MFR of the front resin and the MFR of the rear resin are input to the molding machine controller to obtain the zero shear viscosity of the front resin and the zero shear viscosity of the rear resin from the first database, and the viscosity difference between the zero shear viscosity of the front resin and the zero shear viscosity of the rear resin, and the required amount of purged resin of the rear resin at the time of resin change from the second database, thereby performing at least display processing.

2. 2. The method for supporting resin changeover in a molding machine according to claim 1, further comprising the step of displaying a message indicating that a purging agent is required when the zero shear viscosity of the subsequent resin is lower than the zero shear viscosity of the previous resin.

3. The method for supporting resin changeover in a molding machine according to claim 1, characterized in that, when the heating barrel is divided into three regions, namely, a front region, a middle region, and a rear region, in the axial direction, the set temperature of the heating barrel is set such that the region before the front region is the high temperature region and the region after the middle region is the low temperature region, and the temperature difference between the high temperature region and the low temperature region is set in the range of 0-50°C.

4. a second database registering a required amount of purged resin using the rear resin corresponding to a viscosity difference between the zero shear viscosity of the front resin and the zero shear viscosity of the rear resin; an MFR input function unit for inputting the MFR of the front resin and the MFR of the rear resin; a viscosity difference calculation function unit for obtaining the viscosity difference between the zero shear viscosity of the front resin and the zero shear viscosity of the rear resin from the first database based on each input MFR; a required amount calculation function unit for obtaining the required amount of purged resin of the rear resin at the time of resin change from the second database based on the obtained viscosity difference; and a display processing function unit for displaying at least the obtained required amount of purged resin.

5. The resin change support device for a molding machine according to claim 4, characterized in that when the zero shear viscosity of the rear resin is lower than the zero shear viscosity of the front resin, the viscosity difference calculation function unit performs processing to output a message indicating that a purging agent is necessary, and the display processing function unit provides a purging agent recommendation display unit on a display to indicate that the purging agent is necessary.

6. 5. The resin change assisting device for a molding machine according to claim 4, wherein the molding machine is an injection molding machine.

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