JP5457396B2 - Temperature distribution correction device for injection molding machines - Google Patents

Description

  The present invention relates to a temperature distribution correction device for an injection molding machine, which is suitable for correcting a temperature distribution when a heating cylinder is heated by a heating unit having a plurality of heaters.

  Generally, in an injection molding machine, in the axial direction of the outer peripheral surface of a heating cylinder, a front heater that heats the front part of the heating cylinder (metering zone), an intermediate heater that heats the middle part of the heating cylinder (compression zone), and the rear part of the heating cylinder A heating section is provided which includes a rear heater for heating the (feed zone) and a nozzle heater for heating the injection nozzle provided at the front end of the heating cylinder, thereby providing a predetermined temperature distribution in the axial direction of the heating cylinder. Thus, temperature feedback control for each heater is performed.

  By the way, the heating cylinder is usually heated to a high temperature of about 200 to 300 [° C.], and the front end and the rear end of the heating cylinder are connected to the cooling part. In particular, the rear end of the heating cylinder is connected to a material supply unit to which the material is supplied. The material supply unit is cooled to a low temperature of about 50 ° C. so that the material being supplied is not melted. Yes. Therefore, the temperature of the feed zone at the rear of the heating cylinder is lowered. As a result, the control amount for the heater is increased, overshoot on the high temperature side occurs in the temperature distribution on the front side of the temperature sensor, and the temperature control in the heating cylinder is normally performed. Even if this is done, the temperature distribution characteristics will be disturbed. Eventually, the occurrence of overshoot will cause the molding material to exceed the melting point in a zone where the molding material should not be melted, leading to a problem that the measurement becomes unstable due to the early start of melting. Further, since the injection nozzle comes into contact with the cooled mold, the same phenomenon also occurs at the front end portion of the injection nozzle at the front end of the heating cylinder. In this case, it may cause resin burning and the like.

  Conventionally, an apparatus that copes with such a problem is also known. Patent Document 1 discloses detection of a temperature sensor that detects the temperature of a heating cylinder in a heating apparatus of an injection molding machine in which a heater is attached to a heating cylinder. Disclosed is a heating device for an injection molding machine provided with temperature correction means for correcting the temperature of a heater at another position on the basis of the position, and Patent Document 2 includes a large number of heaters on the outer circumferential surface in the longitudinal direction. A cylinder, a plurality of temperature detecting means installed at predetermined positions in the same longitudinal direction of the cylinder, and a temperature detecting means for controlling the temperature of two or more heaters as a set in response to a signal from each temperature detecting means; And a cylinder temperature control device that controls the heating temperature of the cylinder for each predetermined region in correspondence with each temperature adjustment means. A cylinder temperature control device has been disclosed in which temperature detection means for directly detecting the cylinder temperature of the heater section is newly provided, and the temperature control region can be selectively changed through appropriate switching means. 3, the feed zone is provided with temperature control parts to which temperature sensors can be detachably attached at a plurality of positions in the cylinder direction, and if necessary, one temperature control part is selected and the temperature sensor is attached, A temperature control device for a heating cylinder of an injection molding machine that can perform different temperature control depending on the selection of the temperature control portion is disclosed. Further, Patent Document 4 discloses the temperature at both axial ends of a plurality of heaters. A plurality of temperature sensors to be measured, a plurality of weight setting devices for setting weight coefficients for the temperatures measured by the plurality of temperature sensors, and a plurality of temperature sensors A plurality of arithmetic circuits for calculating a virtual temperature and a plurality of arithmetic circuits by weighting the measured temperatures at both ends in the axial direction of the plurality of heaters using the weighting coefficients set by the plurality of weight setting units. A heating cylinder temperature control device for an injection molding machine that includes a plurality of temperature controllers that control the temperatures of a plurality of heaters based on the calculated virtual temperature is disclosed.

JP-A-2-55114 Japanese Utility Model Publication No. 2-31716 JP-A-10-34725 JP 2006-341502 A

  However, the conventional apparatuses that deal with the temperature distribution of the heating cylinder have the following problems to be solved.

  First, as a method to eliminate the overshoot that occurs at the rear of the heating cylinder, a method that mainly changes part or all of the rear heater that heats the feed zone or changes the mounting position of the temperature sensor is adopted. Therefore, the original (normal) temperature distribution characteristic necessary for the feed zone is affected. In other words, even if overshoot is eliminated, especially the latter half of the feed zone tends to decline gradually, and the amount of heat is partially insufficient. From the point of view of correcting correctly, it was not always sufficient.

  Second, when it is necessary to change the temperature distribution characteristic of the heating cylinder due to a change in material, a change in molding conditions, or the like, it is not easy to change the temperature distribution characteristic and further optimize it. That is, as described above, since the temperature distribution characteristics are corrected by changing part or all of the rear heater or changing the mounting position of the temperature sensor, the elements that can be changed are limited. . Therefore, there is room for further improvement from the viewpoint of increasing the degree of freedom (flexibility) with respect to change, and further enhancing adaptability and versatility.

  An object of the present invention is to provide an apparatus for correcting temperature distribution of an injection molding machine that solves the problems existing in the background art.

  In the present invention, in order to solve the above-described problem, at least the heating cylinder 2 of the injection device M is heated by the heating unit 3 having a plurality of heaters 3m, 3c, 3f... Arranged along the axial direction Fs. When configuring the temperature distribution correction device 1 of the injection molding machine M that corrects the predetermined temperature distribution generated in the axial direction Fs, the rear heater 3f is disposed behind the rear heater 3f that heats the feed zone Zf in the heating cylinder 2. The temperature of the heating cylinder 2 is arranged between the correction heater 3s having a shorter axial direction Fs length and a higher watt density and the rear end 3fr of the rear heater 3f and the center position of the correction heater 3s in the axial direction Fs. The temperature feedback control is performed based on the correction temperature sensor 4s for detecting the temperature, the temperature (correction detection temperature) Tsd detected by the correction temperature sensor 4s, and the preset correction target temperature Tss. And the control means 5, characterized in that it comprises a.

  In this case, according to a preferred embodiment of the invention, the control means 5 detects the temperature at the intermediate position of the feed zone Zf in the heating cylinder 2 by the rear temperature sensor 4f and presets the detected rear detection temperature Tfd. A control function for performing temperature feedback control based on the rear target temperature Tfs can be provided. On the other hand, the axial direction Fs length of the correction heater 3s is selected to be 1/3 or less of the axial direction Fs length of the rear heater 3f, and the watt density of the correction heater 3s is equal to the watt density of the rear heater 3f. On the other hand, it is desirable to select more than 3 times. Further, the correction temperature sensor 4s can be disposed between the rear end 3fr of the rear heater 3f and the front end 3sf of the correction heater 3s. Furthermore, the correction target temperature Tss can be set to a temperature lower than the rear target temperature Tfs by multiplying the rear target temperature Tfs by a predetermined coefficient Ks. The coefficient Ks is preferably selected in the range of 0.90 to 0.99. On the other hand, the second straightening heater 3ns, which is disposed in front of the nozzle heater 3n for heating the injection nozzle 2n provided at the front end of the heating cylinder 2, has a shorter axial Fs length and a higher watt density than the nozzle heater 3n, and A second correction temperature sensor 4 ns for detecting the temperature of the injection nozzle 2 n in the second correction heater 3 ns is provided, and the temperature detected by the second correction temperature sensor 4 ns (second correction detection temperature) is preset in the control means 5. A control function for performing temperature feedback control based on the second correction target temperature can be provided. Further, it is disposed in front of the intermediate heater 3c for heating the compression zone Zc of the heating cylinder 2 and behind the front heater 3m for heating the metering zone Zm of the heating cylinder 2, and is more than the front heater 3m. A third correction heater 3 ms having a short axial length and a high watt density, and a third correction temperature sensor 4 ms for detecting the temperature of the heating cylinder 2 in the third correction heater 3 ms, A control function for performing feedback control based on the temperature detected by the third correction temperature sensor 4 ms (third correction detection temperature) and a preset third correction target temperature can be provided.

  According to such a temperature distribution correcting device 1 of the injection molding machine M according to the present invention, the following remarkable effects are obtained.

  (1) A correction heater 3s having a shorter axial Fs length and a higher watt density than the rear heater 3f is disposed behind the rear heater 3f for heating the feed zone Zf in the heating cylinder 2, and the heating cylinder Since the feedback control of the temperature with respect to the rear end portion of 2 is performed, a heat insulating wall that interrupts the endothermic action by the material supply portion (cooling portion) can be provided behind the feed zone Zf, so that the cooling with respect to the feed zone Zf is performed. The influence of the temperature of the part can be reduced as much as possible. Therefore, during temperature control, unnecessary overshoot that occurs in the temperature distribution of the feed zone Zf can be eliminated, and more accurate correction can be performed so as to obtain a normal temperature distribution.

  (2) In contrast to the temperature control system for the feed zone Zf of the heating cylinder 2, the temperature at the rear end portion of the heating cylinder 2 is controlled by an independent feedback control system that includes the added correction heater 3s and correction temperature sensor 4s. Therefore, for example, even if it is necessary to change the temperature distribution characteristics due to change of material or molding condition, etc., it can be easily optimized by changing the setting for the correction target temperature Tss, etc. The degree of freedom (flexibility) to change, and adaptability and versatility can be enhanced.

  (3) According to a preferred embodiment, the control means 5 detects the temperature at the intermediate position of the feed zone Zf in the heating cylinder 2 by the rear temperature sensor 4f, and detects the detected rear detection temperature Tfd and the preset rear target temperature Tfs. If the control function for performing feedback control of temperature is provided based on the temperature control of the feed zone Zf, the temperature control of the feed zone Zf is not particularly changed even when the correction heater 3s and the correction temperature sensor 4s are additionally provided. It can be performed stably by feedback control from.

  (4) According to a preferred embodiment, if the axial direction Fs length of the straightening heater 3s is selected to be 1/3 or less of the axial direction Fs length of the rear heater 3f, useless overshoot in the feed zone Zf is prevented. Necessary and sufficient operational effects can be ensured from the viewpoint of eliminating and accurately correcting the temperature distribution so as to have proper temperature distribution characteristics.

  (5) If the watt density of the correction heater 3s is selected to be three times or more the watt density of the rear heater 3f according to a preferred embodiment, useless overshoot in the feed zone Zf is eliminated, and the normal temperature distribution is obtained. Necessary and sufficient functions and effects can be ensured from the viewpoint of accurately correcting the characteristics, and in combination with the selection of the length of the correction heater 3s in the axial direction Fs, a larger function and effect can be expected.

  (6) If the correction temperature sensor 4s is disposed between the rear end 3fr of the rear heater 3f and the front end 3sf of the correction heater 3s according to a preferred embodiment, sufficient operational effects based on the present invention can be ensured, and the correction temperature sensor This can be implemented as the most desirable mode from the viewpoint of optimizing the arrangement position of 4s.

  (7) According to the preferred embodiment, if the correction target temperature Tss is selected to be a temperature lower than the rear target temperature Tfs by multiplying the rear target temperature Tfs by a predetermined coefficient Ks, it is necessary and sufficient based on the present invention. From the standpoint of ensuring a satisfactory operational effect, it is possible to set the optimum correction target temperature Tss and to easily set it.

  (8) According to a preferred embodiment, the second correction heater 3 ns and the second correction temperature sensor 4 ns are provided, and the temperature detected by the second correction temperature sensor 4 ns (second correction detection temperature) is preset in the control means 5. If a control function for performing feedback control of temperature based on the second correction target temperature is provided, correction of the temperature distribution at the front end side of the heating cylinder 2, that is, the front end portion of the injection nozzle 2n is also performed at the rear end portion of the heating cylinder 2. It can be realized in the same manner as the correction of the temperature distribution in the above, and can be corrected to a more desirable temperature distribution characteristic as a whole.

  (9) According to a preferred embodiment, a third correction heater 3 ms and a third correction temperature sensor 4 ms are provided, and the temperature detected by the third correction temperature sensor 4 ms (third correction detection temperature) is preset in the control means 5. If a control function for performing feedback control based on the third correction target temperature is provided, the temperature distribution of the metering zone Zm in the heating cylinder 2 can be controlled more precisely, and the flatness of the temperature distribution characteristics can be further improved. More ideal temperature distribution characteristics can be obtained.

Sectional side view which shows the principal part of an injection molding machine (injection apparatus) provided with the temperature distribution correction apparatus which concerns on suitable embodiment of this invention, Block diagram of temperature control system and corresponding temperature distribution characteristic diagram in the temperature distribution correction device, Temperature distribution characteristic diagram showing the temperature relative to the position from the drop port when using the same temperature distribution correction device, A temperature distribution characteristic diagram showing a temperature with respect to a position from a drop opening when using a device according to the background art Sectional side view which shows the principal part of an injection molding machine (injection apparatus) provided with the temperature distribution correction apparatus which concerns on the modified embodiment of this invention, Block diagram of temperature control system and corresponding temperature distribution characteristic diagram in the temperature distribution correction device,

  Next, preferred embodiments according to the present invention will be given and described in detail with reference to the drawings.

  First, a basic configuration of an injection molding machine M including the temperature distribution correction device 1 according to the present embodiment will be described with reference to FIGS. 1 and 2.

  In FIG. 1, Mi is an injection device, and this injection device Mi and a mold clamping device (not shown) constitute an injection molding machine M. The injection device Mi includes a heating cylinder 2, and the heating cylinder 2 has an injection nozzle 2 n at the front end, and the rear end of the heating cylinder 2 is connected to a material supply unit 11 that supplies a molding material to the inside of the heating cylinder 2. Join. The material supply unit 11 includes a hopper 11h at the upper end, and a lower end port of the hopper 11h communicates with the inside of the heating cylinder 2 through a material dropping hole 11r provided in the vertical direction. The material dropping hole 11r and the heating cylinder 2 positioned below the material dropping hole 11r are cooled as a cooling portion Xc including a cooling water jacket (not shown).

  A heating unit 3 is provided on the outer peripheral surface of the heating cylinder 2 including the injection nozzle 2n. The heating unit 3 includes a plurality of heaters 3n, 3m, 3c, and 3f using band heaters sequentially arranged along the axial direction Fs, that is, a nozzle heater 3n that is mounted on the outer peripheral surface of the injection nozzle 2n (nozzle zone Zn). , Attached to the front part of the heating cylinder 2 to heat the metering zone Zm, the front heater 3m, attached to the intermediate part of the heating cylinder 2 to heat the compression zone Zc, to the rear part of the heating cylinder 2 A rear heater 3f for mounting and heating the feed zone Zf is provided, and each of these heaters 3n, 3m, 3c, 3f is mounted based on a general basic mode for heating the heating unit 3.

  Further, the heating cylinder 2 is provided with a plurality of temperature sensors 4n, 4m, 4c, 4f using thermocouples for detecting the temperature at each heating part. That is, the nozzle temperature sensor 4n that detects the temperature of the injection nozzle 2n at the center position in the axial direction Fs of the nozzle heater 3n, and the temperature of the metering zone Zm in the heating cylinder 2 that is at the center position in the axial direction Fs of the front heater 3m In the heating cylinder 2 which is the middle portion temperature sensor 4c and the middle portion temperature sensor 4c which detects the temperature of the compression zone Zc in the heating tube 2 which is the central position in the axial direction Fs of the middle portion heater 3c, A rear temperature sensor 4f for detecting the temperature of the feed zone Zf is provided. Each temperature sensor 4n, 4m, 4c, 4f is attached by being inserted into a mounting hole formed on the outer peripheral surface of the heating cylinder 2 (injection nozzle 2n).

  On the other hand, a screw 12 is inserted into the heating cylinder 2, and a rear end of the screw 12 extends rearward of the material supply unit 11, whereby the screw 12 is driven to rotate and advance / retreat. Connect to.

  On the other hand, the injection molding machine M includes a molding machine controller 21 that controls the entire system. The heater output ports of the molding machine controller 21 are connected to the heaters 3n, 3m, 3c, and 3f, and sensor input ports. The temperature sensors 4n, 4m, 4c, 4f described above are connected to the above. As shown in FIG. 2, the molding machine controller 21 includes a controller main body 22 having a computer function. The controller main body 22 includes a display 23 for displaying various data (graphic display) and a setting unit 24 for performing various settings. Accompanying. The setting unit 24 is configured by a touch panel input method attached to the display 23.

  Further, the molding machine controller 21 includes a temperature control unit 31 that controls the temperature of the heating unit 3, and the temperature control unit 31 is connected to the controller main body 22. In this case, the temperature control unit 31 includes temperature control units 31f, 31c,... Constituting an independent control system corresponding to the heaters 3f, 3c, 3m, 3n. Therefore, the rear temperature sensor 4f and the rear heater 3f are connected to an arbitrary temperature control unit, for example, the temperature control unit 31f. Thereby, since the rear target temperature Tfs is transferred from the controller main body 22 to the temperature control unit 31f, during temperature control, the rear heater 3f is energized to heat the feed zone Zf, and this temperature is also measured by the rear temperature sensor. 4f is detected as the rear detection temperature Tfd, and independent feedback control for the temperature is performed so that the rear detection temperature Tfd becomes the rear target temperature Tfs. The same control is performed in the remaining temperature control units 31c, 31m, and 31n.

  Next, the configuration of the temperature distribution correction device 1 according to the present embodiment will be described with reference to FIGS. 1 and 2.

  First, the correction zone Zs is secured behind the rear heater 3f, and the correction heater 3s is mounted on the outer peripheral surface of the heating cylinder 2 in the correction zone Zs according to the present invention. In this case, when there is no mounting space for the correction heater 3s behind the rear heater 3f, the rear end side of the rear heater 3f is shortened to secure a mounting space necessary for the correction heater 3s. The axial direction Fs length of the straightening heater 3s is selected to be shorter than the axial direction Fs length of the rear heater 3f, preferably 1/3 or less, and the watt density of the straightening heater 3s is In addition, the watt density of the rear heater 3f is selected to be large, preferably 3 times or more.

  Thus, if the axial direction Fs length of the straightening heater 3s is selected to be 1/3 or less of the axial direction Fs length of the rear heater 3f, unnecessary overshoot in the feed zone Zf is eliminated, The necessary and sufficient effect can be ensured from the viewpoint of accurately correcting so as to obtain the temperature distribution characteristic, and if the watt density of the correction heater 3s is selected to be three times or more the watt density of the rear heater 3f, In addition to eliminating unnecessary overshoot in the feed zone Zf, it is possible to ensure a necessary and sufficient function and effect from the viewpoint of correct accurately so as to obtain a normal temperature distribution characteristic, and to select the length of the corrector heater 3s in the axial direction Fs. As a result, a greater effect can be expected.

  On the other hand, a correction temperature sensor 4s using a thermocouple or the like for detecting the temperature of the rear end portion of the heating cylinder 2 heated by the correction heater 3s is provided corresponding to the correction heater 3s. The correction temperature sensor 4s is provided between the rear end 3fr of the rear heater 3f and the front end 3sf of the correction heater 3s, that is, at the boundary position between the rear heater 3f and the correction heater 3s. The correction temperature sensor 4 s can also be attached by being inserted into a mounting hole formed on the outer peripheral surface of the heating cylinder 2. Incidentally, each of the temperature sensors 4n, 4m, 4c, 4f described above is provided with a general basic mode for detecting the temperature of the heating cylinder 2, that is, by selecting a central position of the axial direction Fs in each heater 3f. In the case of the correction temperature sensor 4s, the correction temperature sensor 4s is attached not at the center position in the axial direction Fs of the correction heater 3s but at the boundary position between the rear heater 3f and the correction heater 3s.

  Thus, if the correction temperature sensor 4s is disposed between the rear end 3fr of the rear heater 3f and the front end 3sf of the correction heater 3s, sufficient operational effects based on the present invention are ensured and the correction temperature sensor 4s is disposed. From the viewpoint of optimizing the position, it can be implemented as the most desirable mode. Although the correction temperature sensor 4s can obtain the best performance when arranged at the boundary position between the rear heater 3f and the correction heater 3s, the axial direction Fs of the correction heater 3s from the rear end 3fr of the rear heater 3f. You may select in the range between center positions. In this case, relatively good performance can be obtained even if the correction effect on the temperature distribution is slightly inferior to the case where it is arranged at the boundary position between the rear heater 3f and the correction heater 3s.

  Further, there is provided a control means 5 that performs temperature feedback control based on a temperature (correction detection temperature) Tsd detected by the correction temperature sensor 4s and a preset correction target temperature Tss. This control means 5 is comprised by the molding machine controller 21 mentioned above. For this reason, the controller body 22 in the molding machine controller 21 is provided with a calculation unit 22a shown in FIG. The internal memory built in the controller main body 22 stores processing programs for executing various control (sequence control) processes and various arithmetic processes for causing the temperature distribution correction device 1 according to the present embodiment to function. On the other hand, the temperature control unit 31 includes a temperature control unit 31s that constitutes an independent temperature control system for the correction heater 3s, and the correction temperature sensor 4s and the correction heater 3s are connected to the temperature control unit 31s. As a result, the correction target temperature Tss is transferred from the controller main body 22 to the temperature control unit 31s. Therefore, during temperature control, the rear end portion of the heating cylinder 2 is heated by energization of the correction heater 3s. Is detected as the correction detection temperature Tsd by the correction temperature sensor 4s, and independent feedback control for the temperature is performed so that the correction detection temperature Tsd becomes the correction target temperature Tss.

  Next, the operation of the temperature control system including the operation (function) of the temperature distribution correction apparatus 1 having such a configuration will be described with reference to FIGS.

  First, the target temperature is input by the setting unit 24. That is, the rear target temperature Tfs is input to the feed zone Zf, and the corresponding target temperatures are similarly input to the other zones Zc, Zm, and Zn. Thereby, each target temperature Tfs... Is set in the controller main body 22. The correction target temperature Tss is automatically set based on the setting of the rear target temperature Tfs, as will be described later. The set target temperatures Tfs are transferred to the corresponding temperature control units 31f. In the temperature distribution characteristic graphically displayed in FIG. 2, Tfs indicates the rear target temperature, and the exemplified rear target temperature Tfs is 220 [° C.].

  On the other hand, if the rear target temperature Tfs of the feed zone Zf is set, the correction target temperature Tss in the correction zone Zs is automatically calculated by the calculation unit 22a. That is, when the rear target temperature Tfs is set, the correction target temperature Tss is calculated by multiplying the rear target temperature Tfs by a predetermined coefficient Ks in the calculation unit 22a. Then, the obtained correction target temperature Tss is set in the controller body 22 and further transferred to the temperature control unit 31s. The coefficient Ks is preferably selected in the range of 0.90 to 0.99. Thereby, the correction target temperature Tss is set to a temperature lower than the rear target temperature Tfs. FIG. 2 illustrates a case where the coefficient Ks is set to 0.97 and the correction target temperature Tss is set to 213 [° C.]. Such correction target temperature Tss may be set manually by an operator. Further, the value of the coefficient Ks can be obtained as an optimum value by experiment or the like for each type of the injection molding machine M. As described above, if the correction target temperature Tss is selected to be a temperature lower than the rear target temperature Tfs by multiplying the rear target temperature Tfs by a predetermined coefficient Ks, the necessary and sufficient operational effects based on the present invention can be obtained. From the viewpoint of ensuring, the optimum correction target temperature Tss can be set and can be easily set.

  On the other hand, at the time of temperature control (during operation), the heaters 3f, 3c, 3m, 3n, 3s are energized by the temperature control units 31f, ... 31s, and the corresponding heating cylinders 2 (injection nozzles 2n) The site is heated. Further, the temperature of each part is detected by the corresponding temperature sensor 4f, 4c, 4m, 4n, 4s, and given to each temperature control unit 31f ..., 31s, independent feedback control for the temperature is performed. . For example, the temperature of the feed zone Zf in the heating cylinder 2 is detected as the rear detection temperature Tfd by the rear temperature sensor 4f disposed at the intermediate position of the feed zone Zf, and is given to the temperature control unit 31f. Since the rear target temperature Tfs is set in the temperature control unit 31f, a corresponding control signal (control amount) is sent from the temperature control unit 31f to the rear heater 3f so that the rear detection temperature Tfd becomes the rear target temperature Tfs. ) Is given. As described above, the temperature at the intermediate position of the feed zone Zf in the heating cylinder 2 is detected by the rear temperature sensor 4f, and the temperature feedback control is performed based on the detected rear detection temperature Tfd and the preset rear target temperature Tfs. If the function is provided, even if the correction heater 3s and the correction temperature sensor 4s are additionally provided, the temperature control of the feed zone Zf should be performed stably by conventional feedback control without any particular change. Can do.

  Also, basically the same feedback control is performed on the correction heater 3s attached to the rear end portion of the heating cylinder 2. That is, the temperature of the heating cylinder 2 is detected as the correction detection temperature Tsd by the correction temperature sensor 4s provided at the boundary position between the rear heater 3f and the correction heater 3s, and is applied to the temperature control unit 31s. Since the correction target temperature Tss is set in the temperature control unit 31s, a control signal (control amount) is sent from the temperature control unit 31s to the correction heater 3s so that the correction detection temperature Tsd becomes the correction target temperature Tss. The feedback control with respect to temperature is performed independently.

  By the way, when the correction heater 3s is not provided, the low temperature (usually about 50 [° C.]) state of the cooling portion Xc directly affects the heating temperature in the feed zone Zf. In this case, due to the endothermic action of the cooling part Xc, in the second half of the feed zone Zf, the temperature is greatly lowered from the middle like a temperature distribution characteristic Ar indicated by a virtual line in FIG. As a result, the amount of control for the rear heater 3f increases, and in particular, the front side of the feed zone Zf from the rear temperature sensor 4f causes a problem that it becomes higher than the set temperature due to the occurrence of an overshoot Are.

  However, according to the temperature distribution correction device 1 according to the present embodiment, the axial Fs length is shorter than the rear heater 3f behind the rear heater 3f that heats the feed zone Zf in the heating cylinder 2, and the wattage Since the correction heater 3s having a high density is disposed and the feedback control of the temperature with respect to the rear end portion of the heating cylinder 2 is performed, the endothermic action by the material supply portion (cooling portion) is blocked behind the feed zone Zf. A heat insulating wall can be provided, and the influence of the temperature of the cooling part on the feed zone Zf can be reduced as much as possible. Therefore, during temperature control, unnecessary overshoot that occurs in the temperature distribution of the feed zone Zf can be eliminated, and more accurate correction can be performed so as to obtain a normal temperature distribution.

  In addition, with respect to the temperature control system for the feed zone Zf of the heating cylinder 2, the temperature at the rear end portion of the heating cylinder 2 is controlled by an independent feedback control system including the added correction heater 3s and the correction temperature sensor 4s. Therefore, for example, even if it is necessary to change the temperature distribution characteristics due to change of material or molding condition, etc., it can be easily optimized by changing the setting for the correction target temperature Tss, etc. The degree of freedom (flexibility) to change, and adaptability and versatility can be enhanced.

  In FIG. 3, the temperature distribution characteristic at the time of using the temperature distribution correction apparatus 1 which concerns on this embodiment is shown in detail. The temperature distribution characteristic Ai shown in FIG. 3 is a case where the temperature distribution correction apparatus 1 according to the present embodiment is provided, and the set temperatures of TS150, TS200, TS250, and TS300 are 150 [° C.] and 200 [° C.], respectively. , 250 [° C.], 300 [° C.]. FIG. 4 shows a temperature distribution characteristic Arp based on the background art, in particular, the first embodiment in Patent Document 1 as a comparative example. That is, when the rear heater of the feed zone is equally divided into two in the front and rear, the watt density in the front and rear is changed, and a rear temperature sensor for detecting the temperature in the feed zone is attached to the central position in the axial direction of the rear heater. There is no correction temperature sensor 4s in the present embodiment. As in the case of FIG. 3, TS150, TS200, TS250, and TS300 show cases where the set temperatures are 150 [° C.], 200 [° C.], 250 [° C.], and 300 [° C.], respectively.

  When comparing FIG. 3 and FIG. 4, the temperature distribution characteristic Ar in the background art shows that overshoot hardly occurs if the set temperature of the feed zone Zf is 150 [° C.], but overshoot as the set temperature increases. Increases to 300 ° C. and + 25 ° C. On the other hand, the temperature distribution characteristic Ai in the present embodiment hardly causes overshoot even if the set temperature is different (higher). Therefore, the temperature distribution correction device 1 according to the present embodiment is optimally used for a molding material having a high melting point, and for example, molding of an engineer plastic having a high melting point is also possible.

  Further, from the tendency of the temperature distribution characteristic Arp of the background art, when the set temperature is 300 [° C.], the overshoot can be eliminated by reducing the set temperature of the feed zone Zf to 260 [° C.]. . However, in this case, the temperature gradient at the rear of the heating cylinder 2 becomes gentle, and as a result, flatness cannot be ensured particularly in the latter half of the temperature distribution characteristic Arp of the feed zone Zf. On the other hand, when the temperature distribution correction device 1 according to the present embodiment is used, the axial direction Fs length of the correction heater 3s is set sufficiently shorter than the axial direction Fs length of the rear heater. Since the watt density of the straightening heater 3s is set sufficiently larger than the watt density of the rear heater 3f, the gradient at which the temperature at the rear end portion of the heating cylinder 2 decreases has a steep characteristic regardless of the set temperature. In addition, it is possible to ensure the flatness of the temperature distribution characteristic in almost the entire area of the feed zone Zf and to ensure the optimum (ideal) temperature distribution characteristic.

  Next, a temperature distribution correction device 1 according to a modified embodiment of the present invention will be described with reference to FIGS. 5 and 6.

  The embodiment shown in FIGS. 1 and 2 described above is disposed behind the rear heater 3f for heating the feed zone Zf of the heating cylinder 2, has a shorter axial Fs length than the rear heater 3f, and A straightening heater 3s having a large watt density and a straightening temperature sensor 4s for detecting the temperature of the heating cylinder 2 are provided between the rear end 3fr of the rear heater 3f and the axial position Fs of the straightening heater 3s. Although the control means 5 which performs feedback control based on the temperature (correction detection temperature) Tsd detected by the temperature sensor 4s and the preset correction target temperature Tss is configured, the modified embodiment shown in FIGS. Shows a configuration based on the same principle applied to the tip portion of the injection nozzle 2n.

  That is, the second correction zone Zns is secured in front of the nozzle heater 3n for heating the injection nozzle 2n provided at the front end of the heating cylinder 2, and the outer peripheral surface of the injection nozzle 2n in the second correction zone Zns is more than the nozzle heater 3n. A second correction heater 3ns having a short axial Fs length and a high watt density is additionally provided, and a second correction temperature sensor 4ns for detecting the temperature of the injection nozzle 2n in the second correction heater 3ns is added. Provide. The control means 5 is additionally provided with a control function for performing feedback control of temperature based on the temperature detected by the second correction temperature sensor 4 ns (second correction detection temperature) and a preset second correction target temperature. .

  If such a second correction heater 3 ns and a second correction temperature sensor 4 ns are provided, correction of the temperature distribution at the front end side of the heating cylinder 2, that is, at the tip portion of the injection nozzle 2 n is also performed at the rear end portion of the heating cylinder 2. It can be realized in the same manner as the correction of the temperature distribution. Therefore, it is possible to correct the temperature distribution characteristic to be more desirable in the entire heating cylinder 2. In the modified embodiment shown in FIGS. 5 and 6, a case where the second correction temperature sensor 4 ns is attached to the center position in the axial direction Fs of the second correction heater 3 ns is illustrated. Since the injection nozzle 2n side does not cause much disturbance (overshoot) with respect to the rear end side of the heating cylinder 2, the arrangement position of the second correction temperature sensor 4ns is not necessarily shown in FIGS. As described above, it is not necessary to dispose at the boundary position between the second correction heater 3ns and the nozzle heater 3n.

  Further, in the modified embodiment shown in FIGS. 5 and 6, a case where the same configuration is applied to the metering zone Zm of the heating cylinder 2 is illustrated. That is, a third correction zone Zms is secured in front of the intermediate heater 3c for heating the compression zone Zc of the heating cylinder 2 and behind the front heater 3m for heating the metering zone Zm of the heating cylinder 2. A third correction heater 3ms having an axial length shorter and a higher watt density than the front heater 3m is additionally provided on the outer peripheral surface of the heating cylinder 2 in the third correction zone Zms. A third correction temperature sensor 4 ms for detecting the temperature of the heating cylinder 2 in the heater 3 ms is additionally provided. Further, the control means 5 is additionally provided with a control function for performing feedback control based on the temperature detected by the third correction temperature sensor 4 ms (third correction detection temperature) and a preset third correction target temperature.

  The application to the metering zone Zm is slightly different in purpose and action from the case of applying to the front end and rear end of the heating cylinder 2 (including the injection nozzle 2n). It can be applied for the purpose of setting more precisely. The third correction heater 3ms and the third correction temperature sensor 4ms are provided, and the temperature detected by the third correction temperature sensor 4ms (third correction detection temperature) and a preset third correction target temperature are provided in the control means 5. If the control function for performing feedback control based on the above is provided, the temperature distribution of the metering zone Zm in the heating cylinder 2 can be controlled more precisely, so that the flatness of the temperature distribution characteristics can be further improved, and more ideal. Temperature distribution characteristics can be obtained.

  In FIG. 6, the temperature distribution characteristic when the temperature distribution correction apparatus 1 according to such a modified embodiment is used is indicated by Ai, and the temperature distribution characteristic when the temperature distribution correction apparatus 1 is not used is indicated by Ar. Show. 5 and 6, the same parts as those in FIGS. 1 and 2 are denoted by the same reference numerals to clarify the configuration, and detailed description thereof will be omitted.

  The preferred embodiment (modified embodiment) has been described in detail above, but the present invention is not limited to such an embodiment, and the present invention is not limited to such a configuration, shape, material, quantity, numerical value, and the like. Any change, addition, or deletion can be made without departing from the scope of the above. For example, the axial direction Fs length of the correction heater 3s is selected to be 1/3 or less of the axial direction Fs length of the rear heater 3f, and the watt density of the correction heater 3s is set to the watt density of the rear heater 3f. On the other hand, it is desirable to select three times or more, but these conditions are not necessarily essential. On the other hand, the correction target temperature Tss is desirably set to a temperature lower than the rear target temperature Tfs. However, the correction target temperature Tss may be set to the same value depending on the form of the injection molding machine M, molding conditions, and the like. The case where the temperature is set higher than the target temperature Tfs is not excluded. Further, various heaters such as a band heater can be applied as the heater, and various temperature detecting means such as a thermocouple can be applied as the temperature sensor.

  The temperature distribution correction device according to the present invention can be used for various types of injection molding machines including a heating unit having a plurality of heaters that generate a predetermined temperature distribution in the axial direction of the heating cylinder.

  1: temperature distribution correction device, 2: heating cylinder, 2n: injection nozzle, 3: heating unit, 3f: rear heater, 3fr: rear end of rear heater, 3s: correction heater, 3sf: front end of correction heater, 3m: front Section heater, 3c: Intermediate heater, 3n: Nozzle heater, 3ms: Third correction heater, 3ns: Second correction heater, 4s: Correction temperature sensor, 4ms: Third correction temperature sensor, 4ns: Second correction temperature sensor, 4f : Rear temperature sensor, 5: control means, M: injection device, Fs: axial direction, Zf: feed zone, Zc: compression zone, Zm: metering zone, Tsd: detected temperature (correction detection temperature), Tss: correction Target temperature, Tfd: rear detection temperature, Tfs: rear target temperature

Claims (9)

  A temperature distribution correction device for an injection molding machine that corrects a predetermined temperature distribution generated in the axial direction when at least a heating cylinder of the injection device is heated by a heating unit having a plurality of heaters arranged along the axial direction. A correction heater disposed behind the rear heater for heating the feed zone in the heating cylinder, having a shorter axial length and a higher watt density than the rear heater, and the correction from the rear end of the rear heater. A correction temperature sensor arranged between the axial center positions of the heaters to detect the temperature of the heating cylinder, a temperature detected by the correction temperature sensor (correction detection temperature) and a preset correction target temperature A temperature distribution correction device for an injection molding machine, comprising: a control unit that performs feedback control.   The control means has a control function of detecting a temperature at an intermediate position of the feed zone in the heating cylinder by a rear temperature sensor and performing temperature feedback control based on the detected rear detection temperature and a preset rear target temperature. The temperature distribution correction device for an injection molding machine according to claim 1.   3. The temperature distribution correction device for an injection molding machine according to claim 1, wherein the axial length of the correction heater is selected to be 1/3 or less of the axial length of the rear heater.   4. The temperature distribution correction device for an injection molding machine according to claim 1, wherein the watt density of the correction heater is selected to be three times or more the watt density of the rear heater.   The temperature correction device for an injection molding machine according to any one of claims 1 to 4, wherein the correction temperature sensor is disposed between a rear end of the rear heater and a front end of the correction heater.   The injection molding according to any one of claims 1 to 5, wherein the correction target temperature is set to a temperature lower than the rear target temperature by multiplying the rear target temperature by a predetermined coefficient. Machine temperature distribution correction device.   The temperature distribution correcting device for an injection molding machine according to claim 6, wherein the coefficient is selected in a range of 0.90 to 0.99.   A second correction heater disposed in front of a nozzle heater for heating an injection nozzle provided at a front end of the heating cylinder, having a shorter axial length and a higher watt density than the nozzle heater, and the second correction heater; A second correction temperature sensor for detecting the temperature of the injection nozzle is provided, and the control means is based on a temperature detected by the second correction temperature sensor (second correction detection temperature) and a preset second correction target temperature. 8. A temperature distribution correcting device for an injection molding machine according to claim 1, further comprising a control function for performing temperature feedback control.   It is arranged in front of the intermediate heater for heating the compression zone of the heating cylinder and behind the front heater for heating the metering zone of the heating cylinder, and has an axial length longer than that of the front heater. A third correction heater that is short and has a high watt density, and a third correction temperature sensor that detects the temperature of the heating cylinder in the third correction heater, and that is detected by the third correction temperature sensor in the control means. The temperature of the injection molding machine according to any one of claims 1 to 8, further comprising a control function for performing feedback control based on a temperature (third correction detection temperature) and a preset third correction target temperature. Distribution correction device.

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