Valve Gate Unit

Abstract

To provide a valve gate unit effective in preventing quality deterioration of a resin molded product.SOLUTION: A valve gate unit 1 that injects a molten resin R into a molding die M includes: a nozzle body 10 having a resin flow path 13 through which the molten resin R flows and a gate 14 for injection as an exit of the resin channel 13; a valve pin 40 provided in the resin flow path 13 of the nozzle body 10 and having a valve body part 42 for opening and closing the gate 14 at a pin tip part 41a; a sensor 50 for temperature measurement built into the nozzle body 10; a heater 60 for heating the molten resin R flowing through the resin flow path 13; and a control part 70 that controls a heating output of the heater 60 based on a temperature measured by the sensor 50. The sensor 50 is built in a valve seat part 15 that contacts the valve body part 42 in the nozzle body 10 when the valve pin 40 closes the gate.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a valve gate unit. [Background technology]

[0002] Conventionally, a valve gate type hot runner mold apparatus has been known as an apparatus for molding resin parts. This hot runner mold apparatus is used, for example, to manufacture resin parts for vehicles, and includes a valve gate unit that injects molten resin into a molding die, and a hot runner manifold that supplies molten resin to the valve gate unit. An example of this type of hot runner mold apparatus is disclosed in the following Patent Document 1.

[0003] The valve gate unit of this hot runner mold machine is provided with a heater built into the valve pin to heat the resin, and a temperature sensor built into the heater. According to this valve gate unit, the current supplied to the heater is adjusted based on the temperature measured by the temperature sensor, and the temperature of the valve pin is controlled. This is intended to maintain good fluidity of the resin. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-21502 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the above valve gate unit, there is a concern that a phenomenon called "cold slug" may occur immediately after the start of molding of a resin molded product. This cold slug is a phenomenon in which a part of the resin is injected in an unmelted state due to a temperature drop caused by heat dissipation from the molten resin, or a resin that was once molten is injected in a cooled and solidified state. This phenomenon can be a factor that affects the quality of the resin molded product.

[0006] To address this problem, a structure in which the temperature of the heater itself is measured by a temperature sensor, as in the valve gate unit disclosed in Reference 1, is effective in controlling the temperature of the valve pin, but it is difficult to prevent the occurrence of cold slug because it is not possible to accurately measure the temperature of the heat dissipation portion that is directly related to the occurrence of cold slug. Therefore, when designing this type of valve gate unit, there is a demand for a technology that takes the occurrence of cold slug into consideration and stabilizes the quality of the resin molded product.

[0007] The present invention has been made in view of the above problems, and aims to provide a valve gate unit that is effective in preventing deterioration of the quality of a resin molded product. [Means for solving the problem]

[0008] One aspect of the present invention is A valve gate unit that injects molten resin into a molding die, a nozzle body having a resin flow path through which the molten resin flows and an injection gate which is an outlet of the resin flow path; a valve pin provided in the resin flow path of the nozzle body and having a valve body portion at a tip of the pin for opening and closing the gate; A temperature measuring sensor built into the nozzle body; a heater for heating the molten resin flowing through the resin flow path; a control unit that controls a heating output of the heater based on the temperature measured by the sensor; Equipped with The sensor is built in a valve seat portion of the nozzle body that comes into contact with the valve body portion when the gate is closed by the valve pin. And, a sensor introduction hole is provided inside the nozzle body and extends from the outside of the nozzle body to the valve seat portion; the sensor is installed in the valve seat through the sensor introduction hole of the nozzle body, and is electrically connected to a sensor connection wire extending from the control unit through the sensor introduction hole; The nozzle body has two half-split divided members that can be assembled to each other, and each of the two divided members is provided with a hole-forming groove into which the sensor introduction hole is divided, and the sensor introduction hole is formed by the two hole-forming grooves when the two divided members are assembled. , valve gate unit, is located. Effect of the Invention

[0009] The valve gate unit of the above-mentioned aspect is used to inject molten resin into a molding die. In the nozzle body of this valve gate unit, the molten resin flows through a resin flow path toward a gate, which is the outlet of the resin flow path. At this time, the gate is opened and closed by a valve body portion of a valve pin provided in the resin flow path of the nozzle body. When the valve body portion of the valve pin abuts against the valve seat portion of the nozzle body to close the gate, the molten resin temporarily stays in the resin flow path. On the other hand, when the valve body portion of the valve pin separates from the valve seat portion of the nozzle body to open the gate, the molten resin is injected from the gate into the molding die.

[0010] In this valve gate unit, the temperature is measured by a temperature sensor built into the valve seat of the nozzle body. The control unit controls the heating output of a heater for heating the molten resin flowing through the resin flow path based on the temperature measured by the sensor. If the sensor is built into the valve seat of the nozzle body, the temperature of the heat dissipation part, which is directly related to the occurrence of cold slug, can be accurately measured. As a result, the occurrence of cold slug can be prevented, and the quality of the resin molded product can be stabilized.

[0011] As described above, according to the above-mentioned aspect, it is possible to provide a valve gate unit that is effective in preventing deterioration of the quality of a resin molded product. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a perspective view partially showing a hot runner die apparatus according to a first embodiment. [Diagram 2] FIG. 2 is a side view of the valve gate unit of the first embodiment. [Diagram 3] 3 is a cross-sectional view showing the valve gate unit of FIG. 2 in a state where the valve pin is in a closed position. [Figure 4] 3 is a cross-sectional view showing the valve gate unit of FIG. 2 in a state where the valve pin is in an open position. [Diagram 5] 3 is a perspective view showing a divided structure of a tip portion of the nozzle body in FIG. 2. [Figure 6] FIG. 4 is an enlarged cross-sectional view showing a tip portion of the nozzle body in FIG. 3. [Figure 7] 5 is an enlarged cross-sectional view showing a tip portion of the nozzle body in FIG. 4. [Figure 8] FIG. 4 is a cross-sectional view of a valve gate unit according to a second embodiment, the cross-sectional view corresponding to FIG. 3. [Figure 9] FIG. 4 is a cross-sectional view of a valve gate unit according to a third embodiment, the cross-sectional view corresponding to FIG. 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Preferred embodiments of the above aspects are described below.

[0014] In the valve gate unit of the above aspect, the heater is preferably built into the valve body portion of the valve pin.

[0015] According to this valve gate unit, by incorporating a heater in the valve body of the valve pin, heating can be performed at a position close to the valve seat, which has a temperature measurement sensor built in. This makes it possible to heat the molten resin temporarily retained in the resin flow path when the gate is closed to a desired temperature quickly and with good responsiveness by the heater based on the temperature measured by the sensor.

[0016] In the valve gate unit of the above aspect, it is preferable that a heater introduction hole extending to the valve body portion is provided inside the valve pin, and the heater is installed in the valve body portion through the heater introduction hole of the valve pin and is electrically connected to a heater connection wiring extending from the control unit through the heater introduction hole.

[0017] According to this valve gate unit, the heater can be installed in the valve body by utilizing the heater introduction hole provided inside the valve pin, and the heater connection wiring can be routed from the heater to the control unit, which simplifies the structure for installing the heater in the valve body of the valve pin.

[0018] In the valve gate unit of the above aspect, when the heater is a first heater, it is preferable that a second heater is provided separately from the first heater, and the second heater is configured to heat the outer surface of the nozzle body.

[0019] According to this valve gate unit, the molten resin flowing through the resin flow path of the nozzle body can be heated by the first heater from the valve pin side provided in the resin flow path, and also by the second heater from the outer surface side of the nozzle body. Therefore, the molten resin flowing through the resin flow path of the nozzle body can be efficiently heated by using both the first heater and the second heater.

[0020] In the valve gate unit of the above aspect, it is preferable that a sensor introduction hole extending from the outside of the nozzle body to the valve seat portion is provided inside the nozzle body, and the sensor is installed in the valve seat portion through the sensor introduction hole of the nozzle body and is electrically connected to a sensor connection wiring extending from the control unit through the sensor introduction hole.

[0021] According to this valve gate unit, the sensor can be installed on the valve seat by utilizing the sensor introduction hole provided inside the nozzle body, and the sensor connection wiring can be routed from the sensor to the control unit, which simplifies the structure for installing the sensor on the valve seat of the nozzle body.

[0022] In the valve gate unit of the above aspect, it is preferable that the nozzle body has two half-split divided members which can be assembled to each other, each of the two divided members being provided with a hole-forming groove into which the sensor introduction hole is divided, and the sensor introduction hole is formed by the two hole-forming grooves when the two divided members are assembled.

[0023] According to this valve gate unit, by providing hole-forming grooves into which the sensor introduction hole is divided in each of the two half-split divided members, the accuracy of the shape and installation position of the sensor introduction hole can be improved compared to when the sensor introduction hole is formed by drilling.

[0024] Hereinafter, an embodiment of a valve gate unit will be described with reference to the drawings.

[0025] In the drawings for explaining this embodiment, unless otherwise specified, a first direction which is the axial direction of the valve gate unit is indicated by an arrow X, a second direction perpendicular to the first direction is indicated by an arrow Y, and a third direction perpendicular to both the first and second directions is indicated by an arrow Z.

[0026] (Embodiment 1) 1, a hot runner mold apparatus (hereinafter simply referred to as "mold apparatus") 100 according to the first embodiment is a valve gate type hot runner mold apparatus. This mold apparatus 100 includes a plurality of valve gate units 1 that inject molten resin R into a molding mold (see "molding mold M" in FIG. 2), and a hot runner manifold 101 that supplies the molten resin R to each valve gate unit 1.

[0027] This mold apparatus 100 is for a multi-point gate having multiple valve gate units 1, and is therefore suitable for molding large resin molded products such as bumpers for automobile parts, for example. The number of valve gate units 1 connected to the hot runner manifold 101 is not particularly limited, and can be changed as necessary.

[0028] As shown in FIG. 2, the valve gate unit 1 includes a nozzle body 10, a resin supplying section 20, a driving section 30, a valve pin 40, sensors 50, 51, and 52 for measuring temperature, and heaters 60, 61, and 62 for heating.

[0029] (Nozzle body 10 structure) 2, the nozzle body 10 is connected to a resin supply section 20 having a resin flow path 21 through which the molten resin R in a molten state flows. The nozzle body 10 is a cylindrical member having a cylindrical shape, and is configured by connecting a body main section 11 and a tip section 12 to each other. The nozzle body 10 has a resin flow path 13 through which the molten resin R flows, and an injection gate 14 which is the outlet of the resin flow path 13. The nozzle body 10 is preferably configured from a metal material such as stainless steel.

[0030] The body main body 11 is a cylindrical member provided on the resin supply unit 20 side of the nozzle body 10. The tip end 12 is a cylindrical member provided on the nozzle body 10 on the opposite side of the resin supply unit 20 across the body main body 11. A circular gate 14 is opened and formed on the end face opposite the body main body 11 among both end faces of the tip end 12 in the first direction X. In addition, the wall portion forming the gate 14 of the tip end 12 is configured as a valve seat portion 15 provided corresponding to the valve body portion 42 of the valve pin 40. That is, the gate 14 and the valve seat portion 15 are provided on the tip end 12 of the body main body 11.

[0031] In a connected state between the body main body portion 11 and the tip end portion 12, the cylindrical space of the body main body portion 11 and the cylindrical space of the tip end portion 12 communicate with each other to form a resin flow path 13 through which the molten resin R flows. This resin flow path 13 communicates with a resin flow path 21 of the resin supply portion 20. Therefore, the molten resin R that flows from the resin flow path 21 of the resin supply portion 20 into the resin flow path 13 of the body main body portion 11 flows toward the gate 14.

[0032] (Valve pin 40 structure) 2, the valve pin 40 is a cylindrical member provided in the resin flow path 13 of the nozzle body 10. The valve pin 40 extends with the first direction X as its axial direction, and has a valve body portion 42 that opens and closes the gate 14 at one end, i.e., a pin tip portion 41a. The valve pin 40 has the other end, i.e., a pin rear end portion 41b, fixed to the end portion 31a of the rod 31 of the drive portion 30. The valve pin 40 is preferably made of the same type of metal material as the nozzle body 10.

[0033] The drive unit 30 is a known piston cylinder type actuator and has a function of reciprocating the rod 31 in the first direction X. Therefore, the valve pin 40 is configured to be able to reciprocate in the first direction X in accordance with the movement of the rod 31. When the valve pin 40 is arranged such that, for example, the pin tip portion 41a faces downward, when the valve pin 40 descends downward in the first direction X to be arranged at the closed position P1, the valve body portion 42 comes into contact with the valve seat portion 15 to close the gate 14. In contrast, when the valve pin 40 rises upward in the first direction X from the closed position P1, the valve body portion 42 moves away from the valve seat portion 15 to open the gate 14.

[0034] Each of the sensors 50, 51, and 52 is configured as a sensor using a thermocouple made of two types of conductors. Thermocouples are well known, and a detailed explanation of their structure will be omitted, but they are configured to generate a voltage proportional to the temperature difference at the tip where the two types of conductors are joined. By detecting this voltage, the temperature at the location where the thermocouple is installed can be obtained. Using a thermocouple that has a simple structure and is inexpensive is effective in keeping the cost of the device low.

[0035] As shown in Fig. 2, the sensor 50 is built into the nozzle body 10, particularly into the valve seat portion 15 of the tip portion 12. The valve seat portion 15 is the tip portion of the tip portion 12 in the first direction X. The sensor 51 is built into a receding portion 16 of the tip portion 12. The receding portion 16 is a position receding from the valve seat portion 15 toward the body main portion 11 in the first direction X, and is a position radially outwardly deviated from the valve seat portion 15. The sensor 52 is built into an annular member provided to circumferentially surround the outer surface 11a of the body main portion 11.

[0036] The heaters 60, 61, and 62 are all intended to indirectly heat the molten resin R flowing through the resin flow path 13 of the nozzle body 10.

[0037] 2, the heater 60 is a heater built into the valve body portion 42 of the valve pin 40. The heater 60 is configured to locally heat the valve body portion 42 of the valve pin 40 from the inside. The heater 60 has a known structure, and a detailed description of its structure will be omitted. However, the heater 60 is configured by accommodating an electric resistance heating type heating wire in a cylindrical case having electrical insulation. The heat transferred from the heater 60 to the valve pin 40 is transferred to the molten resin R flowing through the resin flow path 13, which is the external space of the valve body portion 42 of the valve pin 40, and is used to heat the molten resin R.

[0038] The heater 61 is a cylindrical heater provided so as to cover the outer surface 12a of the tip portion 12 in accordance with the cylindrical shape of the tip portion 12. The entire first zone on the tip side of the nozzle body 10, which corresponds to the tip portion 12, is heated by this heater 61. As a result, the heat transmitted from the heater 61 to the tip portion 12 is transmitted to the molten resin R flowing through the resin flow path 13, which is the cylindrical space of the tip portion 12, and is used to heat the molten resin R.

[0039] Similarly, the heater 62 is a cylindrical heater provided so as to cover the outer surface 11a of the main body portion 11 in accordance with the cylindrical shape of the main body portion 11. The entire second zone on the rear end side of the nozzle body 10, which corresponds to the main body portion 11, is heated by the heater 62. As a result, the heat transmitted from the heater 62 to the main body portion 11 is transmitted to the molten resin R flowing through the resin flow path 13, which is the cylindrical space of the main body portion 11, and is used to heat the molten resin R.

[0040] When the heater 60 built into the valve pin 40 is regarded as a first heater, the heaters 61 and 62 are second heaters provided separately from the first heater, and are configured to heat a part of the outer surface 10a of the nozzle body 10 from the outside. These heaters 61 and 62 are generally called "band heaters" and have the advantage that they can be easily attached to the nozzle body 10.

[0041] The molten resin R flowing through the resin flow path 13 of the nozzle body 10 can be heated by the heater 60, which is a first heater, from the valve pin 40 side provided in this resin flow path 13, and can also be heated by the heaters 61 and 62, which are second heaters, from the outer surface side of the nozzle body 10. Therefore, the molten resin R flowing through the resin flow path 13 of the nozzle body 10 can be efficiently heated using both the first heater and the second heater.

[0042] 3 and 4, a control unit 70 is provided in the valve gate unit 1. The control unit 70 is electrically connected to the drive unit 30, the sensors 50, 51, and 52, and the heaters 60, 61, and 62, respectively.

[0043] The control unit 70 outputs a control signal to the drive unit 30. As a result, the valve pin 40 is controlled to either a closed position P1 (see FIG. 3) where the valve body 42 abuts against the valve seat 15 of the nozzle body 10 to close the gate 14, or an open position P2 (see FIG. 4) where the valve body 42 moves away from the valve seat 15 of the nozzle body 10 to open the gate 14.

[0044] The voltages generated at the thermocouples of the sensors 50, 51, and 52 are detected as temperature information by the control unit 70. The control unit 70 is configured to adjust the currents supplied to the heaters 60 and 61 based on the temperatures measured by the sensors 50 and 51 to control the heating outputs of the heaters 60 and 61. The control unit 70 is also configured to adjust the current supplied to the heater 62 based on the temperature measured by the sensor 52 to control the heating output of the heater 62.

[0045] As shown in Figures 3 and 4, a sensor introduction hole 17 extending from the outside of the tip portion 12 to the valve seat portion 15, and a sensor introduction hole 18 extending from the outside of the tip portion 12 to the retraction portion 16 are provided inside the tip portion 12 of the nozzle body 10.

[0046] The sensor 50 is installed in the valve seat 15 through the sensor introduction hole 17, and is electrically connected to a sensor connection wire 50a extending from the control unit 70 through the sensor introduction hole 17. This makes it possible to use the sensor introduction hole 17 provided inside the tip portion 12 of the nozzle body 10 to install the sensor 50 in the valve seat 15, and route the sensor connection wire 50a from the sensor 50 to the control unit 70. This simplifies the structure for installing the sensor 50 in the valve seat 15 of the tip portion 12.

[0047] The sensor 51 is installed in the retracted portion 16 through the sensor introduction hole 18, and is electrically connected to a sensor connection wire 51a extending from the control unit 70 through the sensor introduction hole 18. This makes it possible to use the sensor introduction hole 18 provided inside the tip portion 12 of the nozzle body 10 to install the sensor 51 in the retracted portion 16, and route the sensor connection wire 51a from the sensor 51 to the control unit 70. This simplifies the structure for installing the sensor 51 in the retracted portion 16 of the tip portion 12.

[0048] 3 and 4, a heater introduction hole 43 extending to the valve body portion 42 is provided inside the valve pin 40. The heater 60 is installed in the valve body portion 42 through this heater introduction hole 43, and is electrically connected to a heater connection wire 60a extending from the control unit 70 through the heater introduction hole 43. This makes it possible to utilize the heater introduction hole 43 provided inside the valve pin 40 to install the heater 60 in the valve body portion 42, and to route the heater connection wire 60a from the heater 60 to the control unit 70. This makes it possible to simplify the structure for installing the heater 60 in the valve body portion 42 of the valve pin 40.

[0049] 5, the tip portion 12 of the nozzle body 10 preferably has two half-split divided members 12A, 12B that can be assembled to each other. Each of the two divided members 12A, 12B is provided with respective hole-forming grooves in a state where the sensor introduction hole 17 is divided into two, and respective hole-forming grooves in a state where the sensor introduction hole 18 is divided into two.

[0050] Regarding the division structure of the tip part 12, specifically, a hole forming groove 17a forming a part of the sensor introduction hole 17 and a hole forming groove 18a forming a part of the sensor introduction hole 18 are formed on the joint end surface of one divided member 12A. The hole forming groove 17a extends from the outside of the tip part 12 to the valve seat part 15, and the hole forming groove 18a extends from the outside of the tip part 12 to the retreat part 16. In contrast, a hole forming groove 17b forming the remainder of the sensor introduction hole 17 and a hole forming groove 18b forming the remainder of the sensor introduction hole 18 are formed on the joint end surface of the other divided member 12B. The hole forming groove 17b extends from the outside of the tip part 12 to the valve seat part 15, and the hole forming groove 18b extends from the outside of the tip part 12 to the retreat part 16.

[0051] For this reason, the tip tip portion 12 is configured such that when the two divided members 12A, 12B are assembled, the joining end faces are brought together, so that the sensor introduction hole 17 is formed by the two hole forming grooves 17a, 17b, and the sensor introduction hole 18 is formed by the two hole forming grooves 18a, 18b.

[0052] By providing hole forming grooves 17a, 17b into which sensor introduction hole 17 is divided, in each of two divided members 12A, 12B, it is possible to improve the accuracy of the shape and installation position of sensor introduction hole 17 compared to the case where sensor introduction hole 17 is formed by drilling. Similarly, by providing hole forming grooves 18a, 18b into which sensor introduction hole 18 is divided, in each of two divided members 12A, 12B, it is possible to improve the accuracy of the shape and installation position of sensor introduction hole 18 compared to the case where sensor introduction hole 18 is formed by drilling.

[0053] Next, the temperature control at the tip portion 12 of the nozzle body 10 will be described with reference to FIGS.

[0054] 6, when the valve pin 40 is in the closed position P1, the flow of the molten resin R in the resin flow path 13 of the tip portion 12 of the nozzle body 10 temporarily stops. As a result, the molten resin R temporarily stays in the resin flow path 13. At this time, the valve seat portion 15 of the tip portion 12 and the valve body portion 42 of the valve pin 40 are both in a high temperature state compared to the molding die M, so heat is dissipated by heat transfer to the molding die M side, which is relatively low temperature. As a result, the molten resin R staying in the resin flow path 13 is likely to be at its coldest in the proximity region 13a that is closest to the valve seat portion 15 and the valve body portion 42.

[0055] If a portion of the molten resin R accumulates in this vicinity region 13a in an unmelted or cooled solidified state, a phenomenon known as "cold slug" may occur in which a portion of the resin is injected in a solidified state toward the molding die M immediately after the start of molding of the resin molded product. This phenomenon may cause the solidified resin to flow onto the design surface of the resin molded product, which may result in a deterioration in the quality of the resin molded product.

[0056] Therefore, in this embodiment, in order to accurately measure the temperature of the heat dissipation portion in the tip portion 12 that is directly related to the generation of cold slug, a sensor 50 is built into the valve seat portion 15 of the tip portion 12 of the nozzle body 10. The valve seat portion 15 is in contact with the adjacent region 13a of the resin flow path 13 and corresponds to the heat dissipation portion. Therefore, the sensor 50 built into the valve seat portion 15 is particularly effective in accurately measuring the temperature of the heat dissipation portion in the tip portion 12. As a result, it becomes possible to accurately determine whether or not the molten resin R retained in the adjacent region 13a is at a temperature at which it solidifies.

[0057] In this embodiment, by incorporating the heater 60 in the valve body 42 of the valve pin 40, heating can be performed at a position close to the valve seat 15 incorporating the temperature measurement sensor 50. Since the valve body 42 is in contact with the proximity region 13a of the resin flow path 13, the molten resin R temporarily retained in this proximity region 13a when the gate is closed can be heated to a desired temperature quickly and with good responsiveness by the heater 60 based on the temperature measured by the sensor 50.

[0058] For example, when the sensor 50 detects that the temperature of the valve seat portion 15 has dropped below the threshold at which the molten resin R in the adjacent region 13a solidifies, the control portion 70 controls the heating output of the heater 60 so as to raise the temperature of the valve body portion 42 of the valve pin 40 to a temperature equal to or higher than the threshold. This makes it possible to perform pinpoint temperature control specialized for the heat dissipation portion of the tip portion 12.

[0059] By preventing the molten resin R from solidifying in the vicinity region 13a, the molten resin R is injected in an unsolidified state through the gate 14 into the molding die M even when the set position of the valve pin 40 is switched from the closed position P1 to the open position P2 as shown in Fig. 7. This prevents the solidified resin from flowing onto the design surface of the resin molded product.

[0060] According to the above-mentioned embodiment 1, based on the above content, the following advantageous effects can be obtained.

[0061] The valve gate unit 1 of the first embodiment is used to inject molten resin R into a molding die M. At the tip portion 12 of the nozzle body 10 of this valve gate unit 1, the molten resin R flows through a resin flow path 13 toward a gate 14, which is the outlet of the resin flow path 13. At this time, the gate 14 is opened and closed by a valve body portion 42 of a valve pin 40 provided in the resin flow path 13. When the valve body portion 42 of the valve pin 40 abuts against the valve seat portion 15 to close the gate 14, the molten resin R temporarily stays in the resin flow path 13. On the other hand, when the valve body portion 42 of the valve pin 40 moves away from the valve seat portion 15 to open the gate 14, the molten resin R is injected from the gate 14 into the molding die M.

[0062] In this valve gate unit 1, the temperature is measured by a temperature measuring sensor 50 built into the valve seat 15. Then, the control unit 70 controls the heating output of a heater 60 for heating the molten resin R flowing through the resin flow path 13, based on the temperature measured by the sensor 50. Here, if the sensor 50 is built into the valve seat 15, the temperature of the heat dissipation portion, which is directly related to the occurrence of cold slug, can be accurately measured. As a result, the occurrence of cold slug can be prevented, and the quality of the resin molded product can be stabilized.

[0063] Therefore, according to the first embodiment, it is possible to provide the valve gate unit 1 that is effective in preventing deterioration in the quality of the resin molded product.

[0064] Hereinafter, other embodiments related to the above-mentioned embodiment 1 will be described with reference to the drawings. In the other embodiments, the same elements as those in embodiment 1 are given the same reference numerals, and the description of the same elements will be omitted.

[0065] (Embodiment 2) As shown in FIG. 8, the valve gate unit 2 of the second embodiment differs from the valve gate unit 1 of the first embodiment in that the valve pin 40 is not provided with a heating means such as a heater 60. The other configurations are similar to those of the valve gate unit 1 of the first embodiment.

[0066] In the valve gate unit 2, the control unit 70 is configured to adjust the current supplied to the heater 61 based on the temperatures measured by the sensors 50 and 51, thereby controlling the heating output of the heater 61.

[0067] According to the valve gate unit 2 of the second embodiment, the structure of the valve pin 40 can be simplified and the number of heaters can be reduced, compared to the valve gate unit 1 of the first embodiment. In addition, the same effects as those in the first embodiment are achieved.

[0068] (Embodiment 3) 9, the valve gate unit 3 of the third embodiment differs from the valve gate unit 1 of the first embodiment in that the sensor 51 is not provided. Therefore, the tip portion 12 of the nozzle body 10 does not have a portion corresponding to the sensor introduction hole 18. The other configurations are similar to those of the valve gate unit 1 of the first embodiment.

[0069] In the valve gate unit 3, the control unit 70 is configured to adjust the current supplied to each of the heaters 60, 61 based on the temperature measured by the sensor 50, thereby controlling the heating output of each of the heaters 60, 61.

[0070] According to the valve gate unit 3 of the third embodiment, the structure of the tip portion 12 of the nozzle body 10 can be simplified and the number of sensors can be reduced, compared to the valve gate unit 1 of the first embodiment. In addition, the same effects as those in the first embodiment are achieved.

[0071] The present invention is not limited to the above-described embodiment, and various applications and modifications are possible without departing from the scope of the present invention. For example, the following embodiments can be implemented by applying the above-described embodiment.

[0072] In the above-described embodiment, an example was given of a case in which the two divided members 12A, 12B that constitute the tip tip portion 12 are assembled to form the sensor introduction hole 17 by the two hole forming grooves 17a, 17b, and the sensor introduction hole 18 by the two hole forming grooves 18a, 18b. However, instead, at least one of the sensor introduction hole 17 and the sensor introduction hole 18 may be formed by drilling. [Explanation of symbols]

[0073] 1,2,3 Valve Gate Unit 10 Nozzle body 10a, 11a, 12a Outer surface of nozzle body 12A, 12B Divided parts 13 Resin flow path 14 Gate 15 Valve seat 17 Sensor insertion hole 17a,17b Hole configuration groove 40 Valve pin 41a Pin tip 42 Valve body 43 Heater introduction hole 50 Sensors 50a Sensor connection wiring 60 Heater (1st heater) 60a Heater connection wiring 61,62 Second heater 70 Control section M Molding Tool R Molten resin

Claims

1. A valve gate unit that injects molten resin into a molding die, a nozzle body having a resin flow path through which the molten resin flows and an injection gate which is an outlet of the resin flow path; a valve pin provided in the resin flow path of the nozzle body and having a valve body portion at a tip of the pin for opening and closing the gate; A temperature measuring sensor built into the nozzle body; a heater for heating the molten resin flowing through the resin flow path; a control unit that controls a heating output of the heater based on the temperature measured by the sensor; Equipped with the sensor is built in a valve seat portion of the nozzle body that comes into contact with the valve body portion when the gate is closed by the valve pin, a sensor introduction hole is provided inside the nozzle body and extends from the outside of the nozzle body to the valve seat portion; the sensor is installed in the valve seat through the sensor introduction hole of the nozzle body, and is electrically connected to a sensor connection wire extending from the control unit through the sensor introduction hole; The nozzle body has two half-split divided members that can be assembled to each other, and each of the two divided members is provided with a hole-forming groove into which the sensor introduction hole is divided, and the sensor introduction hole is formed by the two hole-forming grooves when the two divided members are assembled. This valve gate unit is configured as follows.

2. 2. The valve gate unit according to claim 1, wherein the heater is built into the valve body portion of the valve pin.

3. 3. The valve gate unit according to claim 2, wherein a heater introduction hole extending to the valve body portion is provided inside the valve pin, the heater is installed in the valve body portion through the heater introduction hole of the valve pin, and is electrically connected to a heater connection wiring extending from the control unit through the heater introduction hole.

4. 4. The valve gate unit according to claim 2 or 3, further comprising a second heater provided separately from the first heater when the heater is a first heater, the second heater being configured to heat an outer surface of the nozzle body.

Images