Method and injection molding manifold adapted for leak detection during injection molding

Abstract

An injection molding hot runner system adapted for leak detection during injection molding includes a manifold and a housing surrounding the manifold, the manifold and the housing being spaced apart to define one or more pockets, the manifold having at least one junction point establishing a connection to a component attached to the manifold, and a sensor positioned within the pocket at the at least one junction point, the sensor configured to indicate a leak upon contact with molten plastic due to a leak at the junction point.

Description

Technical Field

[0001] This application claims the benefit of U.S. Application No. 16 / 802,874, filed on Feb. 27, 2020, which is hereby incorporated by reference in its entirety.

[0002] The present invention relates to an injection molding machine, and more particularly to an improvement in an injection molding machine of a type having a nozzle attached to inject pressurized molten plastic into a mold cavity through a hot runner system adapted for leak detection during injection molding.

Background Art

[0003] Generally, such injection molding machines use a manifold having one or more nozzles. The nozzles are sealed or fit tightly to prevent leakage of molten plastic between the nozzle and the sprue bushing. However, among other things, there are known recurring problems of such leakage, including insufficient delivery of plastic into the mold, loss of proper pressure, material waste, damage to the high-sensitivity control units and components of the molding machine due to the high temperature of the leaking molten plastic material, and attendant problems including resulting machine downtime for repair and scrapping of high-quality finished parts. Nozzle leakage mainly occurs at the mating surface of the nozzle end cap, but is known to occur at other locations associated with the nozzle, such as at the inlet nozzle to the manifold that delivers molten plastic to the nozzle. Depending on the location where the nozzle leakage occurs and the rate of leakage, the leaking molten plastic can flow along various different paths or routes. For example, in one type of leakage, the molten plastic rapidly spreads or bulges into the air space surrounding the nozzle heater from the nozzle end cap. Other leaks are of the slow glistening type that actually adhere to the nozzle and gradually reach the length of the nozzle, eventually covering the nozzle or reaching the high-sensitivity areas associated with the operation of the molding machine.

Summary of the Invention

Problems to be Solved by the Invention

[0004] Therefore, it would be highly desirable to provide means for detecting leaks associated with the nozzles of such molding machines so that appropriate measurements can be initiated before facing damage to expensive parts or excessive scrap parts of the molding machine.

Means for Solving the Problems

[0005] The problem is solved by an injection molding hot runner system according to the claims.

[0006] An injection molding hot runner system adapted for leak detection during injection molding comprises a manifold and a housing surrounding the manifold. Further components of this hot runner system are an inlet nozzle and an outlet nozzle(s). The manifold can have different structures and components. The manifold can have one or more nozzles and interconnecting surfaces / bores for actuators (to open or close) that drive the nozzles. Also, the manifold can be made from one or more sub-manifolds that are connected to each other at inner joints. The manifold includes internal channels through which molten plastic is transferred to the nozzles. The nozzles are connected to the channels. Further, the manifold is surrounded by the housing. The manifold and the housing are spaced apart to define one or more pockets. The pockets are defined by the space between the outer wall of the manifold and the inner wall of the housing. A support in the form of struts defines a space between the manifold and the housing. The housing can be made from several plates. The manifold includes one or more joints that establish connections to one or more components attached to the manifold. These components can be nozzles, inlet nozzles, inlet lines for plastic, actuators that drive the nozzles, other manifolds / sub-manifolds. At least one sensor can be positioned within the pockets at each joint. The sensor is preferably positioned near the joint so that molten plastic leaking into the joint is detected. In a preferred embodiment, the sensor is positioned such that it is not affected by the properties of the housing or the manifold. For example, the sensor can be positioned such that heat or expansion of the housing or the manifold does not cause false leak alarms.

[0007] Furthermore, the sensor is configured to indicate a leak when it comes into contact with molten plastic due to a leak at the joint.

[0008] In a possible embodiment, the joint is a bore for attaching a support strut spaced from the manifold and the housing. The bore may be due to cracks, fatigue or quality variations of the components and may extend into the manifold, and molten plastic may enter the pocket through the bore. Also, the support may be positioned near the bore of another component, such as a nozzle, and can serve as a support for the sensor. In this case, the support has two functions. One function is for defining the spacing, and the other is for supporting or holding the sensor.

[0009] Another joint is a bore in the manifold or housing for attaching an injection nozzle. The injection nozzle has its inlet connected to the manifold and the channels within the manifold. The nozzle is connected to the bore in the manifold via a nozzle shank. This connection can use threads and sealing. It is conceivable that leakage may occur in the nozzle shank due to sealing defects, and molten plastic may flow out and enter the pocket. The injection nozzle enters the mold through the pocket and into the opening / bore of the housing. The end cap of the nozzle, or the interface between the end cap and the mold at the parting line, can also be a cause of leakage. Also, this area can be defined as a joint for positioning the sensor.

[0010] Another joint can be a bore in the manifold or housing through which a hydraulic, electric or pneumatic actuator that drives the injection nozzle to open and close extends. A valve pin linearly driven by the actuator presses the needle of the nozzle to open or close the nozzle. The valve pin extends through the bore of the manifold to the nozzle. If the seal (either inside for the valve pin or outside for the manifold) does not function well, molten plastic may leak and enter the pocket.

[0011] It can be inferred from the above that the joint can be a joint, thread or interconnecting surface where parts are assembled and leakage can occur, and molten plastic can leak from them.

[0012] In a possible embodiment, the bore of the housing in which the nozzle heater is located communicates with the pocket, so that molten plastic reaches into the pocket due to leakage at the tip of the injection nozzle. The molten plastic flows between the housing wall and the nozzle heater and enters the pocket. In a possible embodiment, a sensor around or on the nozzle heater can detect the flow of molten plastic due to leakage.

[0013] In a possible embodiment, the sensor is one or more of the following, namely, a temperature sensor, a mechanical switch, a temperature coil, a contact sensor, an optical sensor, a pressure sensor, an inductive sensor, a capacitance sensor, a resistance sensor, and a piezoelectric sensor.

[0014] The temperature sensor can detect a temperature deviation compared to normal conditions. In case of leakage, the hot plastic may cause a temperature increase in the pocket compared to the standard temperature. Preferably, leakage can be detected when a preset threshold value is exceeded at a predetermined time of the process. The threshold value can be defined as a function of time.

[0015] The mechanical switch can establish or interrupt a power line when physically contacting the molten plastic. When the temperature increases due to the molten plastic surrounding the coil from the outside, the coil may change its electrical characteristics. For example, the heating coil of the nozzle heater may have a different resistance when surrounded by molten plastic, or require different power / current to heat the nozzle. A deviation in current from normal conditions can be detected and leakage can be indicated.

[0016] Another sensor can be a contact sensor. The contact sensor can be an electrical / optical sensor or a mechanical sensor that is activated when leaking plastic contacts the sensor. By mechanical it is meant that a mechanical element is pushed or bent to activate a switch. By optical it is meant that the light beam or window of the sensor is covered so that the light beam cannot pass through.

[0017] Also, an optical sensor that indicates that a specific area or path is covered by leaking plastic can be used. The optical sensor includes a light source and a detector that detects a specific light pattern, and the specific light pattern cannot be recognized when leaking plastic extends into the space between the light source and the detector. Also, a laser sensor that detects a specific distance measured by a laser can be used, and the laser is blocked by leaking plastic.

[0018] In a possible embodiment, the optical sensor is a fiber sensor that exhibits different light distribution when in contact with molten plastic. The fiber can be covered, broken, or bent, and can cause different light distribution or internal reflection.

[0019] Another example of a sensor can be a pressure sensor or a piezoelectric sensor that measures the pressure exerted by leaking plastic in a pocket. When leaking plastic is pushed into the pocket, a pressure change can be detected and a signal can be generated. The pressure sensor can be implemented as a piezoelectric sensor or another type of pressure sensor. Also, an inductive sensor can be used, and the inductive sensor measures the capacitance change due to the sensor being surrounded by liquid plastic. A resistance sensor or a frequency / alternating current resistance sensor that measures the resistance between two points / electrodes in a pocket can be used. When leaking plastic extends between two points, a different resistance can be measured to indicate that a leak is occurring.

[0020] In a possible embodiment, the temperature sensor is connected to the upper wall of the pocket and extends into the space of the pocket from above. By this hanging attachment, it is possible to minimize the influence of the housing or the manifold on the position in the middle of the space defined by the pocket. The front part of the sensor has an L shape, so that the tip of the sensor extends downward into the pocket. In a possible embodiment, the front part is insulated to avoid heat from the manifold that affects the temperature sensor.

[0021] In a possible embodiment, the temperature sensor is insulated to reduce the temperature influence of the housing and the manifold. An insulating material surrounds the sensor. In a preferred embodiment, only the tip of the sensor extends freely into the pocket. The insulating material holds the sensor in its position and protects the sensor from the heat radiation of the housing and the manifold. Also, the sensor can be positioned within a metal plate sandwiched between insulating materials. The metal plate includes a bore in which the sensor is positioned. The tip of the sensor is positioned within an enlarged bore having a relatively large diameter.

[0022] In a possible embodiment, the temperature sensor is insulated by a ceramic component. Other materials that are heat resistant, such as those based on aluminosilicates, can be selected.

[0023] In a possible embodiment, the insulating material surrounds a support strut and the temperature sensor is attached to the insulating material. The attachment part can be a bore through which the sensor extends. Also, the strut can be made of a material having a relatively low thermal conductivity compared to the manifold. For example, the support strut is made of a metal having a lower thermal conductivity than the metal / steel of the manifold and / or the housing. Also, the support strut can itself be made of a ceramic compound.

[0024] In a possible embodiment, the insulating material has a tubular form with an internal bore in which the strut is positioned and supported. The tubular wall includes a bore along a secant line, and the sensor is positioned parallel to the radius within this bore.

[0025] In some possible embodiments, several sensors are positioned within one tubular insulator. Preferably, the sensors are positioned on opposite sides of a support strut.

[0026] In some possible embodiments, a temperature sensor is configured to detect a temperature deviation when in contact with molten plastic passing through a leak. The sensor is connected to a controller that stores a threshold or parameter curve indicating a leak. The curve can be time-related and / or process-related. The curve can indicate that the sensor value needs to be less than a certain value at a specific point in time / process time.

[0027] In some possible embodiments, a nozzle assembly includes a nozzle shank that is fastened to a manifold. The shank can be screwed into the manifold by using threads. A tubular heater connected to the shank extends within a bore of a housing. In some possible embodiments, a temperature sensor is positioned within a pocket near the tubular heater and the nozzle shank. The shank is partially positioned within the pocket. This location enables the sensor to detect leaks at various different positions.

[0028] In an alternative embodiment, an injection molding hot runner system adapted for leak detection during injection molding is disclosed. The hot runner system includes a manifold and a housing surrounding the manifold, with the manifold and the housing being spaced apart to define one or more pockets. A nozzle assembly extends from the manifold through the pocket and through a bore of the housing. A nozzle end cap is connected to a mold. The nozzle establishes a connection between the manifold and the mold and extends through the housing. The nozzle assembly includes a nozzle heater positioned within the bore. A sensor is positioned within the bore through which the nozzle heater extends to detect leaking plastic being pushed through the bore.

[0029] This embodiment also uses the sensors described above, i.e., the sensors are one or more of the following, namely, temperature sensors, mechanical sensors, mechanical switches, temperature coils, contact sensors, optical sensors, pressure sensors, inductive sensors, capacitance sensors, resistance sensors, and piezoelectric sensors.

[0030] In a possible embodiment, the sensor is positioned on or in the nozzle heater or at the upper end of the nozzle heater.

[0031] In a possible embodiment, the sensor is positioned in the groove or on the outer shell of the nozzle heater. This groove can be circumferential or longitudinal. A temperature sensor can be positioned in the groove to detect leaking plastic that is pressed between the bore in the housing and the nozzle and is pushed towards the nozzle shank.

[0032] In another embodiment, the sensor is positioned in a pocket near the bore in the housing through which the nozzle assembly extends. The sensor can detect the moment when the leaking plastic enters the pocket, i.e., when the plastic enters the pocket through the bore.

[0033] The heating coil used by the heater can also be used as a leak sensor. The controller analyzes the current required to drive the heater to a specific temperature. If the current needs to deviate from a predetermined standard value stored by the controller, the controller indicates a leak. A leak can be detected when the current used to drive the heating coil exceeds a preset threshold at a specific time of the process.

[0034] In a possible embodiment, the mechanical sensor is configured to indicate a leak when in contact with the molten plastic. The mechanical sensor is a switch configured to close and / or open when in contact with the molten plastic. In a possible embodiment, the mechanical sensor is a wire configured to break when in contact with the molten plastic. The wire can be a wire mesh that surrounds the nozzle heater or nozzle assembly and can change its resistance when in contact with the leaking plastic due to deformation or breakage of the wires of the mesh. The mesh can also trigger a mechanical sensor connected to the mesh to indicate a leak if there is a displacement of the mesh.

[0035] In a possible embodiment, the mechanical sensor has the form of a tube positioned around a nozzle assembly and configured to establish contact when pushed by the molten plastic. The tube surrounds the nozzle assembly within the bore of the housing. When the molten plastic reaches into the bore, the tube is pushed and repositioned within the bore, whereby a sensor connected to the tube or capable of detecting the repositioning can indicate a leak.

[0036] The above and further advantages of the present invention can be better understood by reference to the following description in conjunction with the accompanying drawings.

Brief Description of the Drawings

[0037]

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Best Mode for Carrying Out the Invention

[0038] Figure 1a shows a cross-sectional view in a hot runner system, showing a nozzle connected to a manifold and extending through a housing to a mold. The manifold is surrounded by a housing consisting of several plates. These plates may include a fixed plate and an upper clamp plate, both positioned above the manifold. Further, the housing includes one or more manifold plates positioned on the sides of the manifold. Below the manifold are a plate A and a plate B. A mold is positioned between the two plates, and parts are manufactured within this mold. The plate A and the plate B are divided by a parting line. In the plate B, a cavity insert is positioned, defining the mold. Between these plates, a manifold support including an upper support and a lower support is positioned, defining a space between the housing / plates and the manifold. This space is also called a pocket. A sensor can be positioned within this pocket. Also, a tubular heater positioned in a groove within the manifold is accessible through the pocket. A in Figures 1a and 1b indicates a possible location for the sensor.

[0039] The nozzle end cap of the nozzle abuts against the mold at the lower end of the A plate. The end cap seals the nozzle tip in the A plate, also called the gate region, against the mold. The nozzle includes a nozzle heater positioned within the bore of the A plate, and this nozzle heater extends into the pocket. If there is a leak at the end cap, molten plastic may be pushed through the bore and into the pocket, potentially surrounding the nozzle heater.

[0040] Figure 1b shows a mechanical nozzle having a mechanical nozzle tip at the inlet nozzle of the manifold in a possible embodiment. When the injection machine injects, the mechanical nozzle opens and the inlet nozzle opens, and plastic extends into the manifold towards the nozzle(s). Also, the mechanical nozzle has a heater, a shank, and a mechanical nozzle tip. A positioning ring by which the mold is aligned thereby takes care of accurate mold positioning. The nozzle, inlet, and outlet can all be sources of leakage because several parts are assembled via an interconnecting surface. Fixing in the manifold can also be a source of leakage. Figure 1b shows a cross-sectional view in a hot runner system showing a mechanical nozzle that controls the introduction of molten plastic into the manifold.

[0041] Figures 2a and 2b show the joints of the devices of Figures 1a and 1b where leakage can occur. As can be seen from Figure 2a, the inner joint for the nozzle shank (outlet) to the manifold can be a leakage region. Thus, a sensor positioned within this region can quickly detect leakage. The end cap on the inner side of the nozzle shank is a possible leakage region. Similarly, the gate region and the outer joint between the end cap and the mold are possible leakage regions, which can cause plastic to leak from the mold into the bore of the nozzle in the A plate. For the inlet nozzle (Figure 2b), the possible leakage regions are the inner joint between the inlet nozzle and the manifold and the outer joint between the mechanical nozzle tip and the inlet nozzle. The nozzle itself can also leak.

[0042] Figure 3 shows a cross-sectional view of the nozzle tip inside the shank. The end cap and the nozzle tip include an inner joint and an outer joint. The inner joint closes the nozzle by sealing against the shank / tip. The tip is positioned within the shank. The outer joint seals the end cap against the mold. If these joints are not properly fixed, they can both be a source of leakage.

[0043] Figure 4 shows a cross-sectional view of a larger hot runner assembly consisting of two manifolds joined together that can create possible leakage areas. This inner joint between one manifold and the other can cause leakage. Further, shown is a hydraulic, electrical, or pneumatic actuator that drives the (exit) nozzle by means of a pin and extends through the manifold, creating a possible additional leakage area. The pin is moved by the actuator and extends into the manifold towards the tip or retracts from the manifold. The joint of the pin is sealed by a sleeve seal. The seal has its outer side in contact with the manifold and its inner side in contact with the pin. Both of these contact areas can be leakage areas.

[0044] Figures 5a and 5b show the arrangement of temperature sensors attached to support struts that are insulated and sandwiched between ceramic insulation materials. Figure 5a shows a cross-sectional view of two spaced support struts. A sensor is positioned between the two support struts as can be seen from Figure 5b. The sensor is positioned within the bore of a steel plate. The steel plate is sandwiched between two ceramic plates that insulate the sensor from the manifold and the plate / housing. Figure 5b shows that the tip of the sensor (TC probe) is positioned within an enlarged bore that provides a space around the tip where leaking plastic can reach, thereby enabling a higher quality sensor value.

[0045] Figures 6a and 6b show the arrangement of a temperature sensor attached to a support strut that is insulated, with the sensor surrounding the support strut in the insulator. The support strut is surrounded by a tubular ceramic insulator. The insulator includes two bores (one bore is also possible) in which the sensor (TC probe) is held. The bores extend in the form of a secant line through the insulator. The tip of the sensor is outside the insulator.

[0046] Figure 7 shows in cross-section the arrangement of a temperature sensor in a pocket, with the manifold affecting the sensor (TC). The front part of the sensor is bent downward so that the tip of the sensor is positioned in the center of the pocket, or near the nozzle shank and near the bore in the housing through which the heater extends, at least spaced apart from the manifold and the housing. When leaking plastic is pushed through the bore and into the pocket, contact of the tip with the surface of the plastic provides ideal temperature information.

[0047] Figure 8 is a diagram showing the temperature deviation in the event of a leak in the hot runner system or in the mold, as measured by a temperature sensor in the pocket. The diagram shows various different temperature curves over a certain time period. This time period represents an operating cycle. The start of a heating phase is shown, where the temperature in all components rises at the beginning of the operating cycle. The temperature in the hot runner system (manifold) and in the mold also rises. The temperature in the mold is generally lower than that in the hot runner system itself. The dotted line shows the temperature measured by the leak temperature sensor at various different positions. The leak temperature sensor that measures a relatively high temperature is preferably positioned in the pocket as shown in Figures 9a and 9b. The leak temperature sensor that measures a relatively low temperature is preferably positioned near the mold, for example, in the bore of the nozzle in the A plate. In the case of a temperature peak, the controller connected to the sensor stops the operation of the heating system, turns off the power of the heating system or at least gives an alarm.

[0048] Figures 9a and 9b show in cross-section two different arrangements of temperature sensors within the pocket. In one arrangement, the second sensor 2 is attached to a support strut adjacent to the bore of the housing, and the first sensor 1 is fixed to the manifold and extends into the pocket parallel to the manifold. The first sensor measures the temperature of the manifold near a tubular heater attached to the manifold. This sensor can be the sensor in FIG. 8 that measures the temperature of the hot runner system. The second sensor can be a leak detection sensor that measures a relatively high temperature indicated by a dotted line. The sensors are connected to struts made of a metal (steel) with a relatively low thermal conductivity. In the case of a leak as disclosed in FIG. 9b, a temperature peak can be measured at the second sensor as shown in FIGS. 8 and 11. Generally, the manifold temperature is equivalent to the nozzle and inlet nozzle temperatures, which are the highest temperatures. The curve also shows this (T° hot runner). The leak thermocouple indicates the temperature between the manifold temperature and the mold temperature (leak detection in the hot runner).

[0049] Figures 10a and 10b show an embodiment in which the sensor is wound around the support strut and fixed by a clip. The TC probe, which is the sensor, also partially passes through the bore in the support strut and the tip is exposed.

[0050] Figure 11 shows a time-temperature diagram related to the temperature sensors in FIGS. 9a and 9b and the sensor information of the second sensor 2 in the case of a leak. If the temperature difference between the hot runner temperature and the leak detection sensor is less than a predetermined threshold and a leak is detected at a specific point in the manufacturing process, the manufacturing process is stopped.

[0051] Figure 12 shows a sensor (TC) in a nozzle heater sleeve that surrounds the nozzle heater and contacts the molten plastic in case of leakage at the tip of the nozzle / nozzle cap or the mold itself. The sensor can be positioned within the groove of the sleeve or in the sleeve itself. Parallel to the sensor TC for heater control, a sensor for controlling heat detection can be installed. This sensor is positioned near the nozzle end cap so that leakage molten plastic in the mold or end cap can be easily detected.

[0052] Figure 13 shows a mechanical sensor in the form of a sleeve surrounding the heater that is pushed up or down depending on the location of the leak. The position of the sleeve can be defined. When the sleeve is pushed and displaced by the molten plastic, an alarm can be triggered. The position sensor can be an optical sensor, an electrical sensor, or a mechanical sensor that indicates the displacement of the sleeve. Also, the sleeve can be fixed in a specific location and push the plastic into a specific path by the direction of the plastic flow, whereby the plastic can be diverted to a sensor, such as a heat sensor.

[0053] Figure 14 shows a time - temperature relationship diagram in the case of leak detection by the temperature sensor of Figure 12, positioned around the heater sleeve. In case of a leak, the temperature measured in the sleeve rises and the process is stopped (i). The reverse situation is depicted by the dotted line (j).

[0054] Figures 15a and 15b show an embodiment of the mechanical sensor of FIG. 13 where the sleeve is pushed upward by leaking plastic and activates the switch. When the sleeve is pushed upward by leaking plastic, the mechanical switch is triggered, the movement of the sleeve is detected, and the process is processed by the controller to stop. In FIG. 15b, the gap and the flange of the sleeve are shown such that only a very small portion of the sleeve contacts the heater and a relatively large portion of the sleeve is spaced apart, creating a heat-insulating gap.

[0055] Figures 16a and 16b show an optical fiber including grooves that can be covered and filled with molten plastic and that block or reduce the light passing through the optical fiber. Glass fibers extend axially along the heater (radial arrangement is also conceivable), include a plurality of grooves, and in normal operation, light can pass through / across these grooves. When the grooves are filled with plastic, the light cannot pass through or only a limited amount of light can pass through, which is a sign of leakage.

[0056] Figure 17 shows a mesh surrounding the heater of the nozzle that is bent or broken when pushed by leaking molten plastic, changing the resistance of the mesh. This can be detected by a controller connected to the mesh.

[0057] Figures 18a and 18b show an example of a metal contact that is broken due to plastic being pushed into the pocket. A thin metal wire can be stretched between the contact points. When the molten plastic breaks the wire, the metal contact is interrupted, and leakage can be detected due to the interrupted contact. The same technique can be used with thin metal (copper, iron, etc.) plates.

[0058] The present invention has been described by way of example. It should be understood that the terms used are intended to be of an illustrative nature rather than limiting nature. In view of the above teachings, many changes and modifications of the present invention are possible. Therefore, the present invention may be practiced otherwise than as specifically described.

Explanation of Reference Signs

[0059] Possible locations of sensor A 1 Fixed platen 2 Upper clamp plate 3 Upper support 4 Manifold 5 Tubular heater 6 Manifold plate 7 Nozzle shank 8 Nozzle heater 9 End cap 10 A plate 11 Molding part 12 Parting line 13 Cavity insert 14 B plate 15 Machine nozzle 16 Machine nozzle tip 17 Positioning ring 18 Inlet nozzle heater 19 Inlet nozzle 20 Lower support 21 Gate area 22 Ceramic or heat insulator 23 Steel plate 24 TC probe 25 Heat insulator / ceramic 26 Possible leakage area 27 Inner joint of shank and tip 28 Outer joint of end cap and mold 29 Spacer 30 Low T° conductivity steel (iron, titanium) 31 High T° conductivity steel 32 Hot runner e.g. 280°C 33 Mold e.g. 80°C 34 Leakage of molten plastic 35 TC probe wound around a support or fixed with a clip 36 TC probe for heater control 37 Position of the sensor for leakage detection 38 Switch for detecting movement 39 Sleeve pushed upward by plastic leakage 40 Insulating air 41 Leakage guide sleeve for passing plastic towards the TC 42 Glass optical fiber 43 Groove that diffuses light differently when in contact with leaking plastic 44 Mesh that changes resistance or capacitance and shows different behavior when plastic flows by or is moved by plastic 45 Molten plastic that opens an electrical circuit 46 Thin sheets of iron and copper 47 Inner joint of the manifold with the manifold 48 Inner joint sleeve seal for the valve pin that contacts the valve pin (inner) and the manifold (outer contact area) 49 Hydraulic, electrical or pneumatic actuator 50 Sleeve seal 51 Valve pin 52 Outer joint of the gate area and the end cap with the mold 53 Inner joint of the end cap inside the shank 54 Inner joint of the nozzle shank with the manifold 55 Outer joint of the mechanical nozzle tip with the inlet nozzle 56 Inner joint of the inlet nozzle with the manifold

Claims

1. An injection molding hot runner system adapted for leak detection during injection molding, said hot runner system having a manifold and a housing surrounding said manifold, said manifold and said housing being spaced apart to define one or more pockets, said manifold having one or more joints establishing connections to components attached to said manifold, in at least one joint region, a sensor being positioned within said pocket, said sensor being configured to indicate a leak when contacting molten plastic due to a leak at said joint, said sensor being a temperature sensor insulated to reduce the temperature influence of said housing or said manifold, said temperature sensor being positioned between an upper insulator and a lower insulator, injection molding hot runner system.

2. Said joint is a bore or thread within said manifold for attaching an inlet or injection nozzle, a manifold joint connecting two manifold parts, a bore within said manifold through which a hydraulic, electrical or pneumatic actuator for driving said injection nozzle extends one or more of which, the injection molding hot runner system according to claim 1.

3. Said injection nozzle extends through a bore of said housing from said manifold, said bore of said housing communicating with said pocket, whereby, due to a leak at said injection nozzle, molten plastic is within said pocket and detectable by said sensor positioned within said pocket at said bore, the injection molding hot runner system according to claim 2.

4. Said sensor is connected to a support spaced apart from said manifold and said housing, the injection molding hot runner system according to claim 2.

5. The injection molding hot runner system according to claim 1, wherein the housing has a plurality of plates that define the housing.

6. The injection molding hot runner system according to claim 1, wherein the temperature sensor is connected to the upper wall of the pocket.

7. The injection molding manifold assembly according to claim 1, wherein the temperature sensor is thermally insulated by ceramic.

8. The injection molding hot runner system according to claim 1, wherein the thermal insulator surrounds a support, and the temperature sensor is attached to the thermal insulator.

9. The injection molding hot runner system according to claim 1, wherein the temperature sensor and the temperature reading device are configured to detect a temperature deviation when in contact with the molten plastic passing through the leak.

10. The nozzle assembly has a nozzle shank within or attached to the manifold, and the temperature sensor is positioned near the lower or upper end of the manifold near the nozzle shank or the inlet nozzle. The injection molding hot runner system according to claim 2.

11. An injection molding hot runner system adapted for leak detection during injection molding, the hot runner system having a manifold and a housing surrounding the manifold, the manifold and the housing being spaced apart to define one or more pockets, a nozzle assembly extending from the manifold through the pockets and through the bore of the housing, the nozzle assembly having a nozzle heater positioned within the bore, and a sensor positioned within the bore through which the nozzle heater extends for detecting leaking plastic being pushed through the bore, the sensor being a temperature sensor configured to detect a temperature deviation when in contact with the molten plastic passing through the leak.

12. The injection molding hot runner system according to claim 10, wherein the sensor is a temperature sensor configured to detect a temperature deviation when contacting molten plastic passing through the leak.

13. The injection molding hot runner system according to claim 12, wherein the sensor is positioned in a groove of an outer shell of the nozzle heater.

14. The injection molding hot runner system according to claim 12, wherein the heating coil of the nozzle heater is used as a sensor indicating a leak when a current used to drive the heating coil exceeds a preset threshold value.

15. The injection molding hot runner system according to claim 12, wherein a mechanical sensor is configured to indicate a leak when contacting molten plastic.

16. The injection molding hot runner system according to claim 15, wherein the mechanical sensor is a switch configured to close or open when contacting molten plastic.

17. The injection molding hot runner system according to claim 15, wherein the mechanical sensor is a wire configured to break when contacting molten plastic.

18. The injection molding hot runner system according to claim 15, wherein the mechanical sensor has a form of a tube positioned around the nozzle assembly, the tube is configured to be pushed by molten plastic, and is configured to indicate a change in position.

19. The injection molding hot runner system according to claim 12, wherein the sensor is a mesh around the nozzle assembly that changes its electrical or mechanical or optical behavior when contacting molten plastic.

20. The injection molding hot runner system according to claim 12, wherein the sensor is an optical fiber sensor that exhibits different light distribution or passes different amounts of light when in contact with the molten plastic.

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