Injection device

Abstract

The present invention provides an injection molding device that maintains good molding even when the imaging mechanism is located near the drop-off port. [Solution] An injection device 10 comprising a feed cylinder 18 containing a feed screw 19, a hopper 23 for supplying resin material 22 to the feed cylinder 18, a connecting pipe 17 connecting a heating cylinder 12 and the feed cylinder 18 and guiding the resin material 22 to the discharge port 12a of the heating cylinder 12, an imaging mechanism 24 for photographing the discharge port 12a from the outside, and a calculation / control unit 25 that controls the rotation speed of the feed screw 19 to increase or decrease based on the image information obtained by the imaging mechanism 24, wherein the imaging mechanism 24 is positioned above and near the discharge port 12a, and the calculation / control unit 25 further performs control to obtain a metering time determined based on the retraction of the injection screw when the supply of resin material is excessive, and to stop the rotation of the feed screw when this metering time is above a metering threshold.

Description

Technical Field

[0006] , , ,

[0001] The present invention relates to an injection device for injecting a resin material into a mold.

Background Art

[0002] Many metal products and wood products have been replaced by plastic products. Many plastic products are manufactured by injection molding devices. An injection molding device includes a mold, a mold clamping device for clamping the mold, and an injection device for injecting a molten resin material into the mold.

[0003] The injection device mainly includes a heating cylinder having a nozzle at its tip, a screw rotatably and axially movably housed in the heating cylinder, and a hopper for supplying a resin material to the heating cylinder. The resin material dropped from the hopper into the heating cylinder is stirred by the screw in the heating cylinder and plasticized by shear heat while moving toward the nozzle. Molten resin accumulates in the front part (nozzle side) of the heating cylinder. Receiving the reaction force of this molten resin, the screw gradually retreats. When the retreat distance reaches a predetermined value, the screw is advanced to inject the molten resin into the mold.

[0004] In this process, it is important that the resin material is supplied to the heating cylinder without excess or deficiency. Therefore, various techniques for supplying an appropriate amount of the resin material have been proposed (for example, see Patent Document 1 (Figs. 1 and 3)).

[0005] Patent Document 1 will be described based on the following figures. Fig. 11(a) is a cross-sectional view of a conventional injection device, and Fig. 11(b) is a cross-sectional view taken along line b-b of Fig. 11(a). As shown in Fig. 11(a), the injection device 100 mainly includes a heating cylinder 102 having a nozzle 101 at its tip, an injection screw 103 rotatably and axially movably housed in the heating cylinder 102, and a material feeder 105 for supplying a resin material to the heating cylinder 102.

[0006] The material feeder 105 consists of a vertical cylinder 106 extending upward from the heating cylinder 102 at a point sufficiently far from the nozzle 101, a horizontal cylinder 107 extending horizontally from the top of the vertical cylinder 106, a feed screw 108 rotatably housed in the horizontal cylinder 107, and a hopper 109 that supplies resin material to the horizontal cylinder 107.

[0007] The resin material falls from the hopper 109 into the horizontal cylinder 107. The resin material is pushed forward inside the horizontal cylinder 107 by the feed screw 108. Next, it falls into the heating cylinder 102 through the vertical cylinder 106. The fallen resin material is plasticized while rotating by the heating cylinder 102 and the injection screw 103, and moves forward towards the front of the heating cylinder 102 (towards the nozzle 101).

[0008] The heating cylinder 102 is provided with a vent hole 111 located closer to the nozzle 101 than the axial center, for discharging gases and water vapor generated from the resin material. An imaging mechanism 112 is placed above this vent hole 111. The imaging mechanism 112 photographs the inside of the heating cylinder 102 through the vent hole 111. The obtained images are processed to calculate the filling status of the resin material.

[0009] When the filling is insufficient, the controller 113 increases the rotational speed of the feed screw 108 to increase the amount of resin material supplied to the heating cylinder 102. Furthermore, when the filling is excessive, the controller 113 reduces the rotational speed of the feed screw 108, thereby reducing the amount of resin material supplied to the heating cylinder 102.

[0010] As a result, the amount of resin material can be optimized. Incidentally, the heating cylinder 102 is at a low temperature near the vertical cylinder 106, that is, near the drop-off port, but becomes at a high temperature near the vent hole 111 where the plasticization of the resin material has progressed sufficiently. Then, high-temperature gas or water vapor is discharged upward from the vent hole 111. If the imaging mechanism 112 is placed directly above the vent hole 111, then heat-resistant measures will need to be taken for the imaging mechanism 112.

[0011] Therefore, Patent Document 1 recommends a mounting structure in which a mirror (reflector) 114 is placed above the vent hole 111, thereby changing the upward-facing light rays to a sideways direction, and the imaging mechanism 112 is not placed directly above the vent hole 111, as shown in Figure 11(b).

[0012] However, the image is distorted because the mirror 114 fogs up with water vapor. The rising heat also distorts the image. Accurate information cannot be obtained from a distorted image. Correcting the image as a countermeasure would increase the cost of image processing. Furthermore, the imaging mechanism 112, including the mirror 114, has a complex structure, which increases the cost of the device.

[0013] The inventors focused on the fact that the area near the drop-off point is sufficiently cold and considered moving the imaging mechanism 112 to the vicinity of the drop-off point, that is, to the vicinity of the vertical cylinder 106. This measure is expected to have the advantage of keeping the area around the imaging mechanism 112 sufficiently cool, eliminating the need for special heat-resistant measures for the imaging mechanism 112, and preventing image distortion due to water vapor or heat.

[0014] Therefore, the inventors moved the imaging mechanism 112 to the vicinity of the drop opening and conducted repeated injection experiments. Favorable results were obtained in many experiments. However, molding defects occurred, albeit infrequently. Since countermeasures could not be taken in the current situation, it became necessary to move the imaging mechanism 112 to the vicinity of the drop opening while maintaining a technology that would prevent molding defects, that is, maintain good molding. [Prior art documents] [Patent Documents]

[0015] [Patent Document 1] Special Publication No. 6-39119 [Overview of the project] [Problems that the invention aims to solve]

[0016] An object of the present invention is to provide an injection device that can maintain good molding even when an imaging mechanism is provided near a dropping port.

Means for Solving the Problems

[0017] The inventors of the present invention have found that molding defects are caused by clogging of the resin material in the heating cylinder 102. Clogging is likely to occur in the heating cylinder 102 near the dropping port. This is presumably because the resin material is still at a low temperature, has poor fluidity, and is likely to clog. Therefore, countermeasures against clogging were taken. As a result, good molding could be maintained. The invention completed based on the above findings is as follows.

[0018] The invention according to claim 1 includes a heating cylinder having a nozzle at its tip, an injection screw rotatably and axially movably housed in the heating cylinder, a feed cylinder incorporating a feed screw, a hopper for supplying a resin material to the feed cylinder, a connecting pipe that connects a portion of the heating cylinder far from the nozzle and a portion of the feed cylinder far from the hopper to guide the resin material to the dropping port of the heating cylinder, an imaging mechanism for photographing the dropping port from the outside, and an arithmetic / control unit that controls to increase the rotation speed of the feed screw when the supply of the resin material is low based on the image information obtained by this imaging mechanism, and to decrease the rotation speed of the feed screw when the supply of the resin material is high. The injection device is characterized in that the imaging mechanism is disposed above the dropping port and near the dropping port, when the supply of the resin material is excessive, the arithmetic / control unit obtains a metering time determined based on the retreat of the injection screw, and when this metering time is equal to or greater than a metering threshold value, further performs control to stop the rotation of the feed screw.

[0019] The invention according to claim 2 is the injection device according to claim 1, The connecting pipe includes a straight pipe portion that extends linearly outward from the heating cylinder, The imaging mechanism is characterized in that it images the dropping port through the straight pipe portion.

[0020] The invention according to claim 3 is an injection device according to claim 1, The heating cylinder has an opening that leads to the outside at a position near the dropping port and does not interfere with the connecting pipe, The imaging mechanism is characterized in that it images the dropping port through the opening.

Effects of the Invention

[0021] In the invention according to claim 1, the imaging mechanism is arranged near the dropping port. The dropping port is sufficiently low in temperature. Therefore, the imaging mechanism can obtain an image without distortion, and there is no need to provide a special cooling mechanism for the imaging mechanism.

[0022] In addition, in the present invention, the operation and control unit controls the supply of the resin material based on the image obtained by the imaging mechanism. Furthermore, when a problem such as clogging occurs in the heating cylinder, the supply of the resin material is stopped to quickly eliminate the problem such as clogging and correct the problem during molding. Therefore, according to the present invention, it is possible to provide an injection device that can maintain good molding even when the imaging mechanism is provided near the vertical cylinder.

[0023] In the invention according to claim 2, the connecting pipe includes a straight pipe portion that extends linearly outward from the heating cylinder, and the imaging mechanism images the dropping port through the straight pipe portion. In claim 2, the imaging mechanism can be arranged at a distance from the heating cylinder by the length of the straight pipe portion. Although the vicinity of the dropping port is sufficiently low in temperature, in order to arrange the imaging mechanism further away from the vicinity of the dropping port, the thermal environment of the imaging mechanism becomes even better.

[0024] In the invention according to claim 3, the heating cylinder has an opening that leads to the outside at a position near the dropping port and does not interfere with the connecting pipe, and the imaging mechanism images the dropping port through the opening. Claim 3 requires that the heating cylinder have an opening separate from the connecting tube, but the position of the opening can be set relatively freely near the drop-off point. As a result, the degree of freedom in arranging the imaging mechanism is greatly increased. [Brief explanation of the drawing]

[0025] [Figure 1] This is an overall diagram of the injection apparatus according to the present invention. [Figure 2] (a) is an enlarged view of part 2a in Figure 1, (b) is a diagram showing a modified example, and (c) is a diagram showing the operation. [Figure 3] This is a control flow diagram of the arithmetic and control unit according to the present invention. [Figure 4] This is a diagram showing an example of Map A. [Figure 5] (a) is a diagram illustrating the injection screw groove, and (b) is a diagram illustrating the area of ​​the resin material. [Figure 6] Figures (a) to (e) illustrate the supply methods of resin materials. [Figure 7] This figure shows an example of a modified injection device. [Figure 8] This figure shows further examples of modifications to the injection device. [Figure 9] (a) is a diagram showing a further modification of the injection device, and (b) is a cross-sectional view of (a) along line bb. [Figure 10] This figure shows further examples of modifications to the injection device. [Figure 11] (a) is a cross-sectional view of a conventional injection molding machine, and (b) is a cross-sectional view of (a) along line bb. [Modes for carrying out the invention]

[0026] Embodiments of the present invention will be described below with reference to the attached drawings. [Examples]

[0027] [Injection device] As shown in Figure 1, the injection device 10 includes a heating cylinder 12 equipped with a nozzle 11 at its tip, an injection screw 13 housed in the heating cylinder 12 so as to be rotatable and axially movable, a screw rotation motor 14 for rotating the injection screw 13, an injection cylinder 15 for advancing the injection screw 13, a metering sensor 16 for detecting the axial position of the injection cylinder 15, a feed cylinder 18 containing a feed screw 19, a feed rotation motor 21 for rotating the feed screw 19, and a feed cylinder 18 for feeding resin material The system includes a hopper 23 for supplying material 22, a connecting pipe 17 that connects the part of the heating cylinder 12 furthest from the nozzle 11 and the part of the feed cylinder 18 furthest from the hopper 23, guiding the resin material 22 to the discharge port 12a of the heating cylinder 12, an imaging mechanism 24 that photographs the discharge port 12a from the outside, and a calculation / control unit 25 that controls the feed screw 19 to increase its rotation speed when the supply of resin material 22 is low and to decrease its rotation speed when the supply of resin material 22 is high, based on the image information obtained by the imaging mechanism 24.

[0028] [Feed screw posture] The feed screw 19 may be positioned horizontally, but in this embodiment, it is positioned with the hopper 23 side at a lower position and the front end rising as it moves away from the hopper 23. As a result, the resin material 22 always accumulates in the feed cylinder 18 due to gravity, eliminating variations in the supply amount, which is preferable.

[0029] [Imaging mechanism] The imaging mechanism 24 is, for example, a CCD camera.

[0030] [Plasticization] The resin material 22 in the hopper 23 is pushed out by the feed screw 19, falls through the connecting pipe 17 to the drop-off port 12a of the heating cylinder 12, and is pushed by the injection screw 13 towards the nozzle 11.

[0031] During this time, the resin material 22 inside the heating cylinder 12 is compressed between the heating cylinder 12 and the injection screw 13, sheared by the rotation of the injection screw 13, and heated by the heating cylinder 12, resulting in plasticization through a combined action.

[0032] The area near the drop-off port 12a is significantly cooler than the nozzle 11 side. The imaging mechanism 24 is positioned above this drop-off port 12a. No special thermal countermeasures are required for the imaging mechanism 24. In addition, the amount of water vapor and hot air rising inside the connecting pipe 17 is small enough to be acceptable. Therefore, image distortion caused by water vapor and hot air does not occur, and a clear image can be easily obtained.

[0033] [Weighing] The plasticized resin material 22 accumulates on the nozzle 11 side of the injection screw 13. As the amount of this accumulation increases, the injection screw 13 retracts. The measured value of the resin material 22 is calculated using the formula: (internal cross-sectional area of ​​the heating cylinder 12) × (retraction distance of the injection screw 13) = measured value. The retraction distance of the injection screw 13 is detected by the metering sensor 16.

[0034] [Injection] A measurement value is determined corresponding to the volume of the mold cavity. When the measurement value calculated based on the information from the measurement sensor 16 matches the determined measurement value, the injection cylinder 15 advances the injection screw 13. This advancement injects the molten resin material into the mold.

[0035] [Structure of the tip of a feed screw] Figure 2(a) is an enlarged view of section 2a in Figure 1. As shown in Figure 2(a), a bearing portion 27 is provided in the connecting pipe 17. The tip of the feed screw 19 and the portion that protrudes from the feed cylinder 18 is a small-diameter shaft portion 28, which is sufficiently smaller in diameter than the central axis 19a of the feed screw 19. The tip of this small-diameter shaft portion 28 is inserted into the bearing portion 27. Because it is supported by the bearing section 27, the feed screw 19 maintains smooth rotation. Furthermore, because the small-diameter shaft portion 28 has a small diameter, the influence on imaging by the imaging mechanism 24 is mitigated.

[0036] Figure 2(b) shows a modified example. As shown in Figure 2(b), the small-diameter shaft portion 28 may be omitted from the feed screw 19. Since the small-diameter shaft portion 28 is omitted, the field of view of the imaging mechanism 24 is not obstructed. As a result, a higher quality image can be obtained. Since the bearing section 27 is unnecessary, there is also the advantage that the structure of the connecting pipe 17 becomes simpler. Therefore, it is arbitrary to adopt either the structure shown in Figure 2(a) or Figure 2(b).

[0037] Figure 2(c) is a diagram illustrating the operation of the structure shown in Figure 2(b). Because the feed cylinder 18 is angled upwards, the extruded resin material 22 mainly spills out from the lower end 29 of the tip of the feed cylinder 18 into the connecting pipe 17. Then, the resin material 22 flows down along the wall 17b of the connecting pipe 17 that is furthest from the nozzle (Figure 1, reference numeral 11). Therefore, the imaging mechanism 24 allows for the acquisition of better images.

[0038] Next, the control performed by the calculation / control unit 25 will be explained based on Figure 3. In Figure 3, ST (indicating the step number; the same applies hereafter) 01 sets rl, rm, rh, and rhh related to the feed screw. However, 0 <rl<rm<rx<rh<rhhである。

[0039] Prepare a map A as shown in Figure 4. Map A lists the names of the resin materials to be used, as well as the transport efficiency j, plasticization efficiency ε, solid density ρ, and melt density ρ' for each resin material.

[0040] In ST02 of Figure 3, set the resin material name. In ST03, map A (see Figure 4) is used to set the transport efficiency j, plasticization efficiency ε, solid density ρ, and melt density ρ' corresponding to the selected resin material.

[0041] [Hunger rate] When there is a requirement to increase the purity of resin products, it is necessary to remove gases and other substances from the resin material being plasticized before injection molding. In this case, if the resin material is sparse, gases and other substances will escape more easily. The sparseness of a resin material is expressed by its starvation rate.

[0042] In other words, a high rate of hunger indicates a sparse environment. Conversely, a low rate of hunger indicates a dense environment. Therefore, the starvation rate is determined based on factors such as the type of resin material, product quality, and required specifications. It should be noted that the starvation rate is never set to 100%.

[0043] In ST04, set the hunger rate x. In ST05, the rotation command value rx for the feed screw is calculated using the following formula (1).

[0044]

number

[0045] In equation (1), rmax, Qmax, Rmax, and Gmax are fixed values ​​determined for each piece of equipment. R is the rotational speed of the injection screw set during operation. ε, j, and ρ are default values ​​defined by map A. ρGGPS is the solid density of general-purpose polystyrene resin material. x is the value set in ST04. Therefore, using equation (1), the rotation command value rx (rpm) of the feed screw when the starvation rate is x can be calculated. rpm is the number of rotations per minute.

[0046] In Figure 3, the weighing operation is performed in ST06, a still image of the drop-off point is acquired (ST07), and the coverage rate y of the injection screw groove is calculated based on the acquired still image (ST08). In this calculation, as shown in Figure 5(a), the screw groove portion 31, which is marked with a diagonal line ( / / / ), is included in the calculation, while the flight 13a is excluded from the calculation.

[0047] In the model shown in Figure 5(b), the calculation and control unit (Figure 1, reference numeral 25) calculates the area of ​​the resin material 22 in the screw groove 31 (in this example, the area of ​​M1 to M6). At the same time, it calculates the area of ​​the visible portion of the screw groove 31 (in this example, the area of ​​S1 to S3).

[0048] The coverage rate y (%) of the injection screw groove is calculated using the formula 100 × Σ(M1~M6) ÷ {Σ(S1~S3) + Σ(M1~M6)}. Hereafter, the coverage rate y of the injection screw groove may be abbreviated as coverage rate y.

[0049] Figures 6(a) to (e) show the configuration of the resin material supply. Figure 6(a) shows only the resin material 22, indicating an oversupply. The coverage rate y will be, for example, 110% or more. Figure 6(b) shows the resin material 22 and the flight 13a. There is still a relatively large amount of resin material 22. The coverage rate y is, for example, 90-109%.

[0050] Figure 6(c) shows the resin material 22 and the screw groove 31. The resin material 22 is supplied appropriately. The coverage rate y is, for example, 50-89%. Figure 6(d) shows that there are many screw grooves 31 and few resin materials 22. In other words, the amount of resin material 22 is relatively small. The coverage rate y is, for example, 10 to 49%.

[0051] Figure 6(e) shows that the amount of resin material 22 is even less. In other words, there is a shortage of resin material 22. The coverage rate y will be, for example, 9% or less. In other words, the magnitude of the coverage rate y allows us to determine whether the supply is "appropriate" or not, and if not, whether it is "oversupplied," "a little too much," "a little too little," or "undersupplied."

[0052] Therefore, in Figure 3, ST09 checks whether the coverage rate y is "appropriately supplied," and if it is YES, the rotation command value rx of the feed screw is maintained without change (ST10).

[0053] If the answer to ST09 is NO, then ST11 checks whether y is "oversupplied". If YES, then it is necessary to suppress the supply of resin material by the feed screw. However, if the answer to ST11 is YES, several patterns are possible.

[0054] For example, in Figure 1, the resin material 22 may clog at the location indicated by arrow A. In this case, the resin material 22 may not be supplied to the nozzle 11, or the amount supplied may be reduced. As a result, the retraction of the injection screw 13 will be delayed, and the metering time will be longer than the expected time (expected metering time). When there is an oversupply, it is necessary to suspect clogging of the resin material, and therefore it is effective to check the weighing time at that time based on the expected weighing time.

[0055] The expected metric time tx is calculated using the following formula (2).

[0056]

number

[0057] In equation (2), D, S, Qmax, and Rmax are fixed values ​​determined for each piece of equipment. R is the rotational speed of the injection screw set during operation. ρ' and ε are default values ​​defined by map A. x is the value set in ST04. Therefore, using equation (2), the expected measurement time tx (seconds) when the hunger rate is x can be calculated.

[0058] In Figure 3, when the coverage rate y in ST11 is in excess, the starvation rate x becomes 0. Therefore, we substitute 0 for x in equation (2). As a result, we derive equation (3) below, and this equation determines the expected metric time t0.

[0059]

number

[0060] In ST13, it is checked whether the metering time t obtained based on the metering information from the metering sensor (Figure 1, reference numeral 16) is greater than or equal to the expected metering time t0.

[0061] [Measurement threshold] The predicted metric time t0 described above is defined as the metric threshold.

[0062] If the answer to ST13 is YES, a blockage is suspected, so replace rx with "0" and stop the rotation of the feed screw (ST14). By ceasing the supply of resin material, it is expected that the blockage around the injection screw will gradually be resolved.

[0063] If the answer in ST13 is NO, a blockage is not suspected, so it is recognized as simply an oversupply, and in ST15, rx is replaced with "rl". Since rl is sufficiently small, it is expected that the oversupply will be resolved.

[0064] If the answer in ST11 is NO, then in ST16, check whether y is "too much". If the answer is YES, then in ST17, replace rx with "rm". Since rm is small, it is expected that the excess will be resolved.

[0065] If the answer in ST16 is NO, then in ST18, check whether y is "slightly low". If the answer is YES, then in ST19, replace rx with "rh". Since rh is large, it is expected that the supply of resin material will increase and the "slightly low" issue will be resolved.

[0066] In ST18, if the value is NO, there is a supply shortage, and in ST20, replace rx with "rhh". Since rhh is even larger, it is expected that the supply of resin material will increase further and the supply shortage will be resolved.

[0067] After ST10, ST14, ST15, ST17, ST19, or ST20, the status is recorded and graphed in ST21. Then, ST22 checks for the presence or absence of a termination command. If YES, this control flow is terminated; otherwise, it returns to ST06 to perform the next weighing operation.

[0068] By repeating the control flow, it is expected that the "oversupply" will shift to "a little oversupply," and then the "a little oversupply" will shift to "appropriate supply." Furthermore, by repeating the control flow, it is expected that "supply shortage" will transition to "slightly low," and "slightly low" will transition to "appropriate supply."

[0069] Furthermore, in Figures 6(a) to (e), if the occurrence rate of Figure 6(e) is small, in Figure 3, ST18 and ST20 may be omitted, and the NO branch of ST16 may be directly connected to ST19. Therefore, the classifications and y values ​​explained in Figures 6(a) to (e) are merely preferred examples and can be modified as appropriate.

[0070] Next, examples of modifications to the injection apparatus 10 according to the present invention will be described in order with reference to Figures 7 to 10.

[0071] [Example of modification of injection device (1)] As shown in Figure 7, the injection device 10 in modification example (1) differs from the injection device 10 shown in Figure 1 in the structure of the connecting pipe 17, but otherwise remains unchanged. For parts that remain unchanged, the same reference numerals as in Figure 1 are used, and detailed explanations are omitted. The same applies to Figures 8 to 10 described later.

[0072] In other words, the connecting pipe 17 consists of a straight pipe section 17a that extends linearly outward from the heating cylinder 12, a slanted pipe section 17b that extends diagonally upward from the height of the straight pipe section 17a and partway up, and a second straight pipe section 17c that extends upward from the slanted pipe section 17b and connects to the feed cylinder 18. The imaging mechanism 24 is positioned directly above the straight pipe section 17a and photographs the drop-off opening 12a through the straight pipe section 17a.

[0073] According to this modification example (1), the straight pipe section 17a extends along the vertical line. And, due to the presence of the angled pipe section 17b and the second straight pipe section 17c, the area above the straight pipe section 17a is empty. Therefore, a large imaging mechanism 24 can be easily installed. Another advantage is that the imaging mechanism 24 can be easily inspected from above or the side.

[0074] The present invention is suitable for horizontal injection molding machines with a horizontal injection axis, as shown in Figures 1 and 7, but it can also be applied to vertical injection molding machines with a vertical injection axis. A specific example will be explained based on Figure 8.

[0075] [Example of modification of injection device (2)] As shown in Figure 8, the injection device 10 according to modification example (2) is a vertical injection device in which the injection axis is vertical. In other words, the heating cylinder 12 is connected to a part of it that is far from the nozzle 11, and the feed cylinder 18 is connected to a part of it that is far from the hopper 23, by a connecting pipe 17.

[0076] The connecting pipe 17 consists of a straight pipe section 17a that extends diagonally upward from the drop-off opening 12a, and a second straight pipe section 17c that extends upward from the middle of the straight pipe section 17a and connects to the feed cylinder 18. The imaging mechanism 24 is positioned above the drop-off opening 12a and next to the straight pipe section 17a, and photographs the drop-off opening 12a through the straight pipe section 17a.

[0077] In the injection device 10 shown in Figures 1, 7, and 8, the connecting pipe 17 includes a straight pipe section 17a that extends linearly outward from the heating cylinder 12, and the imaging mechanism 24 photographs the drop-off port 12a through the straight pipe section 17a. The imaging mechanism 24 can be positioned at a distance from the heating cylinder 12 equal to the length of the straight tube section 17a. Although the area near the discharge port 12a is sufficiently cold, positioning the imaging mechanism 24 further away from the area near the discharge port 12a improves the thermal environment of the imaging mechanism 24 even more.

[0078] Furthermore, if the imaging mechanism 24 is positioned sufficiently far from the drop-off opening 12a, there is concern about the influence of external light. In this regard, the straight tube section 17a acts as the tube of the telescope, that is, it blocks external light, thus suppressing the influence of external light.

[0079] [Example of injection device modification (3)] The ejection device 10 shown in Figure 9(a) differs from that in Figure 1 in that the imaging mechanism (Figure 1, reference numeral 24) is located at the back of the connecting pipe 17. Figure 9(b) is a cross-sectional view taken along line bb in Figure 9(a).

[0080] As shown in Figure 9(b), the heating cylinder 12 has an opening 33 that leads to the outside, located near the drop-off port 12a and in a place that does not interfere with the connecting pipe 17, and the imaging mechanism 24 photographs the drop-off port 12a through the opening 33. In this modification example (3), although the structure of the heating cylinder 12 becomes more complex because the opening 33 and the connecting pipe 17 are provided separately, it has the advantage of allowing the imaging mechanism 24 to be brought closer to the drop-off opening 12a.

[0081] [Examples of changes to the injection device (4)] As shown in Figure 10, the heating cylinder 12 has an opening 33 that leads outwards near the drop-off port 12a and in a location that does not interfere with the connecting pipe 17, and the imaging mechanism 24 photographs the drop-off port 12a through the opening 33. In other words, in this modified example (4), the imaging mechanism 24 is positioned above the heating cylinder 12, below the feed cylinder 18, and behind the connecting pipe 17.

[0082] In this modification example (4), although the structure of the heating cylinder 12 becomes more complex because the opening 33 and the connecting pipe 17 are provided separately, it has the advantage of allowing the imaging mechanism 24 to be brought closer to the drop-off opening 12a. In addition, there is the advantage that the imaging mechanism 24 is protected by the feed tube 18 and the connecting tube 17.

[0083] In the ejection device 10 shown in Figures 9(a), (b) and 10, the heating cylinder 12 has an opening 33 that leads to the outside, located near the drop-off port 12a and in a place that does not interfere with the connecting pipe 17, and the imaging mechanism 24 photographs the drop-off port 12a through the opening 33. Although it is necessary to provide an opening 33 in the heating cylinder 12 separately from the connecting pipe 17, which has the disadvantage of making the structure of the heating cylinder 12 more complex, the position of the opening 33 can be set relatively freely near the drop-off port 12a, which has the advantage of significantly increasing the degree of freedom in the placement of the imaging mechanism 24.

[0084] Based on the above description, the present invention can be summarized as follows. As shown in Figures 1, 7 to 10, a heating cylinder 12 equipped with a nozzle 11 at its tip, and an injection screw 13 housed within the heating cylinder 12 so as to be rotatable and axially movable, A feed cylinder 18 containing a feed screw 19, and a hopper 23 that supplies resin material 22 to the feed cylinder 18, A connecting pipe 17 connects the portion of the heating cylinder 12 furthest from the nozzle 11 and the portion of the feed cylinder 18 furthest from the hopper 23, and guides the resin material 22 to the drop-off port 12a of the heating cylinder 12. An imaging mechanism 24 for photographing the drop-off opening 12a from the outside, The injection device 10 includes a calculation / control unit 25 that controls the feed screw 19 to increase its rotational speed when the supply of resin material 22 is low, and to decrease its rotational speed when the supply of resin material 22 is high, based on the image information obtained by the imaging mechanism 24. The imaging mechanism 24 is positioned above the drop-off opening 12a and in the vicinity of the drop-off opening 12a.

[0085] Then, as shown in Figure 3, the calculation and control unit 25 further performs control (ST14) which, when the supply of resin material 22 is excessive, obtains a metering time t determined based on the retraction of the injection screw 13, and stops the rotation of the feed screw when this metering time t is equal to the metering threshold t0.

[0086] If, for example, the supply of resin material 22 is excessive, simply reducing the rotation speed of the feed screw 19 will cause some malfunctions when the resin material 22 gets clogged inside the heating cylinder 12. In other words, if resin material is continuously supplied despite a blockage, the blockage will never be cleared.

[0087] In this regard, the present invention detects a blockage based on the metering time and stops the supply of resin material. This stopping the supply resolves the blockage. Therefore, the present invention maintains better injection molding performance.

[0088] Furthermore, in Figure 2(a), the central axis of the imaging mechanism 24 may be offset towards the front or back of the drawing relative to the small-diameter shaft portion 28 of the feed screw 19. This offset eliminates interference between the small-diameter shaft portion 28 and the central axis of the imaging mechanism 24, which is preferable.

[0089] Furthermore, in Figure 1, the feed screw 19 may be positioned horizontally, but preferably it is inclined upwards toward the connecting pipe 17. This inclination allows the feed cylinder 18 to be filled to capacity with resin material 22. [Industrial applicability]

[0090] This invention is suitable for injection molding equipment that injects resin material into a mold. [Explanation of Symbols]

[0091] 10...Injection device, 11...Nozzle, 12...Heating cylinder, 12a...Discharge port, 13...Injection screw, 17...Connecting tube, 17a...Straight tube section, 18...Feed cylinder, 19...Feed screw, 22...Resin material, 23...Hopper, 24...Imaging mechanism, 25...Calculation / control unit, 33...Opening.

Claims

1. A heating cylinder equipped with a nozzle at its tip, and an injection screw housed within the heating cylinder so as to be rotatable and axially movable, A feed cylinder containing a feed screw, and a hopper that supplies resin material to this feed cylinder, A connecting pipe that connects the portion of the heating cylinder furthest from the nozzle and the portion of the feed cylinder furthest from the hopper, and guides the resin material to the discharge port of the heating cylinder, An imaging mechanism for photographing the drop-off opening from the outside, An injection molding device comprising a calculation and control unit that controls the rotation speed of the feed screw to increase when the supply of resin material is low and to decrease when the supply of resin material is high, based on image information obtained by this imaging mechanism, The imaging mechanism is positioned above the drop opening and in the vicinity of the drop opening. The injection device is characterized in that the calculation and control unit further performs control to obtain a metering time determined based on the retraction of the injection screw when the supply of resin material is excessive, and to stop the rotation of the feed screw when this metering time is equal to or greater than a metering threshold.

2. An injection device according to claim 1, The connecting pipe includes a straight pipe section that extends linearly outward from the heating cylinder, The ejection device is characterized in that the imaging mechanism photographs the drop-off opening through the straight pipe section.

3. An injection device according to claim 1, The heating cylinder has an opening that leads to the outside, located near the drop-off port and in a place that does not interfere with the connecting pipe. The imaging mechanism is characterized by photographing the drop opening through the opening.

Images