Patent Description:
In recent years, the impact of climate change or global warming, the rise of environmental protection concepts, and circular economy have gradually received attention, such as recycled products. Recycled plastic in recycled products refers to plastic raw materials obtained after processing waste plastics through physical or chemical methods such as pretreatment, melt granulation, modification, etc. It refers to the reuse of plastics.

However, the production of recycled plastic products with conventional plastic injection machines will encounter some problems. One is that it is not easy to feed the injection machine with material. Part of the recycled plastic that is too light, such as PE coating film fragments, will make it difficult to feed material. If the proportion of PE coating film in plastic is high, the plastic is likely to float upward due to static electricity, thus, causing the injection machine to transport and difficulty in supplying material.

The second is that it is difficult to mass produce. Mass production means a higher the injection volume of injection machine is needed. However, the higher the injection volume, the greater the clamping force of the machine is required and a higher cost and energy is required for the equipment. Thus, it does not meet the concept of economic efficiency and environmental protection.

Therefore, providing an environmentally friendly, low-cost, and high volume injection machine is a problem in the field to be solved. <CIT> discloses an injection molding apparatus comprising: a hopper into which a raw material is input; a transfer unit for heating, fusing and conveying raw materials introduced from the hopper; an injection molding apparatus including an injection plunger and a mold; and a screw for transporting raw materials installed in a body in which a heater is installed. The screw is a spiral blade formed on an inclined shaft which is rotated by a motor. The inclined shaft has a constant inclination angle.

An objective of the present disclosure is to provide an environmentally friendly, low-cost, and high volume injection machine for plastic injection molding.

Accordingly, one aspect of the instant disclosure provides an injection machine for a recycled plastic injection molding system used with at least one molding device to produce an end product from plastic, the injection machine comprises a supplying system having a hopper, a first driver disposed on the hopper, the first driver has a feed screw penetrating the hopper, the first driver is configured to drive the feed screw to rotate; a heating system disposed on a downstream of the supplying system, the heating system having a heating pipe, wherein the feed screw of the first driver extends into the heating system, a second driver is disposed on one end of the heating pipe, the second driver has a heating screw penetrating the heating pipe, the second driver configured to drive the heating screw to rotate; wherein the feed screw and the heating screw are configured to be at a distance from each other, the distance ranges between <NUM>-<NUM>, and a buffer system disposed on a downstream of the heating system, the buffer system having a plunger tube and a plunger rod slidably installed and sealed within the plunger tube.

In some embodiments, the injection machine further comprises a pressure holding system disposed on a downstream of the buffer system, the pressure holding system having a pressure holding pipe and a pressure holding rod slidably installed and sealed within the pressure holding pipe.

In some embodiments, the first driver is configured to drive the feed screw to further drive the plastic from the hopper to the downstream of the supplying system.

In some embodiments, the second driver is configured to drive the heating screw to rotate and drive the plastic to the downstream of the heating system; the heating pipe having a heating device configured to heat and turn the plastic to molten state.

In some embodiments, the injection machine further comprises a drying system disposed on an upstream of the supplying system and configured to deliver the plastic to the supplying system, the drying system having a dry mixing barrel and a side conveyor, the dry mixing barrel having a barrel and a stirring rod disposed within the barrel; the side conveyor disposed between the dry mixing barrel and the supplying system.

In some embodiments, the first driver and the second driver have frequency conversion drive motor.

In some embodiments, the injection machine further comprises at least one blade is arranged at a surface of the feed screw and configure to prevent the plastic from floating upward.

The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the disclosure are shown. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. Rather, these exemplary embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

The terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting of the disclosure. It will be further understood that the terms "comprises" and/or "comprising," or "includes" and/or "including" or "has" and/or "having" when used herein, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof.

In the following text, "plastic" refers to an organic polymer material that uses resin as the main component, is molded into a certain shape at a certain temperature and pressure, and can maintain a predetermined shape at room temperature.

In the following text, "recycled plastic" refers to plastic raw materials that are re-obtained after processing waste plastics through physical or chemical methods such as pretreatment, melt granulation, and modification. For example, PE coating film, HDPE cleaner, HDPE milk bottle, HDPE milk, PP bottle cap, PET bottle cap or PET packing tape, etc..

In the following text, "end product" refers to a plastic product that is finished after being poured into a mold to form a mold shape and cooled. The end product can be applied to various parts and fields. Taking the construction industry as an example, the end product can be a building material, such as permeable bricks, environmental protection bricks, etc..

A recycled plastic injection molding system shown in <FIG> includes an injection machine 1and a molding device <NUM>. The specification of the injection machine is a machine with a clamping force of 600T, but it is not limited to thereof. The injection machine1 includes a supplying system <NUM>, a heating system <NUM>, a plastic channel <NUM>, a plunger system <NUM>, and a pressure holding system <NUM>.

As shown in a sectional view of a supplying system <NUM> in <FIG>, the supplying system <NUM> is disposed on an upstream of a receiving route of the injection machine and configured to supply plastic to the heating system <NUM>. The supplying system <NUM> has a first material drive device. In some embodiments, a first material drive device may include a feed screw <NUM> and a first driver <NUM> as shown in <FIG>. The first material drive device is configured to drive the plastic from the entry end to the downstream of the receiving route. In some embodiments, entry end may be a hopper <NUM> as shown in <FIG>. The first driver <NUM> is disposed over the hopper <NUM>. The feed screw <NUM> is disposed within the hopper <NUM> and coupled to one end of the first driver <NUM>.

The hopper <NUM> of <FIG> is a hollow body and forms a cone-shaped space inside. The hopper <NUM> includes an upper opening 100a and a lower opening 100b. The space connects to the upper opening 100a and the lower opening 100b to allow the plastic to enter from upper opening 100a, exit through the lower opening 100b, and enter into the heating system11. One end of the feed screw <NUM> is coupled to the first driver <NUM> and passes through the inner space of the hopper <NUM> to enter the heating system <NUM> through the lower opening 100b of the hopper <NUM>. The surface of the feed screw <NUM> is provided with a spiral sheet.

The first driver <NUM> shown in <FIG> drives the feed screw <NUM> to rotate along its own axis. A platform <NUM> is disposed above the hopper <NUM> and the first driver <NUM> is disposed on the platform <NUM>.

The surface of the feed screw <NUM> of the supplying system <NUM> shown in <FIG> can be provided with at least one blade <NUM>. The feed screw <NUM> is configured to move the plastic to the lower opening 100b. At the same time, the blade <NUM> prevents the plastic from floating upward due to the lightness and electrostatic effect of the material.

As shown in <FIG> and <FIG>, a heating system <NUM> is disposed on a downstream of the supplying system and includes a second material drive device and a heating device. The second material drive device is configured to drive the plastic to a downstream of the receiving route of the heating system. The heating device is configured to heat the plastic until melted. The first material drive device extends into the heating system <NUM> and is configured to heat the plastic to a molten state. In some embodiments, the second material drive device may include a heating screw <NUM> and a second driver <NUM> as shown in <FIG>. In some embodiments, the heating device may include a heating pipe <NUM> that extends laterally as shown in <FIG>. The second driver <NUM> is disposed on one end of the heating pipe110. The heating screw <NUM> axially penetrates the heating pipe <NUM>. The heating screw <NUM> penetrates one end of the heating pipe <NUM> and connects to the second driver <NUM>.

The heating pipe <NUM> of <FIG> is a hollow body. One end of the heating pipe <NUM> facing one side of the supplying system <NUM> is provided with a heating inlet 110a. Another end of the heating pipe <NUM> at a distance from the heating inlet 110a is a heating outlet 110b. The heating inlet 110a and the lower opening 100b of the hopper <NUM> are connected to each other. The heating outlet 110b and the plastic channel <NUM> are connected to each other. Thus, the plastic can enter the heating pipe <NUM> from the lower opening 100b of the hopper <NUM> through the heating inlet 110a, exit from the heating outlet 110b of the heating pipe <NUM>, and enter into the plastic channel <NUM>. A heating unit (not shown in the figure) is provided on the outer peripheral surface of the heating pipe <NUM> to heat the recycled plastic to a molten state.

The heating screw <NUM> is inserted inside the heating pipe <NUM>. The surface of the heating screw <NUM> is formed with raised threads. One end of the heating screw <NUM> penetrates through the heating pipe <NUM> and connects to the second driver112. The second driver <NUM> drives the heating screw <NUM> to rotate along its axis at high speed and push the recycled plastic in the molten state towards the heating outlet 110b. In some embodiments, the diameter of heating screw <NUM> is about <NUM>, but it is not limited to thereto.

In some embodiments, the feed screw <NUM> of the supplying system <NUM> penetrates through the lower opening 100b to enter the heating pipe <NUM>. The feed screw <NUM> of the supplying system <NUM> may be disposed vertically from the heating screw <NUM>. In some embodiments, a lower end of the feed screw <NUM> is pointed towards the threads of the heating screw <NUM>. Further, the lower end of the feed screw <NUM> is at a distance from the threads of the heating screw <NUM>. When the distance is too big, the lightness and the electrostatic effect of the recycled plastic will cause it to float. As a result, the recycled plastic could not fall down to heating system <NUM> smoothly and lead to insufficient supply of the recycled plastic. But, when the distance is too small, too much recycled plastic that is not in a molten state may accumulate in the heating pipe <NUM> near the heating inlet 110a. In some embodiments, the distance ranges between <NUM>-<NUM>, but it is not limited to thereto.

Furthermore, the nature of plastic is different, especially recycled plastic. The source of plastic can include various waste plastics or a mixture thereof, such as, PE coating from paper tableware and PP bottle caps. The different type of plastics will affect the feeding rate of the injection machine. When there are more light weight plastic (i.e. PE coating), the plastic will not fall easily and cause the supplying system <NUM> and heating system <NUM> to run dry due to insufficient supply. However, when there are more heavy plastic (i.e. PP bottle caps), the plastic will fall down through gravity. If the plastic feeds too fast, it may cause too much material.

In some embodiments, the first driver <NUM> and the second driver <NUM> use a frequency conversion drive motor to adjust the feeding rate between the supplying system <NUM> and the heating system <NUM>. When the plastic is lighter, the speed of the frequency conversion drive motor can be increased to increase the supply rate and prevent the supplying system <NUM> and heating system11 from running idle due to insufficient supply of material. When the plastic is heavier, the speed of the frequency conversion drive motor can be decreased to decrease the supply rate and prevent excess supply.

As shown in <FIG>, the plastic channel <NUM> includes a material pipe <NUM> and a switch valve SH. The material pipe <NUM> is a hollow body. The material pipe <NUM> has a material pipe inlet 120a connected to the heating outlet 110b and a material pipe outlet 120b connected to an enter buffer system <NUM>. The plastic in a molten state passes through the material pipe inlet 120a to enter the material pipe <NUM> after leaving the heating system <NUM>. After, the molten plastic leaves the material pipe outlet 120b. The switch valve SH is disposed on the material pipe <NUM> and is configured to selectively trigger the receiving state and the supplying state of the buffer system <NUM> to control the plastic entering the buffer system <NUM> from the heating system <NUM>. When the switch valve SH is at open state,the buffer system will be at the receiving state and the plastic will pass through the material pipe <NUM> to enter buffer system <NUM>. When the switch valve SH is at close state, the buffer system <NUM> will be at the supplying state and the plastic is not able to pass through the material pipe <NUM>.

If a large amount of plastic continues to be fed directly into the molding device <NUM> from the heating system <NUM>, the plastic accumulated in the heating outlet 110b will cause the heating screw <NUM> to generate a reverse force. The reverse force can cause the heating screw <NUM> to retreat in the opposite direction of the ejection, which in turn can make the filling volume unstable. Therefore, an additional buffer system <NUM> is required to ensure stable plastic filling.

<FIG> and <FIG> shows a diagram of the buffer system <NUM>. The buffer system <NUM> is disposed on a downstream of a heating system <NUM>. The buffer system <NUM> includes a cylinder connected to the second material drive device and a piston, which is outside the scope of the presently claimed invention. In some embodiments of the presently claimed invention, the cylinder may be a plunger tube <NUM> that extends laterally as shown in <FIG>. The piston may be a plunger rod <NUM> that is slidably arranged in the axis of the plunger tube <NUM> and is sealed within the plunger tube <NUM>.

The plunger tube <NUM> has a hollow body to accommodate the plastic and the plunger rod <NUM>. The plunger tube <NUM> near one end of the material pipe <NUM> has a plunger inlet 130a and a plunger outlet 130b. The plunger inlet 130a facing the material pipe outlet 120b is connected to the material pipe outlet 120b. The plunger outlet 130b facing the pressure holding inlet 140a is connected to the pressure holding inlet 140a.

The plunger rod <NUM> of <FIG> is a straight rod. One end of the plunger rod <NUM> facing the material pipe <NUM> is in contact with plastic, and the other end of the plunger rod <NUM> away from the material pipe <NUM> is provided with a plunger cylinder <NUM>. The plunger cylinder <NUM> includes a cylinder body <NUM> and a shaft <NUM>. A chamber is formed inside the cylinder body <NUM> where the shaft <NUM> is inserted and pushed. The shaft <NUM> of the plunger cylinder <NUM> is connected to the plunger rod <NUM> disposed at a distance from one end of the material pipe <NUM>, wherein the plunger cylinder <NUM> hydraulically pushes the plunger rod <NUM> in the plunger tube <NUM> to reciprocate. In some embodiments, a diameter of the plunger rod <NUM> is about <NUM>, but it is not limited to thereto.

The inner surface of the plunger tube <NUM> in <FIG> and one end of the plunger rod <NUM> facing the material pipe <NUM> define a fluid space <NUM>. The molten plastic flows out from the material pipe outlet 120b and enters the fluid space <NUM> through the plunger inlet 130a. That is, the plastic enters the fluid space <NUM> to achieve the desired injection volume. A pressure is generated on the inner surface of the plunger tube <NUM> and the plunger rod <NUM> to push the plunger rod <NUM>. In this way, the plunger rod <NUM> is moved towards the plunger cylinder <NUM> to reach the receiving position. Then, the plunger cylinder <NUM> drives the plunger rod <NUM> in the plunger tube <NUM> using oil pressure to squeeze the plastic in the fluid space <NUM> into the plunger outlet 130b.

In some embodiments, as shown in <FIG> and <FIG>, the pressure holding system <NUM> is disposed on a downstream of buffer system <NUM>. The pressure holding system <NUM> includes a pressure holding device. The pressure holding device is configured to continuously provide a predetermined pressure to the molding device <NUM>. In some embodiments, the pressure holding device may include a pressure holding pipe <NUM> that extends laterally as shown in <FIG>, and a pressure holding rod <NUM> that is slidably arranged in the pressure holding pipe <NUM> along an axial direction and sealingly fitted within the pressure holding pipe <NUM>.

The pressure holding pipe <NUM> as shown in <FIG> is a hollow body used to accommodate the plastic and pressure holding rod <NUM>. The pressure holding pipe <NUM> has a pressure holding inlet 140a that is facing and in communication with the plunger outlet 130b and a nozzle 140b that is facing and in communication with molding device2.

The pressure holding rod <NUM> as shown in <FIG> is a straight rod. One end of the pressure holding rod <NUM> is provided with a pressure holding cylinder <NUM> and the other end facing away from the pressure holding cylinder <NUM> is in contact with the plastic. The pressure holding cylinder <NUM> includes a cylinder body <NUM> and a shaft <NUM>. A chamber is formed within the cylinder body <NUM> for inserting and pushing the shaft <NUM>. The shaft <NUM> of the pressure holding cylinder <NUM> and one end of the pressure holding rod <NUM> away from the nozzle 140b are connected, whereby the pressure holding cylinder <NUM> hydraulically pushes the pressure holding rod <NUM> in the pressure holding pipe <NUM> to reciprocate.

As shown in <FIG> and <FIG>, the inner surface of the pressure holding pipe <NUM> and one end of the pressure holding rod <NUM> away from the pressure holding cylinder <NUM> defines a pressure holding chamber <NUM>. The molten plastic flowing out of the plunger outlet 130b enters the pressure holding chamber <NUM> from the pressure holding pipe inlet 140a and exits into the molding device <NUM> from the nozzle 140b. When the plastic enters the molding device <NUM>, the pressure holding cylinder <NUM> of the pressure holding system <NUM> will drive the pressure holding rod <NUM> to continuously exert a pressure on the plastic in the pressure holding pipe <NUM>.

In this embodiment, the buffer system and the pressure holding system are separate and independent systems. However, in some embodiments, the buffer system and pressure holding system can be combined into one system, and the buffer system has a pressure holding capability.

<FIG> illustrates a top view of a molding device according to some embodiments of the present disclosure. The molding device <NUM> includes a fixed mold plate <NUM> and a movable mold plate <NUM> opposite fixed mold plate22. The fixed mold plate <NUM> is disposed on a side of the molding device <NUM> near the injection machine <NUM>. The movable mold plate <NUM> is disposed on a side of the molding device <NUM> opposite the fixed mold plate <NUM> and away from injection machine <NUM>. The fixed mold plate <NUM> and the movable mold plate <NUM> can be connected to each other to form a mold space <NUM> of a mold <NUM>. The mold <NUM> has a nozzle (not shown in the figures) in contact with the nozzle 140b of the injection machine <NUM>.

The plastic leaves from nozzle 140b, enters the nozzle of mold, and fills the mold cavity in mold <NUM>. When the plastic gradually fills the mold cavity, the pressure holding cylinder <NUM> of the pressure holding system <NUM> will drive the pressure holding rod <NUM> and continuously apply a pressure to the plastic in the pressure holding pipe <NUM>. In this way, the shrinkage of the plastic volume due to cooling is compensated to ensure that the cavity is completely filled. The pressure is applied until the flow gate(not shown in the figure)has solidified and the end product is cooled within the mold. After, the movable mold plate <NUM> will move away from the fixed mold plate <NUM>, and the thimble mechanism (not shown in the figure) on the mold <NUM> will eject the end product.

The plastic injection molding machine can be equipped with a mechanical arm (not shown in the figure) to take out the ejected end product.

In some embodiments, after the end product is ejected from the molding system, the end product may be placed on a cooling rack. <FIG> illustrates a planar view of a cooling rack according to some embodiments of the present disclosure. <FIG> illustrates a side view of a cooling rack according to some embodiments of the present disclosure. <FIG> illustrates a backside view of a cooling rack according to some embodiments of the present disclosure. In some embodiments, the cooling rack includes a platform <NUM> and a plurality of positioning modules. The positioning modules includes a first positioning module <NUM> configured to accommodate a first type of end product. The positioning modules further includes a second positioning module <NUM> configured to accommodate a second type of end product. In some embodiments, the backside of the platform <NUM> includes a plurality of through holes <NUM> used for fastening the positioning modules onto the platform <NUM> and delivering cooling fluid to the end products.

<FIG> illustrates a backside view of a first type of end product according to some embodiments of the present disclosure. The first type of end product may be a protruding brick including a main body <NUM> and tenon structures <NUM> protruding from sidewalls of the main body <NUM>. The bottom surface <NUM> of the main body <NUM> defines a plurality of recessed areas. The recessed areas include a corner recess R111, a side recess R112, and a central recess R113. The bottom surface <NUM> of the tenon structure <NUM> defines a tenon recess R114. The first positioning module <NUM> includes a corner protrusion <NUM> complementing the corner recess R111 of the first type of end product, a side protrusion <NUM> complementing the side recess R112 of the first type of end product, a central protrusion <NUM> complementing the central recess R113 of the first type of end product, and a tenon protrusion <NUM> complementing the tenon recess R114 of the first type of end product. In some embodiments, a height of the tenon protrusion <NUM> is less than a height of the corner protrusion <NUM>, the side protrusion <NUM>, and the central protrusion <NUM>.

<FIG> illustrates a backside view of a second type of end product according to some embodiments of the present disclosure. The second type of end product may be a recessing brick including a main body <NUM> and mortise structures <NUM> protruding from sidewalls of the main body <NUM>. The bottom surface <NUM> of the main body <NUM> defines a plurality of recessed areas. The recessed areas include a corner recess R121, a side recess R122, a central recess R123, and a depression R124. In some embodiments, the mortise structures <NUM> are recessed areas on the sidewall of the main body <NUM>. The mortise structure has an inward side surface <NUM> and the outward side surface <NUM>. The second positioning module <NUM> includes a corner protrusion <NUM> complementing the corner recess R121 of the second type of end product, a side protrusion <NUM> complementing the side recess R122 of the second type of end product, a central protrusion <NUM> complementing the central recess R123 of the second type of end product, and a mortise protrusion <NUM> complementing the mortise structures <NUM> of the second type of end product. The mortise protrusion <NUM> complements the inward side surface <NUM> and outward side surface <NUM> of the mortise structures <NUM>. Further, in some embodiments, the mortise protrusion <NUM> has a toothed portion complementing the depressions R124 in the mortise structures <NUM>. In some embodiments, a height of the mortise protrusion <NUM> is less than a height of the corner protrusion <NUM>, the side protrusion <NUM>, and the central protrusion <NUM>.

<FIG> illustrates a front view of an injection machine and a drying system according to some embodiments of the present disclosure. The injection machine <NUM> further includes a drying system <NUM> configured to supply a large amount of the plastic to the supplying system <NUM>. The drying system <NUM> includes a dry mixing barrel <NUM> and a side conveyor <NUM>.

The dry mixing barrel <NUM> shown in <FIG> includes a barrel <NUM>, a third driver (not shown in figure), and a stirring rod <NUM>. The barrel <NUM> is a hollow body having a space to accommodate the plastic. The barrel <NUM> has a dry inlet (not shown in figure) and a dry outlet 301b. The dry inlet and the dry outlet 301b are in communication within the barrel <NUM> for the plastic to be provided through the dry inlet and discharged from the dry outlet. The barrel <NUM> includes an air outlet, a blower, and a heater (not shown in figure). The blower blows air into the heater to form hot air and increase the temperature of the air in the barrel <NUM>. The hot air enters the barrel <NUM> from the air outlet to dry the plastic.

A stirring rod <NUM> is disposed within the barrel <NUM>. The stirring rod <NUM> is a straight shaft. The surface of the stirring rod <NUM> is provided with a spiral sheet body. One end of the stirring rod <NUM> is fixed to the third driver. The stirring rod <NUM> is driven by the third driver to rotate around its own axis and mix and combine the plastic.

A side conveyor <NUM> includes a delivery pipe <NUM>, a fourth driver <NUM>, and a conveying screw (not shown in figures) disposed on a side of the injection machine <NUM>. The delivery pipe <NUM> is a hollow body having a delivery space inside. The delivery pipe <NUM> has a delivery inlet 310a disposed close to one end of the dry mixing barrel <NUM> and a delivery outlet 310b disposed away from another end of the dry mixing barrel <NUM>. The delivery inlet 310a and delivery outlet 310b of the delivery pipe <NUM> is in communication with each other within delivery pipe <NUM>. The dried plastic is provided to the delivery pipe <NUM> through the delivery inlet 310a and exits the delivery pipe <NUM> through the delivery outlet 310b. The fourth driver <NUM> can be installed near one end of the delivery pipe <NUM> that is near the delivery outlet 310b. The conveying screw has a straight shaft having a spiral sheet on its surface. One end of the conveying screw is affixed to the fourth driver <NUM> and is driven by the fourth driver <NUM> to rotate around its axis and further rotate the plastic. In this way, the plastic is conveyed from the delivery inlet 310a to the delivery outlet 310b.

<FIG> illustrates a flowchart of a method of operation of a plastic injection molding system according to some embodiments of the present disclosure. In step S1, the movable mold plate <NUM> moves toward the fixed mold plate <NUM> to lock the mold <NUM>. In step S2, the plastic that entered the buffer system <NUM> from the heating system <NUM> is squeezed into the pressure holding system <NUM> using the plunger rod <NUM>, and directly enter the molding device <NUM> to fill the mold cavity in the mold <NUM> to form an end product. In step S3, the end product in the molding device <NUM> is cooled in the cavity. In step S4, after the end product has cooled down, the pressure holding rod <NUM> will retreat towards the pressure holding cylinder <NUM>. In step S5, the movable mold plate <NUM> will move away from the fixed mold plate <NUM> to open the mold. In step S6, the mold ejection mechanism will eject the end product. In step S7, the end product is taken out.

Further, before the injection of plastic in step S2, the switch valve SH of injection machine <NUM> will be opened to allow the plastic of heating system <NUM> to enter buffer system <NUM>. When the amount of plastic reaches the desired injection volume, the switch valve SH will be closed to prevent plastic from being squeezed back into heating system <NUM> during injection.

In addition, the thicker the end product is, the longer the time is required for cooling. Therefore, if a thicker end product is to be produced, the cooling step can be performed again before the demolding in step S6. In this way, deformation due to incomplete solidification of the end product after demolding is prevented.

<FIG> illustrates a front view of an injection machine corresponding to two molding device according to some embodiments of the present disclosure. The plastic injection molding machine provides plastic to two molding devices 2A and 2B from one injection machine1. In some embodiments, the injection machine <NUM> includes a supplying system <NUM> and the heating system <NUM> as shown in <FIG>. And, the injection machine <NUM> further includes two material pipes 120A and 120B, two switch valves SH1 and SH2, and two buffer systems 13A and 13B, each corresponding to plastic transport channel <NUM> of molding device 2A and 2B. In this embodiment, the buffer system and the pressure holding system can be combined into one system, and the buffer systems 13A and 13B have the aforementioned pressure holding function.

<FIG> illustrates a flowchart of a method of operation of an injection machine in <FIG> corresponding to two molding device according to some embodiments of the present disclosure. In step S1, the respective movable mold plates <NUM> of the molding devices 2A and 2B will approach the fixed mold plate <NUM> to lock the mold. Then, the buffer system 13A and molding device 2A perform steps S2∼S7. The buffer system 13B and molding device 2B perform steps S8∼S13. The description of steps S2∼S7 and steps S8~S13 are same as in steps S2∼S7 of <FIG> and will not be described again for brevity. In addition, the buffer system 13B and the molding device 2B performing injection B of step S8 is not limited to being performed after the molding device 2A completing step S7. It can also be performed simultaneously with steps S2∼S7.

Before the plastic injection of step S2, the switch valve SH1 of injection machine <NUM> will be turned on and the switch valve SH2 will be turned off to allow the plastic of heating system <NUM> to enter buffer system 13A. When the plastic volume reaches the desired injection volume, the switch valve SH1 will be closed to prevent the plastic from squeezing back into the heating system <NUM> when the plastic is injected. Before step S8, the switch valve SH2 will be opened and the switch valve SH1 will be closed to allow the plastic of heating system <NUM> to enter the buffer system 13B. When the amount of plastic reaches the desired injection volume, the switch valve SH2 will be closed and then steps S8~S13 are performed.

<FIG> illustrates a front view of an injection machine corresponding to four molding devices according to some embodiments of the present disclosure. The plastic injection molding machine supplies plastic to four molding devices 2A, 2B, 2C, and 2D from one injection machine1. The injection machine <NUM> includes the supplying system <NUM> and the heating system <NUM> as shown in <FIG>. The injection machine <NUM> further includes a material pipe 120A, 120B, 120C, and 120D, a switch valve SH1, SH2, SH3, and SH4, and a buffer system13A, 13B, 13C, and 13D, each of above respectively corresponding to the four molding device 2A, 2B, 2C, and 2D. In this embodiment, the buffer system and the pressure holding system can be combined into one system, and the buffer systems 13A, 13B, 13C, and 13D can have the aforementioned pressure holding function.

<FIG> illustrates a flowchart of a method of operation of an injection machine corresponding to four molding devices as shown in <FIG> according to some embodiments of the present disclosure. In step S1, the movable mold plates <NUM> of the molding devices 2A, 2B, 2C, and 2D will approach the fixed mold plate <NUM> to lock the mold. Then, the buffer system 13A and molding device 2A perform steps S2∼S7; the buffer system 13B and the molding device 2B perform steps S8∼S13; the buffer system 13C and the molding device 2C perform steps S14∼S19; the buffer system 13D and the molding device 2D perform steps S20~S25. The description of the above mentioned steps are same as in steps S2∼S7 of <FIG>, and will not be described again for brevity. The abovementioned steps of each buffer system and each molding device need not wait for completing a preceding step of removing end product from molding device before being performed. The abovementioned steps can be simultaneously performed.

Similar to the previous steps, when each buffer system and molding device are in the injection step, only the corresponding switch valve will be opened to prevent the plastic from squeezing back into the heating system <NUM> when the plastic is injected. The other switch valves will be closed. For example, before performing injection A in step S2, the switch valve SH1 of the injection machine <NUM> will be turned on. The other switch valves SH2, SH3, and SH4 will be closed. In this way, the plastic of heating system <NUM> enters buffer system 13A. When the amount of plastic reaches the desired injection volume, the switch valve SH1 will be closed and the steps S2∼S7 will be performed.

According to the disclosure, the exemplary injection machine corresponds to more than one molding device, but the number of molding devices is not limited thereto.

The following table shows the injection units of the injection machine of the present disclosure and the conventional injection machine with a clamping force of 600T:.

It can be seen from the above table that the maximum injection weight of a conventional injection machine with a 600T clamping force can only be <NUM>, while the enhanced injection machine of the disclosure with specification of 600T clamping force has a maximum injection weight of about <NUM>. Generally, to achieve an injection machine with a maximum injection weight of about <NUM>, an injection machine need a specification of 1800T clamping force. However, the injection machine of the present disclosure only requires 600T to reach a maximum injection weight of nearly <NUM>. Therefore, the present disclosure can reduce equipment costs and reduce energy consumption.

Claim 1:
An injection machine (<NUM>) for a recycled plastic injection molding system used with at least one molding device to produce an end product from plastic, the injection machine (<NUM>) comprising:
a supplying system (<NUM>) having a hopper (<NUM>), a first driver (<NUM>) disposed on the hopper (<NUM>), the first driver (<NUM>) has a feed screw (<NUM>) penetrating the hopper (<NUM>), the first driver (<NUM>) is configured to drive the feed screw (<NUM>) to rotate;
a heating system (<NUM>) disposed on a downstream of the supplying system (<NUM>), the heating system (<NUM>) having a heating pipe (<NUM>),
a second driver (<NUM>) disposed on one end of the heating pipe (<NUM>), the second driver (<NUM>) has a heating screw (<NUM>) penetrating the heating pipe (<NUM>), the second driver (<NUM>) configured to drive the heating screw (<NUM>) to rotate;
a buffer system (<NUM>) disposed on a downstream of the heating system (<NUM>), the buffer system (<NUM>) having a plunger tube (<NUM>) and a plunger rod (<NUM>) slidably installed and sealed within the plunger tube (<NUM>);
characterized in that:
the feed screw (<NUM>) of the first driver (<NUM>) extends into the heating system (<NUM>), and
wherein the feed screw (<NUM>) and the heating screw (<NUM>) are configured to be at a distance from each other, the distance ranges between <NUM>-<NUM>.