CN112223696A

CN112223696A - Injection device of plastic injection molding machine

Info

Publication number: CN112223696A
Application number: CN202011028569.0A
Authority: CN
Inventors: 周长春; 周游; 周子婷
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-09-25
Filing date: 2020-09-25
Publication date: 2021-01-15
Anticipated expiration: 2040-09-25
Also published as: CN112223696B

Abstract

The invention discloses an injection device of a plastic injection molding machine, belonging to the field of plastic injection molding equipment manufacture, comprising an injection rod connected with an injection tube, wherein the front end of the injection tube is provided with a nozzle and a flange, the rear end of the injection tube is sleeved with a front connecting plate, the injection rod is connected with an injection piston rod, and the injection piston rod is connected with a piston and then arranged in an injection cylinder; a barrel is obliquely arranged on the horizontal axis of the injection cylinder, the front end of the barrel is connected with the front connecting plate, a screw is arranged in the barrel, the screw is matched with the transmission shaft and the oil motor, and a transmission seat provided with a blanking port is arranged at the rear end of the barrel; the upper end of the front connecting plate is provided with a material pushing and pressurizing oil cylinder, a piston rod and a quick push rod are arranged in the front connecting plate, material pushing, material supplementing and pressurizing are carried out during material storage, glue sucking and injection, another injection force is generated, the injection force of the whole machine is additionally increased, the plasticizing time is shortened, the places which cannot be reached by the corners of the product can be filled, filled and free of residual gas, the mold filling speed is high, the pressure is high, the molding period is fast, the injection amount is large, and high efficiency and energy conservation are achieved.

Description

Injection device of plastic injection molding machine

Technical Field

The invention relates to the field of manufacturing of plastic injection molding equipment, in particular to an injection device of a plastic injection molding machine.

Background

With the progress of society, the application of plastic products is more and more extensive, the plastic molding industry rises rapidly, and the improvement on plastic production machinery is also continuously carried out, and an injection molding machine is a typical mechanical device in the plastic molding machinery. The injection device of the injection molding machine uniformly melts and plastifies specified plastics to a molding temperature within specified time in the cycle process of injection molding, injects the molten material into a mold cavity at certain pressure and speed, and maintains the pressure of the molten material injected into the mold cavity after injection.

Current injection molding devices for plastic injection molding have: the first is a double-cylinder or multi-cylinder injection mode, as shown in fig. 1 and 2 (the numbers in fig. 1 and 2 indicate that 1-screw, 2-machine barrel, 3-transmission shaft, 4-transmission seat injection seat, 5-oil motor, 6-moving guide column, 7-injection oil cylinder, 8-injection device bracket, 9-injection seat, 10-two sets of injection oil cylinders and 11-injection piston rod). The injection device mainly comprises a rack, an injection device bracket, a movable guide pillar, an injection oil cylinder, an injection seat, two or more injection cylinder bodies, an injection piston rod, a screw rod, a machine barrel, a transmission seat, a transmission shaft, a set of thrust bearing, a guide bearing, an oil motor and the like which are correspondingly arranged on the transmission shaft, wherein the injection device can meet the molding requirement of common plastic products, but because two groups of injection cylinder bodies are difficult to synchronize when performing refraction action, the generated injection weight is unstable, the transmission seat and the oil motor are driven to move together to generate resistance, and a moving guide rail below the transmission seat can also generate eccentric force and has larger power loss; and because the oil motor drives a set of transmission mechanism and the screw rod to rotate, the rotating torque is large, the efficiency is low, the plasticizing time is long, the production efficiency is influenced, the injection resistance is large, and a high-density, high-precision and thin-wall product is difficult to mold.

The second is a single injection cylinder injection mode, as shown in fig. 3 (the number in fig. 3 is described as 1-screw, 2-machine barrel, 3-single set of injection cylinder, 4-rotatable piston, 5-plum blossom key sleeve, 6-plum blossom key shaft, 7-oil motor, 8-shooting moving cylinder, 9-injection device base and 10-shooting moving guide rail), although unbalanced force and centrifugal force can be eliminated, the injection action line is lengthened during single cylinder injection, the injection rigidity is reduced, the plum blossom key sleeve and plum blossom key shaft arranged in the injection piston rod can also generate resistance, the air suction and exhaust when the plum blossom key sleeve and the plum blossom key generate relative movement also generate additional resistance, the total injection power is reduced, and a high-precision product is difficult to mold; and during plasticizing, the oil motor rotates to drive the piston and the screw rod to rotate together, so that the path is long, and a larger rotating torque is required. Because of poor injection rigidity, a set of transmission device in the oil cylinder is easy to damage, generates leakage and pressure loss, is difficult to assemble and disassemble, and has high maintenance cost, the device is also difficult to form products with high precision and high requirement on compactness.

The third is a mode that a material storage injection tube and a plasticizing machine barrel screw line are arranged at an angle, as shown in figure 4 (the number in figure 4 indicates that 1-melt through stop valve rod, 2-valve rod driving oil cylinder, 3-injection seat, 4-screw, 5-machine barrel, 6-oil motor, 7-lengthening nozzle, 8-material storage injection tube, 9-injection head, 10-injection device base and 11-injection oil cylinder are used), although the injection rigidity of the device is good and the injection force is large, the plasticized feeding material reaches the front end of the injection head through a longer route, a one-way valve is required to convert the action to seal the strong injection pressure to enter the plasticizing machine barrel screw during injection, and the feeding hole line and the injection hole line of the slender strip are long because the material feeding hole is very close to the end surface of the mold and the normal use is not influenced, severely affecting the delivery of injection force.

In view of the advantages and disadvantages of the above three injection devices, there is room for improvement in the injection devices of the existing plastic injection molding machines.

Disclosure of Invention

1. Technical problem to be solved

The invention aims to provide an injection device of a plastic injection molding machine, which has the characteristics of simple structure, clear function, convenient manufacture, strong stability, capability of molding thin-wall products with high strength and high compactness, first-in first-out sequential flow principle of plastics and high efficiency and energy conservation.

2. Technical scheme

In order to solve the above problems, the present invention adopts the following technical solutions.

An injection unit of an injection molding machine, comprising:

the support frame can move relative to the guide rail surface of the frame;

the injection unit comprises an injection tube, an injection piston rod and an injection oil cylinder, and is connected with the support frame through the front connecting plate;

the plasticizing unit comprises a cylinder for plasticizing, the cylinder is arranged above the axis of the injection piston rod in an inclined mode, and the front end of the cylinder is obliquely matched with the front connecting plate and is fastened by screws;

the pushing and pressurizing unit comprises a pushing and pressurizing oil cylinder arranged at the upper end of the front connecting plate, and the pushing and pressurizing oil cylinder and the front connecting plate are supported and tensioned by a group of high cushion pipes and pull rods.

Furthermore, the front end of the injection tube is provided with a nozzle and a flange, the injection tube is internally sleeved with an injection rod, the front end of the injection rod is provided with an injection head and a check ring, the tail end of the injection rod is connected with an injection piston rod through a water transporting body, and a snap ring is arranged between the injection rod and the water transporting body.

Furthermore, the injection oil cylinder comprises an injection piston rod, an injection cylinder front cover, an injection cylinder and an injection cylinder rear cover, a piston is arranged in the injection piston rod, the injection cylinder front cover and the injection cylinder rear cover are fixedly connected with the support frame, and the injection oil cylinder is connected with the front connecting plate through four large pull rods.

Furthermore, a guide sleeve and a large nut are arranged at the tail end of the injection tube.

Furthermore, an anti-rotation pin is arranged between the front connecting plate and the injection cylinder.

Further, a screw rod is arranged in the machine barrel, a transmission seat and a machine barrel nut are arranged at the tail end of the machine barrel, a blanking port is arranged above the transmission seat, a discharging end of the screw rod is in contact with the injection tube and is provided with a discharging long hole, the tail end of the screw rod is arranged in a transmission shaft through a transmission key and is fastened through a screw, the other end of the transmission shaft is connected with an output shaft of an oil motor, the oil motor is connected with the transmission seat, and the lower side of the transmission seat is connected with a rear cover of the injection cylinder through a connecting block.

Furthermore, a guide shaft sleeve is arranged on the left outer diameter of the transmission shaft, the guide shaft sleeve is arranged in the tail end of the machine barrel, a thrust rotating sleeve and a compression ring are arranged on the right outer diameter of the transmission shaft, and a spigot matched with the nut of the machine barrel is arranged on the compression ring and is positioned and fastened by a screw.

Furthermore, the machine barrel is provided with a cooling water assembly close to the left end face of the transmission seat, and a through hole is formed in the back of one side of the transmission seat and used for a cooling water pipe to enter.

Further, it comprises an upper oil cylinder cover, an oil cylinder sleeve, a lower oil cylinder cover, a piston rod and an oil passing rod arranged in the upper end of the piston rod, wherein the lower end of the piston rod extends into the inner hole of the front connecting plate, the lower end face of the piston rod does not extend into the injection tube, and the top of the oil passing rod is tightly connected with the oil cylinder through a taper pipe thread.

Furthermore, a cooling water assembly is arranged at the extending end of the piston rod, and a cooling water assembly is also arranged at the lower cover of the oil cylinder.

3. Advantageous effects

Compared with the prior art, the invention has the advantages that:

(1) the injection device of the plastic injection molding machine has strong injection pressure and injection rigidity and high energy conservation. When the injection is prepared, the material in the injection tube is a well melted fluid, when the pressure oil is fed to the right side of the injection piston, the generated injection force directly pushes the injection piston rod, the water conveying body, the clamping ring, the injection rod, the non-return ring and the injection head to inject, only the friction resistance related to the action section is consumed, almost all acting force participates in the injection, and the action line of the action section is short, so that the injection rigidity is high, and the molding is facilitated.

(2) The injection device of the plastic injection molding machine has the function of increasing the injection pressure, and can mold thinner, larger, higher-density and more complex products. An annular material storage and passing area is arranged between the small diameter section of the injection rod and the inner diameter of the injection tube, when the injection rod moves in an injection mode, the upper end of the upper piston rod is pushed downwards under the action of pressure oil to push another strand of material to move along with the injection rod, and meanwhile another injection force is generated and is increased or reduced together with the total injection force of the large injection oil cylinder.

(3) The injection device of the plastic injection molding machine changes the traditional screw rotation plasticizing and material storage function. As long as the injection cylinder has a rod cavity for feeding pressure oil, the injection rod retreats, the piston rod pushes the material downwards, the right end of the injection rod and the annular colloid in the injection tube are pressed to jointly generate pressure so as to open the check ring, the melt in the right side flows into the front end of the injection rod, the material quantity required before injection is achieved, and meanwhile, the first-in first-out principle of plastic melting and conveying can be realized, so that the plasticizing time is greatly saved and the plasticizing quality is ensured.

(4) The injection device of the plastic injection molding machine can obtain different injection quantities and injection pressures only by changing the flange, the injection cylinder, the inner diameter and the outer diameter of the check ring and changing the diameter of the outer thread of the guide sleeve, thereby meeting various molding requirements.

Drawings

FIG. 1 is a first schematic structural view of a plastic injection molding apparatus employing dual cylinder injection;

FIG. 2 is a schematic structural view II of a plastic injection molding apparatus using double-cylinder injection;

FIG. 3 is a schematic view showing a structure of a plastic injection molding apparatus using single-cylinder injection;

FIG. 4 is a schematic structural view of a plastic injection molding apparatus employing a storage barrel disposed at an angle to the plasticating barrel screw line

Fig. 5 is a schematic view of the overall structure of one embodiment of the present invention.

The designations in FIG. 5 illustrate:

1-nozzle, 2-flange, 3-injection head, 4-check ring, 5-injection rod, 6-injection tube, 7-front connecting plate, 8-guide sleeve, 9-large nut, 10-snap ring, 11-water conveying body, 12-large pull rod, 13-injection piston rod, 14-injection cylinder front cover, 15-injection piston, 16-injection cylinder, 17-support frame, 18-injection cylinder rear cover, 19-connecting block, 20-transmission seat, 21-transmission key, 22-oil motor, 23-screw, 24-transmission shaft, 25-thrust rotating sleeve, 26-compression ring, 27-machine barrel nut, 28-guide shaft sleeve, 29-screw, 30-machine barrel, 31-pull rod, 32-oil through rod, 33-an upper oil cylinder cover, 34-an oil cylinder sleeve, 35-a lower oil cylinder cover, 36-an equal-height cushion pipe, 37-a piston rod, 38-an anti-rotation pin, 39-a one-way ball valve, 40-a switch plunger, 41-a first oil inlet end, 42-a second oil inlet end, 43-a third oil inlet end, 44-a fourth oil inlet end and 45-a fifth oil inlet end.

Detailed Description

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention; it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and all other embodiments obtained by those skilled in the art without any inventive work are within the scope of the present invention.

In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "top/bottom", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "disposed," "sleeved/connected," "connected," and the like are to be construed broadly, e.g., "connected," which may be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Example 1:

referring to fig. 5, an injection device of a plastic injection molding machine includes:

a support frame 17 which is movable relative to the guide rail surface of the frame;

the injection unit comprises an injection tube 6, the front end of the injection tube 6 is tightly connected with a flange 2 by a group of screws, a small-diameter section of the flange 2 is provided with a heating ring, and a nozzle 1 is arranged at the small-diameter end; the rear end of the injection tube 6 is provided with a front connecting plate 7 and a large nut 9, an anti-rotation pin 38 is arranged between the front connecting plate 7 and the injection tube 6 to prevent mutual rotation, the large nut 9 can meet the maximum total injection force and has an anti-loosening function, and the front connecting plate 7 is fixedly connected with the support frame 17 and can move relative to the guide rail surface of the frame; an injection rod 5 is sleeved in the rear end of an injection tube 6, an injection head 3 and a non-return ring 4 are arranged at the front end of the injection rod 5, sufficient glue passing capacity is provided between the non-return ring 4 and the injection head 3, a section of large-diameter contact surface is provided at the contact end of the injection rod 5 and the non-return ring 4, the rest part is small in diameter until the extension section is formed, and the small diameter and an inner hole of the injection tube 6 form an annular area for glue passing and the other part of materials generates injection force; a guide sleeve 8 is arranged at an inner hole at the tail end of the injection tube 6, the inner diameter of the guide sleeve 8 is matched with the small diameter of the injection rod 5, so that molten material in the injection tube 6 is ensured not to leak and only can move in a matched manner, the coaxial injection rod 5 and the precise wear-resistant guide function are ensured after being connected by threads, and the extending end of the guide sleeve 8 is provided with a slope to facilitate the material flow; the extended end of the injection tube 6 is provided with a heating ring for heat preservation, so that the material is in a molten state to facilitate injection molding. The tail end of the injection rod 5 extends into an injection piston rod 13 and is connected with a water transporting body 11 and a clamping ring 10 to form an injection action line, a piston 15 is arranged in the injection piston rod 13, the piston 15, an injection cylinder front cover 14, an injection cylinder 16 and an injection cylinder rear cover 18 form an injection cylinder, the product of the inner diameter area of the injection cylinder 16 and the system pressure is larger than the set injection force, and the water transporting body 11 is cooled by cooling water to prevent heat transmitted from the injection rod 5 from being transmitted to the injection cylinder. The injection cylinder front cover 14 and the injection cylinder rear cover 18 are fixedly connected with a support frame 17, and the injection cylinder is connected with the front connecting plate 7 by four large pull rods 12 to form a movement stress body. A nozzle moving oil cylinder is arranged between the lower part of the left side surface of the injection cylinder front cover 14 and the support frame 17, one end of the nozzle moving oil cylinder is connected on the injection cylinder front cover 14, and the other end is connected with a fixed plate of the mold locking device. The left cavity and the right cavity of the oil cylinder are filled with oil, the nozzle can be tightly attached to the die or separated from the die, and a space is arranged below the middle of the front connecting plate 7 and used for the nozzle to move the oil cylinder;

the plasticizing unit comprises a machine barrel 30 which is obliquely arranged above the axis of the injection piston rod 13 and used for plasticizing, and the front end of the machine barrel 30 is obliquely matched with the front connecting plate 7 and is fastened by screws; the tail end of the machine barrel 30 is provided with a transmission seat 20 and a machine barrel nut 27, and a blanking port is arranged above the transmission seat 20; a screw 29 is arranged in an inner hole of a machine barrel 30, a discharge long hole is arranged at the contact part of the injection tube 6 at the discharge end of the screw 29, the discharge long hole is communicated through a connecting plate 7, and the discharge long hole has the functions of conveying materials into the right cavity of the injection tube 6, pushing a piston rod 32 back to ascend, returning for storing materials, feeding materials for the injection 6 during injection and pressurizing, and pushing materials to the head of the injection rod 5 when the next mold needs to store materials and suck glue. The tail end of the screw 29 is provided with a driving key 21 and is arranged in a driving shaft 24 together and is tightly screwed by a screw 21, the other end of the driving shaft 24 is connected with an output shaft of an oil motor 22, the oil motor 22 is arranged at the right end of a driving seat 20, and the lower side of the driving seat 20 is fixed with the injection cylinder rear cover 18 by a connecting block 19. The left outer diameter of the drive shaft 24 is provided with a guide sleeve 28, the guide sleeve 28 fitting within the distal end of the barrel 30. The right outer diameter of the transmission shaft 24 is provided with a thrust rotating sleeve 25 and a pressing ring 26 which are enough to meet the maximum thrust generated by the head of the screw 29, the pressing ring 26 is provided with a rabbet matched with a machine barrel nut 27 for positioning and is tightly connected by a group of screws, and the stress of the group of screws is enough to meet the stress strength of the heel thrust rotating sleeve 25. The cooling water is arranged on the left end face of the machine barrel 30 close to the transmission seat 20, so that the cooling function is achieved, the heat of the heating ring of the left extending section of the machine barrel 30 is prevented from being transferred to the transmission seat 20, the blanking of the blanking opening is prevented from being influenced, and the cooling water is also arranged at the position of the compression ring 26. A through hole is arranged at the back of one side of the transmission seat 20 for the inlet of a cooling water pipe, and the function of the through hole is to prevent the heat of the screw 29 from being transferred to the oil motor 22 and ensure the use quality;

the pushing and pressurizing unit comprises a pushing and pressurizing oil cylinder arranged at the upper end of the front connecting plate 7, the pushing and pressurizing oil cylinder and the front connecting plate 7 are supported and tensioned by a group of high cushion pipes 36 and pull rods 31, and the pushing and pressurizing oil cylinder is composed of an oil cylinder upper cover 33, an oil cylinder sleeve 34, an oil cylinder lower cover 35, a piston rod 37 and an oil through rod 32 in the upper large end of the piston rod 37. The tip footpath of piston rod 37 stretches into 7 holes of front connection board and cooperation, and the terminal surface does not surpass into 6 internal diameters of injection tube, should guarantee to push away the material and can satisfy the biggest needs from the material that screw rod 29 sent when the pressure boost is on the earth, injection rod before also satisfying the injection simultaneously, required material reachs the gluey volume of 5 head stores of injection rod when 5 take out glue, the main aspects department of piston rod 37 is equipped with logical oil pole 32 that pushes away fast and use, logical oil pole 32 top and hydro-cylinder upper cover 33 are tightly continuous with the taper pipe screw thread. The intersection of the large diameter and the small diameter of the extending end of the piston rod 37 is provided with cooling water, and the lower cover 35 of the oil cylinder is also provided with cooling water for preventing the heat at the lower part from being transferred to the oil cylinder at the upper part.

The working principle is as follows: the forming action of the device is as follows:

(1) and (5) pumping glue and storing. The piston rod 37 rises to the set material storage height, the second oil inlet end 42 of the injection oil cylinder enters pressure, the first oil inlet end 41 of the oil injection oil cylinder discharges oil, the injection rod 5 retreats, the switch plunger 40 retreats under the pulling of the oil cylinder or the air cylinder at the moment, a flow channel is opened, meanwhile, the oil motor 22 rotates to enable the screw 29 to feed materials, the check ball valve 39 is pushed open to enter the injection tube 6, the check ring 4 is pushed open, the check ring 4 is opened, the molten materials between the injection rod 5 and the injection tube 6 are sent to the head end of the injection rod 5, and the injection rod 5 retreats to the set position to meet the requirement of injection quantity. And finishing the plasticizing, rubber pumping and material storing actions.

(2) And (4) preventing saliva (optional). The second oil inlet end 42 of the injection oil cylinder is filled with pressure oil, the first oil inlet end 41 of the injection oil cylinder is filled with oil, the third oil inlet end 43 and the fourth oil inlet end 44 of the pushing and pressurizing oil cylinder are filled with oil, and the fifth oil inlet end 45 of the pushing and pressurizing oil cylinder is filled with oil. Since the injection rod 5 is retreated and the annular space between the injection rod 5 and the syringe 6 is reduced, the piston rod 37 has a slight upward stroke. At this time, the melt pushes the check ball valve 39 to close the flow passage upward, or the switch plunger 40 driven by the oil cylinder or the air cylinder advances to close the flow passage, so as to prevent the melt from flowing back into the barrel 30.

(3) The injection is slow. Pressure oil from an oil pump slowly enters a first oil inlet end 41 of the injection oil cylinder, a second oil inlet end 42 of the injection oil cylinder discharges oil, a small amount of pressure oil enters a third oil inlet end 43 of the pushing and pressurizing oil cylinder at the oil through rod 32 to push a piston rod 37 to push downwards, the change of the annular space of the injection rod 5 and the injection cylinder 6 is coordinated, a fourth oil inlet end 44 of the pushing and pressurizing oil cylinder sucks oil, and a fifth oil inlet end 45 discharges oil, so that the action does not need larger oil pump pressure. The first oil inlet end 41 and the second oil inlet end 42 of the injection oil cylinder can perform differential slow injection at the same time, the switch plunger 40 is pulled to retreat by the oil cylinder or the air cylinder, a flow passage is opened, the oil motor 22 rotates to feed the screw 29, the one-way ball valve 39 is pushed open and enters the injection cylinder 6, the oil motor 22 stops rotating until the piston rod 37 rises to the set material storage height, and the pre-molding time is fully utilized to reduce the molding period.

(4) The injection is quick. Pressure oil from an oil pump quickly enters a cylinder cavity of a first oil inlet end 41 of an injection cylinder, meanwhile, a second oil inlet end 42 of the injection cylinder quickly discharges oil, a third oil inlet end 43 of a pushing and pressurizing cylinder at an oil through rod 32 also enters a large amount of pressure oil to push a piston rod 37 to quickly push downwards to coordinate with the change of annular spaces of an injection rod 5 and an injection cylinder 6, a fourth oil inlet end 44 of the pushing and pressurizing cylinder sucks oil, and a fifth oil inlet end 45 discharges oil, so that the fast injection can be achieved without increasing the power of the oil pump and a motor, the action can select the differential motion of the first oil inlet end 41 and the second oil inlet end 42 of the injection cylinder, the fast injection only needs to fast mold filling, the high-pressure output of the oil pump is not needed, at the moment, a switch plunger 40 can retreat under the pulling of the oil cylinder or the air cylinder, a flow passage is opened, an oil motor 22 rotates to enable a screw 29 to push away a feeding one, and enters the injection cylinder 6, until the piston rod 37 rises to the set material storage height, the oil motor 22 stops rotating, and the pre-molding time is fully utilized to reduce the molding period.

(5) Slow high pressure injection. Pressure oil from an oil pump enters a cylinder cavity of a first oil inlet end 41 of an injection cylinder of the injection cylinder at a speed reducing high pressure, at the moment, the first oil inlet end 41 of the injection cylinder and a second oil inlet end 42 of the injection cylinder do not have a differential function, oil is discharged from the second oil inlet end 42 of the injection cylinder, a third oil inlet end 43 of a material pushing and pressurizing cylinder at a position 32 of an oil through rod pushes downwards along with the speed reducing high pressure oil inlet of the first oil inlet end 41 of the injection cylinder, simultaneously, the fourth oil inlet end 44 of the material pushing and pressurizing cylinder absorbs oil, and oil is discharged from a fifth oil inlet end 45. The material in the mold cavity is further compacted and filled to form. And at this time, the melt pushes the one-way ball valve 39 to close the flow passage upwards, or the switch plunger 40 driven by the oil cylinder or the air cylinder advances to close the flow passage, so that the melt is prevented from flowing backwards into the machine barrel 30.

(6) And (4) pressurizing (optional). When the boosting function is selected, other actions are continued, namely the fourth oil inlet end 44 of the material pushing and boosting oil cylinder is closed in advance to absorb oil and enter high-pressure oil before the upper action is finished, so that the material at the bottom of the piston rod 37 is boosted, and the material with the boosted pressure transmits another pressure to act on the step at the front end of the injection rod 5 and a part of the annular surface at the back end of the check ring 4 to jointly generate a second injection force. The pressure maintaining function is only required to maintain the upper action once. At this time, the melt pushes the check ball valve 39 to close the flow passage upward, or the switch plunger 40 driven by the oil cylinder or the air cylinder advances to close the flow passage, so as to prevent the melt from flowing back into the barrel 30.

(7) And (4) performing preplasticizing. The oil motor 22 rotates, if the variable speed motor is used for driving, the pressure melt conveyed by the rotation of the screw 29 passes through a channel which is opened by the backward movement of a switch plunger 40 driven by an oil cylinder or an air cylinder in a plasticizing main channel of the front connecting plate 7, the one-way ball valve 39 is pushed open, and the bottom end of the piston rod 37 is acted on, so that the piston rod 37 is lifted to the set material storage height. Stock is made ready for the next cycle.

The foregoing is only a preferred embodiment of the present invention; the scope of the invention is not limited thereto. Any person skilled in the art should be able to cover the technical scope of the present invention by equivalent or modified solutions and modifications within the technical scope of the present invention.

Claims

1. An injection unit of an injection molding machine for plastic, comprising:

the support frame can move relative to the guide rail surface of the frame;

2. The injection apparatus as claimed in claim 1, wherein the injection tube has a nozzle and a flange at a front end thereof, the injection tube is internally provided with an injection rod, the injection rod has an injection head and a check ring at a front end thereof, a rear end of the injection rod is connected to the injection piston rod through a water carrier, and a snap ring is provided between the injection rod and the water carrier.

3. The injection device of a plastic injection molding machine according to claim 2, wherein the injection cylinder comprises an injection piston rod, an injection cylinder front cover, an injection cylinder, and an injection cylinder rear cover, wherein a piston is installed in the injection piston rod, the injection cylinder front cover and the injection cylinder rear cover are fixedly connected with the support frame, and the injection cylinder is connected with the front connection plate by four large pull rods.

4. An injection apparatus for a plastic injection molding machine as claimed in claim 3, wherein a guide sleeve and a large nut are provided at a distal end of said injection tube.

5. The injection unit of an injection molding machine as claimed in claim 4, wherein an anti-rotation pin is provided between said front plate and said injection cylinder.

6. The injection apparatus of a plastic injection molding machine as claimed in claim 1, wherein a screw is provided in the cylinder, a driving seat and a cylinder nut are provided at the rear end of the cylinder, a material dropping opening is provided above the driving seat, a long material discharging hole is provided at the discharging end of the screw in contact with the injection tube, the rear end of the screw is inserted into a driving shaft through a driving key and fastened by a screw, the other end of the driving shaft is connected to an output shaft of an oil motor, the oil motor is connected to the driving seat, and the lower side of the driving seat is connected to the rear cover of the injection cylinder through a connecting block.

7. An injection unit for an injection molding machine as defined in claim 6, wherein a guide sleeve is provided on the left outer diameter of said drive shaft, said guide sleeve being disposed within the distal end of said barrel, a thrust runner and a clamp ring being provided on the right outer diameter of said drive shaft, said clamp ring being provided with a spigot for mating with a nut of said barrel for positioning and fastening with a screw.

8. An injection unit for an injection molding machine as claimed in claim 7, wherein said barrel is provided with a cooling water block adjacent a left end face of said drive base, and a port is provided behind a side of said drive base for receiving a cooling water supply pipe.

9. The injection device of a plastic injection molding machine according to claim 1, wherein the material pushing and pressurizing cylinder comprises an upper cylinder cover, a cylinder sleeve, a lower cylinder cover, a piston rod and an oil through rod arranged in the upper end of the piston rod, the lower end of the piston rod extends into the inner hole of the front connecting plate, the lower end surface of the piston rod does not extend into the injection tube, and the top of the oil through rod is tightly connected with the cylinder through a taper tube thread.

10. The injection apparatus of an injection molding machine according to claim 9, wherein a cooling water unit is provided at the projecting end of the piston rod, and a cooling water unit is also provided at the lower cover of the cylinder.