A plastic part forming apparatus

Abstract

The application relates to the technical field of plastic forming equipment, and discloses a plastic part forming device which comprises a bottom plate, a hopper arranged on the top of the bottom plate, a mold frame arranged on the top of the bottom plate and away from the hopper, and a material blowing mechanism arranged in the bottom plate; the material blowing mechanism comprises a shell arranged in the bottom plate, a sliding groove arranged on the bottom plate and close to the mold frame, a push rod arranged at the bottom of the mold frame, a partition plate arranged at the end of the push rod and away from the mold frame, the outer side of the partition plate is slidably connected with the inner wall of the shell, liquid inlet holes are symmetrically arranged on the upper parts of the two ends of the shell, liquid outlet holes are symmetrically arranged on the lower parts of the two ends of the shell, four one-way valves are arranged on the sides close to the inner wall of the shell of the liquid inlet holes and the liquid outlet holes respectively, a liquid discharge pipe is arranged on the sides close to the outer wall of the shell of the two liquid outlet holes, and a liquid conveying pipe is arranged on the sides close to the outer wall of the shell of the two liquid inlet holes. Through the arrangement of the material blowing mechanism, redundant kinetic energy in the mold opening and closing process can be captured and converted to blow dry the raw materials.

Description

Technical Field

[0001] This invention relates to the field of recycled plastic molding equipment technology, and more particularly to a plastic parts molding device. Background Technology

[0002] Plastic molding equipment is an industrial device that transforms high-molecular polymer raw materials into products with specific shapes and functions. Its core processes include injection molding, extrusion, blow molding, and compression molding. In the field of plastic recycling, this equipment is a key link in realizing the resource utilization of recycled plastics, forming the core technology in the circular economy industrial chain. After pretreatment processes such as sorting, washing, crushing, and melt extrusion granulation, the recycled plastic granules generated need to be reprocessed by molding equipment to manufacture recycled products that meet specific performance requirements, such as logistics pallets, building materials, and municipal facility components. The technological level of this equipment directly determines the application scope and added value of recycled plastics. Advanced molding equipment, through precise temperature control systems, pressure control, and screw design, can effectively address problems such as molecular chain degradation and high impurity content caused by multiple processing of recycled plastics, ensuring that the mechanical properties, dimensional accuracy, and surface quality of recycled products meet the usage standards.

[0003] Traditional plastic molding machines are widely used in the plastic recycling industry, but due to limitations in their structure and working principle, they often suffer from some significant problems. The energy waste inherent in the mold opening and closing motion is particularly prominent in traditional plastic molding devices. During mold closing, the drive system converts electrical energy into mechanical energy, propelling the moving platen at high speed and giving it substantial kinetic energy. However, just before contacting the stationary platen, to prevent a violent impact, the system must apply resistance through hydraulic valve throttling or mechanical brakes to force the moving platen to decelerate. During this process, most of the kinetic energy accumulated in the moving platen is forcibly converted into heat energy and dissipated through hydraulic oil or the brakes, failing to be effectively utilized. Similarly, during mold opening, the system drives the mold to separate, and the moving platen regains kinetic energy. When it reaches the predetermined endpoint, its kinetic energy is again dissipated as useless heat energy through braking. This periodic acceleration and braking pattern means that in each mold opening and closing cycle, the energy input to drive the mold movement is artificially consumed by braking at the end of the action. Due to the lack of an effective kinetic energy recovery and reuse mechanism, this portion of energy that could have been stored or reused for the next acceleration is completely wasted, constituting a direct and enormous energy loss during equipment operation. Summary of the Invention

[0004] In view of the problem that kinetic energy is wasted during the mold opening and closing process of existing molding equipment, a plastic part molding device is proposed.

[0005] Its purpose is to enable molding equipment to utilize the kinetic energy generated during the mold opening and closing process.

[0006] The technical solution of the present invention is a plastic part molding device, including a base plate, a hopper disposed on the top of the base plate, a mold frame disposed on the side of the top of the base plate away from the hopper, and a blowing mechanism disposed inside the base plate; The blowing mechanism includes an outer shell disposed inside the base plate, a sliding groove opened on the base plate near the mold frame, a push rod disposed at the bottom of the mold frame, a partition plate disposed at the end of the push rod away from the mold frame, the outer side of the partition plate being slidably connected to the inner wall of the outer shell, liquid inlets symmetrically disposed at the upper part of both ends of the outer shell, liquid outlets symmetrically disposed at the lower part of both ends of the outer shell, four one-way valves respectively disposed at the liquid inlets and liquid outlets near the inner wall of the outer shell, a drain pipe jointly disposed at the two liquid outlets near the outer wall of the outer shell, a delivery pipe jointly disposed at the two liquid inlets near the outer wall of the outer shell, a pressure chamber disposed at the end of the drain pipe away from the outer shell, an airbag disposed inside the pressure chamber, a receiving chamber disposed at the end of the delivery pipe away from the mold frame, an air supply unit disposed at the end of the pressure chamber near the mold frame, and a pressure relief unit disposed at the top of the pressure chamber; The shell is filled with hydraulic oil. When the mold frame opens and closes, it drives the push rod and the partition to move. When the partition moves, it creates a pressure difference between the two ends of the shell. The hydraulic oil at the end with higher pressure enters the outlet hole through the corresponding check valve and then enters the drain pipe. The end with lower pressure draws in hydraulic oil through the inlet hole and the corresponding check valve.

[0007] Furthermore, a circular hole is provided at one end of the outer shell near the mold frame, and the inner wall of the circular hole is slidably connected to the push rod.

[0008] Furthermore, the check valve corresponding to the inlet hole allows hydraulic oil to enter the housing in only one direction, and the check valve corresponding to the outlet hole allows hydraulic oil to flow out of the housing in only one direction.

[0009] Furthermore, the air supply unit includes a first duct disposed at the end of the pressure chamber near the mold frame, a cover disposed at the side of the hopper near the mold frame, the top end of the first duct being fixedly connected to the side of the cover near the pressure chamber, a second duct disposed at the end of the cover near the mold frame, the bottom end of the second duct being fixedly connected to the receiving chamber, a fan disposed inside the cover, and an impeller disposed at the end of the fan near the mold frame.

[0010] Furthermore, a pump chamber is provided at one end of the cover near the mold frame, and the outer wall of the pump chamber is fixedly connected to conduit one and conduit two.

[0011] Furthermore, the pressure relief unit includes a bend in the top of the pressure chamber, a plunger inside the bend, a threaded sleeve on the top of the bend, a knob on the outside of the threaded sleeve, and a spring on the top of the plunger, with the top and bottom of the spring abutting against the plunger and the knob, respectively.

[0012] Furthermore, a screw hole is provided at the bottom of the knob, and the inner wall of the screw hole is threadedly connected to a threaded sleeve.

[0013] Furthermore, a circular plate is provided on the top of the plunger, and the outer diameter of the circular plate matches the inner diameter of the bend near the plunger.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. By setting up a blowing mechanism, redundant kinetic energy during the mold opening and closing process can be captured and converted, and reintroduced into the system cycle. When the mold opens or closes, the mechanism guides the energy released during the movement, making it a power source to drive other functions, rather than letting it dissipate. This energy reuse method reduces the equipment's consumption of external energy, allowing every part of the kinetic energy to play its value. The blowing mechanism works closely with the mold opening and closing action, and can complete the collection and conversion of energy without additional energy input. The entire operation process is therefore more compact, avoiding the idleness and waste of energy in a single link. This design allows the device to perform its core functions while also managing the energy generated during its own operation. By converting the kinetic energy of mold opening and closing into usable power, the overall energy utilization rate of the device is improved, unnecessary energy output is reduced, and the energy consumption of the production process is more reasonable.

[0015] 2. By setting up an air supply unit, the energy stored in the blowing mechanism can be converted to drive the internal fan to rotate. After the fan rotates, it generates a directional airflow, which continuously acts on the raw material to be processed, removing the moisture attached to its surface and preparing it for the subsequent molding process. The entire process requires no additional power source. The operation of the air supply unit relies entirely on the energy generated by the movement of the equipment itself. This design reduces energy idleness and dissipation, making the energy utilization of the device more efficient and realizing the conversion and application of energy. The raw material gradually dries under the continuous blowing action, improving the state of the raw material before entering the molding process. The addition of the air supply unit allows the equipment to perform its main functions while also taking into account the needs of raw material pretreatment. The operation of the entire system is therefore more coherent, reducing dependence on external energy and making the plastic parts molding process more energy-efficient.

[0016] 3. By setting up a pressure relief unit, the unit will activate when the pressure in the pressure chamber exceeds a preset limit. This unit is connected to the inside of the pressure chamber and can sense pressure changes. Once it detects excessive pressure, it will open a pressure relief channel to guide the excess pressure to the containment chamber, allowing the pressure inside the chamber to return to the normal range. This process occurs automatically without manual intervention. This pressure relief unit has an adjustment function, allowing the setting of a specific pressure value to trigger pressure relief. Operators can adjust this threshold according to different production needs or raw material characteristics. After setting, the unit will monitor and respond according to the new standard. This adjustability makes the equipment's safety protection more flexible and adaptable to changing working conditions. It ensures that the pressure chamber always operates within safe parameters, thereby guaranteeing the stable operation of the entire device. The timely pressure relief action avoids damage to the equipment caused by continuous pressure accumulation, making the production process smoother. Through this settable protection mechanism, the safety of the equipment is enhanced, and its operating status is more reliable. Attached Figure Description

[0017] Figure 1 This is a three-dimensional structural diagram of the entire invention; Figure 2 This is a schematic diagram of the connection between the push rod and the mold frame of the present invention; Figure 3 This is a schematic diagram showing the relative positions of the outer casing and the base plate of the present invention; Figure 4 This is a schematic diagram of the connection between the partition and the push rod of the present invention; Figure 5 This is a schematic diagram of the internal structure of the outer shell of the present invention; Figure 6 This is a schematic diagram of the liquid inlet and one-way valve structure of the present invention; Figure 7 This is a schematic diagram of the internal structure of the pressure chamber of the present invention; Figure 8 This is a schematic diagram showing the connection between the containment chamber and the drain pipe of the present invention; Figure 9 This is a schematic diagram showing the connection between the hopper and the cover of the present invention; Figure 10 This is a schematic diagram of the internal structure of the housing of the present invention; Figure 11 This is a schematic diagram of the connection between the impeller and the fan of the present invention; Figure 12 This is a schematic diagram of the connection between the bend and the plunger in this invention.

[0018] In the picture: 1. Base plate; 2. Hopper; 3. Mold frame; 4. Blowing mechanism; 41. Outer shell; 42. Slide groove; 43. Push rod; 44. Partition plate; 45. Liquid inlet; 46. Liquid outlet; 47. Check valve; 48. Drain pipe; 49. Infusion pipe; 410. Pressure chamber; 411. Airbag; 412. Containment chamber; 413. Conduit 1; 414. Cover; 415. Conduit 2; 416. Fan; 417. Impeller; 418. Bend; 419. Plunger; 420. Threaded sleeve; 421. Knob; 422. Spring. Detailed Implementation

[0019] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0020] Example 1, referring to Figures 1-12 This invention provides a plastic part molding apparatus, comprising a base plate 1, a hopper 2 fixedly connected to the top of the base plate 1, a mold frame 3 fixedly connected to the top of the base plate 1 away from the hopper 2, and a blowing mechanism 4 installed inside the base plate 1. The blowing mechanism 4 includes a housing 41 fixedly connected to the inside of the base plate 1, a groove 42 formed on the base plate 1 near the mold frame 3, a push rod 43 fixedly connected to the bottom of the mold frame 3, a partition plate 44 fixedly connected to the end of the push rod 43 away from the mold frame 3, the outer side of the partition plate 44 being slidably connected to the inner wall of the housing 41, liquid inlet holes 45 symmetrically formed at the upper parts of both ends of the housing 41, liquid outlet holes 46 symmetrically formed at the lower parts of both ends of the housing 41, four one-way valves 47 respectively fixedly connected to the liquid inlet holes 45 and the liquid outlet holes 46 near the inner wall of the housing 41, and a discharge valve 47 fixedly connected to the two liquid outlet holes 46 near the outer wall of the housing 41. The system includes a liquid pipe 48, a delivery pipe 49 fixedly connected to two inlet ports 45 near the outer wall of the outer shell 41, a pressure chamber 410 fixedly connected to the end of the drain pipe 48 away from the outer shell 41, an airbag 411 fixedly connected inside the pressure chamber 410, a containment chamber 412 fixedly connected to the end of the delivery pipe 49 away from the mold frame 3, an air supply unit mounted on the end of the pressure chamber 410 near the mold frame 3, and a pressure relief unit mounted on the top of the pressure chamber 410. The outer shell 41 is filled with hydraulic oil. When the mold frame 3 opens and closes the mold, it drives the push rod 43 and the partition 44 to move. When the partition 44 moves, it creates a pressure difference between the two ends of the outer shell 41. The hydraulic oil at the end of the outer shell 41 with higher pressure enters the outlet port 46 through the corresponding one-way valve 47 and then enters the drain pipe 48 through the outlet port 46. The end of the outer shell 41 with lower pressure draws in hydraulic oil through the inlet port 45 and the corresponding one-way valve 47.

[0021] Specifically, during both mold opening and closing, the mold frame 3 drives the push rod 43 and the partition plate 44 to move linearly. During mold closing, the push rod 43 and the partition plate 44 move towards the hopper 2. Simultaneously, the partition plate 44 increases the pressure inside the outer shell 41 near the hopper 2, and the hydraulic oil at this pressure-increased end is discharged through the outlet hole 46 into the drain pipe 48. The hydraulic oil then enters the pressure chamber 410 through the drain pipe 48, causing the internal pressure of the pressure chamber 410 to rise. This increased internal pressure compresses the airbag 411. At this time, the airbag inside the pressure chamber 410... Hydraulic oil enters the housing 414 through conduit 413, and after passing through impeller 417, it enters the receiving chamber 412 through conduit 415. As the partition 44 moves closer to the hopper 2, the pressure inside the housing 41 near the mold frame 3 decreases. Under the action of the pressure difference, the hydraulic oil inside the receiving chamber 412 flows into the housing 41 through the inlet pipe and inlet hole 45. When the mold is opened, the hydraulic oil near the end of the housing 41 near the mold frame 3 enters the drain pipe 48, and the end of the housing 41 near the hopper 2 draws in the hydraulic oil in the receiving chamber 412.

[0022] Reference Figures 3-5 The outer shell 41 has a round hole at one end near the mold frame 3, and the inner wall of the round hole is slidably connected to the push rod 43.

[0023] Specifically, while allowing the push rod 43 to pass through, the circular hole also constrains the direction of movement of the push rod 43, so that it can only move along its own axis.

[0024] Reference Figure 5 and Figure 6 The one-way valve 47 corresponding to the inlet hole 45 allows hydraulic oil to enter the housing 41 in one direction only, and the one-way valve 47 corresponding to the outlet hole 46 allows hydraulic oil to flow out of the housing 41 in one direction only.

[0025] Specifically, the one-way valve 47 restricts the flow direction of the hydraulic oil, so that the hydraulic oil can only enter the housing 41 through one of the two inlet holes 45 at the same time, and can only exit the housing 41 through one of the two outlet holes 46 at the same time.

[0026] Reference Figures 1-12 The air supply unit includes a first duct 413 fixedly connected to the end of the pressure chamber 410 near the mold frame 3, a cover 414 fixedly connected to the side of the hopper 2 near the mold frame 3, the top end of the first duct 413 fixedly connected to the side of the cover 414 near the pressure chamber 410, a second duct 415 fixedly connected to the end of the cover 414 near the mold frame 3, the bottom end of the second duct 415 fixedly connected to the receiving chamber 412, a fan 416 rotatably connected inside the cover 414, and an impeller 417 fixedly connected to the end of the fan 416 near the mold frame 3.

[0027] Specifically, as the hydraulic oil enters the housing 414 through the first conduit 413 and flows to the second conduit 415, it passes through the impeller 417 inside the housing 414. The impeller 417 rotates due to the impact of the hydraulic oil. As the impeller 417 rotates, it drives the fan 416 to rotate. The airflow generated by the fan 416 blows the raw material in the hopper 2, and the airflow carries away the moisture in the raw material to ensure that the raw material is dry.

[0028] Reference Figure 9 and Figure 10 The cover 414 has a pump chamber at one end near the mold frame 3, and the outer wall of the pump chamber is fixedly connected to the first conduit 413 and the second conduit 415.

[0029] Specifically, the pump chamber restricts the flow path of the hydraulic oil, which must pass through the impeller 417 to enter the conduit 415.

[0030] Example 2, refer to Figures 1-12 This is the second embodiment of the present invention, which differs from the first embodiment in that: the pressure relief unit includes a bent pipe 418 fixedly connected to the top of the pressure chamber 410, a plunger 419 slidably connected inside the bent pipe 418, a threaded sleeve 420 fixedly connected to the top of the bent pipe 418, a knob 421 threadedly connected to the outside of the threaded sleeve 420, and a spring 422 abutting against the top of the plunger 419, with the top and bottom of the spring 422 abutting against the plunger 419 and the knob 421 respectively.

[0031] Specifically, when the pressure in pressure chamber 410 is too high, hydraulic oil enters bend 418 and pushes plunger 419 upward. As plunger 419 is pushed upward, it compresses spring 422, causing it to store force. After plunger 419 moves upward a certain distance, it releases the blockage on bend 418, allowing hydraulic oil to directly enter containment chamber 412 through bend 418. When the pressure in pressure chamber 410 drops to a suitable range, spring 422 causes plunger 419 to move downward, and the downward movement of plunger 419 pushes bend 418... When the valve is blocked, the hydraulic oil cannot enter the containment chamber 412 through the bend 418. By turning the knob 421 to move it down, the spring 422 can store force. The spring 422 transmits the force to the plunger 419, increasing the contact force between the plunger 419 and the inner wall of the bend 418. At this time, a greater pressure is required for the hydraulic oil to push open the plunger 419. Moving the knob 421 down will reduce the contact force between the plunger 419 and the inner wall of the bend 418. At this time, the plunger 419 can be pushed open with a smaller pressure.

[0032] Reference Figure 12 The bottom of the knob 421 has a screw hole, and the inner wall of the screw hole is threadedly connected to the threaded sleeve 420.

[0033] Specifically, as the knob 421 rotates, it moves along the axis of the threaded sleeve under the action of the thread.

[0034] Reference Figure 12 A circular plate is provided on the top of the plunger 419, and the outer diameter of the circular plate matches the inner diameter of the bend 418 near the plunger 419.

[0035] Specifically, the plunger 419 engages with the inner wall of the bend 418 via a circular plate. By adjusting the height of the plunger 419, the opening and closing of the bend 418 can be controlled. The rest of the structure is the same as that in Embodiment 1.

[0036] Based on embodiments 1-2, the working principle of this invention is as follows: During mold opening and closing, the push rod 43 moves the partition 44, which pumps some hydraulic oil from the outer shell 41 to the drain pipe 48. While discharging hydraulic oil, the outer shell 41 simultaneously draws hydraulic oil from the receiving chamber 412 into its interior. Since both ends of the outer shell 41 are equipped with inlet holes 45 and outlet holes 46, the mold frame 3 pumps hydraulic oil to the drain pipe 48 regardless of whether the mold is opening or closing. After entering the pressure chamber 410 through the drain pipe 48, the hydraulic oil, in conjunction with the airbag 411, increases the internal pressure of the pressure chamber 410. The hydraulic oil then enters the cover 414 through the conduit 413, passes through the impeller 417, and is pushed... The impeller 417 rotates, and the hydraulic oil enters the containment chamber 412 through the second conduit 415. While the impeller 417 rotates, it drives the fan 416 to rotate, causing the fan 416 to generate airflow that blows towards the raw material. The airflow carries away moisture, ensuring that the raw material is dry before it is melted. When the pressure inside the pressure chamber 410 is too high, the plunger 419 is lifted, opening the internal passage of the bend 418. The hydraulic oil can then directly enter the containment chamber 412 through the bend 418 until the pressure inside the pressure chamber 410 drops to a normal level. The plunger 419 then blocks the internal passage of the bend 418 again. By rotating the knob 421 to control the preload of the spring 422, the pressure response threshold of the plunger 419 can be adjusted.

[0037] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A plastic part molding apparatus, comprising a base plate (1), a hopper (2) disposed on the top of the base plate (1), and a mold frame (3) disposed on the top of the base plate (1) away from the hopper (2), characterized in that: The blowing mechanism (4) is located inside the base plate (1); The blowing mechanism (4) includes a housing (41) disposed inside the base plate (1), a groove (42) opened on the base plate (1) near the mold frame (3), a push rod (43) disposed at the bottom of the mold frame (3), a partition plate (44) disposed at the end of the push rod (43) away from the mold frame (3), the outer side of the partition plate (44) being slidably connected to the inner wall of the housing (41), liquid inlet holes (45) symmetrically opened at the upper part of both ends of the housing (41), liquid outlet holes (46) symmetrically opened at the lower part of both ends of the housing (41), and four single-channel valves respectively disposed on the side of the liquid inlet hole (45) and the liquid outlet hole (46) near the inner wall of the housing (41). The system includes a valve (47), a drain pipe (48) located on the side of the two outlet holes (46) near the outer wall of the outer shell (41), a delivery pipe (49) located on the side of the two inlet holes (45) near the outer wall of the outer shell (41), a pressure chamber (410) located at the end of the drain pipe (48) away from the outer shell (41), an airbag (411) located inside the pressure chamber (410), a containment chamber (412) located at the end of the delivery pipe (49) away from the mold frame (3), an air supply unit located at the end of the pressure chamber (410) near the mold frame (3), and a pressure relief unit located on the top of the pressure chamber (410). The shell (41) is filled with hydraulic oil. When the mold frame (3) opens and closes the mold, it drives the push rod (43) and the partition (44) to move. When the partition (44) moves, it creates a pressure difference between the two ends of the shell (41). The hydraulic oil at the end of the shell (41) with higher pressure enters the outlet hole (46) through the corresponding one-way valve (47) and enters the drain pipe (48) through the outlet hole (46). The end of the shell (41) with lower pressure draws in hydraulic oil through the inlet hole (45) and the corresponding one-way valve (47).

2. The plastic part molding apparatus according to claim 1, characterized in that: The outer shell (41) has a round hole at one end near the mold frame (3), and the inner wall of the round hole is slidably connected to the push rod (43).

3. The plastic part molding apparatus according to claim 1, characterized in that: The one-way valve (47) corresponding to the inlet hole (45) allows hydraulic oil to enter the housing (41) in one direction only, and the one-way valve (47) corresponding to the outlet hole (46) allows hydraulic oil to flow out of the housing (41) in one direction only.

4. The plastic part molding apparatus according to claim 1, characterized in that: The air supply unit includes a first duct (413) disposed at one end of the pressure chamber (410) near the mold frame (3), a cover (414) disposed at one side of the hopper (2) near the mold frame (3), the top end of the first duct (413) being fixedly connected to the side of the cover (414) near the pressure chamber (410), a second duct (415) disposed at one end of the cover (414) near the mold frame (3), the bottom end of the second duct (415) being fixedly connected to the receiving chamber (412), a fan (416) disposed inside the cover (414), and an impeller (417) disposed at one end of the fan (416) near the mold frame (3).

5. The plastic part molding apparatus according to claim 4, characterized in that: The cover (414) has a pump chamber at one end near the mold frame (3), and the outer wall of the pump chamber is fixedly connected to the first conduit (413) and the second conduit (415).

6. The plastic part molding apparatus according to claim 1, characterized in that: The pressure relief unit includes a bend (418) disposed on the top of the pressure chamber (410), a plunger (419) disposed inside the bend (418), a threaded sleeve (420) disposed on the top of the bend (418), a knob (421) disposed on the outside of the threaded sleeve (420), and a spring (422) disposed on the top of the plunger (419). The top and bottom of the spring (422) abut against the plunger (419) and the knob (421) respectively.

7. The plastic part molding apparatus according to claim 6, characterized in that: The knob (421) has a screw hole at its bottom, and the inner wall of the screw hole is threadedly connected to the threaded sleeve (420).

8. The plastic part molding apparatus according to claim 6, characterized in that: The plunger (419) is provided with a circular plate at the top, and the outer diameter of the circular plate matches the inner diameter of the bend (418) near the plunger (419).

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