Rice depth-measuring fertilizer applicator with intelligent metering function

Abstract

The invention discloses a rice depth-measuring fertilizer applicator with an intelligent metering function, and belongs to the technical field of fertilizer applicators. A rice depth measuring fertilizer applicator with an intelligent metering function comprises a traction truss and a seed fertilizer box, a transmission chain assembly is arranged on one side of the traction truss, the traction truss comprises an outer hanging plate and a longitudinal shaft support, a cutter head assembly is arranged below the longitudinal shaft support, and a land pressing wheel is arranged on one side of the cutter head assembly. In order to solve the problems that the nutrition of deep soil is relatively good and the nutrition cannot be effectively absorbed once the root system of rice is too short due to the fact that the conventional fertilizer applicator is used for covering the field and applying fertilizer once in the automatic fertilizer applying process and the fertilizer is mostly positioned in field mud, the ball shaft design at the tail end of the shaft rod has the multi-angle adjusting capability; fertilization grooves can be formed while soil is scarified, the vertical material pipes directly convey fertilizer to the bottoms of the grooves, the inclined material pipes supplement and cover the grooves from the inclined upper portion, the layered fertilization effect is formed, and the volatilization loss of the fertilizer is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of fertilizer applicators, and particularly to a rice deep fertilization machine with an intelligent metering function. Background Art

[0002] A fertilizer applicator is a machine for applying fertilizers. Its components include a fertilizer tank, a conveying device, a furrow opener, a depth adjustment mechanism, a control system, etc. The furrow opener is used to create a furrow in the soil, and the fertilizer falls into the furrow through the conveying device and is then covered with soil. The depth adjustment mechanism ensures that the fertilization depth is consistent, and may monitor and adjust the furrowing depth through sensors or mechanical devices.

[0003] In the process of automatic fertilization, existing fertilizer applicators mostly perform one-time field fertilization, and most of the fertilizers are located inside the field mud. This will result in better nutrition in the deep soil. Once the rice roots are too short, they will not be able to effectively absorb the nutrients. Summary of the Invention

[0004] The purpose of the present invention is to provide a rice deep fertilization machine with an intelligent metering function. The cutter head assembly is composed of a sleeve, a shaft rod and a joint sleeve. The spherical shaft design at the end of the shaft rod enables it to have the ability to adjust at multiple angles. It can form a fertilization groove while loosening the soil. The vertical feed pipe directly conveys the fertilizer to the bottom of the groove, and the inclined feed pipe replenishes and covers from the upper oblique direction to form a layered fertilization effect, reducing fertilizer volatilization loss, and can solve the problems in the prior art.

[0005] To achieve the above purpose, the present invention provides the following technical solution: A rice deep fertilization machine with an intelligent metering function, including a traction truss and a seed and fertilizer tank. A transmission chain assembly is arranged on one side of the traction truss. Among them, the traction truss includes an outer hanging plate and a longitudinal axis support. A cutter head assembly is arranged below the longitudinal axis support. A press wheel is arranged on one side of the cutter head assembly. Adjustment brackets are arranged above both sides of the traction truss, and the adjustment brackets are installed above the longitudinal axis support. A fertilizer applicator is arranged below the seed and fertilizer tank. Among them, a hopper cabin is arranged inside the seed and fertilizer tank, and a support plate is arranged at the bottom of the seed and fertilizer tank. The support plate is connected to the fertilizer applicator by bolts.

[0006] Further, a hanging bracket is arranged at the front end of the longitudinal axis support. The hanging bracket is rotatably connected to the longitudinal axis support. The hanging bracket is connected to the traction truss through a card slot. Among them, the hanging bracket is connected to the adjustment bracket through a support plate.

[0007] Through the above technical solution, a rotatable hanging bracket is provided at the front end of the longitudinal axis support, which is connected to the tractor traction device through a card slot to adapt to the matching requirements of different traction heights. The adjustment bracket is located above the longitudinal axis support and forms a triangular stable structure with the hanging bracket through a support plate to ensure the lateral balance of the equipment in the rugged field and prevent rollover.

[0008] Furthermore, both ends of the fertilizer applicator are provided with material ports, and a discharging roller is provided inside the fertilizer applicator, wherein the discharging roller is rotatably connected to the fertilizer applicator, a throwing trough is provided on the outer surface of the discharging roller, a vertical material pipe is provided inside the longitudinal axis bracket, and an inclined material pipe is provided on one side of the vertical material pipe.

[0009] Furthermore, the oblique material pipe and the vertical material pipe are connected to the fertilizer applicator via a flange, and the longitudinal axis bracket is connected to the ground pressing wheel via a depth clamp, wherein one end of the depth clamp is rotatably connected to the ground pressing wheel, and the other end of the depth clamp is rotatably connected to the longitudinal axis bracket via a damping shaft.

[0010] Furthermore, a telescopic screw is provided in the middle section of the depth clamping plate, and the depth clamping plate is connected to the longitudinal axis bracket through the telescopic screw. A linkage support shaft is provided inside the damping shaft, and the linkage support shaft is connected to the depth clamping plate through bolts.

[0011] Through the above technical solution, the ground pressing wheel is connected to the longitudinal axis bracket through the depth clamp, and a telescopic screw is provided in the middle section of the clamp to manually adjust the tillage depth.

[0012] Furthermore, the linkage support shaft and the damping shaft are rotatably connected via a rotation groove, a limit block is provided on one side of the rotation groove, wherein the limit block and the linkage support shaft are connected via a slot, a plurality of resistance measuring points are provided on the inner side of the rotation groove, and the resistance measuring points are connected to the rotation groove via the slot.

[0013] Through the above technical solution, the damping shaft is built with a linkage support shaft, and the resistance measuring point is embedded on the support shaft surface to monitor the change of soil resistance in real time, and transmit the data to the control unit through the CAN bus. When the resistance exceeds the preset threshold, the system automatically reduces the speed of the discharge roller and links the tractor hydraulic system to reduce the travel speed, realizing the triple closed-loop control of "resistance-flow-speed".

[0014] Furthermore, the flip angle of the linkage support shaft is 0-30°.

[0015] Furthermore, the cutter disc assembly includes a cover and a joint sleeve, the joint sleeve is located between the cutter disc assemblies, wherein a pull rod is provided on the outside of the joint sleeve, one end of the pull rod is connected to the joint sleeve through a slot, and the other end of the pull rod is connected to the longitudinal axis bracket through a bolt.

[0016] Furthermore, a shaft rod is arranged inside the sleeve, and the shaft rod and the sleeve are rotatably connected via a bearing, wherein an integrally formed ball shaft is arranged at one end of the shaft rod, and the shaft rod is rotatably connected to the joint sleeve via the ball shaft.

[0017] Through the above technical solution, the ball-shaft design at the end of the shaft rod enables it to have multi-angle adjustment capabilities, and can form fertilizer grooves while loosening the soil.

[0018] Furthermore, the vertical material pipe extends to the bottom of the cutter disc assembly, and the oblique material pipe extends to the oblique upper part of the cutter disc assembly.

[0019] Through the above technical solution, the vertical material pipe transports the fertilizer directly to the bottom of the groove, and the inclined material pipe provides additional coverage from the upper side, forming a layered fertilization effect and reducing fertilizer volatilization losses.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention, the rice depth measuring fertilizer applicator realizes the coordinated operation of precise fertilization and soil treatment through the combination of mechanical structure and intelligent sensing technology. Its core structure includes a traction truss, a seed fertilizer box, a cutter head assembly and an intelligent fertilization system. The traction truss serves as the main frame, and the overall operation of the equipment is supported by an external plate and a longitudinal axis bracket. The transmission chain assembly transmits power to the cutter head assembly and the fertilizer applicator;

[0022] 2. The present invention comprises a cutter head assembly consisting of a cover, a shaft and a joint sleeve. The ball shaft design at the end of the shaft enables it to have multi-angle adjustment capability, and can form a fertilizer groove while loosening the soil. The vertical material pipe directly delivers the fertilizer to the bottom of the groove, and the oblique material pipe provides additional coverage from the upper oblique side, thereby forming a layered fertilization effect and reducing the loss of fertilizer volatilization.

[0023] 2. In the present invention, the damping shaft is built with a linkage support shaft, and the surface of the support shaft is embedded with a resistance measuring point to monitor the change of soil resistance in real time, and transmit the data to the control unit through the CAN bus. When the resistance exceeds the preset threshold, the system automatically reduces the speed of the discharge roller and links the tractor hydraulic system to reduce the travel speed, realizing the triple closed-loop control of "resistance-flow-speed". BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is the overall front view of the present invention;

[0025] Figure 2 It is a schematic diagram of the longitudinal axis support structure of the present invention;

[0026] Figure 3 It is a schematic diagram of the structure of the seed fertilizer box of the present invention;

[0027] Figure 4 This is a schematic diagram of the cross-sectional structure of the seed fertilizer box of the present invention;

[0028] Figure 5 It is a schematic diagram of the internal structure of the longitudinal axis support of the present invention;

[0029] Figure 6 It is a schematic diagram of the internal structure of the damping shaft of the present invention;

[0030] Figure 7 It is a schematic diagram of the structure of the cutter head assembly of the present invention;

[0031] Figure 8 Schematic diagram of the internal structure of the cutter head assembly of the present invention.

[0032] In the figure: 1, traction truss; 2, seed and fertilizer box; 3, ground pressing wheel; 4, cutter head assembly; 5, drive chain assembly; 101, outer hanging plate; 102, longitudinal axis support; 103, adjustment support; 1021, hanging bracket; 1022, telescopic screw rod; 1023, vertical material pipe; 1024, inclined material pipe; 1025, pull rod; 1031, support plate; 201, hopper cabin; 202, fertilizer applicator; 2011, support plate; 2021, discharge roller; 2022, throwing chute; 2023, material opening; 301, depth splint; 302, damping rotating shaft; 303, linkage support shaft; 3021, limit block; 3022, rotating groove; 3023, resistance measuring point; 401, envelope; 402, joint sleeve; 403, shaft rod; 4031, spherical shaft. Detailed implementation manners

[0033] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0034] In order to solve the problem that in the process of automatic fertilization of existing fertilizing machines, most of them fertilize the field only once, and the fertilizers are mostly located inside the field mud, which will result in better soil nutrition in the deep layer. Once the rice roots are too short, they will not be able to effectively absorb nutrients; please refer to Figure 1-8 , the following technical solutions are provided in this embodiment:

[0035] A rice depth measurement fertilizing machine with an intelligent metering function includes a traction truss 1 and a seed and fertilizer box 2. A drive chain assembly 5 is arranged on one side of the traction truss 1. Among them, the traction truss 1 includes an outer hanging plate 101 and a longitudinal axis support 102. A cutter head assembly 4 is arranged below the longitudinal axis support 102. A ground pressing wheel 3 is arranged on one side of the cutter head assembly 4. Adjustment supports 103 are arranged above both sides of the traction truss 1. The adjustment supports 103 are installed above the longitudinal axis support 102. A fertilizer applicator 202 is arranged below the seed and fertilizer box 2. Among them, a hopper cabin 201 is arranged inside the seed and fertilizer box 2. A support plate 2011 is arranged at the bottom of the seed and fertilizer box 2. The support plate 2011 is connected to the fertilizer applicator 202 by bolts. A hanging bracket 1021 is arranged at the front end of the longitudinal axis support 102. The hanging bracket 1021 is rotatably connected to the longitudinal axis support 102. The hanging bracket 1021 is connected to the traction truss 1 through a card slot. Among them, the hanging bracket 1021 and the adjustment support 103 are connected through a support plate 1031;

[0036] In this embodiment, the traction truss 1 forms a main frame through the external hanging plate 101 and the longitudinal axis support 102. The transmission chain assembly 5 provides power transmission to the cutter head assembly 4 and the fertilizer applicator 202. The traction truss 1, as the core support structure of the equipment, is welded with high-strength alloy steel. The external hanging plate 101 and the longitudinal axis support 102 are fixed by bolts to form a modular design, which is convenient for disassembly and maintenance. A rotatable hanging bracket 1021 is provided at the front end of the longitudinal axis support, and it is connected to the tractor traction device through a card slot to adapt to the matching requirements of different traction heights. The adjustment bracket 103 is located above the longitudinal axis support and forms a triangular stable structure with the hanging bracket through the support plate 1031 to ensure the lateral balance of the equipment in the rough field and prevent rollover.

[0037] Feeding ports 2023 are provided at both ends of the fertilizer applicator 202. An outlet roller 2021 is arranged inside the fertilizer applicator 202. Among them, the outlet roller 2021 is rotationally connected to the fertilizer applicator 202. According to the rice variety and soil fertility, the rotation speed of the outlet roller 2021 is adjusted. Then, the target fertilization amount is input through the control system. A throwing groove 2022 is arranged on the outer surface of the outlet roller 2021. A vertical material pipe 1023 is arranged inside the longitudinal axis support 102. An inclined material pipe 1024 is arranged on one side of the vertical material pipe 1023. The inclined material pipe 1024 and the vertical material pipe 1023 are connected to the fertilizer applicator 202 through flanges. The longitudinal axis support 102 and the ground pressing wheel 3 are connected through a depth splint 301. Among them, one end of the depth splint 301 is rotationally connected to the ground pressing wheel 3, and the other end of the depth splint 301 is rotationally connected to the longitudinal axis support 102 through a damping rotating shaft 302;

[0038] In this embodiment, the seed and fertilizer box 2 adopts a split design. A moisture-proof coating is provided inside the hopper cabin 201. The bottom tray 2011 is supported by springs and can automatically adjust the opening and closing gap according to the fluidity of the fertilizer. The core of the fertilizer applicator 202 is the outlet roller 2021, and spiral throwing grooves 2022 are evenly distributed on its surface. The rotation speed is driven by a servo motor, and the range is 200 - 500 r / min. The fertilizer flow rate is accurate to ±5 g / m. The ground pressing wheel 3 is connected to the longitudinal axis support through a depth splint 301, and a telescopic screw 1022 is provided in the middle of the splint to manually adjust the tillage depth.

[0039] A telescopic screw 1022 is provided in the middle section of the depth clamping plate 301, and the depth clamping plate 301 is connected to the longitudinal axis bracket 102 through the telescopic screw 1022. The telescopic screw 1022 is rotated to change the length of the depth clamping plate 301. Combined with the pressure of the ground pressing wheel 3, the depth of the cutter head into the soil is controlled. A linkage support shaft 303 is provided inside the damping shaft 302. The linkage support shaft 303 is connected to the depth clamping plate 301 through bolts. The linkage support shaft 303 is rotatably connected to the damping shaft 302 through a rotating groove 3022. A limit block 3021 is provided on one side of the rotating groove 3022, wherein the limit block 3021 is connected to the linkage support shaft 303 through a card slot, and a plurality of resistance measuring points 3023 are provided on the inner side of the rotating groove 3022. The resistance measuring points 3023 are connected to the rotating groove 3022 through a card slot, and the flip angle of the linkage support shaft 303 is 0-30°;

[0040] In this embodiment, the damping shaft 302 has a built-in linkage support shaft 303, and the support shaft surface is embedded with 6 groups of resistance measuring points 3023 to monitor the change of soil resistance in real time and transmit the data to the control unit through the CAN bus. When the resistance exceeds the preset threshold, the system automatically reduces the speed of the discharge roller and links the tractor hydraulic system to reduce the travel speed, thus realizing the triple closed-loop control of "resistance-flow-speed";

[0041] Smart mode parameter settings:

[0042] Basic parameter input: Enter the field area (ha), target fertilizer amount (kg / ha) and fertilizer type (granules / powder) on the control panel, and the system will automatically calculate the theoretical roller speed.

[0043] Soil adaptation settings: Select a preset mode according to the soil type:

[0044] Clay: The resistance threshold is set to 300Ω, the fertilization depth is 12-15cm, and the lower limit of the roller speed is 250r / min.

[0045] Sandy loam: The resistance threshold is set to 150Ω, the fertilization depth is 8-10cm, and the upper limit of the roller speed is 400r / min.

[0046] The cutter disc assembly 4 includes a sleeve 401 and a joint sleeve 402, wherein the joint sleeve 402 is located between the cutter disc assemblies 4, wherein a pull rod 1025 is arranged on the outside of the joint sleeve 402, one end of the pull rod 1025 is connected to the joint sleeve 402 through a slot, and the other end of the pull rod 1025 is connected to the longitudinal axis bracket 102 through a bolt, and a shaft 403 is arranged inside the sleeve 401, and the shaft 403 is rotatably connected to the sleeve 401 through a bearing, wherein an integrally formed ball shaft 4031 is arranged at one end of the shaft 403, and the shaft 403 is rotatably connected to the joint sleeve 402 through the ball shaft 4031, and the vertical material pipe 1023 extends to the bottom of the cutter disc assembly 4, and the oblique material pipe 1024 extends to the oblique upper part of the cutter disc assembly 4;

[0047] In this embodiment, the cutter head assembly 4 is composed of a sleeve 401, a shaft rod 403 and a joint sleeve 402. High-precision bearings are installed inside the sleeve. The end of the shaft rod adopts an integrated ball shaft 4031 design, which supports 360° rotation. The cutter head inclination angle is adjusted to 15 - 25° by the pull rod 1025 as the optimal soil entry angle. When the cutter head is operating, it cuts into the soil at a speed of 200 - 300 r / min, forming a V-shaped groove with a depth of 8 - 15 cm, and at the same time throws the turned-up soil to both sides. The vertical material pipe 1023 extends to the bottom of the cutter head, precisely putting fertilizers into the deep part of the groove; the inclined material pipe 1024 is arranged at an inclination angle of 45°, covering part of the fertilizers on the surface soil, realizing a double-layer fertilization mode of "deep application + shallow covering", reducing ammonia volatilization loss by more than 30%.

[0048] Working principle: Confirm that the seed and fertilizer box 2 is full of fertilizers, check that the vertical material pipe 1023 and the inclined material pipe 1024 are unblocked. The cutter head assembly 4 turns the soil and opens a trench, and the fertilizer applicator 202 synchronously measures and discharges materials. The pressing wheel 3 compacts the soil to cover the fertilizers. Observe the feedback of the control panel in real time. If the resistance is abnormal, such as when encountering a hard soil layer, the system automatically reduces the speed or pauses fertilization. Adjust the bracket 103 and the support plate 1031 to finely adjust the lateral balance of the equipment to avoid rollover. After enabling the intelligent mode, the resistance measurement point 3023 and the linkage support shaft 303 automatically adjust the fertilization amount and depth to adapt to the local soil fertility differences in the field. The built-in sensor records the fertilization amount, depth and soil resistance data, which can be exported through USB for later farmland management analysis. After each shift of operation, use a high-pressure air gun to clean the soil residue on the cutter head assembly 4, and focus on dredging the interface between the vertical material pipe 1023 and the inclined material pipe 1024 to prevent caking and blockage. The ball shaft 4031 and the joint sleeve 402 are filled with lithium-based grease NLGI grade 2 every week; the rotating groove 3022 of the damping rotating shaft 302 is filled with silicone grease every month to avoid oxidation of the resistance measurement point 3023. Check the connecting bolts of the depth clamping plate 301 and the longitudinal axis bracket 102 before each day's operation to ensure that the pre-tightening force reaches 30 N·m; if the limit block 3021 shows wear and indentations, it needs to be replaced immediately.

[0049] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variation thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device.

[0050] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention.

Claims

1. A rice depth fertilization machine with intelligent metering function, characterized in that, It includes a traction truss (1) and a seed and fertilizer box (2). A drive chain assembly (5) is provided on one side of the traction truss (1). Among them, the traction truss (1) includes an outer hanging plate (101) and a longitudinal axis support (102). A cutter head assembly (4) is provided below the longitudinal axis support (102). A ground pressing wheel (3) is provided on one side of the cutter head assembly (4). Adjustment brackets (103) are provided above both sides of the traction truss (1). The adjustment brackets (103) are installed above the longitudinal axis support (102). A fertilizer applicator (202) is provided below the seed and fertilizer box (2). Among them, a hopper compartment (201) is provided inside the seed and fertilizer box (2). A support plate (2011) is provided at the bottom of the seed and fertilizer box (2). The support plate (2011) is bolted to the fertilizer applicator (202).

2. The rice depth fertilization machine with intelligent metering function according to claim 1, characterized in that: A hanging bracket (1021) is provided at the front end of the longitudinal axis support (102). The hanging bracket (1021) is rotatably connected to the longitudinal axis support (102). The hanging bracket (1021) is connected to the traction truss (1) through a card slot. Among them, the hanging bracket (1021) is connected to the adjustment bracket (103) through a support plate (1031).

3. The rice depth fertilizing machine with intelligent metering function according to claim 1, characterized in that: Feeding ports (2023) are provided at both ends of the fertilizer applicator (202). A discharge roller shaft (2021) is provided inside the fertilizer applicator (202). Among them, the discharge roller shaft (2021) is rotatably connected to the fertilizer applicator (202). A material throwing groove (2022) is provided on the outer surface of the discharge roller shaft (2021). A vertical material pipe (1023) is provided inside the longitudinal axis support (102). An inclined material pipe (1024) is provided on one side of the vertical material pipe (1023).

4. The rice depth fertilizing machine with intelligent metering function according to claim 3, characterized in that: The inclined material pipe (1024) and the vertical material pipe (1023) are flange-connected to the fertilizer applicator (202). The longitudinal axis support (102) is connected to the ground pressing wheel (3) through a depth clamping plate (301). Among them, one end of the depth clamping plate (301) is rotatably connected to the ground pressing wheel (3). The other end of the depth clamping plate (301) is rotatably connected to the longitudinal axis support (102) through a damping rotating shaft (302).

5. The rice depth fertilizing machine with intelligent metering function according to claim 4, characterized in that: A telescopic screw rod (1022) is provided in the middle section of the depth clamping plate (301). The depth clamping plate (301) is connected to the longitudinal axis support (102) through the telescopic screw rod (1022). A linkage support shaft (303) is provided inside the damping rotating shaft (302). The linkage support shaft (303) is bolted to the depth clamping plate (301).

6. The rice depth fertilization machine with intelligent metering function according to claim 5, characterized in that: The linkage support shaft (303) is rotatably connected to the damping rotating shaft (302) through a rotating groove (3022). A limiting block (3021) is provided on one side of the rotating groove (3022). Among them, the limiting block (3021) is connected to the linkage support shaft (303) through a card slot. A plurality of resistance measuring points (3023) are provided inside the rotating groove (3022). The resistance measuring points (3023) are connected to the rotating groove (3022) through a card slot.

7. The rice depth fertilizing machine with intelligent metering function according to claim 6, characterized in that: The flipping angle of the linkage support shaft (303) is 0 - 30°.

8. The rice depth fertilizing machine with intelligent metering function according to claim 7, characterized in that: The cutter head assembly (4) includes a sleeve (401) and a joint sleeve (402). The joint sleeve (402) is located between the cutter head assemblies (4). Among them, a pull rod (1025) is arranged on the outer side of the joint sleeve (402). One end of the pull rod (1025) is connected to the joint sleeve (402) through a card slot, and the other end of the pull rod (1025) is connected to the longitudinal axis bracket (102) through a bolt.

9. The rice depth fertilization machine with intelligent metering function according to claim 8, characterized in that: A shaft rod (403) is arranged inside the sleeve (401). The shaft rod (403) is rotatably connected to the sleeve (401) through a bearing. Among them, a ball shaft (4031) is integrally formed at one end of the shaft rod (403). The shaft rod (403) is rotatably connected to the joint sleeve (402) through the ball shaft (4031).

10. A rice depth fertilization machine with intelligent metering function according to claim 9, characterized in that: The vertical material pipe (1023) extends to the bottom of the cutter head assembly (4), and the inclined material pipe (1024) extends to the upper oblique side of the cutter head assembly (4).

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