Abstract:
Stand-on electric pallet trucks, characterized by their compact size, flexibility, and high efficiency, play a crucial role in the logistics and warehousing industries. As market demand continues to grow and technology advances, the upgrading, transformation, and optimization of stand-on electric pallet trucks are also occurring continuously. This article comprehensively analyzes stand-on electric pallet trucks used in warehousing, logistics, and handling from multiple perspectives such as their characteristics, application fields, advantages, and market trends. It also explores and demonstrates the development difficulties and technical measures for the steel casting steering bracket of stand-on electric pallet trucks, aiming to better understand the application of investment casting products in the field of forklifts.
1. Introduction
With the rapid development of human warehousing and logistics, the efficient handling capacity of forklifts has become increasingly prominent. Stand-on electric pallet trucks, in particular, have become the primary handling tools in internal warehousing and logistics due to their advantages of labor-saving, energy-saving, environmental protection, high efficiency, safety, reliability, flexible movement, and low noise. Classified as Class III powered industrial trucks, these forklifts are operated in a stand-on position and are suitable for medium to short-distance transportation. They provide a broader field of view, allowing operators to have better visibility both when moving forward and backward, reducing the risk of accidents caused by obstructed vision. Steering is controlled using a steering arm, with switches on the handle of the steering arm controlling movement. Among them, the steering bracket, which serves as the key connecting component between the steering arm and the steering motor, enables flexible and efficient turning and rapid handling and movement. As a primary functional component of the pallet truck, the performance of the steering bracket directly affects the entire forklift’s working efficiency and steering ability, determining its maneuverability, comfort, and flexibility.
2. Project Overview
Most of the functional components of stand-on electric pallet trucks are modular and standard components, requiring only assembly according to requirements. However, the custom-designed steel casting steering bracket must be comprehensively considered based on actual installation needs, functionality, material selection, casting production processes, cost analysis, and the selection of strategic suppliers. This article takes the steel casting steering bracket development project for a stand-on lever pallet truck as a research case to discuss the design of the steering bracket. The choice of material and process for the newly designed and developed steering bracket is crucial, requiring optimization not only in cost but also in process stability and consistency, volume, and other aspects, necessitating careful attention and comprehensive evaluation. Ultimately, technical difficulties were overcome, and pain points were resolved, with the new steering bracket successfully passing various functional tests and validations.
3. Structure of the Steering Bracket Component
The lever steel casting steering bracket for this pallet truck is shown in Figure 2. Its upper end connects to the end of the steering tiller arm, relying on this bracket for support and positioning, allowing the steering arm to perform various commanded operations as needed. The lower end connects to the steering motor and steering wheel power unit of the pallet truck, serving as a transitional component connecting the steering arm to the power unit, providing 100% conversion of movement commands for power unit steering. The side end reserves holes and grooves for the control wiring of the drive system, using this bracket as a transition point for fixation and wiring passage, enhancing practicality and aesthetics. The steering bracket integrates multiple functions and adopts the investment casting process with steel casting material (G20Mn5), providing more reliable and safer quality assurance. Forklifts equipped with this bracket have gained high recognition and favor upon entering the market, enhancing the market competitiveness of this model of forklift.
Material and Casting Process Analysis:
Table 1 provides a comparison between two potential materials and casting processes for the steering bracket:
| Name | Raw Material and Casting Blank Cost | Steering Bracket Blank Weight | Remarks | Cost Price |
|---|---|---|---|---|
| Nodular Iron 450 | 1513.00 yuan/kg (approx. 3.1 kg) | Due to rough surface, larger machining allowance | 40.3 yuan | |
| Steel Casting G20Mn5 | 16.00 yuan/kg (approx. 2.6 kg) | Due to smooth surface, smaller machining allowance | 41.6 yuan | |
| Cost Difference | 1.3 yuan |
The analysis reveals that while the raw material cost for nodular iron 450 is slightly cheaper per kilogram, the total cost for the steering bracket, considering the machining allowance and surface finish, is higher than that of steel casting G20Mn5. The steel casting material, combined with the investment casting process, offers a more cost-effective solution due to its higher dimensional accuracy and surface finish, reducing the need for extensive machining.
Casting Process Determination:
- Nodular Iron (Resin-Sand Casting): This process involves preparing core boxes, mixing molding sand and core sand, molding, core making, melting, pouring, shakeout, cleaning, and final毛坯 completion. However, it has limitations in terms of dimensional accuracy and casting defects such as sand pores or air holes, leading to a higher rejection rate.
- Steel Casting (Investment Casting): Investment casting, also known as lost-wax casting, involves creating a wax model of the part, coating it with a ceramic slurry to form a mold, melting out the wax, firing the mold, pouring molten metal into the mold, and cooling to obtain the final part. This process offers higher dimensional accuracy (typically CT-6 or CT-7) and a superior surface finish (Ra 1.6–3.2 μm), significantly reducing the need for machining and lowering overall costs.
Quality Assurance Measures:
To ensure the quality of the steering bracket, rigorous inspection procedures are implemented before shipment. This includes magnetic particle inspection for detecting surface defects and ultrasonic inspection for internal defects. The magnetic particle inspection uses a magnetic field to reveal defects by attracting magnetic particles to the area of discontinuity, while the ultrasonic inspection uses high-frequency sound waves to detect reflections from internal surfaces or defects.
Conclusion:
The lever steel casting steering bracket for the pallet truck, with its intricate design and functional integration, significantly enhances the efficiency and maneuverability of the forklift. By selecting the optimal material (G20Mn5 steel) and casting process (investment casting), combined with stringent quality control measures, the steering bracket not only meets but exceeds the requirements for durability, reliability, and safety. The successful implementation of this steering bracket has contributed to the increased market competitiveness and customer satisfaction of the pallet truck model.