GZ500型可變速電動(dòng)缸設(shè)計(jì)【含CAD圖紙、說明書】,含CAD圖紙、說明書,gz500,變速,電動(dòng),設(shè)計(jì),cad,圖紙,說明書,仿單 The design process of a self-propelled floor crane Abstract In order to prevent the hazards associated with the crane application in workshops and factories, a self-propelled hydraulic floor crane with wire remote control was designed. The main focus was directed on remote control of the crane operations such as rotation of booms, rear and forward movements, changing travel speed, steering, braking and hook rotation. This configuration prevents the hazards and damages which may be created due to the proximity of operator to crane and provides the feasibility of utilizing the crane in crowded manufacturing areas, fields and hazardous environments. Research into the stability of crane on a slope route was also performed to obtain the equations of stability in static and dynamic conditions and recognition of the ways to enhance the stability. To validate the research work, a scale-model prototype was built to test the manner of controlling the crane operations from afar. 2010 ISTVS. Published by Elsevier Ltd. All rights reserved. Keywords: Crane; Hazards; Hydraulic; Remote control; Self-propelled 1. Introduction Cranes are devices utilized for loading, unloading and transmitting the loads. They are profitable devices but hazardous in nature. Aneziris et al. knew the crane activities responsible for 4% of the reported accidents and according to OSHA regulations, about 15.2% of crane events are occurred in manufacturing environments. Many researches have been performed regarding the causes of injuries and death from cranes, for instance Hakkinen ; Neitzel et al ; Suruda et al; Yow et al. Crane accidents have been grouped in the following categories according to NIOSH (National Institute of Occupational Safety and Health) report, including: swinging loads, overturning of cranes, falling loads, crushing between moving parts of cranes, falls of people from cranes, power line contact, overloading, contact the hook assembly with boom tip, obstruction of vision, assembly and disassembly of boom. Crane hazards are normally related to design and crane use. From a safety point of view, one of the most important issues in design of a crane is determination of stability. Stability of cranes has been studied by some researchers such as Sochacki ; Towarek ; Klosinski and Janusz . Weak segments, stress, strain, displacement, critical points and strength of parts under definite loads are determined by computer aided finite element analyses. Strength of the components versus the applied loads is determined based on FOS(factor of safety). For a safe performance, FOS is typically considered more than 1. Hydraulic floor crane is a kind of crane which has been used in workshops and factories from olden times. Basically, it is composed of a base, a column, a boom and a hydraulic cylinder for hoisting the boom. Nowadays, its application has been limited because of innumerable defects. The major research contribution of this paper is the use of CAD to design and develop a wire remote control hydraulic floor crane for the aims of decreasing the hazards, improving the performance and efficiency compared to the existing types and application in various locations such as hazardous environments and fields. Hence the main focus was directed on hazards reduction. Furthermore, the design has been also accomplished based on the required functions to perform the corresponding operations and employing peculiarities of the existing types considering their defects including handoperated actuation, lacking of motor supplies, low safety, slow response and low speed. 2. Modeling of the crane Solid Works and Cosmos were used for CAD modeling of the crane and finite element analyses to determine the strength of components respectively. Fig. 2 represents two computer models of the crane. Finite element analyses were performed based on the static and dynamic forces applied to the components in various situations of the booms. A lot of analyses were performed on the components using the maximum forces. The allowable stress method based on ISO 8686 standard 1989 was used to assess the strength of the components. The weak locations were fortified in several stages to enhance the factor of safety up to the optimum values. Table 2 represents the results of analyses after finial fortification of the components. 3. Design process Fig. 3 depicts a model for design strategy. One of the approaches to decrease the hazards in the crane is to reduce sway of the payload which is created by various factors arising mostly from crane maneuvers and the motions of crane components for performing the desired operations. Kim and Singhose [2] believed that the natural sway of crane payload causes safety hazards, time delay and difficulty in positioning payload. The proposed solution to control the sway is to install a (Fig. 4). Another benefit of this measure is to reduce overturning of the crane due to the pendulum motion of payload during displacement. Overturning issue can also be controlled by increasing the stability of crane through the appropriate static and dynamic analyses and fortification of the components as well as the correct selection of the crane dimensions. The other approach to decrease the hazards is to control the crane performance from a distance by utilizing a wire remote control system. This system prevents the hazards which are created by the fall of payload and objects on the operator or the fall of operator off the crane.Increasing visibility is another approach to reduce hazards and to increase safety. According to OSHA regulations [8], safe use of a crane is compromised when the vision of an operator is blocked and employees cannot see what the others are doing. The crane size alone limits the operator’s range of vision and creates blind spots. The crane boom may obstruct the operator’s range of vision. Often a load is lifted several stories high and the crane operator must rely upon others to ensure safe movement of the load being handled. The accidents due to the visibility problems are also occurred by other transporting devices such as lift trucks. Collins et al. [5] found that visibility problems account for more than 80% of forklift truck related accident such as striking pedestrians or other vehicles, falling- off a ramp or loading dock and turning over by hitting obstacles. The visibility can be increased in two ways: (a) Movement of the operator slightly far from the crane increases his visibility to control the crane operations from every side. That is a significant issue especially in busy locations or when the crane is carrying a huge load which limits the operator visibility. (b) Installing the wired or wireless camera in various spots of the crane helps the operator to control the entire crane operations in out of reach and hidden areas from afar (Fig. 5). The entire crane systems are covered by a body to protect the moving parts and to prevent event to people. To enhance flexibility and maneuverability of the crane, a compacted size and a three-piece boom were proposed. A combination of an inverter and a DC electromotor with 4 kW power was utilized to control the rear and forward movement and changing speed of the crane from remote distance. However, in this system by varying the speed of rotation, torque will be maintained constant. Thus a mechanical system consists of several pulleys and belts were designed to reduce the initial speed and to raise the torque (Fig. 6). Therefore, changing speed by inverter will be accomplished in a limited range to give a travel speed between 0 and 2.88 km/h. The normal speed of travel is 2 km/h so that the operator can walk along with the crane. The maximum speed is 2.88 km/h. For the speeds more than 2 km/h in traveling, the operator can sit on the body. The main part of the hydraulic system is directional control valve assembly consists of several four-way valves with three positions (Fig. 7a). These valves are solenoid operated so that the port opening can be achieved by a current flow through the coils. A magnetic field provides electromotive force to move the especially shaped valve spool. This motion is opposed by a centering spring. The ports are represented by pump P, the return tank T, the actuator inlet chamber A and the actuator outlet chamber B (Fig. 7b). Solenoid valves should be used in open-center system that in neutral, oil flows through the control valve and back to the reservoir. The appropriate performance of the hydraulic system is based on the kind of connection among solenoid valves. For an open-center system, the series connection is the sole way; otherwise the system cannot operate properly (Fig. 8). way; otherwise the system cannot operate properly (Fig. 8). As Fig. 8 shows, the entire crane systems except for drive system are equipped with solenoid valves which actuate the double-action hydraulic cylinders. Each solenoid valve runs by receiving the current flow from two push button switches located in control box to open the ports A an B. The oil flows to the corresponding hydraulic cylinder through the open port and performs one of the crane operations. For instance, in steering system, the hydraulic cylinder moves the tie rod which is connected to the front wheels. Accordingly, two switches in control box are used to steer the front wheels to left or right. For braking system, two hydraulic cylinders are used to stick the brake shoes to the internal surface of the rear wheels. In this case, two switches are also used for braking and releasing the brakes. Similarly, other operations such as raising and lowering the booms are achieved in this manner. To take the load from remote distance, an articulated hook consists of a hydraulic cylinder, a micro switch and a magnetic lock for safety operation was designed (Fig. 9). From the viewpoint of power supply, two configurations of DC and AC are proposed. In DC type, two batteries with the capacity of 200 AH are required for the crane. However, it needs to be charged permanently. In AC type, the weight and expense of the batteries are omitted but the cable which is connected to the power outlet port may be a trouble as well as limits its application only for indoors. The use of electromotor instead of combustion engine will make the device fumeless and noiseless that is appropriate for enclosed areas. The maximum grade ability of the crane in unladen condition was obtained equal to 15°.