Hydraulic Power Pack Project Report

Report, Pages 9 (2036 words)

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Abstract

The hydraulic power pack is custom built module for operation and control of any standard or special purpose hydraulic equipment. It consists of pump-motor unit to produce flow of hydraulic fluid to, control block to house various control elements and filtration components. All these components are laid out on top of a reservoir on a super fabricated structure. It is used at isolated places or small independent systems.

The project starts with the observation of the need of an offline hydraulic power pack: To test the hydraulic cylinders for their total performance before installation in their working circuit.

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Checking the stand balancing mechanism of spare mill stands. Moving the cylinder during erection when the regular hydraulic system is under shutdown.

Fixing the sleeve into the tapered ring for production purposes, to decrease the manpower and decrease the production time. Based on the type of problem respective power pack is designed , fixed or mobile etc., e.g., testing of hydraulic cylinders need the system to be offline and even they should be tested before the installation in the working circuit, so a mobile system is to be designed respectively.

Our concentration lies in designing a mobile hydraulic power pack, which not only caters to a particular need but also by the slightest modification (if any) , becomes the solution for the other problems faced in the wire rod mill.

Introduction

Wire rod mills (WRM) – wire rod mills a 4 strand continuous high speed fully sophisticated mill. The mill has 4 zone combination type reheating furnace(walking beam cum walking hearth) of 200 t/hr capacity for heating the billets received from the billet mill of LMMM to rolling temperature of 1200 deg C.

The continuous 4 strand wire mill for the Rastriya Ispat Nigam Limited is a high speed mill of modern technology design, including equipment for controlled cooling of rolled product from rolling heat by stelmor method. The mill is designed for low and high carbon steel up to 0.9% carbon.

Design features of wire rod mill are:

High production within a short time
Reliable loading at high speeds
High wire qualities
Rebars of “Vizag TMT” branding

Material Characteristics:

Billet weight: 1250 kgs
Cross section dimensions: 125 X 125 mm
Billet Length: 10400mm
Rolling program: 5.5 to 12mm round, 8.0 to 12.0mm dia rebar
Maximum coil weight: 1200 kg
Outside coil diameter: 1250 mm
Inside coil diameter: 850mm
Coil height not compacted: Round - approximately 2000mm, Rebar - approximately 2200mm.

Charging material:

The charging material – rolled billets from the billet mill be straight, free from camber, free from shrinkage cavities and additionally free from cracks as far as quality steel grades are concerned so that a continuous at the required quality is guaranteed.

Finish Material:

Based on maximum temperature difference across the billet cross section of 25 deg C on entering the mill train, the following tolerance values are obtained.

5.5 mm – 8mm round (+ / -) 0.15mm
9.0mm – 12mm round (+ / -) 0.20mm

The validity for these dimensions amounts to 80% of the permissible tolerances.

Capacity of the plant:

The annual capacity of the roll mill is 8, 50, 000 tones of finished wire rods by 3 shift operation and specified product mix.

Hydraulic Power Pack

Basically Hydraulic Power Pack is a device that converts Hydraulic energy in to mechanical energy. The hydraulic power pack is nothing but a movable hydraulic system. It contains all the basic components a hydraulic system requires such as tank, pump, valves etc.

Mobility of hydraulic power pack makes them useful for several purposes where oil pipe lines from a stationary hydraulic system cannot be run. The principle on which power pack works can be easily implemented at various sections with little or no modifications.

The hydraulic power pack, which we design, will be used for testing of hydraulic cylinders. There is no cylinder incorporated in this power pack. For testing a cylinder the oil should be pumped in to the cylinder at a pressure and flow rate, which occurs at the actual, operating conditions of that particulars cylinder. Also the oil is to be pumped from both the front end and rod end of the cylinder alternatively for the forward and return strokes of the piston.Moreover the hydraulic power pack must be capable of testing cylinders of different capacities and various operating conditions.

Operations to be performed: shearing and rounding

The cover is attached to the tank by the use of screws, which of is 6 mm dia and 3 inch length. And totally 12 screws are used. On the cover plate counter bored holes are made and on the tank hole of the same size (6mm dia) are made. All the holes are reamed to a high degree of accuracy. Tapping is done with the help of taps of suitable size in a sequential order, on the corresponding point of the tank. The counter boring operation is done for the insertion of the heads of the screws.

A synthetic rubber sealing is provided between the cover plate and to the top of the tank. A square hole is made on the surface of the cover plate so that a plate as shown in the figure is mounted on it.

First of all, oil level indicator is fitted the tank fabricated to the required dimensions. The tank is filled unto 70% of its volume with HLP 46 oil.
A breather is provided on the tank so that the air inside the tank must escape out while the oil returns to the tank
Then the suction line , a pipe of dia 16mm, is welded to the tank such that it dips inside the oil in the tank. But the dipped end of the tube should not be too close to the base of the tank. This is because oil the dirt in the oil be too close to the base of the tank. This is because oil the dirt in the oil gets settled down at the bottom of the tank. A gap of about 15mm must be maintained.
The suction line is connected to the inlet side of the pump.
The pump is coupled to the motor. The outlet of the pump is connected to the delivery line, which is also a pipe of 16mm dia.
To the delivery line, a pressure relief valve is connected using a T-joint. The pressure relief valve is then connected to the tank.
A check valve is fitted in the main delivery line. This check valve is to avoid the back flow of the oil in to the pump thereby it protects the pump.
After the check valve an online filter element is placed. It filters dust particles of size up to 25 microns. Following the filter, a pressure gauge is fitted which reads the pressure of the oil being pumped to the cylinder.
This line finally is connected to the manifold block containing the lever operated control valve.
From the manifold block a return line is connected to the tank this return line should not be dipped deep in to the oil tank, so that the dust particles settled at the bottom of the tank are not disturbed.

Testing Procedure

First of all, the tank filled with oil up to 70% of its volume. The open ends of the two hose pipes running from the ‘A’, ‘B’ ports of the manifold block are connected ot the two ends of the cylinder to be tested.
The motor is switched on , it runs the pump by the help of coupling.
The pressure relief valve is set at the operating pressure of the cylinder to be tested.
The flow control valve is set to the flow rate at the working conditions of the cylinder.
The lever of the directional control valve is pulled to the ‘ A’ side. The oil from the outlet of the pump flows through the check valve into the ‘p’ port of the directional valve. Due to the lever operation the spool moves in such a way that the port ‘p’ is connected to the port ‘A’ and the port ’B’ is connected to the port ‘T’ i.e. to the tank return line.
So the piston moves outwards i.e the forward stroke takes place. If the piston fails to move then it is an indication that the lip seal on the head side of the piston is failed. This may occur even if the lip seals are assembled in the wrong direction.
After the forward stroke is completed i.e. when the piston reaches the rod end or the cylinder, hose pipe connection of the cylinder leading to the port ‘B’ is removed.
The pumping of oil is continued from the other hosepipe and the cylinder is checked for leakage from the road end outlet. Any leakage indicates an internal leakage. This process is followed to identify any minor leakages, which cannot be detected by the previous method. Also any external leakage from the cylinder when the two hosepipes are connected to the cylinder indicates that there is a failure of gland seals i.e. gland seals may be worn out or they may be broken. Then the lever of the direction control valve is pulled to the * B’ side. The port *pr gets connected to the port *B’ and the port ‘A1 gets connected to the tank, due to the movement of the spool in the valve.
If all the seals are in good condition and the seals in the cylinder are assembled properly, then the return stroke of the piston occurs. Else die problem is identified in the case of forward stroke.
The testing of cylinder is also useful when a new cylinder is to De instance in a hydraulic system to check whether it can withstand the operating pressure and flow work properly.

Results and Discussion

In this report, we have introduced the concept of a hydraulic power pack designed for testing hydraulic cylinders, with a particular focus on its use in the wire rod mill industry. The hydraulic power pack described in this project is designed to cater to the specific needs of testing hydraulic cylinders before they are integrated into the working circuit of the mill. Additionally, it is mentioned that the power pack can potentially serve other purposes within the wire rod mill through minor modifications.

The designed hydraulic power pack consists of various components, including a tank, pump, valves, and filtration components. These components work together to pump hydraulic oil at the required pressure and flow rate to test hydraulic cylinders under various operating conditions. The power pack is mobile, allowing it to be easily transported to different locations within the mill, which is particularly useful for offline testing scenarios.

The testing procedure outlined in the report involves checking the hydraulic cylinder for proper functioning, identifying issues such as seal failures or leaks, and ensuring that the cylinder can withstand the operating pressure and flow rates within the mill's requirements. This pre-installation testing is crucial to prevent machinery breakdowns during production, minimizing production delays and material losses.

The key advantages of using this hydraulic power pack for testing cylinders are as follows:

Preventive Maintenance: By testing cylinders before their installation, potential issues can be identified and addressed in advance, reducing the risk of unexpected breakdowns and costly downtime.
Quality Assurance: The testing procedure ensures that cylinders meet the required performance standards, contributing to the production of high-quality wire rod products.
Efficiency: The mobile nature of the power pack allows for flexibility in testing cylinders at different locations within the mill, improving overall operational efficiency.
Cost Savings: Identifying and resolving cylinder issues early on can lead to cost savings by reducing the need for extensive repairs or replacements.
Adaptability: The power pack's design makes it versatile, potentially serving other purposes within the wire rod mill with minor modifications, thus adding value to the initial investment.

Conclusion

Testing of cylinders before using them at work avoids break down of machinery while running, which prevents the delay in production or loss of material. Moreover, the same Power pack the cylinders in the finishing section of wire rod mill. Also by the testing procedure suggested in this project, the actual case of the problem in the cylinder can be detected quite easily. By incorporating some modifications in this Power pack, the same can be used as a Hydraulic system doing mechanical work within its design conditions.