Hydraulic Cylinder Catalogue Danver Hydromatics Private Limited 10/23, Siddhinath Chatterjee Road, Behala, Kolkata -700034 Works: - Chakpara, Balitikuri, Jagacha, Howrah 711113 Contact: - 033-2653 4496, Tele fax: -033-24451112 Email: - dhpl@rediffmail.com Factory_danver@yahoo.co.in Website: - www.danverhydromatics.com www.gammairradiator.in - 1 -
Introduction Although We, Danver Hydromatics Pvt Ltd established in 2004, are one of the leading manufacturer and exporter of Hydraulic and Pneumatic System. We have supplied and satisfied clients of different fields extensively in Steel industries, Rubber industries, Automobile sectors etc. in different critical positions. We are backed by a dexterous team of professionals whose unremitting efforts and perseverance has helped us manufacturing our assortment of industrial hydraulics and pneumatics with unblemished quality. Our adept personnel are instrumental in understanding the exact demands of our clients and developing range as per their specifications. Quality is the essence of our endeavors as it is the decisive factor of our ability to earn client s loyalty and preference. Thus, we have employed a team of quality auditors who adopt stringent quality in all activities. Various quality tests are conducted at each stage of our production process that ensures zero-defect in our comprehensive assortment of industrial hydraulics pneumatics systems. - 2 -
Index Sl. Content Page No. 01 Hydraulic Cylinder 4 02 Hydraulic Cylinder & its operation 5 03 Different Parts of Hydraulic Cylinder 6 04 Seal kit 10 05 Hydraulic Oil 12 06 Load calculation 13 07 Testing of Cylinder 14 08 Mill Duty cylinder 15 09 Welded Cylinder 21 10 Tie Rod Cylinder 30 11 Rod Clevis 36 12 Ordering Code 37 13 Our Customers 38-3 -
HYDRAULIC CYLINDER - 4 -
1.0 What is Hydraulic Cylinder? A Hydraulic cylinder is a mechanical actuator that is used to give a unidirectional force through a unidirectional stroke. It has many applications, notably in engineering vehicles. 2.0 Operation Hydraulic cylinders get their power from pressurized hydraulic fluid, which is typically oil. The hydraulic cylinder consists of a cylinder barrel, in which a piston connected to a piston rod moves back and forth. The barrel is closed on each end by the cylinder bottom (also called the cap end) and by the cylinder head where the piston rod comes out of the cylinder. The piston has sliding rings and seals. The piston divides the inside of the cylinder in two chambers, the bottom chamber (cap end) and the piston rod side chamber (rod end). The hydraulic pressure acts on the piston to do linear work and motion. Flanges, trunnions, and/or clevises are mounted to the cylinder body. The piston rod also has mounting attachments to connect the cylinder to the object or machine component that it is pushing. A hydraulic cylinder is the actuator or "motor" side of this system. The "generator" side of the hydraulic system is the hydraulic pump which brings in a fixed or regulated flow of oil to the bottom side of the hydraulic cylinder, to move the piston rod upwards. The piston pushes the oil in the other chamber back to the reservoir. If we assume that the oil pressure in the piston rod chamber is approximately zero, the force F on the piston rod equals the pressure P in the cylinder times the piston area A:. The piston moves instead downwards if oil is pumped into the piston rod side chamber and the oil from the piston area flows back to the reservoir without pressure. The pressure in the piston rod area chamber is (Pull Force) / (piston area - piston rod area). - 5 -
3.0 Parts of a hydraulic cylinder A hydraulic cylinder consists of the following parts: 3.1 Cylinder Barrel The cylinder barrel is mostly a seamless thick walled forged pipe that must be machined internally. The cylinder barrel is ground and/or honed internally. The surface imperfections are controlled with permissible limit from 25 µm to 200 µm depending upon bore of the cylinder. The barrel is completely complied of Cold Drawn Seamless Tubes CDS-1, CDS-2 or CDS-3 depending upon Yield Stress requirement of the cylinders conforming to IS 9158. 3.2 Cylinder Bottom or Cap In most hydraulic cylinders, the barrel and the bottom portion are welded together. This can damage the inside of the barrel if done poorly. Therefore some cylinder designs have a screwed or flanged connection from the cylinder end cap to the barrel. (See "Tie Rod Cylinders" below) In this type the barrel can be disassembled and repaired in future. 3.3 Cylinder Head The cylinder head is sometimes connected to the barrel with a sort of a simple lock (for simple cylinders). In general however the connection is screwed or flanged. Flange connections are the best, but also the most expensive. A flange has to be welded to the pipe before machining. The advantage is that the connection is bolted and always simple to remove. For larger cylinder sizes, the disconnection of a screw with a diameter of 300 to 600 mm is a huge problem as well as the alignment during mounting. 3.4 Piston The piston is a short, cylinder-shaped metal component that separates the two sides of the cylinder barrel internally. The piston is usually machined with grooves to fit elastomeric or metal seals. These seals are often O-rings, U-cups or cast iron rings. They prevent the pressurized hydraulic oil from passing by the piston to the chamber on the opposite side. This difference in pressure between the two sides of the piston causes the cylinder to extend and retract. Piston seals vary in design and material according to the pressure and temperature requirements that the cylinder will see in service. Generally speaking, elastomeric seals - 6 -
made from nitrile butadiene rubber or other materials are best in lower temperature environments while seals made of Viton are better for higher temperatures. The best seals for high temperature are cast iron piston rings. 3.5 Piston Rod The piston rod is typically a hard chrome-plated piece of cold-rolled steel which attaches to the piston and extends from the cylinder through the rod-end head. In double rod-end cylinders, the actuator has a rod extending from both sides of the piston and out both ends of the barrel. The piston rod connects the hydraulic actuator to the machine component doing the work. This connection can be in the form of a machine thread or a mounting attachment such as a rod-clevis or rod-eye. These mounting attachments can be threaded or welded to the piston rod or, in some cases; they are a machined part of the rod-end. The rod material conforms to BS 970 080M40 (EN8) or EN10277-2 (CK-45) equivalent to IS 1570 part -II. 3.6 Rod Gland The cylinder head is fitted with seals to prevent the pressurized oil from leaking past the interface between the rod and the head. This area is called the rod gland. It often has another seal called a rod wiper which prevents contaminants from entering the cylinder when the extended rod retracts back into the cylinder. The rod gland also has a rod bearing. This bearing supports the weight of the piston rod and guides it as it passes back and forth through the rod gland. In some cases, especially in small hydraulic cylinders, the rod gland and the rod bearing are made from a single integral machined part. 3.7 Stop Tube In order to reduce the charge in the gland on long stroke cylinders we recommend a stop tube. Therefore the distance between piston and rod gland will increase so the cylinder becomes more stable, the life expectancy increases and proper function is provided for. This precaution is not necessary for a cylinder mounted vertically-rod down, strongly guided and without lateral movement. Stop tube length depends on the mounting type and the load guiding factor and are available in 50mm (2 in.) Stop Tubes are required if the stroke of the cylinder is more than 8 times of the bore diameter. 3.8 Other parts - 7 -
Cylinder bottom connection Seals Cushions: The use of cushioning is recommended at speeds greater than 20 mm /sec. (0.8 inches/sec.) to assure proper energy dissipation, without auxiliary sources, and to prevent damage to the cylinder, as well as the machine components. A hydraulic cylinder should be used for pushing and pulling only. No bending moments or side loads should be transmitted to the piston rod or the cylinder. For this reason, the ideal connection of a hydraulic cylinder is a single clevis with a spherical ball bearing. This allows the hydraulic actuator to move and allow for any misalignment between the actuator and the load it is pushing. 4.0 Different Types of Hydraulic Cylinders We manufacture different types of cylinders and considering operation it can be defined as follows - 4.1 Single Acting Cylinder A single acting cylinder can be mechanically moved only in one direction because in this cylinder oil only acts on one side of the piston rod (or more specifically Ram). Generally to perform appropriate activities from these cylinders an external force is required in the form of gravity, or sometimes a spring or another hydraulic cylinder from the opposite direction. We use to manufacture with Φ 40, Φ 50, Φ 63, Φ 80, Φ 100, Φ 125, Φ 160, Φ 200 bore of cylinder tubes with suitable rod sizes as per IS 11146:1999 (ISO 7181:1991). 4.2 Double Acting Cylinder A double acting cylinder has its to and fro motion by supplying pressurized oil at its both end. These types of cylinders are extensively used in industries. Here a piston is mounted with a piston rod and is pressurized from both ends. When oil is supplied from piston end the rod is gradually opened and when supplied from rod end the rod is gradually closed. We use to manufacture with Φ 40, Φ 50, Φ 63, Φ 80, Φ 100, Φ 125, Φ 160, Φ 200 bore of cylinder tubes with suitable rod sizes keeping area ratio 1.4 and 2 as per IS 11146:1999 (ISO 7181:1991). - 8 -
4.3 Double ended Cylinder Piston is connected with two rods at both ends. We may obtain double benefit from this type of cylinder and same flow can be obtained from in to and fro motion. The rod diameter may be different depending upon the application. 4.4 Telescopic Cylinder Telescopic cylinders are a special design of hydraulic cylinder that provides an exceptionally long output travel from a very compact retracted length. Typically the collapsed length of a telescopic cylinder is 20 to 40% of the fully extended length depending on the number of stages. This feature is very attractive to machine design engineers when a conventional single stage rod style actuator will not fit in an application to produce the required output stroke. 4.5 Differential cylinder A differential cylinder acts like a normal cylinder when pulling. If the cylinder however has to push, the oil from the piston rod side of the cylinder is not returned to the reservoir, but goes to the bottom side of the cylinder. In such a way, the cylinder goes much faster, but the maximum force the cylinder can give is like a plunger cylinder. A differential cylinder can be manufactured like a normal cylinder, and only a special control is added. - 9 -
5.0 Seal Kit Hydraulic cylinder often very powerful depends in turn, on sophisticated sealing system to control the hydraulic fluid, often operating under arduous condition. The sealing system has instead become the heart of the hydraulic plant and machinery which must have long life and reliability. Conventional U-cups and chevron packing with fabric reinforcement are no longer to provide adequate film of lubrication which can withstand the bearing pressure of the seal in the sealing gap. This leads to Stick-Slip vibration and lack of hydrodynamic lubrication resulting in detachment of fabric layer and sudden failure of hydraulic system. 5.1 Sealing Concept A totally unique combination of anti-friction and long wearing materials with dynamically balanced multi-element design makes the composite sealing system one of the most versatile dynamic sealing system ever devised. To achieve the versatility, the composite seal principle adds the best features of the so-called Squeeze seals ( such as Chevron Packing, O-ring etc) to the best features of pressure energized. Pure leap seals (Such as U-cups) can add features of its own. Radial squeeze force is balanced around the sealing line to ensure excellent sealing characteristics, both under low and high pressure conditions. A special self-relieving feature permits use of tandem rod sealing arrangement without destructive pressure built up between seals and dose not require inter-seal venting. In contrast Pressure Trap problem almost invariably accompany conventional U-cup and Chevron packing. The seal cannot weld itself to the metal parts after a long period of no movement and no high start up, forces are required. Composite seals combine the best advantages to the latest PTFE materials with a new sealing concept. 5.2 High Stability The composite seal combination of materials and design geometry result in high dynamic seal stability i.e. a high resistance to twisting in the groove regardless of high pressure, shock load and operating speed. The high modulus, high shore PTFE compound is inherently more resistant to twisting torques than elastometric compounds (such as NBR, PU). Its low coefficient of friction (typically less than 0.04 in hydraulic fluid) produces little tangential drag on the dynamic sealing line. Another stabilizing effect comes from the usual fact that its break out friction is equal to or less than the running friction which eliminates the jolting stick-slip - 10 -
torques that are common to conventional shapes (U-cup, V-packing etc.) and elastometric materials. 5.3 Hydromatic Friction This sealing concept allows an extremely low level of running and breakout friction which leads to increased hydraulic cylinder efficiencies and smooth operations. High wear resistance materials ensure a seal life which is expected to outwear old sealing devices in conventional materials. Special bronze filled PTFE-POM bearing elements maximize the hydrodynamic lubrication effect of the composite sealing system and also as linear bearings to take care of transverse loads and contamination damage. The co-efficient of friction of rubber fabric combination of hydraulic seals is around three times higher than the PTFE-based seals. Low friction losses of PTFE-based seals result in considerable saving of energy with added benefits of heat and noise reduction. Also composite seals do not absorb moisture as compared to Nitrile seals which eliminates swelling to further reduction of the frictional drag in hydraulic cylinder. - 11 -
6.0 Hydraulic Oil Hydraulic fluids, also called hydraulic liquids, are the medium by which power is transferred in hydraulic machinery. Common hydraulic fluids are based on mineral oil or water. The primary function of a hydraulic fluid is to convey power. In use, however, there are other important functions of hydraulic fluid such as protection of the hydraulic machine components. There are different types of hydraulic oil in market but we recommend to use ISO 68 for its working flexibility in a wide temperature range. Hydraulic oil ISO 68 Mineral based hydraulic oil Property Value in metric unit Value in US unit Density at 60 F (15.6 C) 0.880 *10³ kg/m³ 54.9 lb/ft³ Kinematic viscosity at 104 F (40 C) 68.0 cst 68.0 cst Kinematic viscosity at 212 F (100 C) 10.2 cst 10.2 cst Viscosity index 135 135 Flash point 204 ºC 400 ºF Pour Point -40 ºC -40 ºF Aniline Point 88 ºC 190 ºF Color max.7.0 max.7.0 Too high a viscosity leads to the formation of air and vapour bubbles as a result of low pressure (cavitation). Too low a viscosity leads to increased leakage losses. Increased leakage losses cause the pressure fluid to heat up more, leading in turn to a further reduction in viscosity. The pressure fluid then loses its ability to lubricate. - 12 -
7.0 Load Calculation For selection of cylinder one must follow the load exerted on the cylinder, both tensile and buckling load. 7.1 The tensile load may be obtained from the formula as follows F= (π x D 2 /4) x P Where, F= Load applied on cylinder in Kgf. D= Cylinder bore in cm. P= Pressure applied on cylinder in Kgf/cm 2 7.2 The compressive or buckling load is obtained from the Euler s formula - F 1 = (π 2 x E x I)/(K x L) 2 Where, F 1 = Buckling Load in Kgf. E= Modulus of Elasticity in Kgf/mm 2 I= Moment of Inertia of Piston Rod = (π x d 4 )/64 [d=piston rod diameter in mm] K= Effective length factor = 1 for both end pinned, = 0.5 for both end fixed, = 0.699 for one end fixed and other end pinned, = 2 for one end fixed and other end free. L= Effective Length in mm. Now, the condition is F 1 F - 13 -
8.0 Testing of Cylinder Testing of Hydraulic Cylinder is carried out as per IS 10585:2002. Testing is carried out with the help of testing unit which contains ISO VG 68 oil. The total process is carried out in following processes- 8.1 Proof Pressure Test: - Keeping the piston at mid-stroke and the piston rod fixed with some fixture, the cylinder is gradually pressurized from each end 1.5 times of the rated pressure and then kept it for 3 minutes. The other port is vented during this period. While testing external leakage at ports, end weldments and seals to be checked. 8.2 The cylinder is opened and closed at its full stroke adequately with the help of pressurized oil to release the entrapped air inside the cylinder. 8.3 Then the piston rod is positioned fully extended, the rod end port is vented and cap end port is pressurized to the rated working pressure. 8.4 The oil flow from the open port over a period of 3 minutes starting from 30 second after attaining the required test pressure is measured. 8.5 The same is repeated from the other port. 8.6 Breakaway Pressure Test: - Break away pressure is the pressure required to overcome frictional resistance between inner wall of barrel and seal of piston. The rod is completely closed and the cap end is connected with power pack, then rod end is vented. After two minutes gradually the cylinder is pressurized and at a certain pressure rod starts to move forward. The same is repeated for cap end position. 8.7 Cushioning Test: - Cushioning testing is done at the end of stroke adjusting its rotating screw to slower the speed of rod. 8.8 Endurance test: - The cylinder can be tested in an endurance test rig and cycled end to end at 130 percent of rated pressure. Another cylinder can be connected with the test cylinder and load is applied externally. Different loads can be applied by changing pressure in the load cylinders and thus internal leakage if any can be confirmed. - 14 -
Mill Duty Cylinder - 15 -
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Welded Cylinder - 21 -
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Tie Rod Cylinder - 30 -
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9.0 Our Customers Our products are extensively used in the following industries - 9.1 Hydraulic Cylinder for continuous slab casting, control of slide gate and material flow: Steel Industry 9.2 Hydraulic Cylinder for Induction Furnace: Steel Industry 9.3 Hydraulic Cylinder for Ladle Furnace: Steel Industry 9.4 Hydraulic Cylinder for Arc Furnace: Steel Industry 9.5 Hydraulic Cylinder for Electrode Slipping and Hoisting for Ferroalloy: Steel Industry 9.6 Hydraulic Cylinder for Bleed Off Valve Control of Blast Furnace: Steel Industry 9.7 Hydraulic Cylinder for Sponge Iron Plant: Steel Industry 9.8 Hydraulic Cylinder for Casting: Steel Industry 9.9 Hydraulic Cylinder for Re-heating Furnace: Steel Industry 9.10 Hydraulic Cylinder for Walking Beam Furnace: Steel Industry 9.11 Hydraulic Cylinder for Battery Spine Casting: Processing Industry 9.12 Hydraulic Cylinder with Complete Clamping System for Pipe Bending Machine: Processing Industry 9.13 Hydraulic Cylinder for Flash Welding Machine: Processing Industry 9.14 Different Type of Hydraulic Cylinder for Machine Tool Applications: Processing Industry 9.15 Hydraulic Cylinder for Die Casting Machine: Processing Industry. - 38 -