Design and Development of Hydraulic Pipe Bending Machine Ankit Vyas1 ,Chandrakant Tiwari2 ,Arnav Tulsian3 ,Ankit Patel4, Kiran Wangikar5, Prashant Anerao6 1,2,3,4 U.G.Vishwakarma Institute of Information Technology, Pune 5,6 Professor, Vishwakarma Institute of Information Technology, Pune Maharashtra,India. [email protected], [email protected], [email protected], [email protected]

Abstract—The design of pipe bending machine has undergone many changes, development and improvements over a period of time. Bending of pipe plays an important role in many of the industries, instruments, transporting of fluids, etc. Keeping in mind the requirement of bend pipe in various fields we have designed a hydraulic pipe bending machine which can be used at construction sites, small scale industries etc. with less cost compared to the existing bending machines in the market, and it also increases the productivity of the bend pipes. The important parameters to be considered in pipe bending are Radius of bend, Angle of bend, Diameter of pipe, and thickness of the pipe. The concept of press bending is used to perform the operation and the required pressing force is applied with help of single acting hydraulic jack. This type of pipe bender is used to bend a round pipe of outer diameter within the range of ½ inch to 3 inches, maximum thickness 3 mm and radius of curvature up to 325 mm with maximum 90⁰ bend angle.

I. INTRODUCTION Types of Bending Processes and Equipment Used in Pipe bending techniques are varied and offer different advantages and disadvantages depending on the function of the bend and the type of material being bent. Some use mechanical force and some use heat treatment, the most common are as follows:  Press Bending  Rotary Draw Bending  Mandrel bending  3 Roll Bending  Bending springs  Heat induction bending  Sand packing/hot-slab bending Press Bending Press bending is the simplest and cheapest method of bending cold pipe and tube. The pipe or tube is restrained at two external points and a ram in the shape of the bend advances on the central axis and deforms the pipe. The bent pipe or tube is

prone to deformation on both the inside and outside curvature. The pipe or tube is often deformed into an oval shape depending on the wall thickness of the material. This process is used where a consistent cross section of the pipe is not required. This type of bending is suitable for bending electrical conduit and similar light gauge product. II.

Description

A. Main Components of Bender Front frame and Back frame: - The front plate and the back plate are required to hold and fix the bobbins. Both the plates consists of number of holes, each hole corresponds to a unique diameter of the pipe. For example to bend a pipe of diameter ½ inch then the bobbins should be fixed in the first hole with help of the bobbin pin. The bobbins should be placed on the respective pipe marking on the plates. Serious damage may be caused to the machine and the piston if they are placed asymmetrically. The material of the plate is selected according to the load applied by the hydraulic jack during operation.

Fig.1. Catia model of Front and back plate of the bender

Base plate: - The base of the bender is 12 mm thick MS plate. The front and the back frame are fixed on the base plate with the help of L angles. The vertical surface of the L angles are attached with the front and back plate with the help of bolts and the horizontal surface of the L angles are welded to the plate. The hydraulic jack is centrally fixed on the base plate. Fig.3.Catia model Hydraulic Jack

Bending formers: - Bending formers or bending dies are the main components of the bender which are used for bending. The inner surface of the die is spherical in shape, and is according to the outer diameter of the pipe which is to be bent. There are different types of dies available according to the radius of the bend and the diameter of the pipe. Bending die is subjected to heavy load so the strength of the die should be sufficient to withstand the load. The pipe is placed on the curved surface of the die. Fig.2. Catia model of Base plate with L angles

Hydraulic jack: - A jack is device that is used to lift heavy loads. The primary mechanism with which force is applied varies, depending on the specific type of jack, but it is typically a screw thread or hydraulic jack or cylinder. Hydraulic jack consists of piston, piston rod, screw rod and hydraulic oil. The hydraulic jack reciprocating handle moves upward and downward continuously, so that the compressed oil goes to the hydraulic jack piston to the end of the piston rod the moving die is fixed. The compressed oil pushes the hydraulic jack piston forward. Already the pipe to be bent is fixed in between revolving die and moving die. The die is supported by the die holders. By changing the die in the hydraulic pipe bending machine, we have to produce different shape of bended pipe such as “V” type, “L” type etc. The ram (moving die) strikes the pipe with the required force, so that the pipe is bended according to the shape of the die in the die holder. This is a simple pressing mechanism (Degarmo et al., 1997 and Khurmi and Gupta, 1997). The main components in a portable hydraulic pipe bending machine are hydraulic cylinder, ram, oil tank, plunger pump, release valve lever, handle, die, die holder and hydraulic drive. Hydraulic systems possess numerous advantages over other systems of power operation. They are light in weight; they are simple and extremely reliable, requiring minimum attention and maintenance. Hydraulic controls are sensitive, affordable and precise controllability.

Fig.4. Catia model of Bending die

Bobbins: - Bobbins or dolly blocks or bending formers will be used to hold the pipe and to support its cross section so that minimal deformation of pipe takes place. The bobbins help the pipe to roll over it so that maximum deflection and minimum deformation of the pipe takes. The radius of curvature of the bobbins is according to the outer diameter of the pipe. So for different outer diameters of the pipe different set of bobbins will be needed. Connector: - The diameter of the plunger of hydraulic jack is not of the same size of the hole of the bending die. So a connector is required to fix the die on the plunger of hydraulic jack.

Fig.5. Catia model of Connector

B.

Construction of the bender

The assembly is as follows: The base plate is kept on the ground. The l angles are welded on to the base plate. Then the hydraulic jack is bolted onto the center portion of the base plate. The connector is attached on top of the plunger of the jack. Now different dies can be mounted on top of this connector according to usage. Now both the frames are arranged in between the l angles and then are bolted with the help of nut and bolts. Finally the bobbins are selected depending on the diameter of the pipe to be bent and then they are aligned with their respective holes on the frame. And these bobbins are fixed with bobbin pins and are tightened by nuts on both sides. For further stability the base plate along with the whole framework can be mounted on stool and for this purpose holes have been provided on the base plate.

III. Design of bender A. Model:Modeling of each and every component the bender is done by using Catia software

C. Working of bender This hydraulic pipe bender is based on the principal of press bending. The hydraulic jack consists of a plunger which is used to apply force required for bending. The plunger moves up when the operator applies the force with help of the handle provided in the lower portion of the jack. The bending die is fixed on plunger with the help of connector. The pipe is placed on the fixed bending die which moves up with the plunger. The bobbins or the clamping die is fixed on the front and the back frame. The clamping die restricts the motion of the pipe from both the ends and allows the motion of the pipe only from the center. The force is applied with the lever till the desired angle is achieved. Now the plunger is retracted and he bobbins are removed which frees the bent pipe.

Fig.7. Catia model of bender

B. Calculations: Load calculations for Hydraulic jack W = Load applied through jack A = Area Syt = Yield strength of material δ = Deflection L = Length between two bobbins E = Modulus of elasticity I = Moment of inertia W = Syt * Area δ = Wl3 / 48EI Table 1. Load and Deflection Calculations

Fig.6. Real image of bender during operation

S. No.

Dia. of Pipe

Max Load (Tons)

1 2 3 4 5 6 7 8

½” ¾” 1” 1 ¼” 1 ½” 2” 2 ½” 3”

3.38 5.59 7.81 10.25 12.39 16.66 21.09 25.52

Max Deflection (cm) 15.82 19.63 26.95 35.74 46.87 61.51 84.94 94.2

According to these calculations the maximum ton capacity of jack is 30 tons and maximum stroke length is 150mm.

 Radius of bend for Die:The bend of the pipe takes place according to the geometry of the die. So different dies have to be manufactured for different diameters of pipes. Different dies were manufactured by casting method. The maximum angle of bend is 90⁰ for each die.

Table 4. Height of holes from base

Table 2. Different Radius of Bend



S. No.

Die

1 2 3 4 5 6 7 8

½” ¾” 1” 1 ¼” 1 ½” 2” 2 ½” 3”

Radius of Bend (mm) 54 67 92 122 160 210 290 325

Frame:

Distance between two bobbins: The distance between two respective bobbins will always be different for every diameter of the pipe. These were calculated by adding the length of the die with the diameter of the pipe and the thickness of the bobbins. Table 3. Distance between 2 respective holes

S. No.

Die

1 2 3 4 5 6 C 8

½” ¾” 1” 1 ¼” 1 ½” 2” 2 ½” 3”

Distance b/w two bobbins (mm) 180 256 324 390 457 534 615 690

Vertical distance of the holes for bobbins from base plate: These were calculated by adding the height of the jack with the height of the connector along with the height of the die and the thickness of the bobbins.

S. No.

Die

1 2 3 4 5 6 7 8

½” ¾” 1” 1 ¼” 1 ½” 2” 2 ½” 3”

Height of hole from base plate (mm) 355.17 362.15 372.65 384.61 398.92 419.91 449.66 463.30

Analytical analysis of components of machine 1. Frame structure Maximum load per member = (26 (load for 3 inch in tons) *1000*9.81) / 4 = 63765 N Permissible value of stress (in yield) =247 MPa FOS=1.5 Material selected = Mild steel plate Fixed constraints (thickness of material) =12 mm Allowable stress = Permissible stress / 1.5 = 164 MPa Required width of frame member = Max load per member / (Allowable stress * thickness) = 63765 / (164 *12) = 33.6 mm 2. Bobbins Maximum load per bobbin = (26 (load for 3 inch in tons) *1000*9.81) / 2 = 127530 N Permissible value of stress (in yield) =247 MPa FOS=2 Material selected = Mild steel bar Fixed constraints (inner diameter of hole for bobbins) = 16 mm Allowable stress = Permissible stress / 2 = 123.5 MPa Generated stress = Max load per member / ( minimum area of bobbin) =127530 / (3.14( (27.5)^2 –(8)^2 ) ) =58.6 MPa