The depth of the cut increments by moving the workpiece, and the workpiece is fed by a pawl and ratchet mechanism. Its cut is analogous to that of a lathe, except that it is archetypally linear instead of helical a wood shaper is a similar woodworking tool, typically with a powered rotating cutting head and manually fed workpiece, usually known simply. Draw an alternative mechanism or combination of mechanisms that will produce the same forwards and backwards motion. This mechanism is known as the quick return mechanism. The crank and slotted lever quick return motion mechanism is shown in the length of links o 1 o 2, o 1 c and o 2 a are 10 cm, 20 cm and 5 cm respectively. The advantages of the new design are easier to be balanced dynamically and more compact in volume as discussed in sec. This mechanism is called slotted lever quick return mechanism and it drives a horizontal ram which reciprocates in the guide ways provided on the top surface of the machine frame. Crank and slotted lever quick return mechanism mechanics. Electric motor runs the driving pinion at a uniform speed. The whitworth quick return mechanism changes rotary to oscillating motion but, unlike the crank and slider, the forward reciprocating motion is at a different rate to the backward stroke. Apr 30, 2018 in the forward stroke, cutting action takes place.
When one of the links of a kinematics chain is fixed, the chain is known as mechanisms. This makes the slotted lever oscillate about the pivoted point a. A usual shaper machine operates by a principle of whit worth quick return mechanism where materials are processed at one end and other end remains idle. This video covers the working of a quick return mechanism using a 3d animation. Now the ram is connected to the crank and crank connected to the gears. These are usually obtained by following the four types of shaper machine mechanisms.
For example, ham, crane and rogers 8 described its use as a crank shaper. The time ratio tr of a qr mechanism is the ratio of the change in input displacement during. The quick return mechanism of a machine can e obtained by the following methods. Draw a diagram of the shaping machine and explain how the quick return mechanism works. The slider on the rocker arm which is also connected to the frame is the piston. There are a number of variations of the quick return mechanism. The most common quick return ratio of the time of the cutting. Hydraulic type i mentioned the working principle of hydraulic shaper machine below in this article. A thesis in mechanical engineering the requirements. An offset slider crank mechanism the radius of the crank and length of the slider are important factors to consider when designing a quick return mechanism.
The total machining time decreases and the rate of production increases. Design and construction of a quick return device for use. The whitworth quick return mechanism changes rotary to oscillating motion but, unlike the crank and slider, the forward reciprocating motion is at a different rate to the backward stroke as can be seen in the animation opposite, the red linking pin has to travel a much greater distance around the top of the crank circle than the bottom during a full right to left stroke cycle. Quick return mechanism, shaper machine mechanism figure. Quickreturn mechanism design and analysis projects ron p. Torque required to accelerate a mass at e is output in this inverse dynamic app.
Explain with the diagram working of crank and slotted. But in a dual side shaper machine, materials are processed at both ends which become advantageous when compared to usual shaper. Is your new mechanism an improvement on the crank and slider mechanism. Introductionthe whitworth quick return mechanism converts rotary motion into reciprocating motion, but unlike the crank and slider, the forward reciprocating motion is slower rate than the return stroke. Quick return mechanism as shown in the diagram, ka indicates the starting point of the forward cutting stroke and kb the end of the cutting stroke. This mechanism is made of a driving crank and of a driven slider crank.
Quick return qr mechanisms feature different input durations for their working and return strokes. It is a four bar mechanism comprised of fixed link, crank, pin sliding in the slot and a sliding pair. These mechanisms are widely used on machine tools to give a slow cutting stroke followed by a fast return stroke with a constantangularvelocity drive crank. Dec 01, 2012 shaper quick return mechanism devesh ranjan loading, animation of quick return mechanism,shaping machine, 247 online lecture 24 hydraulic circuit design and. Feb 10, 2019 quick return ratio qrr ratio of forward stroke to the cutting stroke qrr forward stroke return stroke since, forward stroke return stroke so, qrr 1 for single slider mechanism without any offset, forward stroke return stroke theref. Specialized mechanisms whitworth quick return mechanism. Therefore, in order to reduce total machining time, the shaper mechanisms should be designed. Inside its shellcasing is a crank and slider mechanism that pushes the cutting tool forward and returns it to its original position. Our machine is a crank shaper quick return mechanism designed to run at low speed, to highlight the differences between front and back strokes. The whitworth quick return mechanism converts rotary motion into reciprocating motion, but unlike the crank and slider, the forward reciprocating motion is at a different rate than the backward stroke. The working of the slotter machine is similar to the shaper machine do but the main difference between them is the shaper machine works horizontally whereas slotter machines work vertically. The output gives a slow forward linear motion followed by a quick return to the start position along the same path. By reclamping the material, multiple sides can be cut to any desired shape.
Build a cardboard model and determine the toggle positions and the minimum transmission angle. This mechanism is sensitive to small changes in the lengths of the links and the distance between the two rocker points. Complete the diagram below by adding the missing parts that make up the crank and slider mechanism. Inside the hollow portion the machine drive mechanism is housed. The most common quick return ratio of the time of the cutting stroke to the time of the return stroke is about 3. The following mechanisms are used for quick return of the ram. Design, fabrication and analysis of crank and slotted lever quick return mechanism 1.
Utilizing these two loops, the following sections will go through the kinematic analysis of the crank and slotted lever quick return mechanism. Apr 27, 2015 introductionthe whitworth quick return mechanism converts rotary motion into reciprocating motion, but unlike the crank and slider, the forward reciprocating motion is slower rate than the return stroke. In a shaper, the metal is removed during forward cutting stroke, while in return stroke no metal is removed. Design a fourbar grashof crank rocker for 90 deg of output rocker motion with no quick return. Elliptical trammel inversion of double side crank mechanism. The quick return mechanism was modeled after the crank and slider arm, and this is present in its appearance and function. The quick return and its motion trajectory are shown schematically in figure 1. Design, fabrication and analysis of crank and slotted. What is quick return ratio in slider crank mechanism.
In the crank and slotted link mechanism, the power is transmitted to the bull gear through pinion. For the model to be considered a quick return the desired time ratio should determine the radius of the crank and the length of the slider. Quickreturn mechanism design and analysis projects ron. Crank and slotted lever mechanism engineering essay. A quick return mechanism is a mechanical assembly to create a reciprocating motion which is so designed to reduce ideal time required for return stroke. Whitworth quick return mechanism linkedin slideshare.
The shaper machine involves two theoretical concepts of machine designing i. The shaper mechanism should be so designed that it can allow the ram to move at a slower speed during the forward cutting stroke. The rotation of the crank op in clockwise direction through the angle p 1 rp 2 refers to the forward cutting stroke. Here, the connecting rod is the frame, which is fixed. The time ratio tr of a qr mechanism is the ratio of the change in input displacement during the working stroke to its change during the return stroke. The mechanism analyzed here is a quick return one which has numerous industrial applications. Design and construction of a quick return device for use as a. Draw a diagram of the shaping machine and explain how the quick return mechanism. Two of the most common which are found in shaping, planning and slotting machines for metal cutting are the scotch yoke mechanism and the whitworth quick return motion.
The final fabrication model will be represented as shown below. As the ram moves at a faster rate during return stroke, the time taken becomes less. The crank cb in the fig below revolves about the fixed center c. The high performance and highly powerful, pneumatic operated shaping machine is efficient machine which works by pneumatic power, instered of crank and shaping link mechanism here pneumatic power is employed with quick return mechanism, this system consist of ram, pneumatic cylinder, solenoid valve, timer circuit, when air from compressor is. Whitworths quick return mechanism from wolfram library. Sandor and erdman 9 gave an example of its use in connection with a flow metering pump.
Elliptical trammel is a device used to draw the ellipses. The quick return is a mechanism with numerous industrial applications, such as the shaper mechanism shown in. Quick return mechanism to download and make rob ives. Additionally, the device allows for easy changing of the time ratio. For a quick return mechanism, w w is greater than w r. Crank and slotted lever quick return motion mechanism. Quick return schematic the kinematic length of the coupler goes to zero. Quickreturn qr mechanisms feature different input durations for their working and return strokes.
Feb 27, 2019 a quick return mechanism is an apparatus to produce a reciprocating motion in which the time taken for travel in one direction is less than in the other. Several procedures were devised for selected mechanisms to help designers in the synthesis process, this includes the slider crank, fourbar, crank shaper, point and threetwo point mechanism which will be discussed in this chapter. As can be seen in the animation opposite, the red linking pin has to travel a much greater distance around the top of the crank circle than the bottom during. It is driven by a circular motion source typically a motor of some sort and uses a system of links with three turning pairs and a sliding pair quick return is a common feature of tools in which the action is performed in only one. It houses the screwed shaft for altering the position of the ram with respect to the work. This is an application of the oscillating cylinder mechanism. What is the purpose of quick return mechanism in a shaper. The speed of the bull gear is changed by the different. Jun 27, 2011 crank and slotted lever quick return mechanism it finds application in shaping machine, slotting machine, rotary internal combustion engine.
Oct 24, 2015 this video covers the working of a quick return mechanism using a 3d animation. This mechanism is mostly used in shaping machines, slotting machines and in rotary internal combustion engines. Shaper machine is a production machine in which the single point cutting tools are attached and the workpiece is fixed and while moving forward the tool cuts the workpiece and in return, there is no cut on the workpiece and used for producing flat and angular surfaces. The link 3 corresponds to the connecting rod of a reciprocating steam engine. With the help of above design of different components it has been combined together to form a crank and slotted lever mechanism which is seen mainly in shaper machines. Explain with the diagram working of crank and slotted lever. It finds application in shaping machine, slotting machine, rotary internal combustion engine.
Seminar on shaping machine pdf report free download. In this project you are asked to analyze an existing mechanism and to redesign it for a different timeratio. Feb 17, 2016 the output gives a slow forward linear motion followed by a quick return to the start position along the same path. Cutting stroke is slower than the idle return stroke.
Add a comment or brief description of this mechanism. The cutting speed depending upon the type of material and machining condition whereas during the return idle return time. Pdf quickreturn mechanism design and analysis projects. In a standard shaper, cutting of material takes place during the forward stroke of the ram and the return stroke remains idle. The whitworth quick return mechanism converts rotary motion into reciprocating motion, but unlike the crank and slider, the forward reciprocating motion is slower rate than the return stroke. Quick return mechanisms are used in shapers, powerdriven saws, and many other applications where a slower working stroke in comparison to return stroke is desired.
Shaper consists of a hollow machine bed made of cast iron which rests on the ground. A shaper is a type of machine tool that uses linear relative motion between the workpiece and a singlepoint cutting tool to machine a linear toolpath. The reciprocating movement of the ram and the quick return mechanism of the machine are generally obtained by anyone of the following methods. One known as the whitworth quick return, is used to drive the cutting tool of a shaper which cuts a flat surface off a block of steel as it is advanced perpendicular to the motion of the tool. Mar 23, 2020 it is a reciprocating member of the shaper which holds the tool and the reciprocates on the guideways on the top of the column by means of quick return motion mechanism. Design of a crankdriven toggle quickreturn mechanism.
Mechanism synthesis in achieving thelps his goal in fewer steps. This pinion receives its power from the individual motor. The reciprocating movement of the ram and the quick return mechanism of the machine. The whitworth quick return mechanism, mbm2, is a mechanism able to transform circular movement into reciprocating movement. Moreover, let w w and w r denote the angular displacement of the link 2 for the working and the return strokes, respectively. A quick return mechanism is an apparatus to produce a reciprocating motion in which the time taken for travel in one direction is less than in the other. Based on the type of driving mechanism types of shaper machines. Design and construction of a 6 bar kinematic quick return. The return is governed by a quick return mechanism.
A novel design for quick return mechanisms, where the new mechanism is composed by a generalized oldham coupling and a slider crank mechanism is proposed in 6. Types of quick return mechanism quick, return, machine. Abstract quickreturn qr mechanisms feature different input durations for their working and return. Quick return mechanism explore mechanical expressions.
1033 1359 1239 525 180 1468 450 1042 1525 464 105 723 209 857 645 1177 130 898 481 403 1163 1221 1206 701 1494 1002 282 815 1508 259 119 1243 1337 1416 583 800 266 1396 1316 1212 318 480