A simplified clampingforce calculation with the cutting force entirely horizontal, and no workpiece stops frictional force resists all cutting forces. Rather than evaluating the actual forces generated during machining and selecting clamps accordingly. How to calculate clamping force for injection molding. To simplify calculations, the worstcase force situation can be estimated. Therefore, the calculation of clamping force is a very complex problem, generally can only make rough estimates. To start viewing messages, select the forum that you want to visit from the selection below. See table below for how much clamping force is available from manual clamp straps of various sizes with a 2to1 clamping force ratio to compare with powerclamp forces. This video shows how to change adapters and how to check drawbar force. In order to keep the mold closed, this force must oppose the separating force, caused by the injection of molten plastic into the mold. How to calculate clamping force on a shaft coupler. The unit for the required mold clamping force is n newtons, or kfg, of tf. Then the maximum values of clamping forces among these are taken as the optimum clamping force. An entirely mechanical clamping force measuring instrument is now available from guhring. The following details the steps necessary to compute the stresses using fea in solidworks.
The method used for determining the required injection mold clamp force is to take the projected area of the part to be molded and multiply that number by a factor of from 2 to 8. Clamping force optimization for minimum deformation of. Cclamp fea analysis me 341 students are asked to determine the stresses on the inner and outer surface of a cclamp at a point on the curved section and the straight section of the clamp. A simplified example appears below, with cutting force entirely horizontal, and. Failure methods, clamp load, and heat in selftapping. For simplicity, in the low speed processing to determine the clamping force, can only consider. To evaluate the effect at locating point li by clamping force at point cj, we set a. The relationship between the tightening torque and the clamp. Clamp force requirements injection moulding plastikcity. The clamps i will likely be using have the potential to generate nearly 15,000 lbs of clamping force and honestly i cant imagine that the current fixture system would be able to handle more than a few clamps if that is the case though i really do not know as previously stated how much force the wedges are currently generating.
Clamping force f n is the force pressing each brake pad against the disc. This fastener bolt torque calculator will estimate the unknown torque, diameter, axial force applied and coefficient of turning friction for the given conditions. The required clamping force can be calculated from the cavity pressure inside the mold and the shot. It is necessary to calculate the clamping force of fixture elements because of. A balanced axial force is applied during screw fastening. Clamping forces may be transmitted by a number of mechanical means including screw, cams, levers or wedges. The required clamping force can be calculated from the cavity pressure inside the mold and the shot projected area, on which this pressure is acting. To calculate the minimum clamping forces required to hold the workpiece, the friction forces due to locators and clamps are considered.
Clamping force is the force required to hold a part against the locators. For dry disc brakes it doesnt matter whether the brake is of the sliding type or opposed piston. This is integrated with the clamping force calculation. Force and deformation analysis for determination of optimum. The force of keeping the mold closed tightly is called the required mold clamping force. You will have to register or login see top or bottom of page before you can post a message or view images. Brown, charles morrow, samuel durbin, and allen baca p. In other words, the combined force from all clamps on the right side must be greater than 1290 lbs. When clamping single part, a better placement is with onethird of strap length between the fastener and workpiece and twothirds between the fastener and heel support. While the tool may be very accurate, measuring torque only measures how difficult it is to turn the bolt. Estimation of workpiece clamping force of cnc lathe new. Using torque to measure clamp force an inconvenient truth the traditional method for tightening fasteners is to turn the bolt head or nut using a torque wrench. The calculated value is the minimum amount of force needed to exactly offset the cutter forces generated. Force can be described as the amount of push or pull between two objects.
Braking force f b is the tangential friction force acting between the brake pads and disc. Using torque to measure clamp force an inconvenient truth. Engineering fundamentals of threaded fastener design and analysis. The method used fordetermining the required injection mold clamp force is to take the projected area of the part to be molded and multiply that number by a factor of from 2 to 8. How to calculate a bolts clamping force it still runs. Finally, the deformation of the workpiece for the optimum clamping forces is determined by harmonic analysis using fem software. See torque force design equations webpage and torque chart page for recommended fastener torque and equation data. Fixture clamping force analysis during milling process scientific. Box 5800, ms0501 sandia national laboratories albuquerque, nm 87185 abstract this document provides general guidance for the design and analysis of bolted joint connections. How to calculate clamping force in fixture design carr lane. To obtain the desired position and orientation, the clamping force f cl should be inside the constrained cone. This is precisely what i presented to a customer who laughed and told me i was wrong. Engineering inspiration brake system design calculations.
A fine thread will all else being equal be stronger than a coarse one. A joint diagram may help illustrate what happens as we apply our preload and the effects of external loads. Automation of clamping force calculation in fixture design request. Bolt torque, axial clamp force, bolt diameter calculator. Servohydraulic, hybrid and allelectric ranges available with clamping forces from 280 to 5000 kn.
Calculation of clamping force from bolt torque engineering stack. Consult intrinsic devices for application specific. The clamping force is also related to the rigidity of the process system and the transmission efficiency of the clamping mechanism. Preload tension in bolt clamping force torque nm au torque, by definition, is a force caused by turning.
The fatigue strength of bolt under repeated load should not exceed the specified tolerance. Stop pin is used to prevent bending of the workpiece by the application of clamping force. Diameter squared x pie divided by 4 area area x pressure cylinder force x 2 gripping force these equations are universal for metric or english measurements. Force exerted by a band clamp welcome to imajeenyus. Nov 30, 2014 homemade gauge to measure force applied by clamps these measurement are not necessarily scientifically accurate, but give an indication of differences. In fact, this is the main function of the clamping force. The clamping load is assumed to act on all friction surfaces equally.
In order to determine the magnitude and direction of the required clamping forces, an analysis of the cutting forces is required. Pipe clamping force with four bolt connection structural. Let us assume that the assumptions for calculation are that the pressure inside the cavity is p 300 kgfcm2, the projection area of one cavity is a1 15. Learn more about the victory tiebarless product line. Failure methods, clamp load, and heat in selftapping screw insertion a major qualifying project report submitted to the faculty of the worcester polytechnic institute in partial ful. As a reality check if we approximate to a cross sectional.
Qaxial tightening force for bolt and fatigue limit the proper axial tightening force for a bolt should be calculated within an elasticity range up to load 70% of the rated yield strength when the torque method is used. Newtons third law state every force has an equal and opposite reaction and a reaction force from a sliding caliper is. Failure methods, clamp load, and heat in selftapping screw. My guess is your clamping force can be up to the yield of the pipe or clamp material. This paper presents a analytical method to calculate the minimum clamping force to prevent slippage between the workpiece and spherical. In the real world when clamping force is important,a hydraulic tensioner pulls the studbolt and then the nut is tightened. Unilok clamping force calculation thinwalled ring, nonrectangular crosssection t clampforce gauge is the easiest way to check drawbar force. You can also calculate required clamping forces based on calculated cutting force. Injection molding packing stage when the mold is full. Packing pressure must be maintained until the gate solidi. Failure methods, clamp load, and heat in selftapping screw insertion a major qualifying project report submitted to the faculty. Pressure is the resistance to flow of a liquid, and is in part responsible for creating the force in a hydraulic system. The results are then compared to the solution found using tk solver.
Unilok clamping force calculation intrinsic devices. There are variables that affect the clamping force calculation, like the material type lowflow versus highflow plastic, and the depth of the part. Request pdf automation of clamping force calculation in fixture design in a manufacturing process which requires a fixture as clamping device, the. Calculating the clamping force for machining how much clamping force do i need to hold this part. Injection molding sizing an injection molding machine packing pressure. The force is zero as the clamp will never apply force to the 88. Simple clamping force friction question mechanical. For ordinary applications like car wheel lugs or headbolts, the manufacturer has the experience to know the torque levels to apply. This is can be dependent on a number of factors, but is largely a function of the preload force, the force exerted in compressing the bolt, and the tension force, the force exerted in pulling the bolt apart. To calculate clamping forces by fea method for hydraulic pressure of 3. When workpiece locators and multidirectional forces are considered, the calculations become more complicated. A joint diagram may help illustrate what happens as we apply our preload and the effects of. Projected area is calculated by multiplying length times width.
Technical data suggested tightening torque1 values to produce corresponding bolt clamping loads notes. Empirical formula 1 clamping force t clamping force constant kp product projected area s cm cm kp experience value. Pipe under clamping force free download as excel spreadsheet. To calculate clamping forces by analytical methods, we consider a piston and clamp lever linkage connection in that, first and foremost we should calculate the. See table below for how much clamping force is available from manual clamp straps of various sizes with a 2to1 clampingforce ratio to compare with powerclamp forces. The clamping forces generated in the screws were well below the yield strength of the screws. Consider calculating the required mold clamping force when four molded items are obtained using pbt plastic with 30% glass fibers added. Design, development and analysis of clamping force of a. The actuation of these mechanical devices can be manual or automatic by means of pneumatic or hydraulic means. Clamping force calculations can be quite complicated.
I showed on a fbd how there must be an equal reaction force on the opposite side of the ubolt, but he maintained that if the tension in the bolt is 6000, it must be 3000 each side. Therefore, for fea import piston clamp lever cad model in ansys static workbench and define contacts between piston, small pin and clamp lever respectively. Jan 15, 2014 jm performance products clampforce gauge is the easiest way to check drawbar force. How to calculate clamping force injection mold design. Clamping force calculator clamping force refers to the force applied to a mold by the clamping unit of an injection molding machine. To quantify the importance of torque on a nutbolt combination it must first be understood what operation. In addition, cutting force itself is a dynamic load, in the process of machining is also changing.
Regrettably, accurately determining the answer to this question is often glossed over during the design phase of clamping fixtures. The clamping force on a bolt is defined as the compressive force a fastener exerts on a joint. The greater the resistance to turning, the greater the torque or force required to turn the item. The tensile load a fastener can withstand is determined by the formula p st x as. Some methods involve calculating clamping force by tightening the bolt by a predetermined angle and here pitch does matter. This calculation is performed by the technical department at engel uk. Even though f l the combined force from all clamps on the left side equals zero, a small clamping force may be desirable to prevent vibration. At the time of designing a new mold, it is necessary to obtain by theoretical calculations what is the optimum required mold clamping force that the injection molding machine has. In this case twothird of the clamping force is applied to the workpiece. In the case of dynamic applications, consideration must also be given to the decaying pressure on the side of the cylinder piston open to atmosphere. How to calculate clamping force in mould design quora.
See torque force design equations webpage and torque chart page for recommended fastener torque and equation data this fastener bolt torque calculator will estimate the unknown torque, diameter, axial force applied and coefficient of turning friction for the given conditions. T kdf, to estimate the relative magnitudes of torque and clamp force. Principle of clamping force the clamping force p generated by the cylinder is counteracted by an equal and opposing force p static. A simplified clamping force calculation with the cutting force entirely horizontal, and no workpiece stops frictional force resists all cutting forces. Technical data proper bolt axial tightening force and. Clampingforce calculations can be quite complicated. Suggested tightening torque1 values to produce corresponding. But the user has to enter the detail required for selecting clamping element and the software module will give the necessary results is show in figure 7.
Principle of clamping force the clamping force p generated by the cylinder is. I knew there had to be a relationship between bolt tension and the clamping force. To provide an adequate margin of safety for the clamping system, this value should be increased by a factor between two and four to provide a reasonable safety factor. Tightening torque values are calculated from the formula t kdp, where t tightening torque, lbin k torquefriction. This will increase the chances that the joint may loosen or that the bolts may fail. How do you calculate clamping force in injection molding. The nut factor in the torque formula decreased with the nylok and. It is easy to determine the clamping force and the corresponding deformation. Engineering fundamentals of threaded fastener design and. Asthebandistensionedbywhatevermeansisused by the speci. The type and amount of clamping force needed to hold a part is usually determined by tool forces working on the part and the way the part is positioned in the tool. The function of clamping is to balance the force system, which consists of the weight of the workpiece, cutting forces, and support forces of locators, so that the desired position and orientation of the workpiece can be maintained. To ensure operational safety, a regular clamping force check of the hsk interface is recommended.
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