Jig and Fixture Design
This cardboard proposes a architecture of jigs and accessories for the accumulation accumulation accomplishment of Sportsman Race Series aluminum slipper pistons (Probe Industries) that are acclimated in the Chevrolet LS Series V8 engines. The designs of two sets of jig and accoutrement designs are proposed. The aboriginal set (two vee-blocks and a assignment bushing) is advised for the action of conduct the wrist pin holes in the piston. The added architecture (two vee-blocks and a pin locator) is acclimated in the milling of the skirts and lower anatomy of the piston.
The designs use attempt of accomplishment accessories design, analysis on accomplishment practices and 3D clay software (Catia) in adjustment to optimize affection (accuracy), costs and abundance in the accomplish of such pistons.
An important automated basal of an centralized agitation engine, the agent is basically a solid allotment in an closed butt that moves beneath the burden of a aqueous and transfers the force of the accretion gas to a crankshaft through a abutting rod (The American Heritage, 2005). Pistons about abide of a few capital features.
Pistons are cylindrical. The top allotment of the agent that comes into acquaintance with the accretion gas is the crown. All pistons accept a wrist pin aperture to accommodate a animate wrist pin that attaches the agent to a rod that is affiliated to the crankshaft. The brim of the agent is the end adverse the acme and is generally formed in the abandon to abate weight.
Selected Basal (Chevrolet LS Series V8 Piston)
The specific basal called for the architecture activity is the Sportsman Race Series aluminum slipper agent (Probe Industries) acclimated in the Chevrolet LS Series V8 engine.
The accelerated attributes of a V8 agent requires pistons to accept bargain weight to advance agent balancing. Unlike earlier pistons that were fabricated with casting iron, this agent is fabricated with artificial aluminum admixture to abate its weight as able-bodied as advance fatigue life. Furthermore, this specific agent is a slipper agent with a breadth of alone bisected its bore and has some genitalia formed off in adjustment to abate admeasurement and weight dramatically.
Objectives, Scope, and Assumptions
The aim of this architecture activity is to architecture jigs and accessories for the accumulation accumulation of the aluminum slipper agent acclimated in the Chevrolet LS Series V8 engine.
The ambit of the architecture activity is bound to designing jigs and accessories for the alone two processes in the accomplish of such pistons that crave jigs and fixtures, accurately the conduct of the wrist pin holes and the milling of the skirts and lower anatomy of the piston. The architecture activity does not annual for the exact design, accurateness or ability of the conduct and milling machines. The backbone and acerbity of the abstracts are not considered. The time and motion in amid the processes are not abstinent for optimization.
Manufacturing the Component
The exact blueprint and architecture of the agent for the Chevrolet LS Series V8 agent were taken from a architect of such pistons, Probe Industries. The bore (diameter) of the agent is 4 inches and the acme is 2 inches. The wrist pin aperture is 0. 927 inches in bore and centered at 1. 155 inches beneath the crown. The wrist pin breadth is 2. 5 inches, acceptation that the brim beneath the oil grooves is formed at anniversary end of the wrist pin aperture up to 1. 25 inches abroad from the centermost of the butt (Probe Industries, 2012). These ambit are important in the milling and conduct processes in the accomplish of the piston.
The angel beneath shows the blow of the ambit and the tolerances (calculations apparent later).
Machining Processes in Accomplish of Component
After accomplishment a solid aluminum bang into the basal appearance of the agent with the adapted backbone and stability, the basal undergoes several machining processes. The aboriginal machining action involves application a lathe or a CNC axis apparatus to accomplish the base, cut out oil rings or grooves, and assignment oil holes. The added action is to assignment a ample aperture on one ancillary of the agent through to the other. This (wrist pin hole) is breadth the wrist pin is placed to attach the agent to the abutting rod.
The third action is to use a milling apparatus to barber off actual at the abandon breadth the wrist pin aperture was accomplished in adjustment to abate the weight of the piston. The fourth machining action involves finishing with a lathe machine, wherein the acme is fabricated into its final shape, the basal edges of the brim are shaped, and slots/engravings are made.
Machining Processes Requiring Jigs and Fixtures
The alone processes that crave jigs and accessories are the added and third machining processes, the conduct action and milling process. The aboriginal and the fourth action use CNC turning/lathe machines and they crave no jigs or fixtures.
The action of conduct the wrist pin aperture about requires a bushing to locate the point in the butt that needs to be accomplished as able-bodied as a lower vee-block (with a locator at on end) and an aerial vee-block (with the bushing and a pin/screw abutting to the lower vee-block) to authority the cylinder. The action of milling requires a lower vee-block as able-bodied but with a pin that goes through the wrist pin aperture to authority the agent in abode in the vee-block. A second, aerial vee-block is acclimated to adviser the milling machine. The aerial and the lower vee-block are referenced to anniversary alternative with pins.
Functional Analysis of Jigs and Fixtures
For the conduct process, a vee-block accoutrement is adapted to authority and abutment the annular component. The architecture of the vee-block includes a locator at the end of the butt to accumulate the allotment from affective and to advice put the cylinder/piston in the adapted position. To assignment the hole, a bushing is adapted to adviser the conduct machine. The bushing goes through an backward vee-block that is put in breadth by pins abutting it to the lower vee-block.
For the milling process, the agent charge be captivated in the adapted position and orientation. A vee-block is afresh acclimated to abutment the annular piston. And a analysis pin is placed in the centermost of the vee-block at an exact breadth forth it in adjustment to put the agent in the adapted position forth the vee-block and at the adapted acclimatization (hole adverse upwards) for the milling to be actual (since alone the abandon with the holes charge be formed and alone absolutely beneath the oil rings).
A attenuate backward vee-block is beggared on to the top of the butt and affiliated to the lower vee-block at an exact breadth (using pins or screws) in adjustment to authority the agent in abode and to accumulate the milling apparatus from milling into the oil rings. To comminute the alternative side, the agent is artlessly angry over and adapted into the locator from the anew formed side.
Tolerance Calculation of Jig and Accoutrement for Conduct Process
To compute or the altruism of the aerial jig of the conduct process, the tolerances of the larboard and adapted analysis pins and pin holes are computed first. The tolerances and the clearances charge be aloof abundant so that both analysis pins can fit in the pin holes (in all cases including better and aboriginal admeasurement of one or both pins and of one or both holes). It should be acclaimed that the affliction accessible book is that on one ancillary of the jig, the aperture is the best admeasurement and the pin is the minimum admeasurement while on the alternative side, the aperture is the minimum admeasurement and the pin is the best size. Given that the bore of anniversary pin aperture in the jig is 12. mm (or 0. 5 inches); the altruism called for this is plus/minus 0. 01 mm (leading to a ambit of 12. 69-12. 71 mm for the bore of the hole). A approval of 0. 05 mm is chosen, causing the better bore for the analysis pin to be 12. 64 mm. The altruism called for the analysis pin is plus/minus 0. 005 mm (leading to a ambit of 12. 635-12. 645 mm for the bore of the pin). In the affliction case scenario, on one side, the best aperture admeasurement would be 12. 71 mm while the minimum pin admeasurement would be 12. 635 mm (leading to a abeyant gap of 0. 075 mm and a larboard or adapted about-face of 0. 0375 mm).
In the affliction case book for analysis pins breadth one ancillary has a best aperture of 12. 71 mm and a minimum pin of 12. 635 mm and the alternative ancillary of the jig has a minimum aperture of 12. 69 mm and a best pin of 12. 645 mm, the best about-face of 0. 0375 mm on either ancillary would still acquiesce the beyond pin to fit in the abate aperture aback there would still be a gap of 0. 0075 mm (12. 69 – 0. 0375 – 12. 645 = 0. 0075). Aback the bushing is busted on bound into the jig, there is no approval amid the bushing and the jig and appropriately no charge to differentiate amid the two pieces in agreement of tolerance.
The tolerances of the pins and pin holes would account aberration in the position of the drill. The affliction case book would be if on any side, the pin aperture is of best admeasurement (12. 71 mm) and the analysis pin is of minimum bore (12. 635 mm) arch to a abeyant gap of 0. 075 mm and a larboard or adapted about-face of 0. 0375 mm. This about-face would account the assignment (center of bushing hole) to move 0. 0375 mm in any administration from the centermost of the jig, and appropriately the final wrist pin aperture would be plus/minus 0. 0375 mm from the centermost of the final artefact (50. 7625 - 50. 8375 mm from the ancillary of the agent and 29. 025 - 29. 3775 mm from the top of the piston). This is aural the artefact blueprint wherein the altruism is plus/minus 0. 05 mm (50. 75 - 50. 85 mm from the ancillary of the agent and 29. 29 - 29. 39 mm from the top of the piston). The positions of the analysis pins and pin holes for the aerial and lower vee-block accept a altruism of 0. 005 mm on any administration and appropriately account the position of the accomplished aperture to be amid 29. 335-29. 345 mm from the top of the agent and amid 50. 795-50. 805 mm from the ancillary of the agent (still aural artefact specifications).
The locator on the lower accoutrement as able-bodied as the aback bowl anniversary has a altruism of 0. 005 mm accumulation into a affliction case about-face of 0. 01 mm and would account the position of the assignment to be amid 29. 33-29. 35 mm from the top of the agent (still aural artefact specifications). All the alternative tolerances of the conduct accumulation accept no effect. 4. 2 Altruism Calculation of Jig and Accoutrement for Milling Action For the milling process, the holes in the aerial and lower vee-blocks for the pins that locate the aerial vee-block are absolutely the aforementioned as in the aerial jig for the conduct process.
Thus the tolerances are the aforementioned (0. 01 mm aperture tolerance, 0. 05 mm clearance, and 0. 005 mm analysis pin tolerance) and so is the affliction case book (shift of 0. 0375 mm). Aback the aerial vee-block guides the milling apparatus with a advance barometer of 0. 01 mm, the affliction case book would beggarly that the formed breadth is either 0. 0375 mm too aerial or too low on the agent (16. 7625 - 16. 8375 mm from the top of the piston). This is aural the artefact blueprint wherein the altruism is plus/minus 0. 05 mm (16. 75 - 16. 85 mm from the top of the piston).
As of the lower accoutrement for the milling process, the balanced vee-block allows the annular basal to abide centered after rolling alike back the admeasurement of the basal or the accoutrement varies, appropriately eliminating the charge to set tolerances. However, the altruism charge be affected for the analysis pin that goes through the wrist pin aperture aback a gap actuality would account milling breadth to move up or bottomward from the top of the piston. The aperture that was ahead accomplished with a bore of 23. 55 mm is affected to accept a altruism of 0. 01 mm from the conduct process.
A approval of 0. 05 mm is chosen. And the analysis pin has a altruism of 0. 005 mm, appropriately alignment in admeasurement from 23. 49 - 23. 5 mm. In the affliction case book of a aperture with a best of 23. 56 mm and a analysis pin with a minimum of 23. 49 mm, the abeyant gap would be 0. 07 mm or a about-face of 0. 035 mm up or bottomward the cylinder. This would advance the milling apparatus to alpha milling at a point amid 16. 765 – 16. 835 mm from the top of the piston. This is aural artefact blueprint wherein the altruism is plus/minus 0. 05 mm (16. 75 - 16. 85 mm from the top of the piston).
The locations of all the holes and analysis pins should accept a altruism of 0. 005 on any administration in adjustment to accumulate aural artefact specifications.
Clamp Selection and Force Calculation
For the conduct process, band clamps are activated on the accoutrement by application a brace of atrium arch cap screws on the two abandon of the backward vee-block. The two atrium arch cap screws locate the aerial vee-block and catch it to the lower vee-block back captivation the assignment allotment agent in place. The bore of the holes on lower vee-block for spiral is 12. 7 mm, appropriately M12 admeasurement atrium arch cap screws are called for clamping.
The apparatus force administration of conduct is bottomward and it has a apparatus rotation. The band clamps adhere the backward vee-block and the lower vee-block preventing the butt from rotational motion and accumbent motion. The apparatus force can be taken advantage of anchor bottomward the assignment allotment cylinder. According to Spaenaur (2012), the abbreviating torque of a spiral is the artefact of torque-friction coefficient, nominal spiral diameter, and anchor amount (T = KDP). The Table 1 has apparent that the M12 atrium arch cap spiral has a minimum compactness backbone of 160000 batter per inch, and its actual is Aerial Carbon Quenched Tempered.
In addition, it has a accumulation torque of 125 pound. feet. For the milling process, the band clamps are activated by a brace of atrium set screws on the two abandon of the attenuate backward vee-block. The two atrium set screws locate the aerial vee-block and catch it to the lower vee-block back captivation the assignment allotment agent in place. The bore of the holes on lower vee-block for spiral is 12. 7 mm, appropriately M12 admeasurement atrium set screws are called for clamping.
The table 1 has apparent that M12 atrium set spiral has a minimum compactness backbone of 212000 batter per inch, and its actual is additionally Aerial Carbon Quenched Tempered. It has a accumulation torque of 43 pound. feet. It can be apparent in the accompanying table, the anchor force is about 4286 pound. For a conduct machine, Pirtini and Lazoglu (2005) has accepted that the burden over the assignment allotment as the cutter affective bottomward into the assignment allotment with aforementioned affiliate charcoal a connected value, and added tests accept been adapted that the connected burden P(f) (MPa) can be declared as a action of augment amount (f) (mm/min).
P (f) = 1. 5364f - 103. 06. If the augment amount of the conduct apparatus is 198 mm/min, again the burden is 201. 14 MPa. The blueprint to artful acid force is F= P * A. breadth F is the net force amid the abstinent force and predicted advance force due to acid in the advance administration and A is the contacting breadth of the cutter at an instant. The force is about 87 kN with the 23. 55 mm bore conduct hole. For milling machine, we booty the agent as an example: Amplitude of cut = 79. 3mm = 3. 122 inch Abyss of cut = 19 mm = 0. 748 inch Augment amount = 19. 5 inch/min K” agency =1. 56 MRR = abyss of cut x amplitude of cut x augment amount MRR = 3. 122 x 0. 748 x 19. 5 = 45. 54 inch? /min A blueprint for artful application (HPC) of the milling cutter is HPC = MRR/K HPC = 45. 54 / 1. 56 = 29. 19 hp The formulas aloft are from the commodity ‘A New Milling 101: Milling Armament and Formulas’ (Brian Hamil, 2011). One metric application can be authentic as the ability to accession a accumulation of 75 kilograms adjoin the earth's gravitational force over a ambit of one beat in one second. It can be affected that the apparatus force is about 21 kN.
Thus the absolute amount for our architecture is about 83. 24 AUD. It should be acclaimed that the affairs amount of the final artefact ranges amid 100-200 AUD.
It can appropriately be assured that in the accomplish of Sportsman Race Series aluminum slipper pistons (Probe Industries) for Chevrolet LS Series V8 engines, jig and accoutrement assemblies can be acclimated for the two machining processes (drilling the wrist pin aperture and milling the basal anatomy of the piston).
The jigs and accessories advised were basically assemblies of Vee-Blocks with a bushing for the conduct action and addition accumulation with a analysis pin through the wrist pin aperture for the milling process. The tolerances were advised in adjustment to not beat the tolerances in the artefact specifications. The catch armament were begin to be acceptable and the amount of the jig and accoutrement is actual baby compared to the accumulation fabricated from the final product. The architecture along is actual simple and is appropriately calmly adapted to be chip in a fast-moving accumulation line. Therefore it can be assured that the jig and accoutrement designs are appropriate.
Hamil, B. (2011) 'A New Milling 101: Milling Armament and Formulas’ http://www. mmsonline. com/articles/a-new-milling-101-milling-forces-and-formulas.
Pirtini, M. & Lazoglu, I. (2005) Armament and aperture affection in conduct International Journal of Apparatus Tools & Accomplish 45 (2005) 1271–1281.
Spaenaur (2012) ‘Suggested Abbreviating Torque1 Values to Produce Corresponding Bolt Anchor Loads’. http://www. spaenaur. com/pdf/sectionD/D48. pdf 9. Appendix Table 1 http://www. torqwrench. com/Info/fasteners. php Table 2 http://www. torqwrench. com/Info/fasteners. php
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