Rational planning of the hottest engine production

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The reasonable planning of engine production line

"improving quality and reducing cost" provides a basic guarantee for automobile enterprises in the future competition. For automobile powertrain manufacturing enterprises, reasonable production planning is very important, because reasonable selection can further improve the use value of the production system, improve production efficiency, make the production process more reasonable, and save a lot of expenses for enterprises

for the production equipment used in engine manufacturing, the calculation of its investment cost and service life is not a simple thing: first, enterprises should consider investing a lot of money in the early stage to purchase production equipment; Secondly, in the later use process, we should also consider the use cost and maintenance cost in the processing process. In order to meet the future production demand, when planning the engine production line, we should also consider whether the selected production equipment can meet the changes of future production demand. How to reasonably invest in the construction of production lines has become a careful research topic for each engine manufacturer at present

proposal of the topic

the engine independently developed by Great Wall Motors Co., Ltd. needs to build a new production line to meet the processing and assembly tasks of new products

the models produced are G01 ~ G06 three cylinder and four cylinder gasoline engine series, with a displacement of 0.8L ~ 1.5L. Its structural features are: all aluminum material, using DOHC, plastic intake pipe, electronic throttle, direct injection and supercharging technology, and the emission standards are Euro IV and euro v. The planned production line will undertake 0.8L, 1.0L, 1.1L, 1.3L and 1 However, for the processing, assembly, hot test and other tasks of five 5L engines, the annual production capacity is 100000 sets

selection of production system

considering the expansion of future models, we decided to choose flexible production system. At present, there are two main forms of flexible production lines composed of high-speed machining centers in foreign countries. One is a fully automatic production system composed of truss manipulator conveying workpieces; One is to take each single machine as a unit and form an assembly line with a simple material system. Each machine tool is loaded and unloaded manually or by robots. In the first method, because the truss manipulator is used for workpiece conveying, the structure of the high-speed machining center, which is the basic unit of the flexible line, can be greatly simplified, so as to reduce the manufacturing cost of each unit, and the increased cost of the truss manipulator can be completely balanced by the cost saved by the machine tool manufacturing. Therefore, the final cost of the first scheme is completely acceptable to us

based on various considerations, we made the following choices: the production line of cylinder block and cylinder head is composed of high-speed machining center (cylinder block and honing machine) and auxiliary equipment, so as to complete the tasks of machining, cleaning, assembly of bearing cover, air tightness test, detection and grouping; The crankshaft production line adopts flexible processing mode to carry out multi variety co production, and all adopt manipulator to automatically load and unload materials, realizing the full-automatic production of the production line

model expansion ideas

1 Equipment selection

the basic characteristics of high-speed machining center are: high spindle speed, high feed speed (including fast moving speed), high acceleration (deceleration), micron level machining accuracy, high static (dynamic) stiffness and lightweight moving parts. In order to reasonably demonstrate the rationality of purchasing equipment, we have considered the following aspects: the comparison of different speeds and acceleration times; Starting and stopping time of electric spindle; The relationship between moving distance and time. After comprehensive analysis of various data, we come to the conclusion that: for our products, using German imported processing centers and a large number of PCD blades can reduce the number of equipment, reduce the amount of investment, and ensure reliable processing quality

it can be seen from table 1 and table 2 that German equipment has obvious advantages in high-speed machining. When the machining allowance is large (about 3mm), stable finishing can be directly carried out and good machining quality can be achieved

2. Selection of honing machine

(1) confirmation of cylinder hole processing scheme: the cylinder barrel of the cylinder block is alloy cast iron embedded castings, and the cylinder holes are not grouped according to the design size of the drawing (4- φ 750+0.01), surface quality parameters and platform pattern requirements. The honing machine with platform pattern can meet the requirements

(2) confirmation of main bearing hole reaming and honing: since the main bearing cap of the product is made of cast iron, which is different from the material of the cylinder block, we have fully demonstrated the processing of the two materials, as shown in Table 3

through comprehensive analysis, we believe that the finishing of main bearing holes (bimetal cutting) is more reliable by reaming and honing, and the roundness, straightness and surface roughness are easy to ensure in mass production; The honing machine adopts expandable technology, which can ensure that the honing is in close contact with the hole surface within the full length. Therefore, the machining accuracy of cylinder hole and crankshaft hole can be significantly improved by honing

manipulator on crankshaft line

3 Tool selection

when the machine tool equipment is determined, we should start to select the tool. In order to give full play to the performance and efficiency of the machining center and adapt to the high-speed and efficient advantages of the current engine production line, the following tool brands, MAPAL, Kennametal, Sandvik, widia, valenite, OSG, ghring and KOMET, are preferred, and the tool without regrinding is preferred Now the technical parameters of the sling tensile testing machine are introduced as follows: cemented carbide drill bits, internally cooled drill bits and cutting tools made of new materials such as cubic boron nitride (CBN)

4. Blade selection

taking the production of 70000 cylinder heads as an example, the single piece cost of Using PCD blades in large quantities is lower than that of Using PCD blades in small quantities, so using PCD tools can reduce the single piece production cost. The price of PCD blade is generally 8 ~ 10 times higher than that of cemented carbide, and its service life is about 10 ~ 50 times longer than that of cemented carbide in actual use

5. Selection of auxiliary equipment

in order to reduce costs, reduce labor intensity and ensure product quality, we have planned auxiliary equipment from the following aspects:

(1) the head and tail of the cylinder production line are manually loaded and unloaded from the motorized roller table with the help of a suspension crane

(2) the cylinder head production line adopts manual loading and unloading of workpieces from the motorized roller table (the aluminum cylinder head is light in weight and meets the weight-bearing requirements of human body)

(3) the machining center is equipped with double exchange worktables, and the gantry pneumatic balance is used to lift the workpiece onto the fixture for loading and unloading, and the motorized friction roller table is used for transportation between processes

(4) after the main bearing cap is assembled, the bearing cap is assembled with an electric double headed tightening machine and torque control technology

(5) the special equipment completes the processes such as capping press fitting, air tightness test and detection grouping; The mechanical friction roller table is used for the transportation between equipment such as capping press fitting, air tightness test and detection grouping, which operates automatically

(6) the production line is set up for inter process inspection, equipped with gas and electricity meters, linear measuring tools and corresponding inspection platforms required to detect workpieces, so as to strengthen the quality control of products

achievement display

in line with the business philosophy of ensuring "high-quality products and low-cost investment" to make our products competitive, the equipment of the two production lines of cylinder block and cylinder head is mainly composed of the high-speed machining center of the German Heller company "Gallen said, and the cylinder block is also composed of the automatic honing line of Nagel, the final measuring machine of Italian marpross and the auxiliary equipment produced by well-known domestic manufacturers. Its flexible processing method can meet the needs of multi-sensor collinear production, so that we can know whether there is a problem with the variety. The whole line adopts automatic transmission by motorized roller table. Each production line is equipped with inter process detection function, and is equipped with gas electricity meter and detection platform. All gas electricity and electronic meters have SPC statistical function

the crankshaft production line adopts flexible processing method for multi variety co production, and all adopt manipulator to automatically load and unload materials, realizing full-automatic production. The high-speed follow-up external milling and turning broaching machine of Boehringer company in Germany is used for rough machining, and the follow-up grinding machine of Junker company in Germany with grinding accuracy of roundness within 2mm, cylindricity within 3mm and parallelism of connecting rod journal of about 8mm is used for finish machining. In addition, the production line also has advanced testing equipment such as the dynamic balancing machine of Schenk company in Germany and the comprehensive measuring machine of MARPOSS in Italy, which ensure the production accuracy requirements of crankshaft

in order to give full play to the performance and efficiency of Heller machining center and adapt to the high-speed and efficient advantages of the current engine production line, we choose Kennametal as the first tool supplier. The machining equipment gives priority to the use of machine clamp non regrinding tools, cemented carbide drill bits and internally cooled drill bits, cubic boron nitride (CBN) and other new materials; The HSK tool handle with a taper of 1 ∶ 10 is used, and its double-sided contact point with the spindle ensures the positioning accuracy and connection rigidity; Using the heat expanding tool system, its uniform clamping force makes the concentricity less than 3mm, which is more suitable for high-speed machining. In order to maximize the cutting performance of the tools, all machining center tools adopt the center internal cooling structure; PCD tools are widely used for milling aluminum alloy materials of cylinder block and cylinder head to ensure machining accuracy and surface quality. The cutting speed is 2500m/min; Considering that large centrifugal force will be generated during high-speed rotation, the cutter body is made of high-strength aluminum alloy and steel bimetal materials. The TX type ultra-fine cemented carbide tool of Kennametal has the best centering effect with a particularly thin tip. It can complete two processes of drilling and reaming at the same time, and the machining accuracy can reach level 7

at present, these production lines have been verified in small batches, which meet the planning requirements in terms of processing quality and stability; In terms of the economy of investment, it has also been widely recognized by Great Wall Motors Co., Ltd. and the market. (end)

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