Cylinder crankshaft hole vertical machining process

Abstract

The invention discloses a vertical machining process for a crankshaft hole of a cylinder body, which comprises the following steps: positioning and clamping the cylinder body through a special fixture to enable the axis of the crankshaft hole of the cylinder body to be in the vertical direction; a special cutter suitable for vertical machining is selected and installed on a main shaft of the vertical machining center; according to the size and precision requirements of the crankshaft hole, machining parameters are set through a numerical control system, and a cutter conducts cutting machining on the cylinder crankshaft hole according to a preset movement track; in the machining process, a tool and a machining area are cooled and lubricated through a cooling system, and size detection and surface quality detection are conducted on a cylinder crankshaft hole. The machining method has the beneficial effects that the axis of the crankshaft hole is arranged in the vertical direction, so that the influence of factors such as gravity on the machining precision is reduced; through reasonable machining parameter setting and closed-loop control of the feeding stroke sensor, the machining size precision and the position precision are further improved, tool abrasion and tool changing time are reduced through effective cooling and lubrication of the cooling system, and therefore the overall machining efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cylinder machining, and particularly relates to a vertical machining process for a cylinder crankshaft hole. BACKGROUND

[0002] In the field of mechanical manufacturing, the cylinder crankshaft hole as a key component of an engine directly affects the overall performance, service life and running stability of the engine. The traditional machining process for the cylinder crankshaft hole is horizontal machining, in which the axis of the crankshaft hole is in the horizontal direction. This machining method has many disadvantages, such as difficulty in ensuring machining precision, easy machining errors caused by gravity and other factors, uneven force on the tool during machining, rapid tool wear, increased production cost and tool changing frequency, and certain limitations in chip removal and cooling during horizontal machining, which affect machining efficiency and machining quality.

[0003] Therefore, it is necessary to provide a vertical machining process for a cylinder crankshaft hole in view of the above technical solutions. SUMMARY

[0004] In order to make up for the deficiencies of the prior art, the present application provides a vertical machining process for a cylinder crankshaft hole.

[0005] The technical scheme adopted by the present application to solve the technical problems is:

[0006] A vertical machining process for a cylinder crankshaft hole, comprising the following steps:

[0007] S1, positioning and clamping the cylinder through a special fixture, so that the axis of the crankshaft hole of the cylinder is in the vertical direction;

[0008] S2, selecting a special tool suitable for vertical machining and installing the tool on the spindle of a vertical machining center;

[0009] S3, setting machining parameters including spindle speed, feed speed and cutting depth through a numerical control system according to the size and precision requirements of the crankshaft hole;

[0010] S4, starting the vertical machining center, and the tool cuts and machines the cylinder crankshaft hole according to the preset motion track;

[0011] S5, during the machining process, cooling and lubricating the tool and the machining area through a cooling system, and collecting the chips by using a chip collecting device;

[0012] S6, after the machining is completed, detecting the size and surface quality of the cylinder crankshaft hole.

[0013] The special fixture in step S1 includes a positioning seat, a pressing device and a supporting block, the positioning seat is provided with a positioning surface matched with the profile of the bottom surface of the cylinder body, the supporting block is used for supporting the side surface of the cylinder body, and the pressing device is used for pressing the cylinder body on the positioning seat.

[0014] The special cutter in step S2 is a hard alloy boring cutter, and the cutting edge angle of the cutter is set according to the material of the cylinder body.

[0015] The spindle speed in step S3 is 800-2000 r / min, the feed speed is 50-200 mm / min, and the cutting depth is 0.5-3 mm.

[0016] The cooling system in step S5 adopts emulsion for cooling and lubrication, and the flow of the emulsion is 10-30 L / min.

[0017] In step S6, a three-coordinate measuring instrument is used to detect the dimensional accuracy of the crankshaft hole, and a surface roughness instrument is used to detect the surface quality.

[0018] The calculation of the speed of the hard alloy boring cutter can be calculated according to the cutting theory, and according to the basic theory of cutting, the calculation formula of the boring cutter speed is:

[0019] n = 10000V c / πd,

[0020] In the formula: n is the boring cutter speed, r / min; d is the cutter diameter, mm; Vc is the cutting speed, m / min.

[0021] The determination of the back engagement amount and the feed amount of the hard alloy boring cutter is based on the machining accuracy requirement of the crankshaft hole, and the reasonable cutting parameters of CBN cutter semi-finishing boring and finishing boring of gray cast iron are considered: when semi-finishing boring, the back engagement amount is 0.5-2 mm, and the feed amount is 1-5 mm / r; when finishing boring, the back engagement amount is 0.08-0.3 mm, and the feed amount is 0.04-2 mm / r; in order to make the surface roughness of the crankshaft hole after finishing boring reach the accuracy of 1.2 μm, the smaller feed amount and back engagement amount are selected, the semi-finishing boring feed amount f = 0.06 mm / r, and the back engagement amount ap = 0.5 mm; the finishing boring feed amount f = 0.06 mm / r, and the back engagement amount ap = 0.1 mm;

[0022] The calculation formula of the feed speed is V f = nf,

[0023] In the formula: Vf is the feed speed, mm / min; n is the spindle speed of the machine tool, r / min; f is the feed amount, mm / r.

[0024] The spindle in step S3 is provided with a feed stroke sensor, and the working process steps of the stroke sensor are as follows:

[0025] S1, signal acquisition and physical quantity conversion, analog signal and displacement conversion is adopted, and the linear calibration formula is: S=k x (V-V0)+S0

[0026] Where V is the output voltage of the sensor (V), V0 is the zero voltage (V), k is the sensitivity coefficient (mm / V or rad / V), and S0 is the initial displacement offset;

[0027] S2, signal processing and error filtering, moving average filtering, removing random noise, the formula is:

[0028]

[0029] Where is the filtered displacement value, S(t-i) is the i-th historical sampling value, and M is the window size;

[0030] S3, position calculation and dynamic characteristic analysis, speed and acceleration calculation (difference method)

[0031] The speed is

[0032] The acceleration

[0033] Where Δt is the sampling period;

[0034] Nonlinear error compensation, formula

[0035] Where S meas is the measured displacement, a i is the fitting coefficient; is the polynomial summation operator, indicating the accumulation of all terms from i=0 to i=n; a i is the polynomial fitting coefficient; S true is the compensated true value;

[0036] S4, closed-loop control, position closed-loop PID control is adopted, error calculation: e(t)=S target -S(t);

[0037] PID control output,

[0038]

[0039] Where u(t) is the control quantity (such as motor voltage, current), K p , K i , K d , respectively, are the proportional, integral, and derivative gain coefficients.

[0040] e(t) is the instantaneous error, is the integral of the error, indicating the error accumulation value from the initial time (t=0) to the current time (t), is the differential (rate of change) of the error, reflecting the speed of change of the error over time.

[0041] Advantages of the present application:

[0042] 1. High machining precision: By setting the crankshaft hole axis to the vertical direction, the influence of gravity and other factors on machining precision is reduced; the positioning and support of the special fixture ensure the stability of the cylinder body; reasonable machining parameter setting and closed-loop control of the feed stroke sensor further improve the machining dimensional accuracy and positional accuracy, so that the surface roughness of the crankshaft hole after fine boring can reach 1.2 μm.

[0043] 2. High machining efficiency: The use of hard alloy boring tools, combined with optimized cutting parameters, improves the cutting efficiency; effective cooling and lubrication of the cooling system reduces tool wear and tool changing time, thereby improving the overall machining efficiency.

[0044] 3. Long tool life: Suitable tool type selection, cutting parameter setting, and cooling and lubrication measures ensure that the tool is evenly stressed and has a lower temperature during machining, reducing tool wear and damage and prolonging tool life, thereby reducing production costs.

[0045] 4. Good operation convenience: The entire process steps are clear and explicit, and parameter setting and machining control are performed through the numerical control system, which is simple and easy to operate and facilitates automated production; cooling and lubrication and chip collection measures during machining ensure the stability of the machining environment, and strict detection after machining can timely detect unqualified products, thereby ensuring the quality stability of the cylinder crankshaft hole. BRIEF DESCRIPTION OF DRAWINGS

[0046] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description only constitute some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0047] Fig. 1 is the process principle diagram of the present application;

[0048] Fig. 2 is the relationship curve diagram of spindle speed and cutting line speed of the present application;

[0049] Fig. 3 is the relationship curve diagram of feed speed and spindle speed of the present application. DETAILED DESCRIPTION

[0050] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other in the case of no conflict.

[0051] The embodiments of the present application are described in detail below with reference to the drawings, but the present application can be implemented in various different ways limited and covered by the claims.

[0052] The embodiments of the present application are described in detail below with reference to the drawings, but the present application can be implemented in various different ways limited and covered by the claims. Figs. 1 to 3 The present application is further described in detail below with reference to the drawings,

[0053] A cylinder body crankshaft hole vertical machining process comprises the following steps:

[0054] S1, the cylinder body is positioned and clamped by a special fixture, so that the crankshaft hole axis of the cylinder body is in a vertical direction;

[0055] S2, a special tool suitable for vertical machining is installed on the spindle of the vertical machining center;

[0056] S3, according to the size and accuracy requirements of the crankshaft hole, the machining parameters are set through the numerical control system, including spindle speed, feed speed and cutting depth;

[0057] S4, start the vertical machining center, and the tool cuts the cylinder crankshaft hole according to the preset motion trajectory;

[0058] S5, during the machining process, the tool and the machining area are cooled and lubricated by the cooling system, and the cutting chips are collected by the cutting chip collecting device;

[0059] S6, after the machining is completed, the size and surface quality of the cylinder crankshaft hole are detected.

[0060] The special fixture in step S1 comprises a positioning seat, a pressing device and a supporting block, the positioning seat is provided with a positioning surface matched with the contour of the bottom surface of the cylinder body, the supporting block is used to support the side surface of the cylinder body, and the pressing device is used to press the cylinder body on the positioning seat.

[0061] The special tool in step S2 is a hard alloy boring tool, and the cutting edge angle of the tool is set according to the material of the cylinder body.

[0062] The spindle speed in step S3 is 800-2000r / min, the feed speed is 50-200mm / min, and the cutting depth is 0.5-3mm.

[0063] The cooling system in step S5 uses emulsion for cooling and lubrication, and the flow rate of the emulsion is 10-30L / min.

[0064] In step S6, the three-coordinate measuring instrument is used to detect the size and accuracy of the crankshaft hole, and the surface roughness instrument is used to detect the surface quality.

[0065] The calculation of the hard alloy boring tool rotation speed can be calculated according to the cutting theory. According to the basic theory of cutting, the calculation formula of the boring tool rotation speed is:

[0066] n = 1000V c / πd,

[0067] In the formula: n is the boring tool rotation speed, r / min; d is the tool diameter, mm; Vc is the cutting speed, m / min.

[0068] The determination of the hard alloy boring tool back engagement and the feed amount is based on the crankshaft hole machining precision requirement, and the reasonable cutting parameters of CBN tool semi-finishing boring and finishing boring gray cast iron are considered: when semi-finishing boring, the back engagement is 0.5-2mm, and the feed amount is 1-5mm / r; when finishing boring, the back engagement is 0.08-0.3mm, and the feed amount is 0.04-2mm / r. In order to make the surface roughness of the crankshaft hole after finishing boring reach 1.2μm precision, the smaller feed amount and back engagement are selected, the semi-finishing boring feed amount f=0.06mm / r, and the back engagement ap=0.5mm; the finishing boring feed amount f=0.06mm / r, and the back engagement ap=0.1mm;

[0069] The feed speed calculation formula is V f = nf,

[0070] In the formula: V f is the feed speed, mm / min; n is the spindle speed, r / min; f is the feed amount, mm / r.

[0071] The spindle in step S3 is provided with a feed stroke sensor, and the working process steps of the stroke sensor are:

[0072] S1, signal acquisition and physical quantity conversion, analog signal and displacement conversion are adopted, and the linear calibration formula is: S=k×(V-V0)+S0

[0073] In the formula: V is the sensor output voltage (V), V0 is the zero voltage (V), k is the sensitivity coefficient (mm / V or rad / V), and S0 is the initial displacement offset;

[0074] S2, signal processing and error filtering, moving average filtering, and removing random noise, the formula is:

[0075]

[0076] In the formula: is the filtered displacement value, S(t-i) is the historical i-th sampling value, and M is the window size;

[0077] S3, position calculation and dynamic characteristic analysis, speed and acceleration calculation (difference method)

[0078] Speed is

[0079] Acceleration

[0080] Where Δt is the sampling period;

[0081] Nonlinear error compensation, formula

[0082] Where S meas is the measured displacement, a i is the fitting coefficient; is the polynomial summation operator, indicating the accumulation of all terms from i=0 to i=n; a i polynomial fitting coefficient; S true is the compensated true value;

[0083] S4, closed-loop control, using position closed-loop PID control, error calculation: e(t)=S target -S(t);

[0084] PID control output,

[0085]

[0086] Where u(t) is the control quantity (such as motor voltage, current), K p ,K i ,K d , respectively, are the proportional, integral, and derivative gain coefficients.

[0087] e(t) is the instantaneous error, is the integral of the error, indicating the cumulative value of the error from the initial time (t=0) to the current time (t), is the differential (rate of change) of the error, reflecting the speed of change of the error with time.

[0088] The beneficial effects of the present application are:

[0089] 1. High machining precision: By setting the crankshaft hole axis to the vertical direction, the influence of gravity and other factors on machining precision is reduced; the positioning and support of the special fixture ensure the stability of the cylinder body; reasonable machining parameter setting and closed-loop control of the feed stroke sensor further improve the machining size precision and position precision, so that the surface roughness of the crankshaft hole after fine boring can reach 1.2 μm.

[0090] 2. High machining efficiency: The use of hard alloy boring tools, combined with optimized cutting parameters, improves the cutting efficiency; the effective cooling and lubrication of the cooling system reduces tool wear and tool changing time, thereby improving the overall machining efficiency.

[0091] 3. Long tool life: Appropriate tool type selection, cutting parameter settings, and cooling and lubrication measures ensure that the tool is subjected to uniform force and has a low temperature during machining, reducing tool wear and damage, extending tool life, and lowering production costs.

[0092] 4. Good ease of operation: The entire process is clear and well-defined. Parameter settings and machining control are performed through a CNC system, making operation simple and easy to automate. Cooling, lubrication, and chip collection measures during the machining process ensure a stable machining environment. Strict inspection after machining can promptly detect defective products, ensuring the quality stability of the cylinder block crankshaft bore.

[0093] Example 1:

[0094] The vertical machining process for the crankshaft bore of a certain type of engine block is described in this invention. The specific steps are as follows:

[0095] Positioning and clamping: Select a positioning seat that matches the bottom contour of the cylinder block, place the cylinder block on the positioning seat, support the side of the cylinder block with the support block, and start the clamping device to clamp the cylinder block so that the crankshaft hole axis of the cylinder block is in the vertical direction.

[0096] Tool Installation: Based on the cylinder block material being gray cast iron, a carbide boring bar is selected. The cutting edge angles are set to a rake angle of 10° and a clearance angle of 8°, and it is mounted on the spindle of a vertical machining center. Machining Parameter Settings: The crankshaft bore diameter is 80mm, and the cutting speed Vc is selected as 150m / min, calculated according to the boring bar speed calculation formula. The spindle speed can be obtained The spindle speed is selected as 600 r / min. The semi-finish boring feed rate f = 0.06 mm / r, calculated according to the feed rate formula V. f =n×f, which gives the semi-finishing feed rate V. f =600×0.06=36mm / min, select a feed rate of 50mm / min; semi-finish boring depth of cut a p =0.5mm, fine boring feed rate f = 0.06mm / r, fine boring feed speed V f =600×0.06=36mm / min, select a feed rate of 50mm / min; depth of cut for fine boring a p =0.1mm; simultaneously, set the relevant parameters of the spindle feed stroke sensor: zero-position voltage V0 = 1V, sensitivity coefficient k = 2mm / V, initial displacement offset S0 = 0mm, window size N = 5, sampling period T = 0.01s, polynomial fitting coefficients determined according to calibration, and proportional gain coefficient K. p =5, Integral gain coefficient K i =0.1, differential gain coefficient K d= 0.5.

[0097] Cutting: Start the vertical machining center, the tool according to the preset motion trajectory first semi-precision boring, and then precision boring.

[0098] Cooling and lubrication and chip collection: The cooling system uses emulsion for cooling and lubrication, and the emulsion flow is set to 20 L / min. At the same time, the chip collection device is turned on to collect the chips.

[0099] Quality detection: After processing, the three-coordinate measuring instrument is used to detect the size accuracy of the crankshaft hole, and the diameter error is controlled within ±0.01 mm; the surface roughness instrument is used to detect the surface quality, and the surface roughness reaches 1.0 μm, meeting the design requirements.

[0100] Example 2:

[0101] For the machining of the crankshaft hole of an aluminum alloy cylinder block of a heavy-duty engine, the following process is applied: Positioning and clamping: Use a positioning seat with a special positioning contour for aluminum alloy cylinder blocks. Support the cylinder block side protruding part with three evenly distributed support blocks. Start the pneumatic pressing device to press and fix the cylinder block from the top, ensuring that the crankshaft hole axis is vertical.

[0102] Tool installation: Select an ultra-fine grain carbide boring tool. Set the cutting edge rake angle to 12° and the relief angle to 10° for aluminum alloy materials. Perform passivation treatment (0.02 mm roundness) on the cutting edge. Install it in the main shaft taper hole and fix it through tension test.

[0103] Processing parameter setting: The diameter of the crankshaft hole is 60 mm. The cutting line speed Vc is selected as 200 m / min. The main shaft speed is calculated according to the formula f = 1000 r / min. The semi-precision boring feed amount f is 0.06 mm / r, and the feed speed V p = 600 × 0.06 = 36 mm / min. The semi-precision boring back engagement amount a f = 0.5 mm. The precision boring feed amount f is 0.06 mm / r, and the feed speed V p = 600 × 0.06 = 36 mm / min. The precision boring back engagement amount a p = 0.1 mm. Sensor parameter setting: zero voltage V0 = 0.5 V, sensitivity coefficient k = 3 mm / V, window size N = 8, sampling period T = 0.005 s, PID parameters K i = 6, K d = 0.08, K = 0.6.

[0104] Cutting: The vertical machining center performs a three-stage cutting path of rough boring (with a reserved 0.6 mm machining allowance), semi-precision boring, and finally precision boring. After each stage of processing, the tool position is automatically calibrated.

[0105] Cooling lubrication and chip collection: low concentration emulsion (concentration 5%) cooling is adopted, the flow rate is set to 25 L / min, the cutting area is cooled all-round through annular nozzles, and helical chip collection device is operated synchronously.

[0106] Quality detection: three-coordinate measurement shows that the diameter error of the crankshaft hole is ±0.015 mm, and the cylindricity is 0.008 mm; the detection result of the surface roughness instrument is 0.8 μm, which meets the high-precision requirement of the aluminum alloy cylinder body.

[0107] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application.

Claims

1. A vertical machining process for cylinder block crankshaft bores, characterized in that: Includes the following steps: S1. Position and clamp the cylinder block using a special fixture so that the crankshaft hole axis of the cylinder block is in the vertical direction; S2. Select a special tool suitable for vertical machining and install it on the spindle of the vertical machining center; S3. Based on the size and precision requirements of the crankshaft bore, set the machining parameters through the CNC system, including spindle speed, feed rate, and depth of cut; S4. Start the vertical machining center, and the tool will cut the crankshaft hole of the cylinder block according to the preset motion trajectory; S5. During the machining process, the cutting tool and machining area are cooled and lubricated by the cooling system, and the chips are collected by the chip collection device. S6. After machining, the dimensions and surface quality of the crankshaft bore in the cylinder block are inspected.

2. The vertical machining process for cylinder block crankshaft bores as described in claim 1, characterized in that: The special fixture mentioned in step S1 includes a positioning seat, a clamping device, and a support block. The positioning seat has a positioning surface that matches the contour of the bottom surface of the cylinder. The support block is used to support the side of the cylinder. The clamping device is used to press the cylinder onto the positioning seat.

3. The vertical machining process for cylinder block crankshaft bores as described in claim 1, characterized in that: The special tool mentioned in step S2 is a carbide boring tool, and the cutting edge angle of the tool is set according to the cylinder material.

4. The vertical machining process for cylinder block crankshaft bores as described in claim 1, characterized in that: In step S3, the spindle speed is 800-2000 r / min, the feed rate is 50-200 mm / min, and the depth of cut is 0.5-3 mm.

5. The vertical machining process for cylinder block crankshaft bores as described in claim 1, characterized in that: The cooling system described in step S5 uses an emulsion for cooling and lubrication, with a flow rate of 10-30 L / min.

6. The vertical machining process for cylinder block crankshaft bores as described in claim 1, characterized in that: In step S6, a coordinate measuring machine is used to check the dimensional accuracy of the crankshaft hole, and a surface roughness tester is used to check the surface quality.

7. The vertical machining process for the crankshaft bore of a cylinder block as described in claim 3, characterized in that: The speed of the carbide boring bar can be calculated based on cutting theory. According to basic cutting theory, the formula for calculating the boring bar speed is: n=1000V c / πd, In the formula: n is the boring bar rotation speed, r / min; d is the tool diameter, mm; Vc is the cutting linear velocity, m / min.

8. The vertical machining process for cylinder block crankshaft bores as described in claim 3, characterized in that: The determination of the depth of cut and feed rate of the carbide boring tool is based on the machining accuracy requirements of the crankshaft hole, while also considering the reasonable cutting parameters of CBN tools for semi-finish boring and finish boring of gray cast iron: for semi-finish boring, a depth of cut of 0.5-2 mm and a feed rate of 1-5 mm / r; for finish boring, a depth of cut of 0.08-0.3 mm and a feed rate of 0.04-2 mm / r. To achieve a surface roughness of 1.2 μm for the crankshaft hole after finish boring, a smaller feed rate and depth of cut are selected. For semi-finish boring, the feed rate f = 0.06 mm / r, and the depth of cut a... p =0.5mm; fine boring feed f = 0.06mm / r, depth of cut a p =0.1mm; The formula for calculating the feed rate is V. f =n f , In the formula: V f n is the feed rate, mm / min; n is the machine tool spindle speed, r / min; f is the feed rate, mm / r.

9. The vertical machining process for cylinder block crankshaft bores as described in claim 1, characterized in that: In step S3, the spindle is equipped with a feed stroke sensor, and the working steps of the stroke sensor are as follows: S1. Signal acquisition and physical quantity conversion: Analog signal and displacement conversion are used, and the linear calibration formula is: S=k×(V-V0)+S0 Where V is the sensor output voltage, V0 is the zero-position voltage, k is the sensitivity coefficient, and S0 is the initial displacement offset; S2. Signal processing and error filtering, moving average filtering, removing random noise, the formula is: in S(ti) represents the filtered displacement value, S(ti) represents the i-th historical sample value, and M represents the window size. S3. Position calculation and dynamic characteristic analysis, velocity and acceleration calculation. acceleration Where Δt is the sampling period; Nonlinear error compensation, formula Where S meas To measure displacement, a i These are the fitting coefficients; Let a be a polynomial summation operator, representing the summation of all terms from i = 0 to i = n; i Polynomial fitting coefficients; S true The actual value after compensation; S4. Closed-loop control, using position closed-loop PID control, error calculation: e(t)=S target -S(t); PID control output, 10. The vertical machining process for cylinder block crankshaft bores as described in claim 9, characterized in that: Where u(t) is the control variable, K p K i K d , which are the proportional, integral, and differential gain coefficients, respectively; e(t) is the instantaneous error. Let be the integral of the error, representing the cumulative error from the initial time (t=0) to the current time (t). It is the derivative of the error, reflecting the rate at which the error changes over time.

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