CN112100827A - A Power Consumption Modeling Method for Machine Tool Milling Process Considering Tool Wear - Google Patents

Abstract

The invention relates to a power consumption modeling method in the milling process of a machine tool considering tool wear, more specifically, a milling force wear coefficient related to wear is introduced, a milling force model is revised, and the revised milling force considering tool wear is obtained. The model calculates the cutting power, thereby establishing a power consumption model for the milling process of the machine tool considering tool wear, which greatly improves the prediction accuracy of the power consumption model.

Description

A Power Consumption Modeling Method for Machine Tool Milling Process Considering Tool Wear

technical field

The invention belongs to the field of mechanical processing, and relates to a power consumption modeling method for a milling process of a machine tool considering tool wear.

Background technique

Machinery manufacturing is an important pillar industry of my country's national economy. At present, my country's machinery manufacturing industry generally has problems such as high energy consumption and low efficiency. As the main energy consumption of the machinery manufacturing industry, CNC machine tools have many energy sources, complex energy consumption characteristics and energy consumption processes, and have a large space for energy saving optimization. The tool is the key component and main consumable in the machining process. Therefore, the study of tool wear is of great significance to prolong the service life of the tool and reduce the energy consumption of the machine tool.

The document "Wang Q, Zhang D, Tang K, et al. Energy consumption model for milling processes considering auxiliary load loss and its applications[J]. The International Journal of Advanced Manufacturing Technology, 2019, 105(10): 4309-4323." proposed A modeling method of power consumption model of machine tool milling process based on milling force is proposed. This method uses milling cutting force to calculate cutting power, so as to predict the total energy consumption of machine tool milling process, but does not consider the effect of tool wear on machine tool power consumption. Therefore, it is difficult to accurately predict the power consumption of machine tools in actual machining.

SUMMARY OF THE INVENTION

The technical problem solved by the invention is: in order to overcome the problem of poor prediction accuracy of the energy consumption model modeling method of the existing machine tool milling process, the invention provides a power consumption modeling method for the machine tool milling process considering tool wear, more specifically It is said that the milling force wear coefficient related to tool wear is introduced, the milling force model is revised, and the cutting power is calculated through the revised milling force model, so as to establish a power consumption model for the milling process of the machine tool considering tool wear, which greatly improves the power consumption. prediction accuracy of the consumption model. The method first introduces the milling force wear coefficient related to tool wear, corrects the milling force model, calculates the cutting power through the revised milling force model considering tool wear, and then establishes the air-cut power consumption model in machine tool processing and the accompanying cutting power consumption model. Finally, the total power consumption model of the machine tool considering tool wear is established.

The technical scheme of the present invention is: a power consumption modeling method for a machine tool milling process considering tool wear, which is characterized in that it includes the following steps:

Step 1. Reference the traditional milling force model, and the model does not consider tool wear;

dF _t (ψ, z)=K _te dS+K _tc S _t sinψdz

dF _r (ψ, z)=K _re dS+K _rc S _t sinψdz

dF _a (ψ, z)=K _ae dS+K _ac S _t sinψdz

Among them, dF _t , dF _r , and dF _a are the tangential, radial and axial cutting forces acting on the height dz element respectively, K _te , K _re , and _Kae represent the tool edge force coefficient, K _tc , K _rc , K _ac represents the tool cutting force coefficient, dS represents the length of the cutting edge element, dz represents the axial depth of cut element length, S _t represents the feed per tooth, and ψ represents the radial immersion angle of the cutting edge element;

Step 2: Introduce wear-related milling force wear coefficients ΔK _tw , ΔK _rw , and obtain a milling force model considering tool wear:

是考虑刀具磨损后作用在高度dz微元上的切向，径向切削力；in

It is the tangential and radial cutting force acting on the height dz element after tool wear is considered;

Step 3. Divide the power consumption of the machine tool milling process into air cutting power consumption, cutting power consumption and additional load auxiliary power consumption accompanying cutting, and model and predict the three types of power consumption respectively, so as to calculate and predict the considering tool power consumption. The total energy consumption of the milling process of the worn machine tool; its prediction model is:

P _total =P _aircutting +P _cutting +P _add

Among them, P _total represents the total power consumption of the milling process, P _aircutting represents the air cutting power consumption during the milling process, P _cutting represents the cutting power consumption during the milling process, and P _add represents the cutting power consumption during the milling process. Additional load auxiliary energy consumption;

Step 4. Establish a cutting power consumption model considering tool wear during the milling process of the machine tool:

Among them, r is the tool radius, n is the spindle speed of the machine tool, f is the feed rate, and P _cutting ^w is the cutting power considering the tool wear;

Then the cutting power consumption model of milling is:

为平均切削功耗，

N为刀具齿数in

is the average cutting power consumption,

N is the number of tool teeth

Step 5. Establish an air-cutting power consumption model of the machine tool milling process: measure the air-cutting power consumption of the machine tool at different speeds in a non-cutting state, fit the obtained data, and establish an air-cutting power consumption model:

P _aircutting = f(n)

Among them, n is the spindle speed of the machine tool, and f(n) is expressed as a one-dimensional quadratic function of n;

Step 6. Establish an additional load power consumption model for milling:

According to the data study fitting, it is shown that:

where C ₀ and C ₁ are coefficients obtained from experiments;

Step 7. The power consumption model of the machine tool milling process considering tool wear is:

Invention effect

The technical effect of the present invention is:

1. Firstly, the milling force wear coefficients ΔK _tw and ΔK _rw related to tool wear are introduced, and the milling force model considering tool wear is established, and then the air cutting power consumption model in machine tool processing and the auxiliary power consumption model accompanying cutting are established. Finally, a model of the total power consumption of the machine tool considering tool wear is established. Compared with the energy consumption model that does not consider tool wear in the background art, the prediction accuracy of the power consumption model of the machine tool milling process of the present invention considering tool wear is higher than the actual machining fit. The more serious the tool wear, the better the prediction accuracy of the present invention higher.

2. The present invention considers the unavoidable tool wear factor in actual machining into the power consumption model of machine tool milling, which has a higher degree of fit with actual machining and has high application value to actual mechanical production.

3. The method of the present invention can also be used for monitoring tool wear in the actual production process, etc., and has broad application prospects.

Detailed ways

The technical scheme adopted by the patent of the present invention to solve the above-mentioned technical problems is: a power consumption modeling method for the milling process of a machine tool considering tool wear, which is characterized by comprising the following steps:

Step 1. Refer to the traditional milling force model that does not consider tool wear:

Among them, K _te , K _re , and _Kae represent the tool edge force coefficient, K _tc , K _rc , K _ac represent the tool cutting force coefficient, dS represents the length of the cutting edge element, dz represents the axial depth of cut element length, and S _t represents the feed per tooth, and ψ represents the radial immersion angle of the cutting edge element.

Step 2: Introduce the wear coefficients ΔK _tw and ΔK _rw of the milling force related to wear, and establish the milling force model:

dF _rw =σ·VB·dS=Eδh·VB·dS=ΔK _rw ·dS (2)

dF _tw =μ(dF _rw )=μ(Eδh·VB)dS=ΔK _tw ·dS (3)

where σ is the springback surface contact stress, E is the elastic modulus, d is the material springback, and h is the thickness of the cutting layer.

The milling force model considering tool wear can be obtained:

which is

It can be seen that both ΔK _rw and ΔK _rw are related to the flank wear amount VB.

Step 3. Divide the power consumption of the machine tool milling process into air cutting power consumption, cutting power consumption and additional load auxiliary power consumption accompanying cutting, and model and predict the three types of power consumption respectively, so as to calculate and predict the considering tool power consumption. The total energy consumption of the milling process of the worn machine tool; its prediction model is:

P _total =P _aircutting +P _cutting +P _add (8)

Among them, P _total represents the total power consumption of the milling process, P _aircutting represents the air cutting power consumption during the milling process, P _cutting represents the cutting power consumption during the milling process, and P _add represents the cutting power consumption during the milling process. Additional load auxiliary energy consumption.

Step 4. Establish a cutting power consumption model considering tool wear during the milling process of the machine tool:

which is

Among them, r is the tool radius, n is the spindle speed of the machine tool, and f is the feed rate.

Then the cutting power consumption model of milling is:

为平均切削能耗，

N为刀具齿数in

is the average cutting energy consumption,

N is the number of tool teeth

Step 5. Establish an air-cut power consumption model of the machine tool milling process: measure the air-cut power consumption of the machine tool at different speeds in a non-cutting state, and fit the obtained data. Create an air-cut power model:

P _aircutting = f(n) (12)

where n is the spindle speed of the machine tool.

Step 6. Establish an additional load power consumption model for milling:

According to the data study fitting, it is shown that:

where C ₀ is the coefficient obtained from the experiment.

Step 7: Establish the power consumption model of the machine tool milling process considering tool wear:

This embodiment takes milling and grooving as an example, the material is superalloy GH4169; the tool diameter is a flat-bottomed end mill with a diameter of 10mm, the rotational speed is 400rpm, and the feed per tooth is 0.03mm/r and 0.04mm/r. Using VMC-850 CNC machining center for processing.

The specific steps of the power consumption model modeling method of the machine tool milling process considering tool wear in the present invention are as follows:

Step 1. Refer to the traditional milling force model that does not consider tool wear:

Among them, K _te , K _re , and _Kae represent the tool edge force coefficient, K _tc , K _rc , K _ac represent the tool cutting force coefficient, dS represents the length of the cutting edge element, dz represents the axial depth of cut element length, and S _t represents the feed per tooth, and ψ represents the radial immersion angle of the cutting edge element.

Step 2: Introduce the wear coefficients ΔK _tw and ΔK _rw of the milling force related to wear, and establish the milling force model:

dF _rw =σ·VB·dS=Eδh·VB·dS=ΔK _rw ·dS (2)

dF _tw =μ(dF _rw )=μ(Eδh·VB)dS=ΔK _tw ·dS (3)

where σ is the springback surface contact stress, E is the elastic modulus, d is the material springback, and h is the thickness of the cutting layer.

The milling force model considering tool wear can be obtained:

which is

It can be seen that both ΔK _rw and ΔK _rw are related to the flank wear amount VB.

Step 3. Divide the power consumption of the machine tool milling process into air cutting power consumption, cutting power consumption and additional load auxiliary power consumption accompanying cutting, and model and predict the three types of power consumption respectively, so as to calculate and predict the considering tool power consumption. The total energy consumption of the milling process of the worn machine tool; its prediction model is:

P _total =P _aircutting +P _cutting +P _add (8)

Among them, P _total represents the total power consumption of the milling process, P _aircutting represents the air cutting power consumption during the milling process, P _cutting represents the cutting power consumption during the milling process, and P _add represents the cutting power consumption during the milling process. Additional load auxiliary energy consumption.

Step 4. Establish a cutting power consumption model considering tool wear during the milling process of the machine tool:

which is

Among them, r is the tool radius, n is the spindle speed of the machine tool, and f is the feed rate.

Then the cutting power consumption model of milling is:

为平均切削能耗，

N为刀具齿数in

is the average cutting energy consumption,

N is the number of tool teeth

Step 5. Establish an air-cut power consumption model of the machine tool milling process: measure the air-cut power consumption of the machine tool at different speeds in a non-cutting state, and fit the obtained data. Create an air-cut power model:

P _aircutting = f(n) (12)

where n is the spindle speed of the machine tool.

Step 6. Establish an additional load auxiliary power consumption model for milling processing:

According to the data study fitting, it is shown that:

where C ₀ is the coefficient obtained from the experiment.

Step 7: Establish the power consumption model of the machine tool milling process considering tool wear:

Application example. Slotting superalloy GH4165 material on VMC-850 CNC machining center This example takes milling slotting as an example, a flat-bottom end mill with a tool diameter of 10mm, a rotating speed of 400rpm, and a feed per tooth of 0.03mm/ r, 0.04mm/r, the above method is used to verify the milling process.

(1) Quoting the traditional milling force model that does not consider tool wear:

According to step 1, the traditional milling force modeling without considering tool wear is carried out. The cutting force model is:

dF _t (ψ, z)=K _te dS+K _tc S _t sinψdz

dF _r (ψ, z)=K _re dS+K _rc S _t sinψdz

dF _a (ψ, z)=K _ae dS+K _ac S _t sinψdz

According to the data obtained from the groove milling experiment, K _te =73.08, K _re =106.47, K _tc =4169.1, and K _rc =1074.9.

(2) Establish a milling force model considering tool wear:

ΔK _tw =0.6929VB-35.338 and ΔK _rw =0.8272VB+1.5063 are obtained by calibration according to the experimental data.

(3) Establish a cutting power consumption model considering tool wear in the milling process of the machine tool:

According to the cutting force model, the instantaneous cutting energy consumption model of milling is calculated as

Among them, r is the tool radius, n is the spindle speed of the machine tool, and f is the feed rate.

(4) Establish the air-cut power consumption model of the milling process of the machine tool:

Establish an air-cutting power consumption model according to step 5, measure the power at different speeds in the non-cutting state of the machine tool, and fit and calculate the air-cutting power consumption model:

P _aircutting = 0.00004x ² +0.0656x+873.26

(5) Establish an additional load-assisted power consumption model for milling:

According to step 6, the auxiliary power consumption model of extra load for milling processing is established. The calculated extra load power consumption model is:

(6) Establish a total power consumption prediction model:

Compared with the power consumption model that does not consider tool wear, the prediction accuracy is significantly improved when the tool wear is large.

Table 1 Comparison of power consumption errors under different processing parameters

Claims (1)

1. The power consumption modeling method of the machine tool milling process considering tool wear, is characterized in that, comprises the following steps: Step 1. Reference the traditional milling force model, and the model does not consider tool wear; dF _t (ψ, z)=K _te dS+K _tc S _t sinψdz dF _r (ψ, z)=K _re dS+K _rc S _t sinψdz dF _a (ψ, z)=K _ae dS+K _ac S _t sinψdz Among them, dF _t , dF _r , and dF _a are the tangential, radial and axial cutting forces acting on the height dz element respectively, K _te , K _re , and _Kae represent the tool edge force coefficient, K _tc , K _rc , K _ac represents the tool cutting force coefficient, dS represents the length of the cutting edge element, dz represents the axial depth of cut element length, S _t represents the feed per tooth, and ψ represents the radial immersion angle of the cutting edge element; Step 2: Introduce wear-related milling force wear coefficients ΔK _tw , ΔK _rw , and obtain a milling force model considering tool wear:

in

It is the tangential and radial cutting force acting on the height dz element after tool wear is considered; Step 3. Divide the power consumption of the machine tool milling process into air cutting power consumption, cutting power consumption and additional load auxiliary power consumption accompanying cutting, and model and predict the three types of power consumption respectively, so as to calculate and predict the considering tool power consumption. The total energy consumption of the milling process of the worn machine tool; its prediction model is: P _total =P _aircutting +P _cutting +P _add Among them, P _total represents the total power consumption of the milling process, P _aircutting represents the air cutting power consumption during the milling process, P _cutting represents the cutting power consumption during the milling process, and P _add represents the cutting power consumption during the milling process. Additional load auxiliary energy consumption; Step 4. Establish a cutting power consumption model considering tool wear during the milling process of the machine tool:

Among them, r is the tool radius, n is the spindle speed of the machine tool, f is the feed rate, and P _cutting ^w is the cutting power considering the tool wear; Then the cutting power consumption model of milling is:

in

is the average cutting power consumption,

N is the number of tool teeth Step 5. Establish an air-cutting power consumption model of the machine tool milling process: measure the air-cutting power consumption of the machine tool at different speeds in a non-cutting state, fit the obtained data, and establish an air-cutting power consumption model: P _aircutting = f(n) Among them, n is the spindle speed of the machine tool, and f(n) is expressed as a one-dimensional quadratic function of n; Step 6. Establish an additional load power consumption model for milling: According to the data study fitting, it is shown that:

where C ₀ and C ₁ are coefficients obtained from experiments; Step 7. The power consumption model of the machine tool milling process considering tool wear is: