Positioning drilling and machining method suitable for cylinder cover

Abstract

The invention relates to the technical field of cutting tool positioning drilling, in particular to a positioning drilling and machining method suitable for an air cylinder cover, and the method comprises the steps that the feeding size of a cutting tool in each drilling process of the air cylinder cover and the radial pressure of the cutting tool at all collection moments are collected, and a jitter pressure vector is formed; performing modal decomposition on the radial pressure of the cutting knife at all the acquisition moments to obtain a high-frequency decomposition signal and a low-frequency decomposition signal; determining an overall energy ratio based on the difference of the local energy ratios of the high-frequency decomposition signal and the low-frequency decomposition signal at each acquisition moment; and a feeding adjustment coefficient is determined in combination with a preset energy ratio, feeding during drilling this time is adjusted, and adjustment feeding during drilling next time is obtained. According to the invention, the feeding performance is matched with the performance of the cutter, the shaking of the cutter in the cutting process is reduced, and the drilling quality of the cylinder cover is improved.

Description

Technical Field

[0001] This application relates to the field of cutting tool positioning drilling technology, specifically to positioning drilling and machining methods applicable to cylinder heads. Background Technology

[0002] The cylinder head is an important component of an internal combustion engine. During its manufacturing process, positioning holes are required. The inner walls of these holes need to be smooth to reduce mechanical wear at the valves and improve the durability of the cylinder head.

[0003] Cylinder heads are typically drilled using CNC machine tools. The drilling process requires controlling the rotation and advance of the cutting tool to complete the drilling of the inner wall. During drilling, it is necessary to control the cutting tool to maintain an appropriate feed rate. An appropriate feed rate can improve drilling efficiency while avoiding rough hole walls, thus improving the quality of the cylinder head.

[0004] Existing methods for drilling cylinder heads often use a fixed feed rate to control the cutting tool, without considering the changes in cutting tool performance caused by heat and wear during drilling. As the cutting tool's performance changes due to wear and other factors during use, a mismatch between the feed rate and the cutting tool's performance can occur, resulting in a rough cylinder head bore wall and a decrease in cylinder head quality. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides a positioning drilling and machining method suitable for cylinder heads, thereby resolving the existing issues.

[0006] The positioning drilling and machining method applicable to cylinder heads in this application adopts the following technical solution: One embodiment of this application provides a positioning drilling and machining method for cylinder heads, the method comprising the following steps: A1, collects the feed size of the cutting tool during each drilling process of the cylinder head, and the radial pressure of the cutting tool at all collection moments, forming a jitter pressure vector; A2, perform mode decomposition on the jitter pressure vector to obtain high-frequency decomposition signals and low-frequency decomposition signals; based on the local energy ratio of the high-frequency decomposition signals and low-frequency decomposition signals at each acquisition time, determine the high-frequency vibration energy and low-frequency vibration energy at each acquisition time respectively. A3. Based on the difference between high-frequency vibration energy and low-frequency vibration energy, determine the high-frequency and low-frequency energy ratio at each acquisition moment; based on the difference between the sum of high-frequency and low-frequency vibration energy at each acquisition moment and the cumulative sum at all acquisition moments, determine the energy weight at each acquisition moment; combine the energy weights at all acquisition moments and the high-frequency and low-frequency energy ratio to determine the overall energy ratio. A4. Based on the difference between the overall energy ratio and the preset energy ratio, determine the feed adjustment coefficient; use the feed adjustment coefficient to weight the feed during this drilling to obtain the adjusted feed for the next drilling.

[0007] Preferably, the high-frequency decomposition signal is the IMF decomposition signal after modal decomposition of the jitter pressure vector; the low-frequency decomposition signal is the residual signal after modal decomposition of the jitter pressure vector.

[0008] Preferably, both the high-frequency decomposition signal and the low-frequency decomposition signal are denoted as decomposition signals, and both the high-frequency vibration energy and the low-frequency vibration energy are denoted as vibration energy. The method for determining the vibration energy includes: Obtain the spectrum of the decomposed signal; normalize the amplitude of all signal energy values ​​in the spectrum, and then perform a weighted summation on the corresponding frequencies to obtain the signal frequency; Use the reciprocal of the signal frequency as the signal period to set the window; The average absolute value of all element values ​​within a window at each acquisition time in the decomposed signal is taken as the vibrational energy at each acquisition time.

[0009] Preferably, the high-frequency energy ratio is the ratio of high-frequency vibration energy to low-frequency vibration energy.

[0010] Preferably, the energy weight is determined by the ratio of the sum to the accumulated sum.

[0011] Preferably, the method for determining the overall energy ratio is as follows: using energy weights as weights, the result of weighted summation of the high and low frequency energy ratios at the corresponding acquisition time.

[0012] Preferably, the method for determining the feed adjustment coefficient is as follows: In the formula, It is the feed adjustment factor for the next drilling operation. It is the overall energy ratio during this drilling, and S is the preset energy ratio.

[0013] Preferably, the preset energy ratio is the overall energy ratio calculated when the cutting tool drills a hole for the first time.

[0014] Preferably, the method for obtaining the adjusted feed during the next drilling operation is as follows: In the formula, Fn is the adjusted feed for the next drilling, Fe is the feed for the current drilling, and R is the preset maximum adjustment amount.

[0015] Preferably, after obtaining the adjusted feed, the feed of the cutting tool is controlled by the adjusted feed during the next drilling process.

[0016] This application has at least the following beneficial effects: This embodiment addresses the problem of increased cutting tool vibration and decreased cylinder head drilling quality due to a mismatch between preset feed and cutting tool performance caused by cutting tool wear. It proposes a positioning drilling and machining method suitable for cylinder heads, including: obtaining cutting tool vibration information by detecting the radial pressure of the cutting tool, denoted as a vibration pressure vector; decomposing the vibration pressure vector to obtain high-frequency and low-frequency decomposed signals, calculating the local energy proportions for each signal, and obtaining the high-frequency and low-frequency vibration energy at the corresponding time points; and then using... The high-frequency / low-frequency energy ratio characterizes whether the cutting tool vibration at different times is mainly caused by excessively high or low feed rates. Furthermore, the high-frequency / low-frequency energy ratios at corresponding acquisition times are weighted according to energy weights throughout the drilling process. The weighted sum of these ratios yields the overall energy ratio, which characterizes whether the vibration during the drilling process is primarily caused by excessively high or low feed rates. Then, the cutting tool vibration data from the initial cutting tool replacement is used as the preset energy ratio. The feed rate is adjusted based on this overall energy ratio to maintain the cutting tool vibration at an optimal level. This application analyzes the relationship between cutting tool wear and vibration characteristics using vibration data, thereby monitoring the vibration in real time and adjusting the feed rate to reduce cutting tool vibration during drilling. Compared to the fixed cutting tool feed in traditional drilling methods, this approach matches the feed rate to the cutting tool performance when its performance changes due to wear, reducing vibration during the cutting process and improving the drilling quality of the cylinder head. Attached Figure Description

[0017] To more clearly illustrate the technical solutions and advantages in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A flowchart illustrating a positioning drilling and machining method for a cylinder head, as provided in one embodiment of this application; Figure 2 This is a flowchart illustrating the cutting tool feed adjustment parameters according to one embodiment of this application. Detailed Implementation

[0019] To further illustrate the technical means and effects adopted by this application to achieve the intended inventive purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of the positioning drilling and processing method for cylinder heads proposed in this application. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0021] The following description, in conjunction with the accompanying drawings, details the specific scheme of the positioning drilling and machining method for cylinder heads provided in this application.

[0022] One embodiment of this application provides a positioning drilling and machining method for cylinder heads.

[0023] Specifically, the following positioning drilling and machining methods for cylinder heads are provided; please refer to [link / reference]. Figure 1 The method includes the following steps: A1 collects the feed rate of the cutting tool during each drilling process of the cylinder head, as well as the radial pressure of the cutting tool at all acquisition moments, forming a jitter pressure vector.

[0024] Drilling on CNC machine tools is usually controlled based on preset cutting tool control parameters, including the feed of the cutting tool. In this embodiment, the feed rate is controlled by adjusting the feed rate, thereby reducing the roughness of the drilled hole wall caused by the mismatch between the feed rate and the performance of the cutting tool.

[0025] It should be noted that feed refers to the distance the cutting tool travels per revolution during the cutting process. In this embodiment, the feed changes with the wear of the cutting tool to adapt to the changes in cutting tool performance caused by wear.

[0026] After a drilling operation is completed, this embodiment obtains the feed value Fe during the drilling process; simultaneously, the monitoring data generated during the cutting process is obtained through the CNC machine tool's control system, including: The CNC machine tool control system acquires cutting tool vibration information via pressure sensors. This data is stored as a vector of length N, denoted as the vibration pressure vector. The nth element of the vector represents the radial pressure of the cutting tool at time n, measured in Pascals. Since the radial pressure of the cutting tool is generated by the mutual compression between the cutting tool and the drilling surface, fluctuations in the vibration pressure vector represent cutting tool vibration.

[0027] Finally, in this embodiment, after the drilling is completed, a jitter pressure vector of length N and a feed size Fe are obtained through the CNC machine tool control system, with the feed unit being millimeters per revolution. The length of the jitter pressure vector is the duration of one drilling operation, influenced by the feed size rather than being a constant. In this embodiment, N is set to 100000, the pressure sensor sampling frequency is F = 100000 Hz, and both the drilling time and sampling time are 1 second.

[0028] Meanwhile, in this embodiment, the feed range is set to 0.1 mm per revolution to 0.2 mm per revolution.

[0029] A2 performs mode decomposition on the jitter pressure vector to obtain high-frequency decomposition signals and low-frequency decomposition signals; based on the local energy ratio of the high-frequency decomposition signals and low-frequency decomposition signals at each acquisition time, the high-frequency vibration energy and low-frequency vibration energy at each acquisition time are determined respectively.

[0030] The main purpose of cutting tool feed control is to reduce the vibration of the cutting tool during the drilling process and reduce the roughness of the cylinder head borehole.

[0031] The collision between the cutting tool and the cylinder head when the cutting tool passes through the cutting bore can be divided into two types: One type is the collision of the cutting tool when cutting the cylinder head material. The frequency of the vibration caused by this collision is related to the rotational speed of the cutting tool. Its vibration frequency is low, ranging from tens of hertz to hundreds of hertz. Generally, the larger the feed of the cutting tool, the greater the cutting intensity of the cutting tool on the cylinder head, and thus the larger the amplitude of this low-frequency vibration, resulting in an increase in the energy proportion of low-frequency vibration in the vibration pressure vector. One type is the collision caused by the extrusion and friction between the cutting tool and the cylinder head material. The frequency of the vibration caused by this extrusion is related to the natural frequency of the material used in the cutting tool. The material used in the cutting tool is generally a cobalt alloy, which has a high natural frequency, usually above 1 kilohertz. Generally, the smaller the feed of the cutting tool, the larger the continuous extrusion and friction area between the cutting tool and the cylinder head material, and thus the larger the amplitude of this high-frequency vibration, resulting in an increase in the proportion of high-frequency vibration energy in the vibration pressure vector.

[0032] Therefore, in the jitter pressure vector, the low-frequency component of the signal is caused by a higher feed rate, while the high-frequency component is caused by a lower feed rate. Accordingly, this embodiment calculates high-frequency and low-frequency vibration energy to characterize the jitter difference caused by different feed rates. The specific method for obtaining the high-frequency and low-frequency vibration energy is as follows: In this embodiment, the jitter pressure vector is used as input, and the mode decomposition algorithm is used. The decomposition is performed once, and the output consists of two signals of length N. One signal is the IMF decomposition signal, which is the lower frequency signal component in the jitter pressure vector, and is denoted as the low-frequency decomposition signal. The other signal is the residual signal, which is the higher frequency signal component in the jitter pressure vector, and is denoted as the high-frequency decomposition signal.

[0033] As one implementation method, the EMD decomposition algorithm is used to perform mode decomposition on the jitter pressure vector. The EMD decomposition algorithm is a commonly used technique in the field of signal processing and will not be elaborated here.

[0034] Both the high-frequency decomposition signal and the low-frequency decomposition signal are denoted as decomposition signal, and both the high-frequency vibration energy and the low-frequency vibration energy are denoted as vibration energy.

[0035] Preferably, in this embodiment, the method for determining the vibration energy includes: acquiring the spectrum of the decomposed signal; normalizing all signal energy amplitudes in the spectrum and then weighting and summing the corresponding frequencies to obtain the signal frequency; using the reciprocal of the signal frequency as the signal period to set the window; and taking the average level of the absolute values ​​of all elements within the window at each acquisition time in the decomposed signal as the vibration energy at each acquisition time.

[0036] As one implementation method, for low-frequency decomposition signals, which are caused by excessively high feed rates, the higher the energy, the more the feed rate needs to be reduced. The low-frequency vibration energy of this signal is calculated using the following method: Using the low-frequency decomposed signal as input, the Fast Fourier Transform (FFT) is employed to calculate the output as a spectrum. The spectrum is a 2-row, K=1000-column matrix, where the first row of the k-th column represents the frequency, and the second row represents the signal energy amplitude at the corresponding frequency. The FFT algorithm is a commonly used technique in signal processing and will not be elaborated upon in this application.

[0037] First, the signal energy amplitude is normalized by summing the energy amplitudes of K signals. Then, the sum is divided by the energy amplitude of the kth signal to obtain the kth energy weight. Further, the frequencies are weighted and summed using these energy weights. The resulting value is denoted as the low-frequency signal frequency, representing the magnitude of the low-frequency decomposed signal frequency.

[0038] Then, the reciprocal of the low-frequency signal frequency is taken as the low-frequency signal period T, and the size of the low-frequency decomposed signal is set to... The window, where F is the signal sampling frequency, This rounds up the number in parentheses. W represents the number of element values ​​in the low-frequency decomposition signal corresponding to one period of the low-frequency signal. The window length W corresponds to one period of the signal. By representing the signal energy through the average signal value within one period, calculation errors caused by signal fluctuations can be avoided.

[0039] Finally, for the nth element value of the low-frequency decomposed signal, a window of length W is set with that element as the center. The absolute value of each element value within the window is taken first, and then the mean value is calculated. This mean value is denoted as the low-frequency vibration energy. Specifically, if there are empty values ​​in the window, interpolation is used to fill the empty values.

[0040] It should be understood that the obtained low-frequency vibration energy represents the energy level of the low-frequency decomposed signal at different times. The greater the energy, the more the feed reduction can eliminate the cutting tool jitter at that moment.

[0041] Similarly, the same method for calculating low-frequency vibration energy is used to calculate the energy of the nth high-frequency vibration signal. , representing the vibration energy of the high-frequency decomposed signal at time n. The greater the energy, the more the feed can eliminate the cutting tool chatter at that time.

[0042] A3. Based on the difference between high-frequency vibration energy and low-frequency vibration energy, determine the high-frequency and low-frequency energy ratio at each acquisition moment; based on the difference between the sum of high-frequency and low-frequency vibration energy at each acquisition moment and the cumulative sum at all acquisition moments, determine the energy weight at each acquisition moment; combine the energy weights at all acquisition moments and the high-frequency and low-frequency energy ratio to determine the overall energy ratio.

[0043] At different times, the ratio of low-frequency and high-frequency energy in the jitter pressure vector is different. If the ratio of low-frequency energy to high-frequency energy in the jitter pressure vector at a certain moment is higher than the energy ratio when the cutting tool is normally jittering, it means that the feed of the cutting tool is too large at this time. In this case, the cutting jitter should be reduced by adjusting the feed.

[0044] This embodiment calculates the high-frequency energy ratio to characterize the high-frequency energy ratio of the cutting tool at different times: In the formula, It is the ratio of high-frequency to low-frequency energy at time n. , These are the low-frequency vibration energy and high-frequency vibration energy at time n, respectively.

[0045] It should be understood that the higher the ratio of high to low frequency energy, the more likely the cutting tool vibration at the corresponding moment is caused by a high feed rate. In this case, reducing the feed rate is more likely to reduce the cutting tool vibration. Conversely, the lower the ratio, the more likely the cutting tool vibration is caused by a low feed rate. In this case, increasing the feed rate is more likely to reduce the cutting tool vibration.

[0046] During the drilling process, as the drilling time increases, heat accumulates on the cutting tool, causing it to heat up and its performance to change. Therefore, the same feed will produce different vibrations on the cutting tool at different times.

[0047] The ratio of high-frequency to low-frequency energy varies at different times during the entire drilling process. Therefore, the feed cannot be adjusted based on the ratio of high-frequency to low-frequency energy at a particular moment. Instead, the jitter data throughout the drilling process should be considered to adjust the feed accordingly.

[0048] In this embodiment, when adjusting the feed based on the vibration data throughout the drilling process, the intensity of vibration at different times is characterized by calculating energy weights. When reducing vibration by adjusting the feed, attention should be paid to the high-low frequency energy ratio at the moment of severe vibration. Only in this way can the final feed adjustment reduce the vibration amplitude of the entire drilling process and improve the overall smoothness of the cylinder head borehole.

[0049] The low-frequency vibration energy and high-frequency vibration energy at time n are summed to obtain the vibration energy at time n. Then, the vibration energies at N times are summed. Preferably, in this embodiment, the energy weight at time n is obtained by dividing the vibration energy at time n by the sum of the vibration energies at N times.

[0050] It should be understood that the larger the obtained energy weight, the more intense the vibration pair at time n. When adjusting the feed by the high-low frequency energy ratio, more attention should be paid to the high-low frequency energy ratio at time n.

[0051] Using energy weights as the basis, the high-frequency and low-frequency energy ratios at N acquisition times are summed, and the summation result is denoted as the overall energy ratio. It should be understood that the higher the overall energy ratio, the higher the feed rate during drilling, and vice versa.

[0052] A4. Based on the difference between the overall energy ratio and the preset energy ratio, determine the feed adjustment coefficient; use the feed adjustment coefficient to weight the feed during this drilling to obtain the adjusted feed for the next drilling.

[0053] Furthermore, a preset energy ratio is obtained as a method to determine whether the overall energy ratio is too high or too low. The preset energy ratio is obtained as follows: When a new cutting tool is installed on a CNC machine tool, the technician sets the feed for the drilling process. After the settings are completed, the first drilling is performed. The drilling data during the first drilling process is obtained through the CNC machine tool control system, and the corresponding overall energy ratio is calculated as the preset energy ratio S, which is used as the energy ratio when the cutting tool vibrates normally.

[0054] It is worth noting that no feed adjustment is required before the first drilling; drilling should be performed according to the feed settings provided by the technician.

[0055] After drilling, the overall energy ratio is calculated using data from the CNC machine tool control system. If it is higher than the preset energy ratio S, it indicates that the feed rate during drilling is too high; otherwise, it indicates that the feed rate is too low.

[0056] In this embodiment, the cutting tool's vibration state after the feed is set by the technician is usually the optimal vibration state of the cutting tool. Therefore, this embodiment adjusts the cutting tool with a preset energy ratio as the target, which can keep the cutting tool in the optimal vibration state.

[0057] Furthermore, in this embodiment, the feed for the next drilling operation is obtained through the overall energy ratio, and the method is as follows: First, calculate the feed adjustment factor for the next drilling operation. , In the formula, This is the overall energy ratio during this drilling operation, and S is the preset energy ratio. Specifically, when the feed adjustment coefficient is greater than 1, the feed adjustment coefficient is set to 1.

[0058] It should be understood that if the ratio of the overall energy ratio to the preset energy ratio is greater than 1, it indicates that the low-frequency jitter caused by high feed is dominant in the cutting tool jitter, and the feed should be reduced; conversely, if the high-frequency jitter caused by low feed is dominant, the feed should be increased.

[0059] It is worth noting that in this embodiment, the ratio of the overall energy ratio to the preset energy ratio is numerically adjusted so that its value is between -1 and 1, which facilitates the subsequent setting of the maximum adjustment amount of the feed adjustment coefficient.

[0060] In this embodiment, the maximum adjustment amount of the feed is set to R = 0.05 times the current feed size Fe. This maximum adjustment limits the range of feed adjustment, preventing excessively large single feed adjustments that could cause drastic fluctuations in the system state and affect the quality of the cylinder head during the adjustment process. The specific method for adjusting the feed for the next drilling operation is as follows: In the formula, Fn is the adjusted feed for the next drilling operation, and Fe is the feed for the current drilling operation. It is the feed adjustment factor for the next drilling operation.

[0061] It should be understood that the greater the difference between the feed adjustment coefficient and the value of 0, the greater the adjustment range. The positive or negative value of the feed adjustment coefficient corresponds to the feed being too high or too low, and the feed is correspondingly reduced or increased by this formula.

[0062] Specifically, when the feed adjustment exceeds the feed setting range, feed adjustment is performed. That is, if the adjusted feed is less than 0.1 mm per revolution, the feed for the next drilling operation is set to 0.1 mm per revolution; if the adjusted feed is greater than 0.2 mm per revolution, the feed for the next drilling operation is set to 0.2 mm per revolution.

[0063] In this embodiment of the application, the flowchart of the cutting tool feed adjustment index is attached. Figure 2As shown, in this embodiment, during the cylinder head positioning drilling process, the vibration pressure vector of the cutting tool is obtained, and the frequency domain characteristics of the vibration energy are analyzed to obtain the overall energy ratio. Then, the feed adjustment coefficient is obtained with the preset energy ratio as the target, and the feed is adjusted to complete the control of the cutting tool feed, so that the vibration of the cutting tool is maintained in the optimal working state.

[0064] This embodiment analyzes the relationship between cutting tool wear and cutting tool vibration characteristics using vibration data, and monitors the cutting tool vibration in real time to adjust the feed rate, thus reducing cutting tool vibration during the drilling process. Compared to the fixed cutting tool feed in traditional drilling methods, this approach can match the feed rate with the cutting tool performance when the cutting tool's performance changes due to wear, reducing vibration during the cutting process and improving the drilling quality of the cylinder head.

[0065] The various embodiments in this application are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0066] It should be noted that, unless otherwise specified and limited, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a circuit structure, article, or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such article or device. Without further limitations, an element defined by the phrase “comprising one…” does not exclude the presence of other identical elements in the article or device that includes said element. Furthermore, the term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0067] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not invented in this application.

[0068] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope.

Claims

1. A method for drilling and machining positioning holes applicable to cylinder heads, characterized in that, The method includes the following steps: A1, collects the feed size of the cutting tool during each drilling process of the cylinder head, and the radial pressure of the cutting tool at all collection moments, forming a jitter pressure vector; A2, perform mode decomposition on the jitter pressure vector to obtain high-frequency decomposition signals and low-frequency decomposition signals; based on the local energy ratio of the high-frequency decomposition signals and low-frequency decomposition signals at each acquisition time, determine the high-frequency vibration energy and low-frequency vibration energy at each acquisition time respectively. A3. Based on the difference between high-frequency vibration energy and low-frequency vibration energy, determine the high-frequency and low-frequency energy ratio at each acquisition moment; based on the difference between the sum of high-frequency and low-frequency vibration energy at each acquisition moment and the cumulative sum at all acquisition moments, determine the energy weight at each acquisition moment; combine the energy weights at all acquisition moments and the high-frequency and low-frequency energy ratio to determine the overall energy ratio. A4. Based on the difference between the overall energy ratio and the preset energy ratio, determine the feed adjustment coefficient; use the feed adjustment coefficient to weight the feed during this drilling to obtain the adjusted feed for the next drilling.

2. The positioning drilling and machining method for cylinder heads as described in claim 1, characterized in that, The high-frequency decomposition signal is the IMF decomposition signal after modal decomposition of the jitter pressure vector; the low-frequency decomposition signal is the residual signal after modal decomposition of the jitter pressure vector.

3. The positioning drilling and machining method for cylinder heads as described in claim 1, characterized in that, Both the high-frequency decomposition signal and the low-frequency decomposition signal are denoted as decomposition signals, and both the high-frequency vibration energy and the low-frequency vibration energy are denoted as vibration energy. The method for determining the vibration energy includes: Obtain the spectrum of the decomposed signal; normalize the amplitude of all signal energy values ​​in the spectrum, and then perform a weighted summation on the corresponding frequencies to obtain the signal frequency; Use the reciprocal of the signal frequency as the signal period to set the window; The average absolute value of all element values ​​within a window at each acquisition time in the decomposed signal is taken as the vibrational energy at each acquisition time.

4. The positioning drilling and machining method for cylinder heads as described in claim 1, characterized in that, The high-frequency energy ratio is the ratio of high-frequency vibration energy to low-frequency vibration energy.

5. The positioning drilling and machining method for cylinder heads as described in claim 1, characterized in that, The energy weight is determined by the ratio of the sum to the cumulative sum.

6. The positioning drilling and machining method for cylinder heads as described in claim 1, characterized in that, The method for determining the overall energy ratio is as follows: using energy weights as weights, the high-frequency and low-frequency energy ratios at the corresponding acquisition times are weighted and summed.

7. The positioning drilling and machining method for cylinder heads as described in claim 1, characterized in that, The method for determining the feed adjustment coefficient is as follows: In the formula, It is the feed adjustment factor for the next drilling operation. It is the overall energy ratio during this drilling, and S is the preset energy ratio.

8. The positioning drilling and machining method for cylinder heads as described in claim 1, characterized in that, The preset energy ratio is the overall energy ratio calculated when the cutting tool drills a hole for the first time.

9. The positioning drilling and machining method for cylinder heads as described in claim 7, characterized in that, The method for obtaining the adjusted feed during the next drilling operation is as follows: In the formula, Fn is the adjusted feed for the next drilling, Fe is the feed for the current drilling, and R is the preset maximum adjustment amount.

10. The positioning drilling and machining method for cylinder heads as described in claim 9, characterized in that, After obtaining the adjustment feed, the feed of the cutting tool is controlled during the next drilling process.

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