Lost foam casting method

Abstract

The invention belongs to the technical field of casting engineering, and particularly relates to an evanescent mode casting method which comprises the following steps: analyzing the influence of exhaust speed on the internal air pressure of a mold in a pouring process on the basis of data processing of the internal air pressure and the exhaust speed of the mold in the pouring process in a monitoring period, and judging whether an exhaust system needs to be adjusted or not; the problem that the product quality is influenced by over-high internal air pressure in the pouring process due to the problem of an exhaust system is avoided; data processing is carried out on the pouring speed and the internal temperature of the mold, the influence of the pouring speed and the internal temperature of the mold on the internal air pressure of the mold in the pouring process is analyzed, the situation that the product quality is influenced by too high pouring speed and too high internal temperature of the mold is avoided, and the casting efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of casting engineering, in particular to a lost foam casting method. Background Art

[0002] Lost foam casting is to bond foam models with similar size and shape to the casting into a model cluster, apply refractory paint and dry it, and then bury it in dry quartz sand for vibration molding. When pouring under negative pressure, the model vaporizes, liquid metal occupies the position of the model, and forms a casting after solidification and cooling.

[0003] A Chinese patent application with publication number CN104874734A discloses a lost foam casting method, including the following steps: Step 1: Make a foam white mold, combine the casting system, brush and spray special high-temperature resistant coating on the surface of the gasification mold, and dry it; Step 2: Place the interlayer sand box on the workbench, fill it with dry sand, vibrate it, scrape it flat, place the dried gasification mold on the bottom sand, fill it with dry sand, and slightly vibrate it for a suitable time to scrape the box mouth flat; Step 3: Cover it with plastic film, put on the pouring cup, connect the vacuum system to absorb the vacuum, and after the dry sand is firmly formed, pour it, the white mold vaporizes and disappears, and the molten metal replaces its position; Step 4: Release the vacuum, turn the box over after the casting is condensed, and take out the casting from the loose dry sand. The lost foam casting method disclosed in the present invention has a reasonable process route design, the castings produced have high surface finish and dimensional accuracy, simple production procedures, high metal utilization rate, and basically all the old sand is reused, which reduces the modeling cost;

[0004] In the prior art, the internal air pressure of the mold during the casting process is monitored and analyzed to avoid the reduction of casting efficiency and product quality caused by excessive internal air pressure. When excessive internal air pressure occurs, there are deficiencies in analyzing the causes of excessive internal air pressure, accurately adjusting parameters, and timely reducing the internal air pressure.

[0005] To this end, the invention provides a lost foam casting method. Summary of the invention

[0006] In order to make up for the deficiencies of the prior art, at least one technical problem raised in the background technology is solved.

[0007] The technical solution adopted by the present invention to solve the technical problem is: comprising:

[0008] S1: Filling the pre-foamed and matured foam beads into the cavity of a metal mold to form a mold with a smooth surface;

[0009] S2: Drying the prepared foam model, and bonding the processed foam model to the pouring and riser model to form a model cluster;

[0010] S3: Place the coated and dried model cluster on the bottom sand, fill it with dry sand, vibrate it, place the pouring cup on it, and connect the negative pressure system;

[0011] S4: Under negative pressure, pour the molten metal into the model position in the sand box. After the metal liquid cools and solidifies, close the negative pressure system and release the vacuum to naturally separate the casting from the dry sand.

[0012] The internal air pressure and exhaust speed of the mold during the casting process are obtained, the exhaust influence value is analyzed and compared with the exhaust influence threshold, and a non-exhaust influence signal or an exhaust influence signal is generated according to the comparison result. If an exhaust influence signal is generated, an exhaust adjustment instruction is sent to the negative pressure system;

[0013] Based on the non-exhaust influence signal, the pouring speed and the internal temperature of the mold during the pouring process are processed to obtain the air pressure influence value; the air pressure influence value is compared with the air pressure influence threshold to generate a non-influence signal and an influence signal. If an influence signal is generated, an adjustment instruction is sent to the temperature control system and the pouring system;

[0014] S5: Clean the dry sand and residue on the surface of the casting, and grind and trim the casting.

[0015] As a further technical solution of the present invention, the exhaust impact value is obtained by:

[0016] The exhaust impact value is obtained by ratioing the mean value of the exhaust anomaly slope to the mean value of the air pressure anomaly slope.

[0017] As a further technical solution of the present invention, the method for obtaining the mean value of the exhaust abnormality slope is:

[0018] The exhaust speed during the pouring process of all monitoring sub-cycles is obtained, and an XY two-dimensional coordinate system is constructed with the exhaust speed and time during the pouring process; the exhaust speed of each monitoring sub-cycle is marked in the XY two-dimensional coordinate system and connected to obtain the exhaust speed change curve; the exhaust speed change curve corresponding to the abnormal sub-cycle is marked as the exhaust abnormality sub-curve; the slopes of all exhaust abnormality sub-curves are obtained and averaged to obtain the exhaust abnormality slope average.

[0019] As a further technical solution of the present invention, the abnormal sub-period is obtained in the following manner:

[0020] The internal air pressure of the mold during the pouring process is compared with the internal air pressure threshold, and if the internal air pressure of the mold during the pouring process is greater than or equal to the internal air pressure threshold, an air pressure abnormality signal is generated;

[0021] Based on the abnormal air pressure signal, the monitoring period is divided into several monitoring sub-periods, and the sub-period in which the abnormal signal is generated within the monitoring period is marked as an abnormal sub-period.

[0022] As a further technical solution of the present invention, the process of obtaining the mean value of the pressure anomaly slope is as follows:

[0023] The internal air pressure of the mold during the casting process of all monitored sub-cycles is obtained, and an XY two-dimensional coordinate system is constructed with the internal air pressure of the mold and time; the internal air pressure of the mold in each sub-cycle is marked in the XY two-dimensional coordinate system and connected to obtain the internal air pressure change curve of the mold during the casting process; the internal air pressure change curve of the mold corresponding to the abnormal sub-cycle is marked as the air pressure abnormality sub-curve; the slopes of all air pressure abnormality sub-curves are obtained and averaged to obtain the average of the air pressure abnormality slopes.

[0024] As a further technical solution of the present invention, the process of comparing the exhaust impact value with the exhaust impact threshold is as follows:

[0025] The exhaust impact value is compared with the exhaust impact threshold. The specific process is as follows:

[0026] If the exhaust impact value is less than the exhaust impact threshold, a non-exhaust impact signal is generated;

[0027] If the exhaust impact value is greater than or equal to the exhaust impact threshold, an exhaust impact signal is generated.

[0028] As a further technical solution of the present invention, the process of obtaining the air pressure influence value is as follows:

[0029] The obtained speed over-limit value SD and temperature over-limit value WD are processed to obtain the air pressure influence value, which is marked as QY.

[0030] As a further technical solution of the present invention, the method for obtaining the speed exceeding limit value is:

[0031] Based on the non-exhaust influence signal, the pouring speed of all abnormal sub-cycles is obtained, the pouring speed of the abnormal sub-cycle is summed and averaged, the average pouring speed of the abnormal sub-cycle is ratioed with the standard value of the pouring speed, and the speed exceeding the limit value of the abnormal sub-cycle is obtained, which is marked as SD.

[0032] As a further technical solution of the present invention, the method for obtaining the temperature over-limit value is:

[0033] Get the internal temperature of the mold for all abnormal sub-cycles, compare the internal temperature of the mold for all abnormal sub-cycles with the standard value of the internal temperature of the mold, and perform ratio processing on the number of abnormal sub-cycles in which the internal temperature of the mold is greater than the standard value of the internal temperature of the mold and the total number of abnormal sub-cycles to obtain the temperature out-of-bounds value of the abnormal sub-cycle, which is marked as WD.

[0034] As a further technical solution of the present invention, the process of comparing the air pressure impact value with the air pressure impact threshold is as follows:

[0035] The air pressure impact value is compared with the air pressure impact threshold, and the specific process is as follows;

[0036] If the air pressure impact value is less than or equal to the air pressure impact threshold, a non-impact signal is generated;

[0037] If the air pressure impact value is greater than the air pressure impact threshold, an impact signal is generated.

[0038] The beneficial effects of the present invention are as follows:

[0039] 1. The technical solution of an embodiment of the present invention is: obtaining the internal air pressure of the mold during the pouring process and the exhaust speed during the pouring process within a monitoring period, constructing an XY two-dimensional coordinate system, performing data analysis, and obtaining an exhaust influence value; comparing the exhaust influence value with the exhaust influence threshold, determining whether the exhaust speed during the pouring process is the cause of the abnormal internal air pressure of the mold during the pouring process, and generating a non-exhaust influence signal or an exhaust influence signal according to the comparison result; the present invention is based on data processing of the internal air pressure and exhaust speed of the mold during the pouring process within a monitoring period, analyzing the influence of the exhaust speed on the internal air pressure of the mold during the pouring process, determining whether the exhaust system needs to be adjusted, and avoiding excessive internal air pressure of the mold during the pouring process due to problems with the exhaust system, thereby affecting product quality.

[0040] 2. The technical solution of the embodiment of the present invention is: based on the non-exhaust influence signal, data processing is performed on the casting speed and internal temperature of the mold of all abnormal sub-cycles, and the influence of the casting speed and the internal temperature of the mold on the internal air pressure of the mold during the casting process is analyzed to obtain the air pressure influence value; the air pressure influence value is compared with the air pressure influence threshold to determine the influence of the casting speed change and the internal temperature change of the mold during the abnormal sub-cycle on the abnormal internal air pressure of the mold during the casting process; the present invention performs data processing on the casting speed and internal temperature of the mold of the abnormal sub-cycle, and analyzes the influence of the casting speed and the internal temperature of the mold on the internal air pressure of the mold during the casting process, thereby avoiding the influence of excessive casting speed and excessive internal temperature of the mold on product quality and improving casting efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The present invention will be further described below in conjunction with the accompanying drawings.

[0042] Figure 1 This is a flow chart of the steps of a lost foam casting method according to an embodiment of the present invention;

[0043] Figure 2 This is a flow chart of the steps of obtaining exhaust impact value in a lost foam casting method according to an embodiment of the present invention;

[0044] Figure 3It is a flow chart of the steps of obtaining the air pressure influence value in a lost foam casting method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0045] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0046] Example 1

[0047] like Figure 1 As shown, a lost foam casting method according to an embodiment of the present invention comprises:

[0048] S1: Filling the pre-foamed and matured foam beads into the cavity of a metal mold to form a mold with a smooth surface;

[0049] S2: Drying the prepared foam model, and bonding the processed foam model to the pouring and riser model to form a model cluster;

[0050] S3: Place the coated and dried model cluster on the bottom sand, fill it with dry sand, vibrate it, place the pouring cup on it, and connect the negative pressure system;

[0051] S4: Under negative pressure, pour the molten metal into the model position in the sand box. After the metal liquid cools and solidifies, close the negative pressure system and release the vacuum to naturally separate the casting from the dry sand.

[0052] The internal air pressure and exhaust speed of the mold during the casting process are obtained, the exhaust influence value is analyzed and compared with the exhaust influence threshold, and a non-exhaust influence signal or an exhaust influence signal is generated according to the comparison result. If an exhaust influence signal is generated, an exhaust adjustment instruction is sent to the negative pressure system;

[0053] Based on the non-exhaust influence signal, the pouring speed and the internal temperature of the mold during the pouring process are processed to obtain the air pressure influence value; the air pressure influence value is compared with the air pressure influence threshold to generate a non-influence signal and an influence signal. If an influence signal is generated, an adjustment instruction is sent to the temperature control system and the pouring system;

[0054] S5: Clean the dry sand and residue on the surface of the casting, and grind and trim the casting.

[0055] Example 2

[0056] like Figure 2 As shown, a lost foam casting method according to an embodiment of the present invention comprises:

[0057] Step 1: Obtain the internal air pressure of the mold during the pouring process and the exhaust speed during the pouring process within the monitoring period, construct an XY two-dimensional coordinate system, perform data analysis, and obtain the exhaust impact value;

[0058] The internal air pressure of the mold during the pouring process is obtained, and the internal air pressure of the mold during the pouring process is compared with the internal air pressure threshold to analyze whether the internal air pressure is too high; the comparison process is as follows:

[0059] If the internal air pressure of the mold during the casting process is less than the internal air pressure threshold, a normal air pressure signal is generated;

[0060] If the internal air pressure of the mold during the casting process is greater than or equal to the internal air pressure threshold, an air pressure abnormality signal is generated;

[0061] It should be noted that when the internal air pressure of the mold exceeds the internal air pressure threshold during the pouring process, it may cause casting defects such as back spray and box collapse. During the pouring process, it is necessary to control the internal air pressure of the mold to be less than the internal air pressure threshold; the pouring speed of the molten metal, the internal temperature of the mold and the exhaust speed during the pouring process will all affect the internal air pressure of the mold during the pouring process;

[0062] The monitoring period is divided into a number of monitoring sub-periods, and based on the abnormal signal, the sub-period in which the abnormal signal is generated within the monitoring period is marked as an abnormal sub-period;

[0063] Obtain the exhaust speed during the pouring process of all monitored sub-cycles, and construct an XY two-dimensional coordinate system with the exhaust speed during the pouring process as the Y-axis and time as the X-axis; mark the exhaust speed during the pouring process of each sub-cycle in the XY two-dimensional coordinate system and connect them to obtain the exhaust speed change curve during the pouring process; mark the exhaust speed change curve during the pouring process corresponding to the abnormal sub-cycle as the exhaust abnormality sub-curve; obtain the slopes of all the exhaust abnormality sub-curves and calculate the average value to obtain the exhaust abnormality slope average;

[0064] Obtain the internal air pressure of the mold during the pouring process of all monitored sub-cycles, and construct an XY two-dimensional coordinate system with the internal air pressure of the mold during the pouring process as the Y-axis and time as the X-axis; mark the internal air pressure of the mold during the pouring process of each sub-cycle in the XY two-dimensional coordinate system and connect them to obtain a change curve of the internal air pressure of the mold during the pouring process; mark the change curve of the internal air pressure of the mold during the pouring process corresponding to the abnormal sub-cycle as an air pressure abnormality sub-curve; obtain the slopes of all air pressure abnormality sub-curves and calculate the average value to obtain the air pressure abnormality slope average;

[0065] The exhaust impact value is obtained by performing ratio processing on the mean value of the exhaust anomaly slope and the mean value of the air pressure anomaly slope;

[0066] Step 2: Compare the exhaust influence value with the exhaust influence threshold value to determine whether the exhaust speed during the casting process is the cause of the abnormal internal air pressure of the mold during the casting process, and generate a non-exhaust influence signal or an exhaust influence signal according to the comparison result;

[0067] The exhaust impact value is compared with the exhaust impact threshold. The specific process is as follows:

[0068] If the exhaust impact value is less than the exhaust impact threshold, a non-exhaust impact signal is generated;

[0069] If the exhaust impact value is greater than or equal to the exhaust impact threshold, an exhaust impact signal is generated;

[0070] Adjust the exhaust system based on the exhaust impact signal, adjust the exhaust speed during the pouring process, and restore the internal air pressure of the mold to normal during the pouring process;

[0071] The technical solution of the embodiment of the present invention is: obtaining the internal air pressure of the mold during the pouring process and the exhaust speed during the pouring process within the monitoring period, constructing an XY two-dimensional coordinate system, performing data analysis, and obtaining an exhaust influence value; comparing the exhaust influence value with the exhaust influence threshold, judging whether the exhaust speed during the pouring process is the cause of the abnormal internal air pressure of the mold during the pouring process, and generating a non-exhaust influence signal or an exhaust influence signal according to the comparison result; the present invention is based on data processing of the internal air pressure and exhaust speed of the mold during the pouring process within the monitoring period, analyzing the influence of the exhaust speed on the internal air pressure of the mold during the pouring process, judging whether the exhaust system needs to be adjusted, and avoiding problems with the exhaust system that cause the internal air pressure of the mold to be too high during the pouring process, thereby affecting product quality.

[0072] Example 3

[0073] like Figure 3 As shown, a lost foam casting method according to an embodiment of the present invention comprises:

[0074] Step 3: Based on the non-exhaust influence signal, the casting speed and the internal temperature of the mold of all abnormal sub-cycles are processed, and the influence of the casting speed and the internal temperature of the mold on the internal air pressure of the mold during the casting process is analyzed to obtain the air pressure influence value;

[0075] Based on the non-exhaust influence signal, the pouring speed of all abnormal sub-cycles is obtained, the pouring speed of the abnormal sub-cycle is summed and averaged, the average pouring speed of the abnormal sub-cycle is ratioed with the standard value of the pouring speed, and the speed exceeding limit value of the abnormal sub-cycle is obtained, which is marked as SD;

[0076] Obtain the mold internal temperature of all abnormal sub-cycles, compare the mold internal temperature of all abnormal sub-cycles with the mold internal temperature standard value, perform ratio processing on the number of abnormal sub-cycles in which the mold internal temperature is greater than the mold internal temperature standard value and the total number of abnormal sub-cycles, and obtain the temperature out-of-bounds value of the abnormal sub-cycle, which is marked as WD;

[0077] The obtained speed over-limit value SD and temperature over-limit value WD are processed and the formula QY = s1*SD + s2*WD is used. 2 , get the air pressure influence value, marked as QY, where s1 and s2 are preset proportional coefficients;

[0078] It should be noted that the air pressure influence value QY indicates the influence of the pouring speed and the internal temperature of the mold on the internal air pressure of the mold during pouring. The air pressure influence value QY can be used to determine whether the pouring speed and the internal temperature of the mold are the causes of the abnormal internal air pressure of the mold during the pouring process.

[0079] Step 4: Compare the air pressure impact value with the air pressure impact threshold to determine the impact of the casting speed change and the mold internal temperature change in the abnormal sub-period on the abnormal internal air pressure of the mold during the casting process;

[0080] The air pressure impact value is compared with the air pressure impact threshold, and the specific process is as follows;

[0081] If the air pressure impact value is less than or equal to the air pressure impact threshold, a non-impact signal is generated;

[0082] If the air pressure impact value is greater than the air pressure impact threshold, an impact signal is generated, and based on the impact signal, an adjustment instruction is sent to the temperature control system and the pouring system.

[0083] The technical solution of the embodiment of the present invention is: based on the non-exhaust influence signal, data processing is performed on the casting speed and the internal temperature of the mold of all abnormal sub-cycles, and the influence of the casting speed and the internal temperature of the mold on the internal air pressure of the mold during the casting process is analyzed to obtain the air pressure influence value; the air pressure influence value is compared with the air pressure influence threshold to determine the influence of the casting speed change and the internal temperature change of the mold in the abnormal sub-cycle on the abnormal internal air pressure of the mold during the casting process; the present invention performs data processing on the casting speed and the internal temperature of the mold of the abnormal sub-cycle, and analyzes the influence of the casting speed and the internal temperature of the mold on the internal air pressure of the mold during the casting process, thereby avoiding the influence of excessive casting speed and excessive internal temperature of the mold on product quality and improving casting efficiency.

[0084] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A lost foam casting method, characterized in that: include: S1: Filling the pre-foamed and matured foam beads into the cavity of a metal mold to form a mold with a smooth surface; S2: Drying the prepared foam model, and bonding the processed foam model to the pouring and riser model to form a model cluster; S3: Place the coated and dried model cluster on the bottom sand, fill it with dry sand, vibrate it, place the pouring cup on it, and connect the negative pressure system; S4: Under negative pressure, pour the molten metal into the model position in the sand box. After the metal liquid cools and solidifies, close the negative pressure system and release the vacuum to naturally separate the casting from the dry sand. The internal air pressure and exhaust speed of the mold during the casting process are obtained, the exhaust influence value is analyzed and compared with the exhaust influence threshold, and a non-exhaust influence signal or an exhaust influence signal is generated according to the comparison result. If an exhaust influence signal is generated, an exhaust adjustment instruction is sent to the negative pressure system; Based on the non-exhaust influence signal, the pouring speed and the internal temperature of the mold during the pouring process are processed to obtain the air pressure influence value; the air pressure influence value is compared with the air pressure influence threshold to generate a non-influence signal and an influence signal. If an influence signal is generated, an adjustment instruction is sent to the temperature control system and the pouring system; S5: Clean the dry sand and residue on the surface of the casting, and grind and trim the casting.

2. A lost foam casting method according to claim 1, characterized in that: The exhaust impact value is obtained in the following manner: The exhaust impact value is obtained by ratioing the mean value of the exhaust anomaly slope to the mean value of the air pressure anomaly slope.

3. A lost foam casting method according to claim 2, characterized in that: The method for obtaining the mean value of the exhaust abnormality slope is as follows: The exhaust speed during the pouring process of all monitoring sub-cycles is obtained, and an XY two-dimensional coordinate system is constructed with the exhaust speed and time during the pouring process; the exhaust speed of each monitoring sub-cycle is marked in the XY two-dimensional coordinate system and connected to obtain the exhaust speed change curve; the exhaust speed change curve corresponding to the abnormal sub-cycle is marked as the exhaust abnormality sub-curve; the slopes of all exhaust abnormality sub-curves are obtained and averaged to obtain the exhaust abnormality slope average.

4. A lost foam casting method according to claim 3, characterized in that: The abnormal sub-period is obtained in the following manner: The internal air pressure of the mold during the pouring process is compared with the internal air pressure threshold, and if the internal air pressure of the mold during the pouring process is greater than or equal to the internal air pressure threshold, an air pressure abnormality signal is generated; Based on the abnormal air pressure signal, the monitoring period is divided into several monitoring sub-periods, and the sub-period in which the abnormal signal is generated within the monitoring period is marked as an abnormal sub-period.

5. The lost foam casting method according to claim 2, characterized in that: The process of obtaining the mean value of the pressure anomaly slope is as follows: The internal air pressure of the mold during the casting process of all monitored sub-cycles is obtained, and an XY two-dimensional coordinate system is constructed with the internal air pressure of the mold and time; the internal air pressure of the mold in each sub-cycle is marked in the XY two-dimensional coordinate system and connected to obtain the internal air pressure change curve of the mold during the casting process; the internal air pressure change curve of the mold corresponding to the abnormal sub-cycle is marked as the air pressure abnormality sub-curve; Obtain the slopes of all pressure anomaly sub-curves and calculate their averages to obtain the average pressure anomaly slope.

6. The lost foam casting method according to claim 1, characterized in that: The process of comparing the exhaust impact value with the exhaust impact threshold is as follows: The exhaust impact value is compared with the exhaust impact threshold. The specific process is as follows: If the exhaust impact value is less than the exhaust impact threshold, a non-exhaust impact signal is generated; If the exhaust impact value is greater than or equal to the exhaust impact threshold, an exhaust impact signal is generated.

7. The lost foam casting method according to claim 1, characterized in that: The process of obtaining the air pressure impact value is as follows: The obtained speed over-limit value SD and temperature over-limit value WD are processed to obtain the air pressure influence value, which is marked as QY.

8. A lost foam casting method according to claim 7, characterized in that: The method for obtaining the speed exceeding limit value is as follows: Based on the non-exhaust influence signal, the pouring speed of all abnormal sub-cycles is obtained, the pouring speed of the abnormal sub-cycle is summed and averaged, the average pouring speed of the abnormal sub-cycle is ratioed with the standard value of the pouring speed, and the speed exceeding limit value of the abnormal sub-cycle is obtained, which is marked as SD.

9. The lost foam casting method according to claim 7, characterized in that: The method for obtaining the temperature over-limit value is as follows: Get the internal temperature of the mold for all abnormal sub-cycles, compare the internal temperature of the mold for all abnormal sub-cycles with the standard value of the internal temperature of the mold, and perform ratio processing on the number of abnormal sub-cycles in which the internal temperature of the mold is greater than the standard value of the internal temperature of the mold and the total number of abnormal sub-cycles to obtain the temperature out-of-bounds value of the abnormal sub-cycle, which is marked as WD.

10. The lost foam casting method according to claim 1, characterized in that: The process of comparing the air pressure impact value with the air pressure impact threshold is as follows: The air pressure impact value is compared with the air pressure impact threshold, and the specific process is as follows; If the air pressure impact value is less than or equal to the air pressure impact threshold, a non-impact signal is generated; If the air pressure impact value is greater than the air pressure impact threshold, an impact signal is generated.

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