System and method for calculating optimal transfer rate based on physical machining load, using physical machining data and CNC machining path

Abstract

The present invention proposes a method for calculating an optimal transfer rate in consideration of a physical machining load by using physical machining data and a machining path in CNC machining, and a system for implementing the method. Specifically, provided is a system for calculating an optimal transfer rate based on a physical machining load by using a machining path of an NC code and physical machining data, the system comprising: an NC code processing unit that generates the machining path through the NC code, segments the machining path according to a geometric shape, and derives a segmentation interval; a physical machining data processing unit that acquires data generated in a physical machining process and calculates a segmented machining interval by using the acquired data; a data mapping unit that maps machining path data of the NC code processing unit and physical machining data of the physical machining data processing unit; and a machining load setting and adjusting unit that sets and adjusts a machining load for each machining position on the basis of the physical machining load, wherein an optimal transfer rate is calculated on the basis of the set and adjusted machining load, and the NC code is corrected and converted by reflecting the calculated optimal transfer rate.

Description

System and method for calculating optimal feed rate based on actual machining data and CNC machining paths

[0001] The present invention proposes a method for calculating an optimal feed rate considering the actual machining load by utilizing actual machining data and a machining path in CNC machining, and a system for implementing the method.

[0002] Generally, CNC equipment in manufacturing sites is installed gradually over a period of time, except in cases of all-time large-scale facility investment. Since CNC equipment is often used for more than 10 years, its condition changes due to factors such as the operating environment. For example, among machines with identical specifications, the condition of one that primarily performed heavy-load roughing will inevitably differ significantly from that of one that primarily performed low-load finishing. Furthermore, even for machines primarily used for heavy-load roughing, changes in spindle motor characteristics occur over long-term use, resulting in differences in machining loads across the equipment. To explain further, in manufacturing sites where multi-product, small-batch production is becoming widespread, machining is performed on various machines using the same master NC code. Even when using the same master NC code, machines acquire different characteristics due to varying operation over extended periods; consequently, even when using the same master NC code, normal machining may occur on one machine, while machining process defects may arise depending on the specific machine.

[0003] The CNC machining process proceeds as follows: (a) product design using CAD, (b) machining process design, (c) generation of machining paths using CAM, (d) verification and refinement of the machining paths through test machining on specific CNC equipment, and (e) mass production machining using CNC equipment at the manufacturing site. Among the above steps, the machining path (or master NC code) verified based on the test equipment in (d) is input into various CNC machines to perform the machining process.

[0004] The above machining path includes machining conditions such as the machining position, feed rate, and rotational speed of the machining position, and the CNC equipment performs the machining process along the machining path according to those machining conditions. At this time, a problem may occur because the master NC code has been verified only on the test equipment, so a situation arises where a high-quality machining process cannot be performed on other equipment in (e). Even if the equipment has the same specifications as the test equipment, the physical state and characteristics of each piece of equipment differ, so even if machining is performed with the same NC code, different machining loads occur, leading to the above problem.

[0005] Typically, a machining path is generated based on a product geometry model using a CAM solution, and a master NC code is created after verification on test equipment. This master NC code includes machining conditions, such as tool rotational speed and feed rate, to enable the cutting tool to overcome material resistance at the machining position and perform physical cutting to machine the product's geometric shape from the material. However, if the rotational force of the tool edge or the machining load of the spindle, controlled by the machining conditions of the master NC code, is not greater than the resistance caused by the material strength, physical machining cannot proceed. In other words, since the conditions of multiple machines in actual operation differ from those of the test equipment, it becomes impossible to machine products using the master NC code, or machining defects may occur. Therefore, a method is required to calculate the optimal feed rate based on the machining load of each machine according to its state, enabling high-quality machining using the master NC code. Currently, manufacturing sites address this issue by appointing dedicated operators for each piece of equipment and utilizing their tacit knowledge and experience to modify and supplement parts of the master NC code.

[0006] In this regard, the inventor of the present invention conceived a method to modify and supplement the master NC code based on an optimal feed rate considering the actual machining load, so that the code is suitable for each piece of equipment.

[0007] To overcome the above problem, the method proposed in this invention does not aim for precise measurement of the machining load, but rather aims to provide a method and system for performing machining with an optimal feed rate that considers the machining load characteristics of each piece of equipment, in order to solve the problems that arise in manufacturing sites where machining is performed on multiple CNC machines using a single master NC code.

[0008] The present invention for solving the technical problems described above is,

[0009] A method is presented to correct the NC code by applying an optimal feed rate based on the actual machining load that varies for each machine, by mapping the actual machining load of each machine to the machining path or master NC code generated in CAM.

[0010] The present invention corrects the NC code by adjusting the machining load based on the machining position through interpolation, in mapping data obtained from a theoretical machining path or a master NC code with machining load data measured during machining at each piece of equipment.

[0011]

[0012] Although the condition of the equipment owned by a manufacturing company varies by individual piece of equipment and various processing load patterns may be observed even on the same processing path, the present invention enables the improvement of productivity and quality of the processing process by applying an optimal transfer to the processing path that considers the actual processing load condition of each piece of equipment.

[0013] Currently, the optimization of machining for each piece of equipment in manufacturing sites relies on the experience and tacit knowledge of equipment operators. However, due to factors such as the recent decrease in manufacturing personnel, the technical capability for optimizing machining for each piece of equipment has become insufficient, which can act as a factor threatening manufacturing competitiveness. Nevertheless, the present invention is expected to contribute to machining technology for improving productivity for individual pieces of equipment in the field of CNC machining for the digital transformation, smart manufacturing, and autonomous manufacturing of manufacturing.

[0014] FIG. 1 is a conceptual diagram for implementing the present invention.

[0015] FIG. 2 is a flowchart for implementing the present invention

[0016] FIG. 3 is a system configuration diagram for implementing the present invention.

[0017] FIG. 4 is an example of a processing load and feed rate mapping map according to the present invention.

[0018] Detailed descriptions regarding the implementation of the present invention are specifically described below through the attached drawings and description. Unless otherwise specifically defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms defined in commonly used dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in the present invention.

[0019]

[0020] First, the concept devised by the present invention will be explained through [Fig. 1], with reference to the reference numerals below.

[0021] CL: Machining position, RCL: Actual machining position

[0022] CF: Command feed rate (included in NC code)

[0023] OF: Adjusted optimal feed rate, OSL: Adjusted optimal processing load

[0024] RF: Actual transfer rate (obtained via OT, etc.),

[0025] RSL: Actual machining load (obtained via IoT, etc.)

[0026] RSL_adj: Machining load of the nearest machining position

[0027]

[0028] The machining method illustrated in (a) of [Fig. 1] is an optimal machining method according to the present invention, and is implemented as an optimal machining path including an optimal machining load (OSL) and an optimal feed rate (OF). Conceptually, the optimal machining path of (a) is a combination and mapping of the machining method of an actual CNC machine illustrated in (b) and the machining method of an NC code illustrated in (c) based on the machining position.

[0029]

[0030] In other words, since the machining method based on the NC code of (c) lacks actual machining load data, it is a method that utilizes machining load data extracted from the actual machining data of (b). In order to map the machining load of (b) to the machining path of (c), when setting the machining position, the present invention requires calculating the machining load corresponding to that machining position and the optimal feed rate for that machining load. The calculation method is explained in detail together with [Fig. 2].

[0031]

[0032] [Fig. 2] presents a specific method of the present invention for mapping the data of (b) and (c) of [Fig. 1] to each other. First, ①, ②, and ③ of [Fig. 2] relate to the process of segmenting each data by section and extracting data at the segmented location for mapping between NC code data and actual machining data.

[0033] First, the segmentation process for NC data is explained as ①-ⓐ, ②-ⓐ, and ③-ⓐ. That is, a machining path is generated based on the input NC code (①-ⓐ), the machining path is divided into equal intervals (②-ⓐ), and the machining position of the divided machining path is determined (③-ⓐ).

[0034] In addition, the segmentation process for actual machining data is described as ①-ⓑ, ②-ⓑ, and ③-ⓑ. That is, a material is mounted on the CNC machine to be machined and the actual machining operation is performed to acquire actual machining data (①-ⓑ); segmented machining intervals are calculated from the actual machining data and the average is calculated (②-ⓑ); and actual machining load and actual feed rate for each machining position are extracted from the machining data along the segmented machining intervals (③-ⓑ).

[0035] Meanwhile, ④, ⑤, ⑥, ⑦, and ⑧ in [Fig. 2] propose a method for mapping and adjusting the machining load and feed rate after segmenting the machining path according to the NC code and the actual machining data, respectively. Specifically, ④ maps the machining position on the actual machining data to the nearest machining position on the machining path, and maps based on the nearest machining position on the machining path. Here, the nearest machining position refers to the closest machining position based on the time series and machining position in (b) and (c) of [Fig. 1] when machining along the machining path.

[0036] As shown in [Fig. 1], the nearest machining position is placed on the machining path through mapping, but there is a problem in that the actual machining load corresponding to the nearest machining position cannot be known. This is because the actual machining load corresponding to the machining position could not be obtained due to the communication cycle of the CNC equipment being non-uniform and not constant. Accordingly, in the present invention, the machining load RSL(i)_adj of the nearest machining position is obtained by utilizing the interpolation function of the starting point machining load RSL(i) and the ending point machining load RSL(i+1) of the section to which the nearest machining position belongs in ⑤.

[0037] The machining load RSL(i)_adj at the nearest machining position is calculated by performing linear interpolation on the machining loads of the segmented section containing the nearest machining position, using the following equation. The machining load RSL(i)_adj at the nearest machining position is utilized as the adjusted optimal machining load OSL(i) for calculating the optimal feed rate. Based on [Fig. 1], a method for calculating the machining load at the nearest machining position is presented as follows.

[0038]

[0039]

[0040] Then, in ⑥, the optimal feed rate is calculated based on the adjusted machining load of the nearest machining position. At this time, a mapping map of the machining load and feed rate extracted from actual machining data is utilized. The mapping map is configured as shown in [Fig. 4]. In this mapping map, each symbol is used as follows. That is,

[0041] SL_i : i-th range of machining load

[0042] F_i : i-th range of feed rate

[0043] Range_ij : Feed rate range, ijth range

[0044]

[0045] The above mapping map divides the machining load and feed rate extracted from actual machining data into specific ranges, classifies them based on the correlation between the machining load and feed rate, and maps them to a specific feed rate range corresponding to a specific machining load range. SL_i and F_i are upper ranges corresponding to the i-th, and Range_ij is a feed rate range corresponding to the j-th detailed range within the upper range determined by F_i. In other words, SL_i and F_i are ranges primarily determined by the spindle motor torque curve, while Range_ij serves as a fine feed rate adjustment based on the machining state of a specific machining part on the torque curve. Finally, a machining path including the machining position and feed rate calculated according to the above method in ⑦ is generated, and the NC code corresponding to that machining path is converted and generated. The above NC code contains CNC machining commands with machining load-based optimal feed rates at uniformly spaced machining positions and can be used as a correction master NC code.

[0046] However, even when machining with this new compensation master NC code, the process will result in uneven machining intervals due to segmented processing caused by the CNC equipment's numerical control and non-uniform data communication. Nevertheless, when applied to individual machines, the machining load fluctuation is less and more stable compared to existing master NC codes, and in most cases, it enables improved productivity through reduced machining time compared to conventional methods.

[0047] In addition, an exemplary embodiment of a system configuration for implementing the above invention is shown in [Fig. 3]. Segmentation is performed to map the respective data in the NC code processing unit of A-ⓐ and the actual machining data processing unit of A-ⓑ. Then, mapping between the NC code and the actual machining data is performed in B, and setting and adjusting the machining load for each machining position is performed in C based on the actual machining load. Next, in D, the data in which the machining path and the actual machining load are matched is corrected and converted into an NC code.

[0048]

[0049] The explanation will focus on [Fig. 1]. (b) is data provided by actual machining, and (c) is data provided from a machining path generated by an NC code. Furthermore, (a) is data generated by the present invention. Specifically, (b) is actual machining data acquired by an edge device, etc., and includes the actual machining position and machining load. (c) is a machining path or NC code and includes the machining position and feed rate that give commands to the CNC. Although actual machining is performed according to the commands in (c), the actual machining state is implemented differently depending on the CNC control characteristics and the physical condition of the equipment. Accordingly, in order to perform optimal machining by considering the machining load characteristics for each piece of equipment, a method is used to combine the actual machining data of (b) and the machining path of (c).

[0050] First, in (b), the interval between actual machining positions and the machining load of those machining positions are calculated using actual machining data. When dividing the NC code in (c), the average value of the intervals is utilized to divide the code into equal intervals for efficient division of the NC code and the generation of new optimized NC codes. Consequently, the machining positions in (b) and (c) become mismatched, and since the actual machining load cannot be determined for the mismatched machining positions, the machining position mapping and the machining load for the mapped machining positions are calculated and utilized according to the [Specific details for implementing the invention] above. The optimal feed rate is calculated for the machining load by utilizing the machining load and feed rate map. As shown in [Fig. 1], the machining process can be performed at the optimal feed rate for each machining section. For example, in the RCL(i) ~ RCL(i+1) interval, a machining process state with a commanded feed rate of 1000 and an actual feed rate of 950 as in (b) can be improved to an actual feed rate of 980 as in (c). This is possible because the optimal machining load OSL(i) in (c) is smaller than the RSL(i) in (b), allowing the feed rate to be increased. Then, the data in (a), including the above machining position and final feed rate, is converted into NC code and used as a new master NC code, etc.

[0051]

[0052] The present invention has industrial applicability as it improves productivity by presenting a method to correct NC codes by applying an optimal feed rate based on the actual machining load that varies for each piece of equipment, by mapping the actual machining load of each piece of equipment to a machining path or master NC code generated in CAM.

Claims

1. An NC code processing unit that generates a machining path through NC code, segments the machining path according to geometric shape, and derives segment intervals, Actual processing data processing unit that acquires data generated during the actual processing process and uses it to calculate segmented processing intervals, A data mapping unit that maps the machining path data of the NC code processing unit and the actual machining data of the actual machining data processing unit, A machining load setting and adjustment unit that sets and adjusts the machining load for each machining position based on the actual machining load, Characterized by calculating the optimal feed rate based on the above-mentioned set and adjusted processing load, and correcting and converting the NC code by reflecting this. Optimal feed rate calculation system based on actual machining load utilizing machining path of NC code and actual machining data.

2. The method for calculating the optimal feed rate based on the actual processing load of the optimal feed rate calculation system of Paragraph 1 is, A step of generating a machining path from NC code for shape machining from a CAM solution; A step of segmenting the above processing path into equal intervals; A step of classifying the processing positions based on the geometric shape by segmenting the above processing path; Step of acquiring actual machining data for each CNC machine; A step of segmenting according to the processing interval calculated through the above-mentioned acquired processing data; A step of extracting the actual feed rate and actual processing load for each processing position obtained from the above actual processing; A step of mapping the nearest machining position on a machining path that is close to the machining position in the actual machining data, wherein the mapping is performed based on the nearest machining position; A step of adjusting the machining load of the mapped machining position by f(RSL); A step of calculating the optimal feed rate based on the above-mentioned adjusted processing load; A method for calculating an optimal feed rate based on actual machining load, characterized by utilizing a CNC machining path and actual machining data, comprising the step of generating a machining path including the mapped machining position and the calculated optimal feed rate and converting it into an optimal NC code.

3. In Paragraph 2, The step of adjusting the machining load of the mapped machining position by f(RSL) is: Linear interpolation is performed on the machining loads of the segmented section including the nearest machining position to obtain the machining load at the nearest machining position, wherein the machining load RSL(i)_adj at the nearest machining position is calculated by the following formula, and A method for calculating an optimal feed rate based on actual machining load using a CNC machining path and actual machining data, characterized by obtaining an adjusted optimal machining load OSL(i) at each machining position based on the machining load of the nearest machining position calculated by the above formula.

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