Finish-milling machining method for metal mold
By monitoring the workpiece's reference edge and the finished surface, and dynamically adjusting the machining coordinate system and milling parameters, the problems of coordinate system offset and vibration instability in the precision milling of metal molds were solved, thus achieving high-precision metal mold machining.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GUANGDONG LONGGUANG MOLD STEEL IND CO LTD
- Filing Date
- 2026-03-20
- Publication Date
- 2026-05-12
AI Technical Summary
Existing precision milling processes for metal molds suffer from problems such as sudden changes in cutting force, tool deformation, and vibration instability caused by shifts in the machining coordinate system. Furthermore, traditional devices struggle to effectively collect metal chips.
By monitoring the workpiece reference edge and the finishing surface, the machining coordinate system is dynamically corrected. Combined with the monitoring of cutting force, vibration, temperature and cutting fluid turbidity, the milling depth and feed rate are adjusted in real time to achieve high precision in finish milling.
It effectively reduces coordinate system offset and vibration instability during machining, improves the accuracy of precision milling, and avoids dimensional deviations caused by thermal deformation and lubrication failure.
Smart Images
Figure CN122007972A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of metal mold technology, and specifically relates to a precision milling method for metal molds. Background Technology
[0002] The processing of metal molds typically involves the following steps: initial cutting of raw materials, initial milling, heat treatment, finishing and surface treatment. During the finishing process, the metal mold needs to be precisely milled.
[0003] Traditional milling devices for steel billets have revealed numerous problems in practical applications. During milling, a large amount of metal chips are generated, and some of these chips fly everywhere, making effective collection difficult. To address this, Chinese Patent Publication CN120155592A discloses a milling device and method for steel billet manufacturing. The device includes a main body with a milling cutter on it. A chip-blocking cover moves synchronously with the milling cutter on its outer side. The chip-blocking cover contains cooling pipes for spraying and cooling the milling cutter. Below the milling cutter is an adjustable worktable with a collection tank. The collection tank contains multiple vertically movable and rotatable support plates. A clamp is also provided on the worktable. Multiple spray pipes with spray holes for rinsing the surface of the support plates are located at the bottom of the collection tank. The chip-blocking cover effectively prevents metal chips from flying everywhere during milling, allowing them to be better concentrated on the worktable and fall into the collection tank, achieving automatic chip recovery. The vertically movable and rotatable design of the support plates enables automatic cleaning of metal debris from their surface.
[0004] However, the above solution only involves the removal of debris. The accumulation of reference deviation during the previous machining process will cause the machining coordinate system to shift, which in turn will lead to sudden changes in cutting force, causing core problems such as tool deformation and vibration instability. The milling accuracy is not high. Therefore, a precision milling method for metal molds that can be adjusted according to the error of the previous process and has high milling accuracy is needed. Summary of the Invention
[0005] To address the aforementioned problems in the prior art, this invention provides a precision milling method for metal molds, which features adjustable milling accuracy based on errors in previous processes.
[0006] The objective of this invention can be achieved through the following technical solutions: A method for precision milling a metal mold, comprising the following steps: Step 1: The control module automatically collects points on the workpiece's reference edge and the finished surface through the monitoring module, compares the monitoring data with the CAD drawings, calculates the rotation and translation deviations of the theoretical coordinate system, and dynamically corrects the machining coordinate system based on the deviations. Step 2: The control module monitors the cutting force and vibration through the monitoring module, calculates the comprehensive risk coefficient based on the deviation values of the cutting force and vibration, and executes Step 3 when the comprehensive risk coefficient exceeds the risk coefficient threshold, until completion. When completion, Step 4 is executed. Step 3: Tool Deflection Compensation: The control module adds compensation based on the value of the comprehensive risk coefficient, and at the same time reduces the feed rate within a set time, returning to Step 2; Step 4: Machining Completion Determination and Coordinate System Reset: When all finishing paths have been executed, the control module automatically resets to the initial machining coordinate system; As a preferred technical solution of the present invention, step two further includes: the control module calculates the comprehensive risk coefficient Z based on the deviation values of cutting force F and vibration V, where Z=k1×F / F0+k2×V / V0, k1 and k2 are weighting coefficients, k1+k2=1, and F0 and V0 are the pre-input benchmark thresholds for cutting force and vibration, respectively.
[0007] As a preferred embodiment of the present invention, step three further includes: the control module adds a compensation step value of B units according to the value of the comprehensive risk coefficient Z, where B = Z / Z0 × d, d is the pre-input correction coefficient, and Z0 is the risk coefficient threshold.
[0008] As a preferred technical solution of the present invention, step three further includes: the control module reduces the feed rate during the time period t0 after determining that the comprehensive risk coefficient exceeds the risk coefficient threshold, where t0 = Z / Z0 × t1, and t1 is the preset deceleration duration.
[0009] As a preferred embodiment of the present invention, step two further includes: the control module monitors the temperature through the monitoring module; step three further includes: when the control module determines that the temperature exceeds the threshold, it further reduces the milling depth of the tool.
[0010] As a preferred technical solution of the present invention, when the control module determines that the temperature t exceeds the threshold t0, the milling depth of the tool is reduced by B1 units, where B1 = (t / t0) × e, and e is a preset depth correction coefficient.
[0011] As a preferred embodiment of the present invention, step two further includes: the control module obtains the turbidity of the cutting fluid in the cutting fluid tank through the monitoring module, and further reduces the milling depth of the tool when the turbidity exceeds the threshold.
[0012] As a preferred embodiment of the present invention, step one further includes: inputting the values of t0, F0, V0, Z0, e, d, k1 and k2.
[0013] The beneficial effects of this invention are as follows: (1) By setting up automatic sampling of the workpiece reference edge and the finishing surface, the monitoring data and CAD drawings are compared to calculate the rotation and translation deviation of the theoretical coordinate system. The machining coordinate system is dynamically corrected according to the deviation, so that the problem of tool deformation and vibration instability caused by the deviation of the machining coordinate system in the previous process is mitigated or eliminated, thus improving the accuracy of precision milling. (2) By giving the corresponding tool deflection compensation amount and the time period of reducing feed rate based on the comprehensive risk coefficient derived from cutting force and vibration, the corresponding tool deflection compensation and feed rate control can be automatically triggered according to whether the abnormal working condition occurs and its severity during the machining process, which further improves the accuracy of precision milling. (3) By adjusting the milling depth of the tool according to the temperature and the turbidity of the cutting fluid, the milling depth of a single milling is dynamically adjusted when the temperature is abnormal or the turbidity of the cutting fluid is too high, so as to avoid dimensional deviations caused by thermal deformation and lubrication failure. Attached Figure Description
[0014] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.
[0015] Figure 1 This is a block diagram of the control loop. Detailed Implementation
[0016] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided.
[0017] Please see Figure 1 A method for precision milling a metal mold, comprising the following steps: Step 1: The control module automatically collects points on the workpiece's reference edge and the finished surface through the monitoring module, compares the monitoring data with the CAD drawings, calculates the rotation and translation deviations of the theoretical coordinate system, and dynamically corrects the machining coordinate system based on the deviations. Specifically, the control module is electrically connected to the monitoring module. The monitoring module includes at least a temperature sensor, a vibration sensor, a pressure sensor, and a turbidity sensor. The sensing module also includes sensors for automatically sampling points on the workpiece reference edge and the finishing surface. After the control module collects the point coordinate data of the current workpiece, it compares the point coordinate data with the theoretical coordinates of the corresponding reference edge and finishing surface in the CAD drawing, calculates the translation amount of each surface to be processed, and then automatically inserts the translation correction amount into the pre-input processing program. In step one, the control module is input with the values of t0, F0, V0, e, d, k1, and k2; Step 2: The control module monitors the cutting force and vibration through the monitoring module, calculates the comprehensive risk coefficient based on the deviation values of the cutting force and vibration, and executes Step 3 when the comprehensive risk coefficient exceeds the risk coefficient threshold. This process continues until completion, at which point Step 4 is executed. Specifically, in step two, the control module calculates the comprehensive risk coefficient Z based on the deviation values of cutting force F and vibration V, where Z = k1 × F / F0 + k2 × V / V0, k1 and k2 are weighting coefficients, k1 + k2 = 1, and F0 and V0 are the pre-input benchmark thresholds for cutting force and vibration, respectively. When one or both of F or V are large, the Z value will be significantly increased. Therefore, the overall risk coefficient is positively correlated with the actual risk. The cutting force is sensed by a piezoelectric triaxial force sensor to collect force components, and the vibration signal is collected by an accelerometer, processed and uploaded to the control module. Step 3: Tool Deflection Compensation: The control module adds compensation based on the value of the comprehensive risk coefficient, and at the same time reduces the feed rate within a set time, returning to Step 2; In this embodiment, the tool finger is used to reduce the milling depth; The control module adds a compensation step value of B units based on the value of the comprehensive risk coefficient Z, where B = Z / Z0 × d, d is the pre-input correction coefficient, and Z0 is the risk coefficient threshold. When Z is larger, it means that the required amount of tool deflection compensation is greater. At this time, the larger the B value, the more significant the corresponding amount of tool deflection compensation. Meanwhile, the control module reduces the feed rate within the time period t0 after determining that the comprehensive risk coefficient exceeds the risk coefficient threshold, where t0 = Z / Z0 × t1, and t1 is the preset deceleration duration. At this time, the larger the comprehensive risk coefficient Z is, the longer the deceleration duration is to ensure safety, while the smaller the comprehensive risk coefficient is, the shorter the deceleration duration is to reduce the impact on efficiency, thus achieving a balance between dynamic response and efficiency. In this embodiment, the compensation step value is 0.01mm-0.03mm; Step 4: Machining Completion Determination and Coordinate System Reset: When all finishing paths have been executed, the control module automatically resets to the initial machining coordinate system; By setting up automatic point sampling of the workpiece reference edge and the finishing surface, comparing the monitoring data with the CAD drawings, calculating the rotation and translation deviation of the theoretical coordinate system, and dynamically correcting the machining coordinate system based on the deviation, the problem of the machining coordinate system shift in the previous process, which leads to sudden changes in cutting force causing tool deformation and vibration instability, is mitigated or eliminated, thus improving the accuracy of precision milling. In the above process, when the temperature is abnormal, it means that there is an abnormality in the processing, such as local deviation in the hardness of the mold material or local abnormal shape. In this case, it is necessary to reduce the depth of cut or the milling depth. Therefore, step two also includes: the control module monitors the temperature through the monitoring module; step three also includes: when the control module determines that the temperature exceeds the threshold, it further reduces the milling depth of the tool. In this embodiment, temperature monitoring uses an embedded thermocouple to collect the temperature of the contact area between the tool and the workpiece in real time. Reducing the depth of cut means moving the tool further away from the metal mold; Because the temperature decreases the milling depth in step three, the control module instructs the tool to perform milling again to compensate for the dimensional deviation caused by moving away from the metal mold. Specifically, when the control module determines that the temperature t exceeds the threshold t0, the milling depth of the tool is reduced by B1 units, where B1 = (t / t0) × e, and e is a preset depth correction coefficient; Meanwhile, when the temperature is too high, the cutting fluid will deteriorate and become turbid. A single temperature sensing method may not be able to accurately monitor the temperature alone. In order to introduce more monitoring signals, the control module simultaneously collects the turbidity of the cutting fluid, which is output in real time by an optical turbidity sensor installed in the coolant circuit. When the turbidity exceeds the threshold, the milling depth of the tool is further reduced. By adjusting the milling depth of the tool based on temperature and cutting fluid turbidity, the milling depth of a single milling operation can be dynamically adjusted when the temperature is abnormal or the cutting fluid becomes too turbid due to excessive temperature, thus avoiding dimensional deviations caused by thermal deformation and lubrication failure.
[0018] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.
Claims
1. A method for precision milling a metal mold, characterized in that: Includes the following steps: Step 1: The control module automatically collects points on the workpiece's reference edge and the finished surface through the monitoring module, compares the monitoring data with the CAD drawings, calculates the rotation and translation deviations of the theoretical coordinate system, and dynamically corrects the machining coordinate system based on the deviations. Step 2: The control module monitors the cutting force and vibration through the monitoring module, calculates the comprehensive risk coefficient based on the deviation values of the cutting force and vibration, and executes Step 3 when the comprehensive risk coefficient exceeds the risk coefficient threshold, until completion. When completion, Step 4 is executed. Step 3: Tool Deflection Compensation: The control module adds compensation based on the value of the comprehensive risk coefficient, and at the same time reduces the feed rate within a set time, returning to Step 2; Step 4: Machining Completion Judgment and Coordinate System Reset: When all finishing paths have been executed, the control module automatically resets to the initial machining coordinate system.
2. The precision milling method for a metal mold according to claim 1, characterized in that: Step two further includes: the control module calculates the comprehensive risk coefficient Z based on the deviation values of cutting force F and vibration V, where Z = k1 × F / F0 + k2 × V / V0, k1 and k2 are weighting coefficients, k1 + k2 = 1, and F0 and V0 are the pre-input benchmark thresholds for cutting force and vibration, respectively.
3. The precision milling method for a metal mold according to claim 2, characterized in that: Step three further includes: the control module adds a compensation step value of B units based on the value of the comprehensive risk coefficient Z, where B = Z / Z0 × d, d is the pre-input correction coefficient, and Z0 is the risk coefficient threshold.
4. The precision milling method for a metal mold according to claim 1, characterized in that: Step three further includes: the control module reduces the feed rate during the time period t0 after determining that the comprehensive risk coefficient exceeds the risk coefficient threshold, where t0 = Z / Z0 × t1, and t1 is the preset deceleration duration.
5. The precision milling method for a metal mold according to claim 4, characterized in that: Step two further includes: the control module monitors the temperature through the monitoring module; Step three further includes: when the control module determines that the temperature exceeds the threshold, it further reduces the milling depth of the tool.
6. The precision milling method for a metal mold according to claim 5, characterized in that: When the control module determines that the temperature t exceeds the threshold t0, it reduces the milling depth of the tool by B1 units, where B1 = (t / t0) × e, and e is the preset depth correction coefficient.
7. The precision milling method for a metal mold according to claim 1, characterized in that: Step two further includes: the control module obtains the turbidity of the cutting fluid in the cutting fluid tank through the monitoring module, and further reduces the milling depth of the tool when the turbidity exceeds the threshold.
8. The precision milling method for a metal mold according to claim 1, characterized in that: Step one also includes: inputting the values of t0, F0, V0, Z0, e, d, k1, and k2.