Automatic loading and unloading device and method for numerical control machine tool

Abstract

The present invention belongs to the field of automatic control of conveyor belts, and specifically relates to an automatic loading and unloading device and method for CNC machine tools. Automatic loading and unloading of CNC machine tools is realized by using loading and unloading conveyor belts in conjunction with robots, and parts in different positions are positioned and detected by using sawtooth limit devices and proximity switches. Compared with vision-based detection and positioning devices, this part position detection device has low cost and high reliability. Interactions between conveyor belts, robots and machine tools are realized by using I / O terminals, and distribution of parts on the loading conveyor belt is detected by using weight sensors. The running speed of the loading conveyor belt is adjusted according to a fuzzy logic reasoning algorithm. Due to the imperfections in the reasoning rules of fuzzy logic reasoning, the speed of the loading conveyor belt obtained by fuzzy reasoning is corrected according to a correction formula to realize efficient operation of the loading conveyor belt. The present invention realizes the automation of loading and unloading of CNC machine tools, saves manpower, has low system cost, can improve production efficiency, and is suitable for industrial production.

Description

Technical Field

[0001] The invention belongs to the field of automatic control of conveyor belts, and relates to the technical field of an automatic loading and unloading device and method for a numerically controlled machine tool. Background Art

[0002] CNC machine tools are program-controlled automated machine tools. Various control signals are sent by computers or human-machine interface operators. The movements of the machine tools are controlled by programs. Parts are automatically processed according to the shapes and sizes required by the drawings. CNC machine tools play an important role in the construction of national economic modernization. When using CNC machine tools to process parts, it is usually necessary to manually load the parts, put the parts into the machine tool, and then start the CNC machine tool to start processing. After the parts are processed, they are manually taken out and enter the next operation link. This operation is not only inefficient, but also requires workers to perform repeated operations of putting in and taking out without stopping during batch processing. The conveyor belt is a conveyor system with a load-bearing belt for mechanized and automated material handling systems. The conveyor belt consists of two or more pulleys, and the belt rotates around the pulley to form a closed loop. The pulley is driven by an electric motor. Two conveyor belts can be used to realize automatic loading and unloading of CNC machine tools. The loading conveyor belt is responsible for transporting raw parts, and the unloading conveyor belt is responsible for transporting finished parts to the next processing link. The robot takes parts from the loading conveyor belt and stacks the processed parts on the unloading conveyor belt. The transmission belt control part controls the automatic operation of the loading and unloading conveyor belts and interacts with the robot to complete the automatic loading and unloading of the machine tool.

[0003] Therefore, designing an automatic loading and unloading device for CNC machine tools and its method has great practical application value for improving processing efficiency, reducing production costs, and improving the reliability of device operation. Summary of the invention

[0004] The technical problem to be solved by the present invention is to design an automatic loading and unloading device and method for CNC machine tools to improve the processing efficiency and save labor costs in view of the low processing efficiency caused by manually operating CNC machine tools to process parts in batches.

[0005] The technical solution adopted by the present invention is: designing an automatic loading and unloading device for CNC machine tools and a method thereof. The whole device consists of a loading conveyor belt, a unloading conveyor belt, a conveyor belt control part, a robot and a CNC machine tool. The loading conveyor belt conveys the parts to be processed, and the unloading conveyor belt conveys the finished parts after processing. A weight sensor is installed at the bottom of the loading conveyor belt to detect the number of parts on the loading conveyor belt and adjust the running speed of the loading conveyor belt in real time to improve production efficiency. The conveyor control part controls the automatic operation of the loading and unloading conveyor belts, and uses the I / O terminals to realize the interaction between the conveyor belt and the robot. The position of the parts detected by the proximity switch is sent to the robot so that the robot can grab the parts. After the parts are processed, the robot will stack the parts on the unloading conveyor belt; the robot is responsible for the picking and placing of parts, and interacts with the conveyor belt and the CNC machine tool. The robot can control the start and stop of the CNC machine tool, and send a processing completion signal to the robot after the CNC machine tool is processed; the CNC machine tool is responsible for the processing of parts. One or more CNC machine tools can be set up, each machine tool completes a process, and the CNC machine tool only interacts with the robot. The entire processing process does not require human participation and realizes fully automatic operation.

[0006] The purpose of the present invention is to design an automatic loading and unloading device and method for a CNC machine tool, which uses a proximity switch sensor to detect the position of parts, uses I / O terminals to realize the interaction between a conveyor belt, a robot and a machine tool, and uses a weight sensor to automatically adjust the speed of the loading conveyor belt, thereby realizing the automatic loading and unloading function of the CNC machine tool, improving processing efficiency, and having good practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is the overall block diagram of the device.

[0008] Figure 2 This is the schematic diagram of the feeding position detection.

[0009] Figure 3 It is a fuzzy logic reasoning structure diagram.

[0010] exist Figure 1 and Figure 2 Included are:

[0011] 1-1 Loading conveyor belt, 1-2 Unloading conveyor belt, 1-3 Conveyor belt control part, 1-4 Robot, 1-5 CNC machine tool 1, 1-6 CNC machine tool 2, 1-7 CNC machine tool 3

[0012] 2-1 Sawtooth limit device, 2-2 Proximity switch DETAILED DESCRIPTION

[0013] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0014] The overall block diagram of the device of the present invention is as follows Figure 1As shown, it is composed of 1-1 loading conveyor belt, 1-2 unloading conveyor belt, 1-3 conveyor belt control part, 1-4 robot, 1-5 CNC machine tool 1, 1-6 CNC machine tool 2 and 1-7 CNC machine tool 3. The conveyor belt control part 1-3 interacts with the robot 1-4 through I / O terminals, and the robot 1-4 also interacts with the three CNC machine tools through I / O terminals.

[0015] The conveyor has two operation modes: manual and automatic. In the manual mode, the forward and backward movement of the loading and unloading conveyor can be manually controlled by the forward or backward buttons of the loading and unloading conveyor. The manual mode is generally used in the debugging stage of the device. In the automatic operation mode, the 1-1 loading conveyor is used to place the parts to be processed. The parts can be arranged in 9 rows on the 1-1 loading conveyor. The 9 rows of parts move along the forward direction of the 1-1 loading conveyor. The head end of the 1-1 loading conveyor is equipped with a 2-1 sawtooth limit device. The 2-1 sawtooth limit device is equipped with 9 2-2 proximity switch sensors. The 2-2 proximity switch is used to detect whether there are parts transported to the head end of the 1-1 loading conveyor. When the parts are transported to the head end of the 1-1 loading conveyor, the 2-1 sawtooth limit device prevents the parts from continuing to move forward. The 2-2 proximity switch detects the parts and transmits the signal to the 1-3 conveyor control part, and the 1-3 conveyor control part immediately stops the operation of the 1-1 loading conveyor. The 4 output terminals of the 1-3 conveyor belt control part are wired to the input terminals of the 1-4 robot. These 4 signals send part position signals to the 1-4 robot in the form of binary coding. The numbers 1 to 9 respectively indicate which position has parts for the robot to grab. Sending 0 means that there are no parts in any of the 9 positions. At this time, the 1-4 robot cannot grab. If there are parts in multiple positions, the position number with the smallest number is sent. The 2 output terminals of the 1-4 robot are wired to the input terminals of the 1-3 conveyor belt control part. The 1-4 robot sends the Ready and Step signals to the conveyor belt with the help of these two output terminals. In the process of grabbing parts, the 1-1 feeding conveyor belt is not allowed to move in order to prevent collision. Only when the 1-4 robot grabs the parts to a certain height, the Ready signal is set to a high level, and the 1-1 feeding conveyor belt is allowed to continue to move forward and load when there are no parts in any of the 9 positions. After the 1-2 unloading conveyor belt is filled with 9 rows of processed parts, the 1-4 robot sends a Step pulse signal to the 1-3 conveyor belt control part. The 1-3 conveyor belt control part controls the 1-2 unloading conveyor belt to step a certain distance to leave space for stacking the next row of parts. A proximity switch is installed at the tail end of the 1-2 unloading conveyor belt. This proximity switch is used to detect whether the 1-2 unloading conveyor belt is full of parts. If it is full, the 1-3 conveyor belt control part stops the movement of the unloading and loading conveyor belts and controls the sound and light alarm to alarm.

[0016] The 1-4 robot uses the teaching method to record the position coordinates of 9 parts. The 1-3 conveyor belt control part only needs to send the position numbers 1 to 9 to the 1-4 robot, and the 1-4 robot can accurately grab the parts at different positions according to the recorded position coordinates. The 1-3 conveyor belt control part uses the 2-1 sawtooth limit device and the 2-2 proximity switch to locate and detect parts at different positions. Compared with the detection and positioning device based on the visual sensor, this device has low cost, strong practicality and high reliability. The 1-4 robot grabs the parts from the 1-1 feeding conveyor belt and puts them into the 1-5 CNC machine tool 1, and starts the 1-5 CNC machine tool 1 to run the processing. The three CNC machine tools are responsible for the processing of the parts. According to the requirements of the part processing process, one or more CNC machine tools can be set up. Each machine tool completes a process, and each CNC machine tool only interacts with the 1-4 robot. There are two air grippers at the end of the 1-4 robot, and the positions of the two air grippers are controlled by the rotation of the motor. After each CNC machine tool is processed, a processing completion signal is sent to the 1-4 robot. The 1-4 robot uses one air gripper to take the part out of a CNC machine tool, and uses another air gripper to put the part to be processed, and starts the CNC machine tool. The taken-out parts are ready to be put into the next CNC machine tool, and the processing is carried out in this order until the last CNC machine tool is processed. The 1-4 robot takes out the parts and stacks them in a row of 9 in sequence on the 1-2 unloading conveyor belt. After each row of parts is stacked, the 1-2 unloading conveyor belt is controlled to step a certain distance. After the 1-4 robot stacks the parts on the 1-2 unloading conveyor belt, it returns to the 1-1 loading conveyor belt to grab the parts to be processed. The use of two air grippers to grab and place can greatly improve the processing efficiency. The entire processing process does not require human participation and can achieve fully automatic operation.

[0017] The 1-3 conveyor belt control part and the 1-4 robot, as well as the 1-4 robot and the CNC machine tool, all interact using I / O terminals. Compared with RS485 communication or Ethernet communication, the interaction using I / O terminals does not require a special hardware communication interface and communication cable, avoiding complex network communication programming. In addition, the I / O signals are all isolated by relays and photoelectric isolation. Each signal line only transmits high and low level signals, which improves the anti-interference ability and ensures the reliability of the interaction.

[0018] The feeding speed of the 1-1 feeding conveyor belt should be adjusted in time according to the number and distribution of parts on the 1-1 feeding conveyor belt. For example, when there are no parts or fewer parts at the head of the 1-1 feeding conveyor belt, the 1-1 feeding conveyor belt should feed at a faster speed to improve production efficiency; when there are more parts at the head, middle and tail of the 1-1 feeding conveyor belt, the 1-1 feeding conveyor belt should feed at a lower speed to prevent the accumulation and collision of parts at the head of the 1-1 feeding conveyor belt; when there are too many and overweight parts on the 1-1 feeding conveyor belt, the motor cannot drive the 1-1 conveyor belt to run, or when there are no parts on the 1-1 feeding conveyor belt, the operation of the 1-1 feeding conveyor belt should be stopped and an alarm should be issued. In order to be able to adjust the running speed of the 1-1 feeding conveyor belt in time, weight sensors are installed at the head, middle and tail of the 1-1 feeding conveyor belt to detect the number of parts at the head, middle and tail of the 1-1 feeding conveyor belt. The output signal of the weight sensor is a 4-20mA current signal, which is input into the 1-3 conveyor belt control part. According to the fuzzy logic reasoning algorithm, the running speed of the 1-1 feeding conveyor belt is adjusted. The output signals of the weight sensors at the head, middle and tail of the 1-1 feeding conveyor belt are g 1 , g 2 and g 3 , the speed of the 1-1 feeding conveyor is determined by using the fuzzy logic inference algorithm. The input language variable of the fuzzy logic inference is g 1 , g 2 and g 3 ; Output language variable is 1-1 feeding conveyor belt running speed V f , the fuzzy logic reasoning structure is as follows Figure 3 As shown. The input and output language variables are fuzzified using the triangular membership function. The fuzzy rules are determined based on the operator's control experience. The fuzzy logic decision method uses the Mamdani maximum and minimum reasoning method, and the precision method uses the center of gravity method. Due to the imperfection of the reasoning rules of fuzzy logic reasoning, the speed V of the 1-1 feeding conveyor belt is obtained by reasoning. f It needs to be corrected according to formula (1):

[0019]

[0020] Where exp() is an exponential function with the natural constant e as the base, a is the speed adjustment coefficient, which is generally 1, V max The maximum speed allowed for the 1-1 feeding conveyor belt, V c is the corrected speed. According to formula (2), the running speed V of the 1-1 feeding conveyor belt is determined r :

[0021]

[0022] Where Vmin This is the minimum speed allowed for the 1-1 feeding conveyor. The purpose of setting the minimum speed is to avoid the conveyor motor creeping at a lower speed.

[0023] The advantages of the present invention are that the automatic loading and unloading of CNC machine tools is realized by using conveyor belts and robots, the positions of parts of 1-1 feeding conveyor belt are detected by using 2-1 sawtooth limit devices and 2-2 proximity switches, I / O interaction is adopted between 1-3 conveyor belt control parts and 1-4 robots, and between CNC machine tools and 1-4 robots, and fuzzy logic reasoning is used to realize real-time adjustment of the speed of 1-1 feeding conveyor belt. The present invention realizes the automation of machine tool parts processing, saves manpower, has low system cost, simple programming, improves production efficiency, and is suitable for industrial production.

Claims

1. A method for automatic loading and unloading of CNC machine tools, characterized in that: The whole device consists of a loading conveyor belt, a unloading conveyor belt, a conveyor belt control part, a robot and a CNC machine tool. The loading conveyor belt conveys the parts to be processed, and the unloading conveyor belt conveys the finished parts. A weight sensor is installed at the bottom of the loading conveyor belt to detect the number of parts on the loading conveyor belt and adjust the running speed of the loading conveyor belt in real time to improve production efficiency. The conveyor belt control part controls the automatic operation of the loading and unloading conveyor belts, and uses the I / O terminals to realize the interaction between the conveyor belt and the robot, and sends the part position detected by the proximity switch to the robot so that the robot can grab the parts. After the parts are processed, the robot stacks the parts on the unloading conveyor belt; the robot is responsible for the picking and placing operations of the parts, and interacts with the conveyor belt and the CNC machine tool. The robot controls the start and stop of the CNC machine tool, and sends a processing completion signal to the robot after the CNC machine tool completes the processing; the CNC machine tool is responsible for the processing of the parts. One or more CNC machine tools are set up, and each machine tool completes a process. The CNC machine tool only interacts with the robot; the robot uses the teaching method to record the position coordinates of 9 parts. The conveyor belt control part only needs to send the position numbers 1 to 9 to the robot, and the robot accurately grabs the parts at different positions according to the recorded position coordinates; the conveyor belt control part uses the sawtooth limit device and the proximity switch to locate and detect the parts at different positions The feeding speed of the feeding conveyor belt is timely adjusted according to the number and distribution of parts on the conveyor belt. Weight sensors are respectively installed at the head, middle and tail of the feeding conveyor belt to detect the number of parts at the head, middle and tail of the feeding conveyor belt. The output signal of the weight sensor is a 4-20mA current signal, which is input into the conveyor belt control part. According to the fuzzy logic reasoning algorithm, the running speed of the feeding conveyor belt is adjusted; the output signals of the weight sensors at the head, middle and tail of the feeding conveyor belt are g1, g2 and g3 respectively. The speed of the feeding conveyor belt is determined by the fuzzy logic reasoning algorithm. The input language variables of the fuzzy logic reasoning are g1, g2 and g3, and the output language variable is the running speed V of the feeding conveyor belt. f ; The input and output language variables are fuzzified using the triangle membership function, the fuzzy logic decision method uses the Mamdani maximum and minimum reasoning method, and the precision method uses the center of gravity method; Due to the imperfection of the reasoning rules of fuzzy logic reasoning, the speed V of the feeding conveyor belt obtained by reasoning is f It needs to be corrected according to formula (1): Where exp() is an exponential function with the natural constant e as the base, a is the speed adjustment coefficient, which is 1, V max V is the maximum speed allowed by the feeding conveyor belt. c is the corrected speed. According to formula (2), the running speed V of the feeding conveyor belt is determined r : Where V min The minimum speed allowed for the loading conveyor. The purpose of setting the minimum speed is to avoid the conveyor motor creeping at a lower speed.

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