JPH07246552A - Burr grinding method by robot - Google Patents

Abstract

PURPOSE:To improve the finish accuracy of forming a burr, by calculating the smallest square infer value by a specific formula by using the residual burr heights at the i-1 number operation and at the i number operation, and the pressing force, in a grinding operation, applying the infer value to a specific formula, and setting the pressing force instruction value of the i number operation within the scope of a tolerable pressing force. CONSTITUTION:The pressing force of a grinder 3 to a work 5 is controlled by the pressing force control device 2 of a robot 1, and the work 5 is ground from the starting point to the finishing point. In this case, the residual burr heights hi-i (s) and hi (s) in the grinding condition at the i-1 number and the i number are measured by a burr height measuring sensor 4. And the residual burr heights hi-i (s) and hi (s), and the pressing force fi (s) and the feed speed V0 at that time are applied in the formula I, so as to calculate the smallest square infer value K. And the smallest aquare infer value K is applied to the formula IC, so as to determine the pressing force instruction value fi+1 (s) in the grinding at the i+1 number within the scope of a tolerable pressing force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic flash grinding method using an articulated robot or the like.

[0002]

2. Description of the Related Art In a flash grinding method by a robot,
In order to ensure high finishing accuracy, a sensor that measures the flash height is essential. However, it is often impossible to measure the height of the flash in real time during grinding due to a mounting problem of the grinder and the sensor, a vibration problem during grinding, and the like.

Therefore, in the current technology, a method is adopted in which the measuring operation for measuring the residual flash height and the shaving operation are alternately repeated separately, and the processing is finished when the desired finishing accuracy is obtained. In this method, it is important to set the two work parameters, that is, the grinder feed speed and the grinder pressing force at the time of the shaving operation, to desired values according to the situation of the tool, the work and the like.

[0004]

If the grinder feeding speed is too low or the grinder pressing force is too large, the problem arises that the base material surface is damaged due to excessive cutting. On the other hand, if the grinder feed speed is too high or the grinder pressing force is too small, the grinding efficiency is low, the number of repetitions is large, and the work time is long.

A typical example of the conventional method using the above method is as follows.
Masayuki Ichinohhe et al., “Dvelo
moment of deburring robot
for cast iron with vision
and force sensing ", Proc.
References of of 24th ISIR, p49, 1993 are mentioned. In the method according to this document, a huge amount of familiar operation is performed for each work material and each tool, and a desired work parameter is determined based on the result.

However, this method has a problem that it is necessary to repeat a preliminary experiment with a change of a work or a tool, and the working time as a whole becomes long. Also, due to the clogging of the tool, the grinding ability is reduced, etc.
There is a problem that it is difficult to deal with the factors that change with each repetition.

The present invention has been made in view of the above problems, and the deburring work with high finishing accuracy can be achieved in a short time by the system acquiring desired work parameters by itself without relying on an enormous experiment database of proficiency operation It is an object of the present invention to provide a flash grinding method by a robot capable of executing.

[0008]

That is, according to the present invention, a robot having a sensor for measuring the height of flash and a grinder for grinding the flash is used, and the line on which the flash exists and the intersection of the base metal surface. An arbitrary point is represented by a travel parameter s from the grinding start point along the intersection line, and a measurement operation for measuring the residual flash height along the parameter and a cutting operation with a constant feed speed v ₀ are separately performed. And repeats alternately,
In a flash grinding method by a robot in which the pressing force is variable, the residual flash height h _i-1 due to the i-1th operation
(S) and the residual flash height h _i (s) at the i-th operation
And a pressing force f _i (s), the first step of calculating the least square estimated value k represented by the above equation (1), and i
Pressing force command value f in + 1st grinding operation
The second step of setting _{i + 1} (s) to the above equation (2) within a range that does not exceed the allowable pressing force f _max .

Further, the present invention uses a robot having a sensor for measuring the height of the flash and a grinder for cutting the flash to determine an arbitrary point on the intersection of the line where the flash is present and the base metal surface. The feed rate v is expressed by the distance parameter s from the grinding start point along the line, and the measurement operation of measuring the residual flash height along the parameter and the scraping operation by the pressing force f are repeated separately and alternately. In the flash grinding method using a variable robot, the residual flash height h _i-1 (s) in the i−1th motion, the residual flash height h _i (s) in the i-th motion, and the feed speed v _{Using i} (s),
Estimated least squares value k'for k expressed by the above equation (3)
The feed rate command value v _{i + 1} (s) in the first step of calculating
_A second step of setting the above equation (4) within a range that does not exceed _max and the minimum allowable speed v _min .

[0010]

In the flash grinding method using the robot according to the present invention, in the operation of alternately repeating the measurement operation for measuring the residual flash height and the cutting operation, a vast amount of prior skill is required for determining the conventional work parameters. While it requires operation and does not have an online learning function, it has a learning function that changes the next work parameter from the previous operation result to a desired value online.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2A is a diagram showing an example of a flash grinding robot for executing the flash grinding method of the present invention.

A pressing force control device 2 is attached to the tip of the arm portion of the deburring robot body 1. A grinder 3 as a grinding tool is provided below the pressing force control device 2. Further, the pressing force control device 2 is provided with a flash height measuring sensor in the vicinity thereof.

FIG. 2B is a diagram schematically showing a working situation by the flash grinding robot shown in FIG. In the figure,
The reference number 5 represents the work to be deburred. Next, a flash grinding robot as shown in FIG.
The work shown in FIG. 3B will be described as an example.

When an arbitrary point on the line of intersection between the flash and the base metal is represented by a road parameter s from the grinding start point along the line of intersection, the height of the flash is expressed by a function h (s) of s. Can be represented. The purpose of the work is to finish with the desired precision e in all the sections without damaging the base material. That is, 0 ≦ h (s) ≦ e for all s.

FIG. 3 is an enlarged view of the work portion of FIG. 2B, and the base material surface is represented by a straight line for simplification.
In the case of a general curve, h (s) is defined by the height at the point s in the normal direction to the base metal surface.

Next, a deburring method using the flash grinding robot having the above construction will be described. Generally, the flash height Δh (s) and the feed rate v that are ground in one grinding operation
(S) and the pressing force f (s) approximately have the following relationship.

[0017]

[Equation 5]

Here, k is a constant that varies depending on the material of the work, the width of the flash, the state of the tool, etc. The larger this value, the higher the grinding efficiency. The major feature of this method is that this k is estimated for each repeated operation and reflected in the next cutting operation. It is also assumed that the maximum allowable speed v _max , the minimum allowable speed v _min , and the maximum allowable pressing force f _max are given depending on the tool and the work.

Based on the above assumption, the operation of the embodiment is carried out by the procedure shown in the flowchart of FIG. First, an appropriate feed speed v ₀ (v _min <v ₀ <v _max ) is set. Then, along the parameter s, step S
At 1, the initial flash height h ₀ (s) is measured. In step S2, i = 1 is set, and the initial cutting operation is performed at an appropriate f _i (s) <f _max .

Next, in step S3, the residual flash height h _i
(S) is measured. Then, in step S4, i-
Using remaining Beam according first operating height h _i-1 and (s), in the remaining beams in the i-th operation height h _i (s) is the pressing actual value f _i (s), the expression (1) The least squares estimation value k represented by is calculated.

Here, in step S5, it is judged whether or not the residual flash height h _i (s) is larger than e. h _i
If (s)> e, the process proceeds to step S6 and f _{i + 1}
It is determined whether (s) is greater than or equal to the maximum allowable pressing force f _max . When the maximum allowable pressing force f _max or more, the process proceeds to step S7, and pressing is performed with f _{i + 1} (s) = f _max . On the other hand, when it is smaller than the maximum allowable pressing force f _max , the process proceeds to step S8, where h _i (s)> e,

[0022]

[Equation 6] Is commanded as the pressing force.

When the pressing force is determined in steps S7 and S8, the scraping operation is performed in step S9. On the other hand, in step S5, h _i (s) ≦
If it is e, the process proceeds to step S10 and this h _i
In the section of (s) ≦ e, f _{i + 1} (s) = 0, v _{i + 1}
With (s) = v _max , the process proceeds to step S11 without grinding.

In step S11, the residual flash height h _{i + 1}
(S) is measured. Then, in step S12, if h _{i + 1} (s) ≦ e for all s, the process ends. If not, i = i + 1 is set and the process returns to step S4.

As described above, the constant k is re-estimated for each repetitive operation and reflected in the next shaving operation, so that it is possible to perform a fine work according to the grinding efficiency. Next, a second embodiment of the present invention will be described.

The assumption based on the above equation (5) is the same as that of the first embodiment. Hereinafter, with reference to the flowchart of FIG.
The operation of the second embodiment will be described. First, an appropriate pressing force f = f ₀ (0 <f ₀ <f _max ) is set. Then, along with the parameter s, the initial flash height h ₀ (s) is measured in step S21. In step S22,
With i = 1, the initial cutting operation is performed at an appropriate v _min <v _i (s) <v _max .

Next, in step S23, the residual flash height h
_i (s) is measured. Then, in step S24,
The residual flash height h _i-1 (s) due to the ( _i-1 ) th operation, and i
Using the residual flash height h _i (s) and the actual feed rate v _i (s) in the th motion, the least square estimated value k ′ for k expressed by the above equation (3) is calculated.

Here, in step S25, it is determined whether the residual flash height h _i (s) is greater than e. h _i
If (s)> e, the process proceeds to step S26, where h _i
In the section where (s)> e, it is determined whether or not v _{i + 1} (s) is equal to or higher than the maximum allowable feed speed v _max . When the maximum permissible feed speed v _max or more, the process proceeds to step S27, where v
_{i + 1} (s) = v _max, and in step S31

[0029]

[Equation 7] It is ground with a pressing force.

In step S26, v _{i + 1} (s)
Is smaller than the maximum permissible feed speed v _max , it is determined in the following step S28 whether or not the permissible feed speed v _{min is} equal to or less than the minimum permissible speed v _min . Here, when the speed is equal to or lower than the minimum allowable speed v _min , the process proceeds to step S29, and v _{i + 1} (s) = v _min is sent. Then, in steps S26 and S28, if the maximum allowable feed speed v _max and the minimum allowable speed v _min are within the range, the process proceeds to step S30,

[0031]

[Equation 8] Is commanded as the feed rate. After this, step S31
At, the shaving operation is performed.

On the other hand, in step S25, if h _i (s) ≦ e, the process proceeds to step S32, where f = 0 and v _{i + 1} (s) = v _max. Then, the process proceeds to step S33 without grinding.

In step S33, the residual flash height h _{i + 1}
(S) is measured. Then, in step S34, if h _{i + 1} (s) ≦ e for all s, the process ends. If not, i = i + 1 is set and the process returns to step S24. Even with such a method, the constant k is re-estimated for each repetitive operation and reflected in the next cutting operation, so that it is possible to perform a fine work according to the grinding efficiency.

[0034]

As described above, according to the present invention, the deburring work with high finishing accuracy can be performed in a short time by acquiring desirable work parameters by the system itself without relying on an enormous experiment database of familiar operation. A flash grinding method by a robot that can be executed can be provided.

[Brief description of drawings]

FIG. 1 is a flow chart for explaining an operation for carrying out a flash grinding method in a first embodiment of the present invention.

FIG. 2A is a diagram showing an example of a flash grinding robot for executing the flash grinding method of the present invention, and FIG. 2B is a view schematically showing a working situation by the flash grinding robot shown in FIG. 2A. Is.

FIG. 3 is an enlarged view of a work portion of FIG. 2 (b).

FIG. 4 is a flow chart for explaining the operation for carrying out the flash grinding method in the second embodiment of the present invention.

[Explanation of symbols]

1 ... Robot, 2 ... Pressing force control device, 3 ... Grinder, 4 ... Burr height measuring sensor, 5 ... Work.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nao Okada 1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation (72) Inventor Shuichi Ohara 1-6-1, Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation

Claims (2)

[Claims] 1. A robot having a sensor for measuring the height of flash and a grinder for grinding the flash is used to set an arbitrary point on the intersection of the line where the flash exists and the base metal surface as the intersection. Expressed by the distance parameter s from the grinding start point, the measurement operation of measuring the residual flash height along the parameter and the cutting operation by the constant feed speed v ₀ are repeated separately and alternately, and the pressing force is variable. In the flash grinding method by the robot, the residual flash height h _i-1 (s) by the i−1th motion and i
Using the residual flash height h _i (s) and the pressing force f _i (s) in the th motion, And the pressing force command value f in the (i + 1) th grinding operation.
_{i + 1} (s), within a range that does not exceed the allowable pressing force f _max , And a second step of setting the above. 2. A robot having a sensor for measuring the height of the flash and a grinder for cutting the flash is used to set an arbitrary point on the intersection of the line where the flash exists and the base metal surface to the intersection. It is expressed by the distance parameter s from the grinding start point along the distance, and the measurement operation of measuring the residual flash height along the parameter and the cutting operation by the pressing force f are repeated separately and alternately, and the feed speed v is variable. In the flash grinding method by the robot, the residual flash height h _i-1 (s) due to the i−1th motion and i
Residual flash height h _i (s) and feed rate v in the th motion
_{Using i} (s), The first step of calculating the least squares estimation value k ′ for k, and the feed speed command value v _{i + 1 in the} (i + 1) th cutting operation
(S) within a range not exceeding the maximum permissible speed v _max and the minimum permissible speed v _min : A flash grinding method by a robot, comprising: