JP4425232B2 - Method and apparatus for determining presence or absence of cracks in press-fitting process - Google Patents

Description

  The present invention relates to a method and apparatus for determining the presence or absence of cracks in a press-fitting process in an automatic assembly line or the like.

  In general, when a workpiece member is press-fitted, a cylinder is driven to move a plunger (rod) in a state where the workpiece member is placed at a press-fitting position of a member to be pressed. In the press-fitting process, the plunger moves while pressing the work member into the press-fitted member, and reaches the stroke end. The stroke end may or may not have a pressing end that is a contact surface of the work member.

  Conventionally, in order to determine whether or not the press-fitting process has been normally performed, the thrust of the cylinder, that is, the press input of the work member by the plunger is detected during the press-fitting process. In order to detect press input, a gate is provided at an arbitrary position (point) during the press-fitting process. At each gate position, the pressure input is measured, and it is determined whether or not the measured pressure input is within a predetermined range.

  By the way, in the press-fitting process, a “crack” may occur between the work member and the press-fitted member. “Crack” is a phenomenon in which a part of a work member is cracked or cracked, as shown in FIG. Cracking occurs when the coaxiality or concentricity between the work member and the press-fit member is impaired, when foreign matter is mixed between the work member and the press-fit member, or when the press-fitting tolerance is too tight. It is thought that it is easy to occur. Although it is not known in which part of the work member cracking occurs, it can be empirically recognized that when a groove or a recess is provided on the peripheral surface of the work member, the probability of occurrence of the crack is high.

When a “crack” occurs, the workpiece member and the press-fitted member need to be treated as defective products. However, conventionally, the presence or absence of galling during the press-fitting process is checked (Patent Document 1), but the presence or absence of cracks described above is not checked.
JP 2005-131745 A

  Therefore, to check for cracks, it is conceivable to provide a gate at the position during the press-fitting process, measure the pressure input at each gate position, and detect an abnormality based on the crack from the measurement result. Since it is not known where the crack occurs, the position for measuring the pressure input cannot be determined. Also, it is not easy to determine how the pressure input is determined to be a crack.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to determine whether or not there is a crack in the press-fitting process and to accurately determine the quality of press-fitting.

The method according to the present invention is a method for determining the presence or absence of cracks in a process of press-fitting a work member into a press-fit member by a linearly driven rod, and the thrust information and position information of the rod are obtained during the press-fitting process. Each time the position based on the position information advances within the set movement distance of the rod , a drop in thrust is detected in the thrust information within the range of the crack determination distance α in the position information from the current position. It is checked whether or not it is within the range of the crack determination thrust β, and when there is a drop in thrust exceeding the range of the crack determination thrust β, it is determined that there is a crack during the press-fitting process.

An apparatus according to the present invention is an apparatus for determining whether or not there is a crack in a process of press-fitting a work member into a press-fit member by a linearly driven rod, the thrust detecting means for obtaining thrust information of the rod, and the rod Position detecting means for obtaining the position information, storage means for storing the thrust information and the position information, means for storing a set value of the movement distance for the rod, and reduction in thrust of the rod Each time the position based on the position information advances within the set moving distance based on the thrust information and the position information stored in the storage means. checks whether there is a reduction in the thrust exceeds the set allowable value from time to time in the position within the range indicated by the set value of the moving distance of the rod, the set allowable value When there reduction in thrust obtaining it is determined that there is a crack in the press-fitting step includes a judging means.

  Preferably, in the determination by the determination means, the determination is not made within the range of a predetermined movement distance after the workpiece member contacts the press-fitted member.

  In the above description, the travel distance of the rod is used. However, when the travel speed of the rod is constant or known, the travel time can be used instead of the travel distance. That is, in this case, the movement distance and the movement time are equivalent.

According to the present invention, it is possible to determine the presence or absence of cracks in the press-fitting process, and it is possible to accurately determine the quality of press-fitting.

FIG. 1 is a diagram illustrating a configuration of a press-fitting system PF using a determination device 1 according to the present invention, and FIG. 2 is a diagram illustrating a press-fitting curve AK1 when there is a crack for explaining the operation of crack detection in the determination device 1. Figure 3 is a view showing a press-fitting curve a K 2 in the case without cracking, diagram showing another example of the press-fit curve AK3 in the case of FIG. 4 is cracked there, 5 is a sectional view showing an example of the work member WK, FIG. 6 is a diagram showing an example of cracking.

  2 to 4, the vertical axis represents the thrust TH of the cylinder CY, that is, the pressure input by the press-fit jig PR, and the horizontal axis represents the position LL of the press-fit jig PR.

  As shown in FIG. 1, the press-fitting system PF includes a press-fitting device, a determination device 1, a sequencer 18, and the like. The press-fitting device includes a cylinder CY, a load cell 11, a position sensor 12, and the like. The determination device 1 includes amplifiers 13 and 14, an arithmetic processing unit 15, a setting unit 16, a memory 17, and the like. The determination device 1 can be configured using a CPU, a ROM and a RAM that store appropriate programs, other memories, peripheral elements, and appropriate hardware circuits.

  The cylinder CY is fixed to an appropriate frame FM via a support fitting FA, and a press-fitting jig PR is attached to the tip of the piston rod PD. A press-fitting member BZ is disposed immediately below the press-fitting jig PR.

  In a state where the work member WK is placed at the press-fit position AP of the press-fit member BZ, the work member WK is press-fit into the press-fit member BZ by driving the cylinder CY and moving the press-fit jig PR downward. That is, the press-fitting jig PR moves in the press-fitting section from the press-fitting start position LL1 to the press-fitting end position.

  The work member WK is a columnar member, a cylindrical (pipe-shaped) member, a member provided with a groove, a screw, a recess, or the like on the surface thereof. A workpiece member WK2 shown in FIG. 5A has a cylindrical shape, and a plurality of triangular grooves MZ1 are provided on the surface. In this case, cracks are likely to occur from the bottom of the triangular groove MZ1. A workpiece member WK3 shown in FIG. 5B is cylindrical and has a plurality of packing grooves MZ2 on its surface. In this case, cracks are likely to occur from the corners of the packing groove MZ2.

  In FIG. 1, the press-fit member BZ does not have a press-cut end that is a contact surface of the work member WK, and press-fit is completed at the stroke end of the cylinder CY. However, the press-fit member BZ may be provided with a pressing end, and the piston rod PD may be moved until the lower end surface of the work member WK comes into contact with the pressing end.

  The load cell 11 detects the thrust TH of the cylinder CY, that is, the pressure input of the work member WK by the press-fitting jig PR. The amplifier 14 amplifies the output signal of the load cell 11 and outputs a thrust signal S1.

  The position sensor 12 detects the position LS of the press-fitting jig PR and the work member WK by detecting the position of the piston rod PD in the cylinder CY. The amplifier 13 outputs a position signal S2 based on the output from the position sensor 12. The amplifiers 13 and 14 may include appropriate converters for signal conversion.

  Based on the thrust information and the position information stored in the memory 17, the arithmetic processing unit 15 performs the press-fitting process when the thrust falls below the set allowable value within the set value of the movement distance of the piston rod PD. It is determined that there was a crack.

The arithmetic processing unit 15, a crack determination unit 15 a and the determination computing unit 15b is provided. The arithmetic processing unit 15 determines whether or not there is a crack, determines whether or not the press fit is good, and sends a control signal CS to the sequencer 18. The processing contents of the arithmetic processing unit 15 will be described later.

  The setting unit 16 is for setting values such as the data acquisition start position LL2, the data acquisition end position LL3, the crack determination distance α, and the crack determination thrust β. These settings can be made by the user. A predetermined value may be set in advance.

  The data acquisition start position LL2 is the position of the work member WK when the memory 17 starts storing the thrust signal S1 and the position signal S2. The data acquisition end position LL3 is the storage of the thrust signal S1 and the position signal S2. Is the position of the work member WK when ending. That is, the thrust signal S1 and the position signal S2 are stored in the memory 17 from the data acquisition start position LL2 to the data acquisition end position LL3 (data acquisition section RM).

  The data acquisition start position LL2 is appropriately set according to the shape and the like of the work member WK and the press-fit member BZ. The data acquisition end position LL3 is normally set to the press-fitting end position. The press-fitting end position is a stroke end of the press-fitting jig PR, a point when the press input becomes substantially equal to the thrust of the cylinder CY, or the like.

  That is, the memory 17 stores the thrust signal S1 and the position signal S2 in the data acquisition section RM as press-fitting data (thrust information) and position data (position information). These are stored in association with each other. Further, the memory 17 stores a value (set value) set by the setting unit 16.

  The sequencer 18 performs overall control of the press-fitting system PF based on the control signal CS sent from the arithmetic processing unit 15.

  Next, the operation and processing of the arithmetic processing unit 15 will be described.

  First, the determination process of the presence or absence of the crack by the crack determination part 15a is demonstrated.

  In the press-fitting curve AK1 shown in FIG. 2, the thrust gradually increases from the press-fitting start position LL1 to the first peak point P1, then gradually decreases and then gradually increases, and gradually increases even after the data acquisition start position LL2. It gradually decreases from the peak point P2 to the low peak point P3, and gradually increases from there.

  By the way, for a while from the press-fitting start position LL1, there is a tendency to gradually decrease after the peak point P1 even if it is normal. Therefore, actually, data is acquired in the data acquisition section RM from the data acquisition start position LL2 to the data acquisition end position LL3. Data in the acquired data acquisition section RM is a determination target. With respect to the acquired data, it is checked whether or not there is a portion where the thrust is reduced by exceeding the crack determination thrust β during the crack determination distance α.

  That is, in the press-fitting curve AK1 in FIG. 2, the thrust decreases between the peak point P2 and the crack determination distance α and decreases beyond the range of the crack determination thrust β. Therefore, it is determined that the press-fit curve AK1 is “cracked”.

  That is, in the press-fitting curve AK1 of the data acquisition section RM, the upper left vertex of the rectangle with the crack determination thrust β being vertical and the crack determination distance α being horizontal is moved along the press-fitting curve AK1, and the press-fitting curve AK1 is the lower side of the rectangle Is determined to be “cracked” for the press-fit curve AK1.

  In data processing, for example, every time the position in the press-fitting section advances, the peak value up to that point is updated, and the thrust is reduced within the range of the crack determination distance α from the peak position at that time. It can be determined by checking whether or not it is within the range of the crack determination thrust β. It can also be determined by detecting a high peak and a low peak within the subsequent crack determination distance α and checking whether the difference is within the range of the crack determination thrust β.

  Note that the workpiece member WK and the press-fitted member BZ that are determined to have cracks are determined to be defective, and identification information for removal in a later process is attached. In this description, after all the data of one press-fitting process is temporarily stored in the memory 17, it is determined whether or not there is a crack in the process, but cracking is performed in real time while performing the press-fitting process. When the presence / absence determination is performed, it may be determined that there is a crack when the thrust exceeds the range of the crack determination thrust β while storing necessary data, and may be processed as a defective product.

  In the press-fitting curve AK2 shown in FIG. 3, since there is no portion where the thrust decreases beyond the crack determination thrust β during any crack determination distance α, it is determined as “no crack”.

  In the press-fitting curve AK3 shown in FIG. 4, the thrust is reduced from the peak point P4 and is reduced beyond the crack determination thrust β within the range of the crack determination distance α. Note that the press-fitting curve AK3 in FIG. 4 shows a case where the press-fitting end is provided in the press-fitted member BZ, so that the thrust increases rapidly just before the press-fitting end. Of course, if there are a plurality of locations determined to have cracks, it will be a defective product.

  Next, the determination of the quality of press-fitting by the determination calculation unit 15b will be described.

  The determination calculation unit 15b performs the determination only when the press-fitting member BZ is provided with a pressing end. First, when it is determined that there is a crack, it is determined that press-fitting is not possible. When it is determined that there is no crack and the value of the thrust signal S1 thereafter exceeds the upper set value, it is determined that the press-fitting is good. That is, in this case, it is determined that the workpiece member WK has been normally press-fitted with a predetermined pressure input.

  Therefore, even if it is determined that there is no crack, if the subsequent thrust signal S1 does not exceed the upper set value, it is determined that press-fitting is not possible. This is because the pressure input should increase due to the lower end surface of the work member WK coming into contact with the cut end KT, but if the upper set value is not exceeded, it will not come into contact with the cut end. Because it becomes. Therefore, such a check is unnecessary in the case of the press-fitted member BZ that does not have a cut end.

  Various other methods can be employed in determining whether the press-fitting is good or bad. For example, the methods described in JP-A-2002-283149 and JP-A-2000-158244 can be employed. Further, the determination of galling described in JP-A-2005-131745 may be used in combination.

  The sequencer 18 outputs an instruction AS necessary for the next press-fitting to the cylinder CY or the like in real time based on the control signal CS.

  Thus, according to the determination apparatus 1 of the present embodiment, it is possible to accurately determine the presence or absence of cracks in the press-fitting process, and to accurately determine whether or not the press-fitting is good.

  In the above embodiment, the crack determination distance α and the crack determination thrust β may be determined by trial and error or empirically according to the shape, dimensions, material, press-fitting tolerance, press-fitting purpose, and the like of the work member WK. Note that the crack determination distance α corresponds to the “set value of the moving distance for the rod” in the present invention, and the crack determination thrust β corresponds to the “set allowable value for reduction in the thrust of the rod” in the present invention. The piston rod PD and the press-fitting jig PR correspond to the rod in the present invention.

  In the above-described embodiment, the data acquisition section RM is set from the data acquisition start position LL2 to the data acquisition end position LL3. However, the data acquisition start position may be widened, for example, as the press-fitting start position LL1. Even in that case, in order to avoid erroneous determination due to instability of thrust in the vicinity of the press-fitting start position LL1, it is preferable to exclude a predetermined distance range from the determination target.

  The shape, size, material, and the like of the press-fitting jig PR can be various. The press-fitting jig PR is attached to the tip of the piston rod PD, but may be integrated with the piston rod PD. The load cell 11 may be attached to the tip of the piston rod PD.

  In the above-described embodiment, the configuration, structure, dimensions, shape, material, number, etc. of the whole or each part of the determination device 1 and the press-fitting system PF can be variously changed in accordance with the gist of the present invention.

  In addition, the determination apparatus 1 of this embodiment can be applied to the determination of the presence or absence of cracks such as wrinkles in the press-fitting during caulking, in addition to the determination of the presence or absence of cracks in press-fitting of pipes and rings.

It is a figure which shows the structure of the press injection system using the determination apparatus which concerns on this invention. It is a figure which shows the press fit curve in the case of a crack. It is a figure which shows the press fit curve in the case of no crack. It is a figure which shows the press fit curve of the other example in the case with a crack. It is sectional drawing which shows the example of a workpiece | work member. It is a figure which shows the example of a crack. DESCRIPTION OF SYMBOLS 1 Determination apparatus 11 Load cell (thrust detection means) 12 Position sensor (position detection means) 15a Crack determination part (determination means) 15b Determination calculation part 16 Setting part 17 Memory (storage means) PR Press-fitting jig BZ Press-fit member WK Work member RM Data acquisition section S1 Thrust signal (thrust information) S2 Position signal (position information) LL2 Data acquisition start position LL3 Data acquisition end position α Crack determination distance (set value of travel distance for rod) β Crack determination thrust (rod thrust force) Lower setting tolerance)

Claims (3)

A method of determining the presence or absence of cracks in the process of press-fitting a workpiece member into a press-fit member by a linearly driven rod,
Obtaining thrust information and position information of the rod during the press-fitting process;
Each time the position based on the position information advances within the set movement distance of the rod, the reduction in thrust is within the range of the crack determination distance α in the position information from the current position, and the crack determination thrust in the thrust information Check if it is in the range of β,
When there is a drop in thrust exceeding the crack determination thrust β range, it is determined that there was a crack during the press-fitting process,
The determination method of the presence or absence of the crack in the press fit characterized by the above-mentioned. A device for determining the presence or absence of cracks in the process of press-fitting a work member into a press-fit member by a linearly driven rod,
Thrust detecting means for obtaining thrust information of the rod;
Position detecting means for obtaining position information of the rod;
Storage means for storing the thrust information and the position information;
Means for storing a set value of a moving distance for the rod;
Means for storing a set allowable value of a reduction in thrust of the rod;
Based on the thrust information and the position information stored in the storage means, each time the position according to the position information advances within the set movement distance of the rod, the movement distance of the rod is changed from the current position . It is checked whether there is a drop in thrust exceeding the set allowable value within the range indicated by the set value , and if there is a drop in thrust exceeding the set allowable value, there is a crack in the press-fitting process. and it determines the determination means has,
An apparatus for determining the presence or absence of cracks in press-fitting, comprising: In the determination in the determination means, the workpiece member is excluded from the determination within the range of a predetermined movement distance after contacting the pressed member.
The determination apparatus of the presence or absence of the crack in the press fit of Claim 2.