CN106733788A - Automatic brushing method of charger PCBA board - Google Patents

Abstract

The invention discloses an automatic board brushing method for a PCBA board of a charger, which comprises the following steps: stopping the uncleaned PCBA board synchronously moving with the automatic conveying device at a designated position; taking the PCBA stopped by the automatic conveying device away, and transferring the PCBA stopped to a brushing mechanism; the PCBA is brushed, and the PCBA after brushing is placed back on the automatic conveying device and is transmitted to the next process; the automatic board brushing method for the PCBA of the charger disclosed by the invention realizes automation in the whole process, reduces the labor cost and ensures the stable board brushing quality.

Description

Automatic brushing method of charger PCBA board

technical field

The invention relates to automatic production and processing equipment for chargers, in particular to a method for automatically brushing PCBA boards of chargers.

Background technique

During the production process of the charger, numerous electronic components need to be soldered on the PCB board to obtain the PCBA board, so it is easy to leave residues of tin beads, tin slag and other waste residues on the PCB board. If it is not removed, the product is very prone to abnormal electrical performance due to tin bead residue. In the prior art, the method of removing wastes such as tin beads and tin slag on the PCBA board is manually cleaned with a brush. Although this method can remove waste debris on the PCBA board, it needs to be manually removed one by one with a brush. The efficiency is low and the labor cost is high. At the same time, the removal quality is greatly affected by the level and experience of the operator, and the product quality is not good. Unite.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for automatically brushing the PCBA board of a charger that saves manpower, saves costs, improves production efficiency, and has stable cleaning quality.

In order to solve the problems of the technologies described above, the present invention adopts the following technical solutions:

A method for automatically brushing a charger PCBA board, comprising the following steps:

Step 1, stop the uncleaned PCBA board synchronously moving with the automatic conveying device at the designated position;

Step 2, taking the stopped PCBA board from the automatic conveying device, and transferring it to the board brushing mechanism;

Step 3, brushing the PCBA board, and putting the PCBA board after brushing back on the automatic conveying device, and transferring it to the next process;

Further, in step 2, the PCBA board is taken away by the automatic conveying device, rotated 180 degrees and parked at the board brushing mechanism;

In step 3, the PCBA board after brushing is taken away by the brushing mechanism, rotated 180 degrees and put back on the automatic conveying device.

Furthermore, in step 2, the clamping and rotating mechanism set vertically to the conveying direction of the automatic conveying device will take the stopped PCBA board away from the automatic conveying device, and rotate it by 180 degrees to park it at the brushing mechanism;

In step 3, the PCBA board after brushing is taken away by the brushing mechanism by adopting the clamping and rotating mechanism set in the conveying direction of the vertical automatic conveying device, and then rotated 180 degrees and put it back on the automatic conveying device;

The clamping and rotating mechanism includes a clamping mechanism and an elevating and rotating mechanism that can drive the clamping mechanism to rise, fall, and rotate 180 degrees; the clamping mechanism includes two sets of clamping components that are symmetrically arranged and work at the same time, one set While the clamping component removes the unbrushed PCBA board from the automatic conveying device and transfers it to the brushing mechanism, another set of clamping component fixes another PCBA board for brushing and the PCBA after brushing Put it back on the automatic conveying device by the brush plate mechanism.

Most preferably, in step 3, the electrostatic brush of the brushing mechanism rotates and reciprocates back and forth within the length range of the PCBA board in the X direction to brush the board.

A method for automatically brushing a charger PCBA board, using a charger PCBA board automatic brushing machine to brush the board, the charger PCBA board automatic brushing machine includes an automatic conveying device that can work together under the coordination of a PLC control system, a stop Parking mechanism, clamping and rotating mechanism, brushing mechanism and bracket; it can not only stop the unbrushed PCBA board running on the automatic conveying device, but also make the brushed PCBA board move synchronously with the automatic conveying device The stop and release mechanism is arranged between the lateral sides of the automatic conveying device; the brush plate mechanism is set on the support corresponding to the stop and release mechanism and parallel to the conveying direction of the automatic conveying device; The stopped PCBA board is taken away from the automatic conveying device, rotated 180 degrees to stay at the brushing mechanism for brushing, and the PCBA board after brushing can be removed from the brushing mechanism, rotated 180 degrees and put back into the automatic The clamping and rotating mechanism on the conveying device is arranged on the bracket, and is located above the automatic conveying device and the brush plate mechanism.

Further, the automatic conveying device includes a guide rail with adjustable width, and the two inner side walls of the guide rail are symmetrically provided with conveyor belts, and the middle part of the PCBA board is suspended on the two conveyor belts;

The stop-and-release mechanism is arranged between two conveyor belts, and includes a sensor positioned lower than the lower surface of the conveyor belt, and also includes a stopper that rises and falls repeatedly at intervals when the sensor senses the PCBA board.

Furthermore, the clamping and rotating mechanism includes a clamping mechanism for clamping/releasing plates and a lifting and rotating mechanism that drives the clamping mechanism to rise, fall, and rotate 180 degrees; the clamping mechanism is connected to the lifting and rotating mechanism. top;

The clamping mechanism includes a top plate and a clamping assembly, and the clamping assembly includes two first linear cylinders that are parallel to the conveying direction of the automatic conveying device and are fixed on the lower surface of the top plate at intervals. The opposite setting of the first cylinder rod moving inward or outward synchronously, the first cylinder rod is provided with a clamp arm that can move synchronously with the first cylinder rod, the extended end of the clamp arm is connected to the clamp block, and the two clamps The blocks respectively protrude inwards with a supporting platform that can firmly support one side of the PCBA board.

Preferably, the conveying direction of the vertical automatic conveying device on the top plate is symmetrically provided with two sets of clamping and placing components working in coordination under the PLC control system.

More preferably, the brush plate mechanism includes an electrostatic brush, a brush holder supporting the electrostatic brush and driving the electrostatic brush to rotate, and a forward and backward moving device driving the brush holder to reciprocate back and forth in the X direction.

Most preferably, the forward and backward moving device includes a screw arranged parallel to the conveying direction of the automatic conveying device, and the screw is electrically connected to drive the first power to rotate forward and reverse repeatedly;

The brush holder includes a base, the bottom of the base is provided with a connecting block that is threaded on the screw rod, and the base moves forward or backward with the forward rotation and reverse rotation of the screw rod, and two vertical plates are arranged on the base along the X direction , the vertical plate is correspondingly provided with rotating shaft holes, and the external sleeve is provided with an electrostatic brush, and the rotating shaft that can rotate around its axis core under the drive of the second power is horizontally arranged in the two rotating shaft holes.

Compared with the prior art, the automatic brushing method of the charger PCBA board of the present invention realizes automation in the whole process, reduces labor costs and ensures stable quality of the brushing board; the brushing mechanism of the charger PCBA board automatic brushing machine is set in parallel with the automatic conveying device The clamping and rotating mechanism is set above the brush plate mechanism and the automatic conveying device, which does not affect the overall conveying function of the automatic conveying device, and can efficiently brush the plate; the electrostatic brush can rotate around its axis and can be placed on the PCBA The X-direction of the board reciprocates back and forth to ensure short brushing time, good brushing effect, and improve the quality of PCBA boards; further, two sets of clamping and placing components are used to alternately perform board brushing, board placement, and board removal processes to increase the production capacity of the assembly line. Greatly improve and save costs.

Description of drawings

The present invention will be further explained in detail below in conjunction with the accompanying drawings and specific embodiments.

Fig. 1 is the overall schematic diagram of the automatic board brushing machine of the charger PCBA board of the embodiment

Fig. 2 is a three-dimensional schematic diagram of the stop-and-release mechanism, clamping and rotating mechanism, and brush plate mechanism of the embodiment

Fig. 3 is a three-dimensional schematic diagram of the clipping and rotating mechanism and the brush plate mechanism of the embodiment.

Figure 4 is a three-dimensional schematic diagram of the clipping and rotating mechanism and the brush plate mechanism of the embodiment II

detailed description

For the convenience of description, as shown in Figure 1, in the embodiment, the longitudinal direction of the automatic conveying device 1 is defined as the X direction in the three-dimensional coordinates, and the lateral direction of the automatic conveying device 1 is defined as the Y direction, perpendicular to the X direction and the Y direction The direction of the plane is defined as the Z direction, and all the brackets used to support or fix the parts on the charger PCBA board automatic brushing machine are collectively called the bracket 9 .

A method for automatically brushing a charger PCBA board according to the present invention comprises the following steps:

Step 1, stop the uncleaned PCBA board synchronously moving with the automatic conveying device 1 at a designated position;

Step 2, the PCBA board that has been stopped and not brushed is taken away from the automatic conveying device 1, and transferred to the brushing mechanism 4; preferably, the PCBA board is rotated 180 degrees and parked in the brushing mechanism 4 place;

Step 3, brush the PCBA board; put the PCBA board after brushing back on the automatic conveying device 4; preferably, rotate the PCBA board after brushing 180 degrees and put it back on the automatic conveying device 1; The electrostatic brush of the brush plate mechanism 4 rotates, and brushes the plate by reciprocating back and forth within the length range of the PCBA board X direction;

In order to improve work efficiency, in step 2, the clipping and rotating mechanism 3 set vertically to the conveying direction of the automatic conveying device 1 will take the stopped PCBA board away from the automatic conveying device 1, and rotate it 180 degrees to park it in the brushing mechanism 4 places; in step 3, take the clipping and rotating mechanism 3 set in the conveying direction of the vertical automatic conveying device 1 to remove the PCBA board after brushing by the brushing mechanism 4, and return it to the automatic conveying device after rotating 180 degrees 1 above; the clipping and rotating mechanism 3 includes a clipping mechanism 31 and an elevating and rotating mechanism 32 that can drive the clipping mechanism 31 to rise, fall, and rotate 180 degrees; the clipping mechanism 31 includes symmetrically arranged and simultaneously working Two sets of clamping components, one set of clamping components removes the unbrushed PCBA board from the automatic conveying device and transfers it to the brushing mechanism, and the other set of clamping components fixes another PCBA board for brushing and cleaning. The PCBA after brushing is put back on the automatic conveying device from the brushing mechanism.

As shown in Figures 1 to 4, an automatic charger PCBA board brushing machine includes an automatic conveying device 1 that can work in coordination with the PLC control system, a stop and release mechanism 2, a clamping and rotating mechanism 3, and a brush plate Mechanism 4, and support 9. The stop and release mechanism 2, clamping and rotating mechanism 3, and brush plate mechanism 4 can be mounted on the support 9; the automatic conveying device 1 is used to transport PCBA boards; the stop and release mechanism 2 is arranged on the automatic conveying device 1 Between the two sides of the horizontal direction, stop the movement of the unpainted PCBA board running on the automatic conveying device 1, and release the PCBA board after brushing, so that it moves synchronously with the automatic conveying device 1; corresponding to the stop and release mechanism 2. There is a board brushing mechanism 4. The board brushing mechanism 4 is set on the support 9 parallel to the conveying direction of the automatic conveying device 1, which can brush off the tin slag and rosin residue on the PCBA board; the clamping and rotating mechanism 3 is installed on the support 9, it is set above the automatic conveying device 1 and the brushing mechanism 4, which can remove the PCBA board stopped by the stop and release mechanism 2 from the automatic conveying device 1, rotate 180 degrees and stop at the brushing mechanism 4 After brushing, the PCBA board after brushing can be removed by the brushing mechanism 4, rotated 180 degrees and put back on the automatic conveying device 1 again.

In this embodiment, the automatic conveying device 1 includes a guide rail 11 with adjustable width, two conveyor belts 12 are arranged symmetrically on the inside of the guide rail 11, and the middle part of the PCBA board is suspended on the two conveyor belts 12, and can move synchronously with the conveyor belts , the width of the guide rail 11 is adjusted according to the width of the PCBA board to be conveyed, so as to ensure that the conveyed PCBA board will not fall or be damaged.

The stop-and-release mechanism 2 is arranged between two conveyor belts 12, and includes a sensor 21 and a stopper 22 positioned lower than the lower surface of the conveyor belt 12, and the stopper 22 is spaced repeatedly when the sensor 21 senses the PCBA board. Rise and fall. That is to say, the stopper 22 rises when the sensor 21 senses the PCBA board that has not been brushed, and prevents the movement of the PCBA board on the conveyor belt. synchronized movement. In this embodiment, the sensor 21 is a photoelectric sensor, the stopper 22 is a third linear cylinder, and the third cylinder rod of the third linear cylinder is set upward. When the board passes, under the control of the PLC control system, the rod of the third cylinder extends upward beyond the height of the PCBA board on the conveyor belt 12 to block the movement of the PCBA board. When the printed PCBA board is returned to the automatic conveyor 1, the photoelectric sensor The sensor senses the PCBA board again, and the rod of the third cylinder retracts to be lower than the lower surface of the conveyor belt, and the PCBA board can pass through smoothly and move synchronously with the conveyor belt. Specifically, programming in the PLC control system can be used to set the blocker 22 to rise and fall at intervals of the number of times the PCBA board is sensed by the sensor 21 during the normal board brushing process.

As shown in Figure 4, the clamping and rotating mechanism 3 includes a clamping mechanism 31 and a lifting and rotating mechanism 32 that can drive the clamping mechanism 31 to rise, fall, and rotate 180 degrees. The clamping mechanism 31 is connected to the lifting and rotating mechanism. The top of the mechanism 32 can not only take away the unpainted PCBA board from the automatic conveying device 1, but also put the PCBA board after brushing on the automatic conveying device 1.

The clamping mechanism 31 includes a top plate 311 and a clamping assembly, the clamping assembly includes two first linear cylinders 312 fixed on the lower surface of the top plate 311, and the first cylinder rods of the two first linear cylinders 312 are parallel to each other. The conveying direction of the automatic conveying device 1 is set at intervals, the first cylinder rod of the first linear cylinder 312 is provided with a clamp arm 313 that can move synchronously with the first cylinder rod, and the extended end of the clamp arm 313 is fixed with a clamp block 314, The two clamping blocks 314 protrude inward respectively with a supporting platform 315 that can hold one side of the PCBA board firmly. The two first linear cylinders 312 drive the two clamping arms 313 to move inward synchronously (towards movement) to clamp the PCBA board, or to move outwards synchronously (towards opposite movement) to release the PCBA board. In this embodiment, two sets of clamping and placing components are symmetrically arranged on the conveying direction of the vertical automatic conveying device 1 on the top plate 311, and the two sets of clamping and placing components work in coordination under the PLC control system. The lifting and rotating mechanism 32 rotates 180 degrees every time , while the PCBA board after the previous board brushing is transferred from the brushing mechanism 4 to the automatic conveying device 1, the next PCBA board to be brushed is transferred from the automatic conveying device 1 to the brushing mechanism 4, as a set During the process of clamping and placing an unpainted PCBA board on the upper and lower parts of the automatic conveying device 1, another set of clamping and placing components is fixed on a PCBA board just to carry out the brushing process. Board efficiency is doubled.

As shown in Figure 4, the bottom of the lifting and rotating mechanism 32 is installed on the support 9, including a base plate 321 fixed on the support, a second linear cylinder 322 is arranged above the base plate 321, and the second cylinder rod 3221 of the second linear cylinder 322 Vertically upwards, the top of the second cylinder rod 3221 is provided with a 180-degree rotating cylinder 323 that can move up and down synchronously with the second cylinder rod 3221, the turntable 3231 of the 180-degree rotating cylinder 323 is vertically upward, and the bottom of the top plate 311 The surface is connected to the upper surface of the turntable 3231 . Preferably, in this embodiment, the top plate 311 and the turntable 3231 are fixedly connected by a connecting column 324 .

As shown in Figures 2 and 3, the brush plate mechanism 4 includes an electrostatic brush 41, a brush seat 42, and a front and rear moving device 43 that drives the brush seat 42 to reciprocate back and forth in the X direction. On the brush seat 42 , the brush seat 42 supports the electrostatic brush 41 and can drive the electrostatic brush 41 to rotate. In this embodiment, the two ends of the forward and backward moving device 43 are fixed on the bracket 9, the forward and backward moving device 43 includes a screw 431 arranged parallel to the conveying direction of the automatic conveying device 1, and the electric connection of the screw 431 can drive it to rotate forward and backward. direction reciprocating rotation of the first power 432; the brush seat 42 includes a base 421, the bottom of the base 421 is provided with a connecting block 4211 threaded on the screw 431, and the base 421 is provided with two vertical plates 422 along the X direction. The vertical plate 422 is correspondingly provided with rotating shaft holes, and the rotating shaft 424 is horizontally arranged in the two rotating shaft holes. In use, the brush holder 42 moves forward or backward with the forward rotation and reverse rotation of the screw rod 431, and the relationship between the moving direction of the brush holder 42 and the rotation direction of the screw rod 431 is determined by the direction setting of the thread on the screw rod 431.

As shown in Figures 2 and 3, the second power 425 is a gear transmission system, including one end of the rotating shaft 424, which can drive the rotating shaft 424 to rotate the first gear 4251 synchronously, the second gear 4252 with power and the first gear 4252 The gear 4251 is meshed at 90°, the power drives the second gear 4252 to rotate, and then drives the first gear 4251 and the rotating shaft 424 to rotate to realize the rotation of the electrostatic brush 41 .

When using the charger PCBA board automatic brushing machine described in this embodiment to brush the board, the PLC control system programming adjusts the coordination of various parts, and utilizes various methods of the prior art to make the PCBA boards on a group of clamping components be carried out. When brushing the board, another group of clamping components takes another PCBA board to be brushed. So far, the charger PCBA board automatic brushing machine with two sets of clamping components enters the normal brushing program. Each group of clamping and placing components can operate according to the following process: the clamping and placing components place the PCBA board after brushing on the automatic conveying device 1, the sensor 21 senses the PCBA board, the stopper 22 descends, and the PCBA after brushing the board The board flows to the next process with the conveyor belt, and when the next PCBA board moves above the sensor 21, the stopper 22 rises, and the clamping and placing rotating mechanism 3 drives the clamping and placing assembly to descend and clamp the plate, and then the clamping and placing rotating mechanism 3 rises, The lifting and rotating mechanism 32 rotates 180 degrees and descends, contacts the PCBA board on the clamping assembly with the electrostatic brush 41, and starts brushing the board. After the brushing is completed, the lifting and rotating mechanism 32 rotates 180 degrees, and the clamping assembly The printed PCBA board is returned to the conveyor belt, and the cycle is repeated; the two sets of clamping and placing components work in harmony; the brushing action, board removal and board action are performed in turn, which greatly improves production efficiency.

Claims (10)

1. A charger PCBA board automatic board brushing method, is characterized in that, comprises the following steps: Step 1, stopping the uncleaned PCBA board synchronously moving with the automatic conveying device (1) at a designated position; Step 2, the stopped PCBA board is taken away from the automatic conveying device (1), and transferred to the brushing mechanism (4); Step 3, brushing the PCBA board, and putting the PCBA board after brushing back on the automatic conveying device (1), and transferring it to the next process. 2. The method for automatically brushing boards of charger PCBA boards as claimed in claim 1, characterized in that, In step 2, the PCBA board is taken away by the automatic conveying device (1), rotated 180 degrees and parked at the brush plate mechanism (4); In step 3, the PCBA board after brushing is taken away by the brushing mechanism (4), rotated 180 degrees and put back on the automatic conveying device (1). 3. The method for automatically brushing the PCBA board of a charger as claimed in claim 2, is characterized in that, in the step 2, the clamping rotation mechanism (3) that takes the conveying direction of the vertical automatic conveying device (1) to set will be stopped The PCBA board is taken away by the automatic conveying device (1), rotated 180 degrees and parked at the brush plate mechanism (4); In step 3, take the clipping and rotating mechanism (3) set in the conveying direction of the vertical automatic conveying device (1) to remove the PCBA board after brushing by the brushing mechanism (4), rotate 180 degrees and put it back On the automatic conveying device (1); The clipping and rotating mechanism (3) includes a clipping mechanism (31) and a lifting and rotating mechanism (32) that can drive the clipping mechanism (31) to rise, fall, and rotate 180 degrees; the clipping mechanism (31) It includes two sets of clamping components that are symmetrically arranged and work at the same time. One set of clamping components removes the PCBA board that has not been brushed from the automatic conveying device and transfers it to the brushing mechanism, while the other set of clamping components fixes the other A PCBA board is brushed and the PCBA after the brushing is put back on the automatic conveying device by the brushing mechanism. 4. The method for automatically brushing a PCBA board of a charger as claimed in claims 1 to 3, wherein in step 3, the electrostatic brush of the brush board mechanism (4) rotates and is within the length range of the X direction of the PCBA board Brush the board with reciprocating motion. 5. The automatic brushing method of the charger PCBA board as claimed in claim 1, characterized in that, the automatic brushing machine of the charger PCBA board is used to brush the board, and the automatic brushing machine of the charger PCBA board includes a PLC control The automatic conveying device (1), the stop and release mechanism (2), the clamping and rotating mechanism (3), the brush plate mechanism (4) and the support (9) work together under the coordination of the system; both the automatic conveying device (1) ) to stop the movement of the unbrushed PCBA board running on the board, and the stop and release mechanism (2) that can make the PCBA board after brushing move synchronously with the automatic conveying device (1) is arranged in the horizontal direction of the automatic conveying device (1) between the two sides; the brush plate mechanism (4) is set on the support (9) corresponding to the conveying direction of the stop and release mechanism (2), and the parallel automatic conveying device (1); both the stopped and release mechanism ( 2) The stopped PCBA board is taken away from the automatic conveying device (1), rotated 180 degrees and stops at the brushing mechanism (4) for brushing, and the PCBA board after brushing can be sent by the brushing mechanism (4) Remove it, rotate 180 degrees and put it back on the automatic conveying device (1) and put the rotating mechanism (3) on the support (9), above the automatic conveying device (1) and the brush plate mechanism (4). 6. The automatic brushing method of charger PCBA board as claimed in claim 5, characterized in that, the automatic conveying device (1) includes a guide rail (11) with adjustable width, and the two inner sidewalls of the guide rail (11) are symmetrical Conveyor belts (12) are set, and the middle part of the PCBA board is suspended and placed on two conveyor belts (12); The stop and release mechanism (2) is arranged between two conveyor belts (12), including an inductor (21) whose position is lower than the lower surface of the conveyor belt (12), and also includes when the inductor (21) senses the PCBA board The stopper (22) of the rise and fall of repeated intervals. 7. The method for automatically brushing the PCBA board of the charger as claimed in claim 6, characterized in that, the clamping rotation mechanism (3) includes a clamping mechanism (31) that can clamp the plate/put the plate and drives the clamping mechanism ( 31) Lifting and rotating mechanism (32) for rising, falling, and 180-degree rotation; the clipping mechanism (31) is connected to the top of the lifting and rotating mechanism (32); The clipping mechanism (31) includes a top plate (311) and a clipping assembly, and the clipping assembly includes two first ones parallel to the conveying direction of the automatic conveying device (1) and fixed on the lower surface of the top plate (311) at intervals. Linear cylinders (312), the first cylinder rods of the two first linear cylinders (312) move inwards or outwards synchronously, and the first cylinder rods are provided with a cylinder that can move synchronously with the first cylinder rods. Clamp arm (313), the protruding end of clamp arm (313) is connected with clamp block (314), and two described clamp blocks (314) protrude inward respectively and have the supporting plate platform (315 that can firmly hold up one side of PCBA board) ). 8. The automatic brushing method of charger PCBA board as claimed in claim 7, is characterized in that, the conveying direction of vertical automatic conveying device (1) on the described top board (311) is symmetrically provided with two sets of coordinates under the PLC control system Working clamp-and-place components. 9. The method for automatically brushing a PCBA board of a charger according to claims 1 to 8, wherein the brushing mechanism (4) includes an electrostatic brush (41), supports an electrostatic brush (41) and can The brush holder (42) that drives the electrostatic brush (41) to rotate, and the front and rear moving device (43) that drives the brush holder (42) to reciprocate back and forth in the X direction, the two ends of the front and rear moving device (43) are arranged on on the bracket (9). 10. charger PCBA board automatic plate brushing machine as claimed in claim 9, is characterized in that, described forward and backward moving device (43) comprises the screw rod (431) that the conveying direction of parallel automatic conveying device (1) is provided with, screw rod ( 431) The electrical connection can drive the first power (432) to rotate forward and reverse repeatedly; The brush seat (42) includes a base (421), and the bottom of the base (421) is provided with a threaded connection on the screw rod (431), and the forward rotation and reverse rotation of the screw rod (431) drive the base (421) forward or For the backward moving connecting block (4211), the base (421) is provided with two vertical boards (422) along the X direction, and the vertical boards (422) are correspondingly provided with shaft holes, and an electrostatic brush (41 ), the rotating shaft (424) that can rotate around its axis core under the drive of the second power (425) is horizontally arranged in the two rotating shaft holes.