CN213658907U

CN213658907U - Multi-path parallel test system

Info

Publication number: CN213658907U
Application number: CN202021991456.6U
Authority: CN
Inventors: 刘旱雨; 林观火生; 刘万全; 洪波
Original assignee: Zhangzhou Leedarson Lighting Co Ltd
Current assignee: Zhangzhou Leedarson Lighting Co Ltd
Priority date: 2020-09-11
Filing date: 2020-09-11
Publication date: 2021-07-09
Anticipated expiration: 2030-09-11

Abstract

The utility model provides a but parallel test system of multichannel belongs to circuit board test technical field, including the host computer body, a tool, execution unit and control organism, tool detachable installs on the host computer body, the tool is split type structure and includes the fixed body and moving body, be equipped with restraint groove on the fixed body, restraint groove is used for placing a plurality of circuit boards under test simultaneously, be equipped with the probe in the restraint groove, execution unit is equipped with the power take off end of connecting the moving body, the moving body is close to the fixed body and presss from both sides tight circuit board under test with the help of execution unit, make the probe contact the contact on the circuit board under test, control organism installs a plurality of test module, test module passes through probe and circuit board under test electric connection and one-to-one, man-machine interface electric connection test module shows the test result; the utility model provides a but parallel test system of multichannel can solve the technical problem that the test pattern that goes on one by one can't satisfy circuit board production.

Description

Multi-path parallel test system

Technical Field

The utility model belongs to the technical field of the circuit board test, more specifically say, but relate to a but parallel test system of multichannel.

Background

The circuit board is also called a circuit board, a PCB board or a printed circuit board, various electronic components are integrated on the circuit board, and the electronic components are organically connected through a circuit, so that the circuit board becomes a constituent unit with a specific function. After the production of the circuit board product is completed or during the production process, the circuit board product needs to be tested to ensure that the circuit board product can work normally, has expected functions and can be used as a stable electric element by consumers. The test efficiency of the circuit board can influence the overall production efficiency, and particularly, when the circuit board is produced in large scale, the number of products is large, the models are multiple, and the test modes which are carried out one by one can not meet the production requirements far away.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a but parallel test system of multichannel aims at solving the technical problem that the test pattern that goes on one by one can't satisfy circuit board production.

In order to achieve the above object, the utility model adopts the following technical scheme: the test system capable of realizing multi-path parallel comprises a main machine body, a jig, an execution unit and a control machine body;

the jig is detachably arranged on the main machine body, is of a split structure and comprises a fixed body and a moving body, wherein the fixed body is provided with a constraint groove, the constraint groove is used for placing a plurality of tested circuit boards at the same time, and a probe is arranged in the constraint groove;

the execution unit is provided with a power output end connected with the moving body, and the moving body approaches to the fixed body by virtue of the execution unit, clamps the tested circuit board and enables the probe to contact a contact on the tested circuit board;

the control machine body is provided with a plurality of test modules, and the test modules are electrically connected with the circuit board to be tested through probes and correspond to the circuit board to be tested one by one;

the human-computer interface is electrically connected with the test module and displays a test result.

As another embodiment of this application, the relative setting from top to bottom of moving body and fixed body, the fixed body is located the below, restraint the groove opening up, be equipped with on the host computer body and be used for the location the first locating column of fixed body, the fixed body through first bolt with host computer body detachable connection.

As another embodiment of the present application, the execution unit is an air cylinder installed on the main body, the air cylinder is located above the fixed body, and a manual button for controlling the pushing end of the air cylinder to be pushed out or retracted is arranged on the main body.

As another embodiment of this application, the moving body pass through the intermediate block connect in the top of pushing of cylinder, be equipped with on the intermediate block and be used for fixing a position the second reference column of moving body, the moving body pass through the second bolt with the detachable connection of intermediate block.

As another embodiment of this application, be equipped with the guide post on the intermediate block, the guide post is on a parallel with the piston rod of cylinder, be equipped with on the host computer body with the sleeve of guide post adaptation.

As another embodiment of the application, the multi-path parallel test system further comprises a mechanical arm with horizontal rotation and rotation freedom, and a tool head used for grabbing the tested circuit board is arranged at the tail end of the mechanical arm.

As another embodiment of the application, the human-computer interface is a computer with a display screen.

As another embodiment of the present application, the control machine body includes an electrical cabinet, a drawer structure is provided in the electrical cabinet, and the test module is installed in the electrical cabinet in a drawable manner through the drawer structure.

As another embodiment of the present application, the test module includes a substrate, the drawer-type structure includes a card rail fixedly disposed on the electrical cabinet, a card slot slidably and fixedly coupled to an edge of the substrate is disposed on the card rail, one end of the card slot is closed, the other end of the card slot is open and allows the substrate to be inserted into the card slot, an open end of the card slot is provided with an elastic clamping block, and the elastic clamping block is used for preventing the test module from accidentally sliding out of the card slot.

As another embodiment of the present application, the elastic clamping block includes an elongated portion and a clamping head portion, one end of the elongated portion is connected to the clamping rail, the other end of the elongated portion extends from the open end of the clamping groove along the length direction of the clamping groove, the clamping head portion is disposed at the extending end of the elongated portion, and the clamping head portion is used for bending outward and avoiding the passing path of the substrate or resetting inward and limiting the sliding of the substrate.

Compared with the prior art, the multi-path parallel test system provided by the utility model is provided with the restraint groove capable of accommodating a plurality of tested circuit boards, and the control machine body is provided with a plurality of test modules which are in one-to-one correspondence with the circuit boards in the restraint groove, and the test modules are connected with the tested circuit boards through cables and probes in the restraint groove; after the circuit board to be tested is placed in the restraining groove, the power output end of the execution unit drives the moving body to approach the fixed body, so that the circuit board to be tested is clamped, and the probe is enabled to be in close contact with a preset contact on the circuit board to be tested; after the tested circuit board is clamped in place, the test module powers on the tested circuit board, then inputs an excitation signal and collects a feedback signal, firmware information of the tested circuit board and the like, so as to realize the test of the tested circuit board; during testing, a plurality of test modules work simultaneously, and multi-path parallel testing is realized, so that the testing efficiency is greatly improved; in addition, the main machine body and the control machine body are in a split type design, the jig is detachably connected with the main machine body, when the type of the tested circuit board is changed, the control machine body does not need to be changed, the purpose of adapting the changed tested circuit board is achieved by replacing the jig or the main machine body, and the applicability of the test system is greatly improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

Fig. 1 is a schematic structural composition diagram of a test system capable of performing multiple parallel tests according to an embodiment of the present invention;

fig. 2 is a schematic perspective view of a main body in a multi-channel parallel test system according to an embodiment of the present invention;

fig. 3 is a schematic diagram of an explosion structure at a connection between a fixed body and a main body in a multi-channel parallel test system according to an embodiment of the present invention;

fig. 4 is a schematic view of a split structure where an execution unit is disposed on a main body in a multi-channel parallel test system according to an embodiment of the present invention;

fig. 5 is a schematic structural diagram of a control body in the multi-channel parallel test system according to the embodiment of the present invention;

fig. 6 is a schematic structural diagram of a test module connected to an electrical cabinet in a multi-path parallel test system according to an embodiment of the present invention;

fig. 7 is a schematic top view of the connection between the test module and the card rail and the open end of the card slot in the multi-channel parallel test system according to the embodiment of the present invention.

In the figure: 1. a main body; 11. a first positioning post; 12. a first bolt; 2. a jig; 21. a fixed body; 211. a confinement groove; 22. a moving body; 221. a second bolt; 3. an execution unit; 31. a manual button; 32. a middle block; 321. a second positioning column; 322. a guide post; 33. a connecting plate; 331. a sleeve; 4. controlling the machine body; 41. a test module; 411. a substrate; 42. an electrical cabinet; 43. a cabinet door; 44. clamping a rail; 45. an elastic clamping block; 451. a long strip; 452. a card head portion; 5. and (4) a human-computer interface.

Detailed Description

In order to make the technical problem, technical solution and advantageous effects to be solved by the present invention more clearly understood, the following description is given in conjunction with the accompanying drawings and embodiments to illustrate the present invention in further detail. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Referring to fig. 1 and fig. 2, a multi-path parallel test system according to the present invention will now be described. The multi-path parallel test system comprises a main machine body 1, a jig 2, an execution unit 3, a control machine body 4 and a human-computer interface 5; the jig 2 is detachably mounted on the main machine body 1, the jig 2 is of a split structure and comprises a fixed body 21 and a moving body 22, a restraining groove 211 is formed in the fixed body 21, the restraining groove 211 is used for placing a plurality of tested circuit boards at the same time, and probes are arranged in the restraining groove 211; the execution unit 3 is provided with a power output end connected with the moving body 22, and the moving body 22 approaches the fixed body 21 by means of the execution unit 3 and clamps the tested circuit board to enable the probe to contact a contact point on the tested circuit board; the control machine body 4 is provided with a plurality of test modules 41, and the test modules 41 are electrically connected with the circuit board to be tested through probes and correspond to one another; the human-machine interface 5 is electrically connected to the test module 41 and displays the test result.

Compared with the prior art, the multi-path parallel test system provided by the utility model is provided with the restraint groove 211 which can hold a plurality of tested circuit boards, and the control machine body 4 is provided with a plurality of test modules 41 which are in one-to-one correspondence with the circuit boards in the restraint groove 211, and the test modules 41 are connected with the tested circuit boards through cables and probes in the restraint groove 211; after the circuit board to be tested is placed in the restraining groove 211, the power output end of the execution unit 3 drives the moving body 22 to approach the fixed body 21, so as to clamp the circuit board to be tested, and the probe is tightly contacted with a preset contact on the circuit board to be tested; after the circuit board to be tested is clamped in place, the test module 41 powers on the circuit board to be tested, then inputs the excitation signal and collects the feedback signal and the firmware information of the circuit board to be tested, and the test on the circuit board to be tested is realized; during testing, the plurality of test modules 41 work simultaneously, and multi-path parallel testing is performed, so that the testing efficiency is greatly improved; in addition, the main machine body 1 and the control machine body 4 are in a split type design, the jig 2 and the main machine body 1 are detachably connected, when the type of the tested circuit board is changed, the control machine body 4 does not need to be changed, the purpose of adapting the changed tested circuit board is achieved by replacing the jig 2 or the main machine body 1, and the applicability of the test system is greatly improved.

Specifically, the circuit boards to be tested placed in the constraint slot 211 are generally a whole circuit board before being separated into boards, each circuit board to be tested is used as a test unit, six slot positions are provided in the constraint slot 211 in fig. 2, and six test units, that is, six circuit boards to be tested, are correspondingly provided on the whole circuit board; after the whole circuit board is placed in the constraining groove 211, a tested circuit board is arranged in each groove, a group of probes is arranged in each groove, each group of probes is provided with a cable and connected with a testing module 41, and the one-to-one corresponding connection of the tested circuit board and the testing module 41 is realized.

As a specific implementation manner of the multi-channel parallel testing system provided by the present invention, please refer to fig. 1, the moving body 22 and the fixed body 21 are disposed up and down relatively, the fixed body 21 is disposed below, the opening of the constraint groove 211 is upward, the main body 1 is provided with the first positioning column 11 for positioning the fixed body 21, and the fixed body 21 is detachably connected to the main body 1 through the first bolt 12.

The fixing body 21 is arranged below, the opening of the constraint groove 211 faces upwards, and a tested circuit board can be conveniently placed in the constraint groove 211 no matter through manual work or machine during testing. Through first bolt 12 and main body 1 connection for the dismouting that fixed body 21 can be convenient when the type of being tested circuit board changes, change tool 2 that can be quick, furthest's reduction down time. The first positioning column 11 is used for positioning the position of the fixed body 21, because the size and distance of the contact on the circuit board to be tested are often very small, the fixed body 21 and the movable body 22 are required to have high relative position accuracy, so that the circuit board to be tested can be completely clamped, the probes are tightly attached to the corresponding contacts, and the conduction of signals and power supply is realized.

Besides the probe, the constraining groove 211 is generally provided with a positioning block for positioning the circuit board to be tested, and the positioning block can be clamped with a hole or a clamping structure on the circuit board to be tested, so that the relative position of the circuit board to be tested and the fixture can be positioned, and the preset contact on the circuit board to be tested can be in contact with the probe after the circuit board to be tested is placed into the constraining groove 211.

As a specific implementation manner of the multi-channel parallel testing system provided by the present invention, please refer to fig. 2 and fig. 4, the execution unit 3 is a cylinder installed on the main body 1, the cylinder is located above the fixing body 21, and the main body 1 is provided with a manual button 31 for controlling the pushing end of the cylinder to be pushed out or withdrawn. The pushing end of the cylinder is the power output end of the execution unit 3. The cylinder is the current product of mature application, chooses for use it as execution unit 3, acquires easily, and the stable performance can be fine satisfies the operation requirement.

When the testing mechanism is used for loading and unloading manually, the manual button 31 is used for controlling the piston rod of the air cylinder to be pushed out or retracted, so that the pushing end of the manual button drives the moving body 22 to ascend or descend, the moving body 22 is far away from the fixed body 21 when ascending, the moving body 22 is close to the fixed body 21 when descending, and the tested circuit board is clamped in the constraint groove 211 by matching with the fixed body 21; specifically, the number of the manual buttons 31 is three, two of the two manual buttons are pressed simultaneously to control the lifting of the pushing top end of the cylinder, and the middle manual button is an emergency stop button.

When the testing mechanism is used for loading and unloading the machine, the manual button 31 is also used for controlling the pushing out or withdrawing of the piston rod of the air cylinder, and is only used during debugging; after debugging is completed, the machine can send a put-in-place instruction to the test module 41, and then the test module 41 controls the action of the execution mechanism to realize automatic testing.

Specifically, the main body 1 is further provided with three to four groups of electrically controlled electromagnetic valve islands which can be expanded more according to requirements, and is further provided with an independent pressure regulating valve, an independent pressure relief regulating valve, a cylinder push end up-down in-place sensor and the like, so that the complete control of the cylinder is realized. Specifically, the main body 1 has a box-type housing to which the cylinder is fixed.

As a specific embodiment of the multi-channel parallel test system provided in the present invention, please refer to fig. 4, the moving body 22 is connected to the top end of the cylinder through the middle block 32, the middle block 32 is provided with a second positioning column 321 for positioning the moving body 22, and the moving body 22 is detachably connected to the middle block 32 through a second bolt 221.

The moving body 22 can determine the relative position with respect to the cylinder as the actuator unit 3 fixed to the main body 1 by the second positioning post 321, so that the moving body 22 actually determines the relative position with respect to the main body 1 by the second positioning post 321. Meanwhile, the fixed body 21 is fixed by the first positioning post 11, and the relative position with the main body 1 can be determined by the first positioning post 11, so that the relative position of the fixed body 21 and the moving body 22 is determined, and the circuit board to be tested can be accurately aligned and clamped in the constraint groove 211.

Through second bolt 221, the movable body 22 can be conveniently disassembled from the middle block 32, and the fixed body 21 is disassembled from the main body 1 through the first bolt 12, so that the jig 2 can be detachably mounted on the main body 1, replacement is facilitated, and the universality of the test system is improved. Specifically, the intermediate block 32 has a plate shape.

As a specific implementation manner of the multi-path parallel test system provided in the present invention, please refer to fig. 4, the middle block 32 is provided with a guiding post 322, the guiding post 322 is parallel to the piston rod of the cylinder, and the main body 1 is provided with a sleeve 331 adapted to the guiding post 322. Specifically, the sleeve 331 is fixedly arranged on the connecting plate 33, the connecting plate 33 is fixed with the cylinder body of the air cylinder, and is provided with a through hole for a piston rod of the air cylinder to pass through, and the piston rod of the air cylinder is fixedly connected with the middle block 32 after passing through the through hole to drive the middle block 32 to move up and down; the middle block 32 moves to drive the moving body 22 and the guide post 322 to move together.

By means of the guide post 322 and the sleeve 331, the movement direction of the pushing end of the cylinder is stable, the positioning accuracy is higher, the moving body 22 and the fixed body 21 can be aligned, the circuit board to be tested can be clamped, and the contact on the circuit board to be tested can be attached to the probe.

As the utility model provides a but a concrete implementation way of the parallel test system of multichannel, but the parallel test system of multichannel still including the arm that has the horizontal rotation rotational degree of freedom, the end of arm is equipped with the instrument head that is used for snatching the circuit board under test.

Mechanical arm and tool head are prior art, can acquire through the purchase. Specifically, the mechanical arm is suspended and mounted on a roof close to the main machine body 1, one end of the mechanical arm is connected with the roof through a connecting arm, the other end of the mechanical arm extends out and rotates by taking the connecting end of the roof as a circle center, the rotation angle of the mechanical arm can reach 360 degrees, and the arm extension can reach 1.2 meters; the extending end of the mechanical arm can rotate to the main machine body 1 and between the fixed body 21 and the moving body 22, and then the grabbed circuit board to be tested is placed in the constraint groove 211 through the action of the tool head; after the test is finished, the extending end of the mechanical arm rotates to the position above the constraint groove 211 again, and the circuit board to be tested is taken out of the constraint groove 211. The mechanical arm further improves the automation degree of the test system, reduces the labor input and saves the labor cost.

As a specific implementation manner of the testing system capable of realizing multipath parallel, the human-computer interface 5 is a computer with a display screen. The computer is used as an upper computer, and software matched with the control machine body 4 can be compiled; after installing the software, the computer may read the feedback data of the test module 41 and determine whether the feedback data meets expectations. If the feedback data is not in accordance with the expectation, it indicates that the circuit board to be tested connected with the test module 41 may have a quality problem, and sends a notification image to the display screen to enable the worker to know that the problem occurs; after the circuit board with the problem appears, the software sends an instruction to the test module 41 to retest the circuit board with the problem, if the circuit board with the problem still appears, the pushing end of the software control cylinder continuously presses the circuit board to be tested, the pressed state of the circuit board to be tested is different from the state when the circuit board to be tested normally passes the test, and therefore a worker can visually determine that the pressed circuit board to be tested is the circuit board with the problem; the tested circuit board with the problem of quality and the tested circuit board passing the test can not be mixed due to negligence of operators, so that a fool-proof mechanism is objectively formed, manual errors are prevented, and the product quality is better ensured.

In addition, an operator can configure the plurality of test modules 41 in the control machine body 4 through software visualization on a computer, so that the test modules are matched with the types and the number of the current circuit boards to be tested, and the universality of the test system is further improved; the testing system can be accessed to the monitoring system of the intelligent factory through software on the computer, and the testing system can be used as a link of the intelligent factory to fully exert the high-efficiency circuit board testing efficiency.

As a specific implementation manner of the testing system that can be used in parallel in multiple paths, please refer to fig. 5, the control machine body 4 includes an electrical cabinet 42, a drawer structure is provided in the electrical cabinet 42, and the testing module 41 is installed in the electrical cabinet 42 through the drawer structure in a drawable manner. Specifically, the electrical cabinet 42 is provided with a cabinet door 43 which can be opened and closed, and the cabinet door 43 is provided with a threading hole through which a cable can pass to connect the test module 41 with a probe arranged on the fixing body 21. With the help of the drawer-type structure, the test modules 41 can be conveniently installed in the electrical cabinet 42 and also can be conveniently taken out of the electrical cabinet 42, so that the number of the test modules 41 can be adjusted or the test modules can be overhauled and maintained.

Specifically, the number of the test modules 41 is ten, and besides the test modules 41, a switching power supply and an integrated power supply interface for supplying power to the test system are further arranged in the electrical cabinet 42, and the electrical cabinet 42 is further provided with a USB serial port integrator, a sectional type USB serial port controller, a DB40 adapter, a DB40 adapter and the like.

As a specific implementation manner of the testing system that can be used in multiple paths in parallel, please refer to fig. 6 and fig. 7, the testing module 41 includes the substrate 411, the drawer-type structure includes the card rail 44 that is fixed on the electrical cabinet 42, the card rail 44 is provided with the clamping groove that slides the clamping with the edge of the substrate 411, one end of the clamping groove is closed, the other end is open and is provided for the substrate 411 to insert, the open end of the clamping groove is provided with the elastic clamping block 45, and the elastic clamping block 45 is used for preventing the testing module 41 from accidentally slipping out from the clamping groove.

The test module 41 is a conventional art, and the test module 41 includes an electronic component disposed on the substrate 411 in addition to the substrate 411. The size of the card slot is matched with the thickness of the substrate 411, and the substrate 411 cannot move randomly after being inserted into the card slot. Each test module 41 is correspondingly provided with two clamping rails 44, is positioned at two sides of the substrate 411 and is clamped with the edges at two sides of the substrate 411 in a sliding manner; one of the other two edges of the substrate 411 is limited by the closed end of the clamping groove, and the other edge of the substrate is limited by the elastic clamping block 45, so that the test module 41 can be stably installed in the electrical cabinet 42.

As a specific embodiment of the multi-channel parallel test system according to the present invention, please refer to fig. 7, the elastic fixture block 45 includes an elongated portion 451 and a head portion 452, one end of the elongated portion 451 is connected to the fixture rail 44, the other end of the elongated portion extends from the open end of the fixture groove along the length direction of the fixture groove, the head portion 452 is disposed at the extending end of the elongated portion 451, and the head portion 452 is used to bend to the outside and avoid the passing path of the substrate 411, or reset to the inside and limit the sliding of the substrate 411.

Fig. 7 shows a state in which the board 411 is inserted into the card slot and the card head portion 452 is reset. When the substrate 411 is inserted into the slot, the clamping head portion 452 can be bent and bent outward, so that the clamping head portion 452 avoids the passing path of the substrate 411 and can be smoothly inserted into the slot; after the head portion 452 is reset, the substrate 411 is located on a path of sliding out of the card slot, so that a limit position can be formed, and the test module 41 is prevented from sliding out of the card slot accidentally.

The above description is only exemplary of the present invention and should not be taken as limiting the scope of the present invention, as any modifications, equivalents, improvements and the like made within the spirit and principles of the present invention are intended to be included within the scope of the present invention.

Claims

1. A multi-way parallel test system, comprising:

a main body;

the control machine body is provided with a plurality of test modules, and the test modules are electrically connected with the circuit board to be tested through probes and correspond to the circuit board to be tested one by one; and

and the human-computer interface is electrically connected with the test module and displays the test result.

2. The multi-channel parallel test system according to claim 1, wherein the moving body and the fixed body are disposed opposite to each other, the fixed body is located below, the opening of the restriction slot faces upward, the main body is provided with a first positioning column for positioning the fixed body, and the fixed body is detachably connected to the main body through a first bolt.

3. The system of claim 2, wherein the execution unit is a cylinder mounted on the main body, the cylinder is located above the fixing body, and a manual button for controlling the pushing end of the cylinder to push out or retract is disposed on the main body.

4. The multi-channel parallel test system according to claim 3, wherein the moving body is connected to the pushing end of the cylinder through an intermediate block, a second positioning post for positioning the moving body is provided on the intermediate block, and the moving body is detachably connected to the intermediate block through a second bolt.

5. The multi-channel parallel test system according to claim 4, wherein said middle block is provided with a guide pillar parallel to the piston rod of said cylinder, and said main body is provided with a sleeve adapted to said guide pillar.

6. The multi-lane parallelizable test system of claim 1, further comprising a robotic arm with a horizontal rotational degree of freedom, the robotic arm having a distal end with a tool head for grasping a circuit board under test.

7. The system of claim 6, wherein the human-machine interface is a computer with a display screen.

8. The multi-path parallel test system of claim 1, wherein the control body comprises an electrical cabinet, a drawer structure is disposed in the electrical cabinet, and the test module is installed in the electrical cabinet in a drawable manner through the drawer structure.

9. The system according to claim 8, wherein the testing module comprises a substrate, the drawer-type structure comprises a clamping rail fixed to the electrical cabinet, the clamping rail is provided with a clamping groove slidably clamped to an edge of the substrate, one end of the clamping groove is closed, the other end of the clamping groove is open and the substrate can be inserted into the clamping groove, and an elastic clamping block is arranged at an open end of the clamping groove and used for preventing the testing module from accidentally sliding out of the clamping groove.

10. The system of claim 9, wherein the resilient latch comprises an elongated portion and a catching portion, the elongated portion is connected to the catch rail at one end and extends from the open end of the catch groove along the length direction of the catch groove at the other end, the catching portion is provided at the extending end of the elongated portion, and the catching portion is configured to bend outward and avoid a passing path of the substrate or to return inward and limit sliding of the substrate.