timestamps field in mysql not working

Why did I set a field type to timestamps, but it did not automatically fill in the current timestamp when updating or adding as I expected?

The same goes for the data table I generated using Laravel's migrate. The timestamps field in the generated table has no effect at all. what's going on?

This is the migration file

<code><?php

use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class CreateEquip extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('equip', function (Blueprint $table) {
            // $table->increments('id');
            $table->smallInteger('equip_id')->unsigned()->comment('装备id');
            $table->string('eqiup_name')->comment('装备名称');
            $table->string('eqiup_desc')->comment('装备描述');
            $table->timestamps();
            $table->primary('equip_id');
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        //
    }
}
</code>